As published in the February and March 2007 issues of Chemical Engineering Magazine

With regard to material of construction, the ongoing evolution of technology has raised expectations

throughout industry… William M. (Bill) Huitt

W. M. Huitt Co.

This is the first in a series of three articles that will

cover a wide range of piping topics. Topics that will cross

industry lines to include chemical, petroleum refining,

pharmaceutical, and other industries as well. It will be the

intent of these articles to address questions and

misunderstandings as they relate to industry on a general

basis.

“Pipe is pipe”. This is a euphemism (jargon if you will)

quite often used among piping designers and engineers.

Taken at face value, this is a true statement…pipe is

certainly pipe. However, taken in context, it means that no

matter which industry you work in when designing piping

systems it‟s all the same. And in that context it could not be

further from the truth.

The pharmaceutical industry, in its current state of

growth, is a relative new comer to design, engineering and

construction compared to the oil refining, bulk chemical,

pulp & paper and nuclear industries. As a frame of reference

the American Society of Mechanical Engineers (ASME) was

established in 1880; the American Petroleum Institute (API)

was established in 1919; 3-A Standards (for food & dairy)

were first developed in the 1920‟s; the ASME committee for

BPVC (Boiler Pressure Vessel Code) Section III for nuclear

power was proposed in 1963; Semiconductor Equipment and

Materials Institute (SEMI) was established in 1973; the

International Society of Pharmaceutical Engineers (ISPE)

was established in 1980; and ASME Biopharmaceutical

Equipment (BPE) issued its first Standard in 1997. Prior to

ASME-BPE much of the 3-A piping Standards were

plagiarized to facilitate design of pharmaceutical facilities.

While some of the above Standards Committees, and

their resulting Codes and Standards, are specific to a

particular industry others are more generalized in their use

and are utilized across the various industries.

As an example, Not only does the design and

construction of a large pharmaceutical facility require the

need for pharmaceutical based Standards, Codes, Guidelines

and Industry Practices such as those generated by ISPE and

ASME-BPE, it also requires those Standards created for

other industries as well. Meaning that, when designing and

constructing a bulk pharmaceutical finishing facility, or a

bulk Active Pharmaceutical Ingredient (API) facility the

engineers and constructors will also be working under some

of the same standards and guidelines as they would when

designing and building in other industries such as a

petroleum refinery or bulk chemical facility.

It is not that the pharmaceutical industry itself is young,

but the necessary engineering standards and practices are.

Within the past fifteen or so years, industry practice,

including dimensional standards for high purity fittings,

were left to the resources of the pharmaceutical Owner or

their engineering firm (engineer of record). The same applies

to construction methods and procedures, including materials

of construction. These requirements were basically

established for each project and were very dependent upon

Piping Design

Part 1: The Basics

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what the Owner‟s personnel and the engineering firm

brought to the table. Industry standards did not exist.

With regard to material of construction, the ongoing

evolution of technology has raised expectations throughout

industry, but even more so in the pharmaceutical,

biopharmaceutical and semiconductor industries.

For instance, out of the research and development that

went into the Hubble Space Telescope came new

methodology and technology to better measure and define

the all too tangible limits of surface roughness required in

material used in hygienic fluid service contact piping. This is

of particular interest to the pharmaceutical,

biopharmaceutical and semiconductor industries, where

cross-contamination at the molecular level cannot be

tolerated in many cases. This requires surfaces to be very

cleanable.

Surface roughness used to be expressed as polish

numbers (ie, #4 or #7) then grit numbers such as 150, 180 or

240). The problem with either of these two methods lay in

their subjectivity and their generality. These indicators were

not specific enough and the accept/reject result relied too

much on a subjective visual verification. There will be more

on surface finish requirements in Part II.

With acute awareness of the ongoing problems currently

faced in the pharmaceutical industry and, for altogether

different reasons, the semiconductor industry, various

Standards organizations have taken steps to alleviate the

consistent problems that have plagued the industry in the

past with high purity welding issues, standardization of

fittings, and guidelines for industry practice. We will discuss

some of the finer points of these issues and in some cases

what these Standards organizations, are doing to promote

and consolidate some of the better thinking in this industry

and in this field.

In these early paragraphs it seems as though I am

singling out the pharmaceutical industry as the focal point of

these discussions. As you will see this is not true. And in

saying pharmaceutical I do mean to include

biopharmaceutical (biopharm) as well.

In making an example of the pharmaceutical industry it

is simply an attempt on my part to utilize its relative

newness in the development of its own particular brand of

standards to give the reader a sense of standards

development and how these standards evolve.

This article and the two that follow will address metallic

piping topics including a discussion on hygienic piping.

While non-metallic piping is worthy of discussion it is too

broad a topic to try and capture here and will not be a part of

these articles. Some of the points that will be covered in this

and the following articles are topics such as:

1. ASME flange ratings, is it 150 and 300 pound

flange or is it Class 150 and Class 300 flange?

2. Does the 150, 300, etc. actually mean anything

or is it simply an identifier?

3. In forged fittings, is it 2000 pound and 3000

pound, or is it Class 2000 and Class 3000?

4. How do you determine which Class of forged

fitting to select for your specification?

5. Corrosion allowance in piping; how do you

determine and then assign corrosion

allowance?

6. How do you select the proper bolts and gaskets

for a service?

7. How is pipe wall thickness determined?

8. What is MAWP?

9. What is Operating and Design Pressure?

10. What is Operating and Design Temperature?

11. How do Design Pressure and Temperature

relate to a PSV set point and leak testing?

12. What Code should you be designing under?

13. What kind of problems can you expect with

sanitary clamp fittings?

14. How do you alleviate those problems with

sanitary clamp fittings?

15. What is ASME-BPE?

16. How does ASME B31.3 and ASME-BPE work

in concert with one another?

17. What is ASME BPE doing to bring

accreditation to the pharmaceutical Industry?

18. Design is the culmination and application of

industry standards and industry requirements

that take into account constructability along

with maintenance and operational needs. These

points will be covered as well.

We will first of all lay some groundwork by beginning

with the basics of general piping. By understanding the basic

elements of piping the designer and engineer can improve

their decision making in the material selection process and

system design effort. These articles will also make clear a

number of misconceptions with regard to terminology and

general practices.

What we will try to avoid is a lot of in-depth discussion

and elaborate analysis on specific points. What I would like

to achieve is a general discussion on many topics rather than

finite rhetoric on only a few.

With that said, this first article is entitled:

Piping Design Part I – The Basics

This article will not attempt to cover all of the various

types of piping components and joints that are available in

industry today. To keep the discussion focused we will

discuss only that segment of joints, fittings and components

most frequently used in general piping design.

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Neither will we duplicate the dialog of previous articles

that have provided excellent commentary on segments of

this same topic. Articles such as the one written by John C.

Cox and published by Chemical Engineering for their

January 2005 edition titled “Avoid Leakage in Pipe

Systems”. John provides a concise and descriptive narrative

on threaded and compression type connections. And the

article by Trinath Sahoo published by Chemical Engineering

for their June 2005 edition titled “Gaskets: The Weakest

Link”. In his article Trinath gives the reader some excellent

insight into the mechanics of gasket selection and design.

PIPE FLANGES

Pipe flanges are used to mechanically connect pipe

sections to other pipe sections, inline components, and

equipment. Flanges also allow pipe to be assembled and

disassembled without cutting or welding, eliminating the

need to issue a burn card for cutting and welding when

dismantling is required. In providing a breakable joint,

flanges unfortunately provide a potential leak path for the

service fluid contained in the pipe. Because of this, as in all

other joints, they need to be minimized where possible.

The most prevalent flange standards to be used in

industry are based on requirements of the American Society

of Mechanical Engineers (ASME) Standards. These include:

B16.1 – Cast Iron Pipe Flanges and Flanged Fittings,

B16.5 - Pipe Flanges and Flanged Fittings (NPS 1/2 through

NPS 24),

B16.24 – Cast Copper Alloy Pipe Flanges and Flanged

Fittings,

B16.36 – Orifice Flanges,

B16.42 – Ductile Iron Pipe Flanges and Flanged Fittings,

Large Diameter Steel Flanges (NPS 26 through NPS 60)

B16.47 – Large Diameter steel flanges (NPS 26 through

NPS 60) NPS, indicated above, is an acronym for Nominal Pipe Size.

Flanges are available with various contact facings (the

flange-to-flange contact surface) and methods of connecting

to the pipe itself. The flanges under B16.5 are available in a

variety of styles and pressure classifications. The different

styles, or types, are denoted by the way each connects to the

pipe itself and/or the type of face. The type of pipe-to-flange

connections consist of Threaded, Socket Welding (or Socket

Weld), Slip-On Welding (or Slip-On), Lapped (or Lap

Joint), Welding Neck (or Weld Neck), and Blind.

Threaded Flange

Figure 1

The Threaded flange, through Class 400, is connected to

threaded pipe in which the pipe thread conforms to ASME

B1.20.1. For threaded flanges in Class 600 and higher the

length through the hub of the flange exceeds the limitations

of ASME B1.20.1. ASME B16.5 requires that when using

threaded flanges in Class 600 or higher Schedule 80 or

heavier pipe wall thickness be used, and that the end of the

pipe be reasonably close to the mating surface of the flange.

Note that the term “reasonably close” is taken, in context,

from Annex A of ASME B16.5, it is not quantified.

In order to achieve this “reasonably close” requirement

the length of the thread has to be longer and the diameters of

the smaller threads become smaller than that indicated in

ASME B1.20.1. When installing Threaded flanges Class 600

and higher, ASME B16.5 recommends using power

equipment to obtain the proper engagement. Simply using

arm strength with a hand wrench is not recommended.

The primary benefit of threaded flanges is in eliminating

the need for welding. In this regard Threaded flanges are

sometimes used in high-pressure service in which the

operating temperature is ambient. They are not suitable

where high temperatures, cyclic conditions or bending

stresses can be potential problems.

Socketweld Flange

Figure 2

The Socketweld flange is made so that the pipe is

inserted into the socket of the flange until it hits the shoulder

of the socket. The Pipe is then backed away from the

shoulder approximately 1/16” before being welded to the

flange hub.

If the pipe were resting against the shoulder (This is the

flat shelf area depicted in Fig. 2 as the difference between

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diameters B and B2) of the socket joint during welding, heat

from the weld would expand the pipe longitudinally into the

shoulder of the socket forcing the pipe-to-flange weld area to

move. This could cause the weld to crack.

The Socketweld flange was initially developed for use

on small size, high-pressure piping in which both a back-

side hub weld and an internal shoulder weld was made. This

provided a static strength equal to the Slip-On flange with a

fatigue strength 1.5 times that of the Slip-On flange.

Because the two-welds were labor intensive it became

the practice to weld only at the hub of the flange. In doing

this it relegated the socketweld flange to be more frequently

used for small pipe sizes (NPS 2” and below) in non-high-

pressure, utility type service piping. The Socketweld flange

is not approved above Class 1500.

Slip-On Flange

Figure 3

Unlike the Socketweld flange, the Slip-On flange allows

the pipe to be inserted completely through its hub opening.

Two welds are made to secure the flange to the pipe. One

fillet (pronounced “fill-it”) weld is made at the hub of the

flange and a second weld is made at the inside diameter of

the flange near the flange face.

The end of the pipe is offset from the face of the flange

by a distance equal to the lesser of the pipe wall thickness or

1/4” plus approximately 1/16”. This is to allow for enough

room to make the internal fillet weld without damaging the

flange face.

The Slip-On flange is a preferred flange for many

applications because of its initial lower cost, the reduced

need for cut length accuracy and the reduction in end prep

time. However, the final installed cost is probably not much

less than that of a Weld Neck flange.

The strength of a Slip-On flange under internal pressure

is about 40% less than that of a Weld Neck flange. The

fatigue rate is about 66% less than that of a Weld Neck

flange. The Slip-On flange is not approved above Class

1500.

Lap Joint Flange

Figure 4

The Lap Joint flange requires a companion lap joint, or

Type A stub-end (ref. Fig. 5) to complete the joint. The

installer is then able to rotate the flange. This allows for

quick bolthole alignment of the mating flange during

installation without taking the extra precautions required

during prefabrication of a welded flange.

Their pressure holding ability is about the same as a

Slip-On flange. The fatigue life of a Lap Joint/stub-end

combination is about 10% that of a Weld Neck flange, with

an initial cost that is a little higher than that of a Weld Neck

flange.

The real cost benefit in using a Lap Joint flange

assembly is realized when installing a stainless steel or other

costly alloy piping system. In many cases the designer can

elect to use a stub-end specified with the same material as

the pipe, but use a less costly, e.g. carbon steel, Lap Joint

Flange. This prevents the need of having to weld a more

costly compatible alloy flange to the end of the pipe.

Just a quick word about stub-ends; they are actually

prefabricated or cast pipe flares that are welded directly to

the pipe. They are available in three different types: Type A,

(which is the lap-joint stub-end), Type B and Type C (ref.

Fig. 5).

Type A (Fig 5) is forged or cast with an outside radius

where the flare begins. This radius conforms to the radius on

the inside of the Lap-Joint flange. The mating side of the

flare has a serrated surface.

Type B (Fig. 5) is forged or cast without the radius

where the flare begins. It is used to accommodate the Slip-

On flange or Plate flange as a back-up flange.

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Type C (Fig 5) is fabricated from pipe using five

suggested methods indicated in ASME B31.3. The most

prevalent of these is the machine flare. This is done by

placing a section of pipe into a flaring machine, flaring the

end of the pipe and then cutting it to length.

As you can see in the assembly detail of Fig. 5, stub-end

types B & C have no radius at the flare while Type A does.

This allows it to conform to the Lap-Joint flange. Due to the

radius of the type A stub-end, a slip-on flange would have a

poor fit, creating non-uniform loading of the flare face as

well as an undesirable point load at the radius of the flare.

Weld Neck Flange

Figure 6

The reinforcement area of the Weld Neck flange

distinguishes it from other flanges. This reinforcement area

is formed by the added metal thickness, which tapers from

the hub of the flange to the weld end. The bore of the flange

needs to be specified in order to obtain the same wall

thickness at the weld end as the pipe it will be welded to.

This will give it the same ID bore as the pipe.

The Weld Neck flange is actually the most versatile

flange in the ASME stable of flanges. Much of its use is for

fitting-to-fitting fabrication in which the flange can be

welded directly to a fitting, such as an elbow, without the

need for a short piece of pipe, as would be required with a

Slip-On flange. It can be used in low-pressure, non-

hazardous fluid services as well as high-pressure, high-

cyclic and hazardous fluid services.

While the initial cost of the Weld Neck flange may be

higher than that of a Slip-On flange the installed cost

reduces that differential. And for conditions of possible high

thermal loading, either cryogenic or elevated temperatures,

the Weld Neck flange would be essential.

Blind Flange

Figure 7

While the Blind flange is used to cap off the end of a

pipeline or a future branch connection it is also used for

other purposes. It can be drilled and tapped for a threaded

reducing flange or machined out for a Slip-On reducing

flange. The reduced opening can be either on-center or

eccentric.

Flange Pressure Ratings

ASME B16.5 flange pressure ratings have been

categorized into material groupings. These groupings are

formulated based on both the material composition and the

process by which the flange is manufactured.

The available pressure Classifications under ASME

B16.5 are: 150, 300, 400, 600, 900, 1500 and 2500. The

correct terminology for this designation is Class 150, Class

300, etc. The term 150 pound, 300 pound, etc. is a carry over

from the old ASA (American Standards Association)

Classification. ASA is the precursor to the American

National Standards Institute (ANSI).

Taking a quick step back, ANSI was founded as a

committee whose responsibility was to coordinate the

development of standards and to act as a standards

traffic cop for the various organizations that develop

standards. Its basic function is not to develop standards,

but rather to provide accreditation of those standards

Originating as the American Engineering

Standards Committee (AESC) in 1918, ANSI had, over

its first ten years, outgrown its Committee status and in

1928 was reorganized and renamed as the American

Standards Association (ASA). In 1966 the ASA was

reorganized again under the name of the United States

of America Standards Institute (USASI). In 1969 ANSI

adopted its present name.

While the B16 and B31 Standards have previously

carried the ASA and ANSI prefix with its various

Standards titles ASME has always been the

administrative sponsor in the development of those

standards. In the 1970’s the prefix designation changed

to ANSI/ASME and finally to ASME.

Referring to ANSI B16.* or ANSI B31.* is no

longer correct. Instead it is correct to refer to a

standard as ANSI/ASME B16.* in that it indicates an

Figure 5

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ANSI accredited ASME standard. Or you can simply

refer to the standard as ASME B16.* or ASME B31.*.

Development of ASME B16.5 began in 1920. In 1927

the American Tentative Standard B16e was approved. This

eventually became what we know today as ASME B16.5.

Until the 1960‟s the pressure Classifications, as addressed

earlier, were referred to as 150 pound, 300 pound, etc. It

was at this point the pressure Classification was changed to

the Class designation. These designations have no direct

correlation with pounds of pressure. Rather, they are a factor

in the pressure rating calculation found in B16.5. In Part II

of this series, we will discuss how these designations are

factored into the design of the flange.

Flange Pressure Ratings

Flanges, whether manufactured to ASME (American

Society of Mechanical Engineers), API (American

Petroleum Institute), MSS (Manufacturers Standardization

Society), AWWA (American Water Works Association) or

any other Standard, are grouped into pressure ratings. In

ASME these pressure ratings are a sub-group of the various

material groups designated in B16.5.

Figure 8 represents one of the Tables from the Table 2

series in ASME B16.5. This is a series of Tables that lists

the Working Pressures of flanges based on material

groupings, temperature and Classification.

There are 34 Tables segregated into three material

Categories of Carbon and low alloy steels, austenitic

stainless steels, and nickel alloys. These are further

segregated into more defined material sub-groups. Figure 8

shows Table 2-1.1, which indicates, in reverse sequence,

sub-category 1 of material group 1 (carbon and low alloy

steels).

If you had an ASME B16.5, Class 150, ASTM A105

flange this is the table you would use to determine the

Working Pressure limit of the flange. To find the Working

Pressure of the above mentioned flange enter the column of

this table designated as 150 then move down the column to

the operating temperature. For intermediate temperatures,

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linear interpolation is permitted.

In the previous paragraph you will notice that I

indicated “operating temperature” when looking to

determine the Working Pressure of a flange. „Operating‟ and

„working‟ are synonymous. The indication of a working

pressure and temperature of a fluid service is the same as

indicating the operating pressure and temperature.

There exists some confusion in this area. That confusion

becomes apparent when the engineer is determining design

pressure and temperature and applying that to the flange

rating. On the surface there appears to be a conflict between

rating a flange for design conditions when Table 2 only

indicates working pressures.

Operating and design pressures and temperatures will be

explained in more detail in Article 2. For now I will explain

that every service should have an operating

pressure/temperature and a design pressure/temperature. A

design condition is the maximum coincidental pressure and

temperature condition that the system is expected or allowed

to see. This then becomes the condition to which you should

design for, and to which the leak test is based on, not the

operating condition.

Tables 2, as it indicates, represents the working or

operating pressures of the flange at an indicated temperature

for a specific Class. The maximum hydrostatic leak test

pressure for a Class 150 flange in Table 2-1.1 is 1.5 times

the rated working pressure at 100°F, or 285 x 1.5 = 427.5

rounded off to the next higher 25 psi, or 450 psig.

We can extrapolate that piece of information to say that

since hydrostatic leak test pressure is based on 1.5 x design

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pressure the working pressure limit given in the Table 2

matrix ostensibly becomes the design pressure limit.

When working with ASME B31.3 Category D fluid

services, and initial service leak testing is performed, the

working pressure limit then remains the working pressure

limit because testing is performed at operating or working

pressures. In saying that however, there are caveats that

address the fact that not all Category D fluid services should

waive the hydrostatic leak test for an initial service leak test.

These conditions, such as steam service, will also be

discussed in a subsequent article.

Category D fluid services are those fluid services that

are nonflammable, nontoxic and not damaging to human

tissue. Category D fluids additionally do not exceed 150 psig

and 366º F.

In initial service leak testing the test fluid is the service

fluid. Leak testing occurs during or prior to initial operation

of the system. As the service fluid is introduced to the piping

system and brought to operating pressure, in pressure

increments, all joints are observed for possible leaks. If no

leaks are detected the pipeline simply remains in service.

Other ASME B31.3 fluid services may be expected to

operate at one set of conditions, but are designed for another

set. For those systems, which might include periodic steam-

out (cleaning, sterilization, sanitization) or passivation, you

therefore want to base your flange rating selection on those

more extreme, periodic design conditions. To clarify

periodic in this context, the sanitization process can be done

as frequently as once per week and last for one to one and

half shifts in duration.

Flange Facing & Surface Finishes

Standard flange facing designations (ref. Fig. 9) are as

follows: Flat Face, Raised Face, Ring Joint, Tongue and

Groove, Large and Small Male and Female, Small Male and

Female (on end of pipe), Large and Small Tongue and

Groove. The height of the raised face for Class 150 and 300

flanges is 0.06”. The height of the raised face for Class 400

and above is 0.25”.

Across industry, not discounting the lap-joint flange and

stub-end combination, the two most widely used flange

facings are the flat face and the raised face.

The surface finish of standard raised face and flat face

flanges has a serrated concentric or serrated spiral surface

finish with an average roughness of 125 μin to 250 μin. The

cutting tool used for the serrations will have a 0.06 in. or

larger radius and there should be from 45 to 55 grooves per

inch.

BOLTS, NUTS & GASKETS

Sealing the flange joint, and as you will see further in

this article, the hygienic clamp joint, is paramount in

providing integrity to the overall piping system. This is

achieved with the use of bolts, nuts and gaskets. Making the

right selection for the application can mean the difference

between a joint with integrity and one without.

ASME B16.5 provides a list of appropriate bolting

material for ASME flanges. The bolting material is grouped

into three strength categories; high, intermediate and low,

which are based on the minimum yield strength of the

specified bolt material.

The High Strength category includes bolt material with

a minimum yield strength of not less than 105 ksi. The

Intermediate Strength category includes bolt material with a

minimum yield strength of between 30 ksi and 105 ksi. The

Low Strength category includes bolt material with a

minimum yield strength no greater than 30 ksi.

As defined in ASME B16.5, the High Strength bolting

materials "…may be used with all listed materials and all

gaskets". The Intermediate Strength bolting materials

"…may be used with all listed materials and all gaskets,

provided it has been verified that a sealed joint can be

maintained under rated working pressure and temperature”.

The Low Strength bolting materials "…may be used with all

listed materials but are limited to Class 150 and Class 300

joints", and can only be used with selected gaskets as

defined in ASME B16.5.

ASME B31.3 further clarifies in para. 309.2.1, "Bolting

having not more than 30 ksi specified minimum yield

strength shall not be used for flanged joints rated ASME

B16.5 Class 400 and higher, nor for flanged joints using

metallic gaskets, unless calculations have been made

showing adequate strength to maintain joint tightness".

B31.3 additionally states in para. 309.2.3, “…If either flange

is to the ASME B16.1 (cast iron), ASME B16.24 (cast

copper alloy), MSS SP-42 (valves with flanged and buttweld

ends), or MSS SP-51 (cast flanges and fittings)

specifications, the bolting material shall be no stronger than

low yield strength bolting unless: (a) both flanges have flat

faces and a full face gasket is used: or, (b) sequence and

torque limits for bolt-up are specified, with consideration of

sustained loads, displacement strains, and occasional loads

(see paras. 302.3.5 and 302.3.6), and strength of the flanges.

In specifying flange bolts, as well as the gasket, it is

necessary, not only to consider design pressure and

temperature, but fluid service compatibility, the critical

nature of the fluid service and environmental conditions all

in conjunction with one another.

To better understand the relationship of these criteria I

will list and provide some clarification for each:

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1. The coincident of design pressure and temperature

is what determines the pressure Class of a flange

set. That, in turn, along with flange size, will

determine the number and size of the flange bolts.

The flange Class will also determine the

compressibility range of the gasket material.

2. Fluid service compatibility will help determine the

gasket material.

3. The critical nature of the fluid will determine the

degree of integrity required in the joint. This will

help determine bolt strength and material as well as

gasket type.

4. Environmental conditions will also help determine

bolt material (Corrosive atmosphere, wash-down

chemicals, etc.).

What this ultimately means is that all of the variables

that come together in making up a flange joint have to do so

in a complementary fashion. Simply selecting a gasket based

on material selection and not taking into account the

pressure rating requirement could provide a gasket that

would get crushed under necessary torque requirements

rather than withstand the bolt load and create a seal.

Selecting a low strength bolt to be used with a Class 600

flange joint with proper gasketing will require the bolts to be

torqued beyond their yield point, or at the very least beyond

their elastic range. To explain this briefly; bolts act as

springs when they are installed and loaded properly. In order

for the flange joint to maintain a gasket seal it requires

dynamic loading. Dynamic loading of flange bolts allows

expansion and contraction movement in and around the joint

while maintaining a seal. This is achieved by applying

sufficient stress to the bolt to take it into the material‟s

elastic range.

If the bolts are not stressed sufficiently into their elastic

range any relaxation in the gasket could reduce the sealing

ability of the joint. To the other extreme, if the bolts were

stressed beyond their elastic range and into the plastic range

of their material of construction the same issue applies, they

will lose their dynamic load on the gasket. In this case, if

they do not shear they will take a set. Any relaxation in the

gasket will then result in the reduction or elimination of the

joints sealing ability.

With regard to the nut, it should be selected to

compliment the bolt. Actually the bolt material specification

will steer you, either partially or completely, into the proper

nut selection.

ASTM A307, a material standard for bolts in the low-

strength category, states that the proper grade for bolts to be

used for pipe flange applications is Grade B. A307 goes

further to state that when used for pipe flanges Grade B bolts

require a Heavy Hex Grade A nut under ASTM A563. In

writing a pipe spec that includes the A307 bolt you would

not need to specify the nut since it is already defined in

A307.

However, ASTM A193, alloy and stainless steel bolts,

goes only so far when it states that nuts shall conform to

ASTM A194, but there are several grades of A194 nuts to

select from. This is an example of where the matching nut is

not always explicitly called out in the ASTM Standard.

Because the ASTM Standards are inconsistent in that regard

the spec-writer must make sure it is covered in a

specification.

You can see from this bit of information that all four

components, flanges, bolts, nuts and gaskets have to be

selected in conjunction with one another in order for the

joint assembly to perform in a way that it is expected to for a

given application.

Pipe, Tube & Fittings

One of the big differences between pharmaceutical and

semi-conductor piping and other industrial piping, is the

requirements of high purity, or hygienic fluid services.

These requirements, as dictated by current Good

Manufacturing Practices (cGMP) and defined and quantified

by the ISPE and ASME-BPE, are stringent with regard to the

manufacture, documentation, fabrication, installation,

qualification, validation and quality control of hygienic

piping systems and components.

The man-hours required in generating, maintaining and

controlling the added documentation required for hygienic

fabrication and installation is in the range of 30% to 40% of

the overall cost of fabrication and installation. Part II in this

series will get more into the requirements of hygienic

fabrication and where that added cost comes from.

For now we will stay with general pipe and fittings. In

an attempt at keeping this article concise we will only cover

those fittings that are predominantly used throughout

industry, both in process and in utility services.

Pipe fittings are manufactured by the following

processes: cast, forged and wrought.

Cast Fittings

Cast fittings are provided in cast iron, malleable iron,

steel, stainless steel, brass, bronze, and other alloy material

as follows:

Cast Iron: Cast iron threaded fittings, under ASME

B16.4, are available in Class 125 and Class 250 for sizes

NPS 1/4” through 12”. Cast iron flanged fittings, under

ASME B16.1, are available in Class 25, 125 and 250 in sizes

NPS 1” through 48”.

Malleable Iron: Malleable iron fittings, under ASME

B16.3, are available in Class 150 and Class 300 in sizes NPS

10

1/8” though 6” for Class 150 and 1/4” through 3” for Class

300.

It needs to be noted here that Classifications such

as 150 and 300 are not universal throughout the ASME

Standards. They are specific to the Standard that they

are associated with. You cannot automatically transfer

the pressure/temperature limits of a flange joint in

ASME B16.5 to that of a fitting in B16.3.

Cast Steel: Cast steel, stainless steel and alloy steel

flanged fittings, under ASME B16.5, are available in Class

150, 300, 400, 600, 900, 1500 & 2500 in sizes 1/2” though

24”.

Cast Brass: Cast Brass and bronze threaded fittings,

under ASME B16.15, are available in Class 125 and 250, in

sizes NPS 1/8” through 4” for Class 125 and 1/4” through 4”

for Class 250.

Cast Copper: Cast copper solder joints, under ASME

B16.18, are available in sizes 1/4” through 6”.

Forged Fittings

Before getting into forged fittings I would like to

explain the difference between forged and wrought fittings.

There seems to be some vague misconception of what the

term forged means and what the term wrought means and

how it applies to pipe fittings.

The term forging actually comes from the times when

metal was worked by hand. A bar of steel would be placed

into a forge and heated until it reached its plastic state, at

which time the metal would be pulled out of the forge and

hammered into some desired shape. Today forging metal

basically means working the metal by means of hydraulic

hammers to achieve the desired shape.

As a small bit of trivia, up until the late 1960‟s, when

mills stopped producing it, wrought iron was the choice of

ornamental iron workers. It is still produced in Europe, but

most of what we see manufactured as wrought iron in the

U.S. is actually various forms of steel made to look like

wrought iron.

True wrought iron is corrosion resistant, has excellent

tensile strength, welds easily and in its plastic range is said

to be like working taffy candy. What gives wrought iron

these attributes is the iron silicate fibers, or “slag” added to

the molten iron with a small percentage of carbon, whereas

cast iron, with a high carbon content, is more brittle and not

as easily worked.

The smelters, where the iron ore was melted to produce

wrought iron, were called bloomeries. In a bloomery the

process does not completely melt the iron ore, rather the

semi-finished product was a spongy molten mass called a

bloom, derived from the red glow of the molten metal,

which is where the process gets its name. The slag and

impurities were then mechanically removed from the molten

mass by twisting and hammering which is where the term

wrought originates.

Today forged and wrought are almost synonymous. If

we look in ASTM A234 - Standard Specification for Piping

Fittings of Wrought Carbon Steel and Alloy Steel for

Moderate and High Temperature Service we can see in Para

4.1 and in Para 5.1 that wrought fittings made under A234

are actually manufactured or fabricated from material pre-

formed by one of the methods listed previously, which

includes forging. In ASTM A961 - Standard Specification

for Common Requirements for Steel Flanges, Forged

Fittings, Valves and Parts for Piping Applications the

definition for the term Forged is, “the product of a

substantially compressive hot or cold plastic working

operation that consolidates the material and produces the

required shape. The plastic working must be performed by a

forging machine, such as a hammer, press, or ring rolling

machine, and must deform the material to produce a

wrought structure throughout the material cross section.”

The difference therefore between forged and wrought

fittings is that forged fittings, simply put, are manufactured

from bar, which while in its plastic state is formed into a

fitting with the use of a hammer, press or rolling machine.

Wrought fittings, on the other hand, are manufactured from

killed steel, forgings, bars, plates and seamless or fusion

welded tubular products that are shaped by hammering,

pressing, piercing, extruding, upsetting, rolling, bending,

fusion welding, machining, or by a combination of two or

more of these operations. In simpler terms wrought signifies

“worked”. There are exceptions in the manufacture of both,

but that is the general difference.

Something worth noting at this point concerns the

ASTM specifications. In quoting from ASTM A961 I was

quoting from what ASTM refers to as a General

Requirement Specification, which is what A961 is. A

General Requirement Specification is a specification

that covers requirements that are typical for multiple

individual Product Specifications. In this case the

individual Product Specifications covered by A961 are

A105, A181, A182, A360, A694, A707, A727 and A836.

The reason I point this out is that many designers

and engineers are not aware that when reviewing an

A105 or any of the other ASTM individual Product

Specifications you may need to include the associated

General Requirement Specification in that review.

Reference to a General Requirement Specification can

be found in the respective Product Specification.

Forged steel and alloy steel socketweld and threaded

fittings, under ASME B16.11, are available in sizes NPS

1/8” through 4”. Forged socketweld fittings are available in

pressure rating Classes 3000, 6000 and 9000. Forged

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threaded fittings are available in pressure rating Classes

2000, 3000 and 6000.

What I see quite often, and this includes all of the

industries I have been associated with, is a misapplication of

pressure rating in these fittings. This leads me to believe that

the person specifying components does not fully understand

the relationship between the pressure Class of these fittings

and the pipe they are to be used with.

In ASME B16.11 is a table that associates, as a

recommendation, fitting pressure Class with pipe wall

thickness, as follows:

Table 1 – Correlation of Pipe Wall Thickness & Pressure Rating

Pipe Wall Thk. Threaded Socketweld

80 or XS 2000 3000

160 3000 6000

XXS 6000 9000

The ASME recommendation is based on matching the

I.D. of the barrel of the fitting with the I.D. of the pipe. The

shoulder of the fitting (the area of the fitting that the end of

the pipe butts against), either socketweld, as shown in Fig.

10, or threaded, is approximately, allowing for fabrication

tolerances, the same width as the specified mating pipe wall

thickness.

Figure 10 – Socket Weld Fitting Joint from ASME B16.11

As an example, referring to Table 1, if you had a

specified pipe wall thickness of Sch. 160 the matching

threaded forged fitting would be a Class 3000, for

socketweld it would be a Class 6000. The fitting pressure

Class is selected based on the pipe wall thickness. Referring

to Fig. 10, you can readily see that by not matching the

fitting Class to the pipe wall thickness it will create either a

recessed area or a protruding area the length of the barrel of

the fitting, depending on which side you error on. For forged

reinforced branch fittings refer to MSS Standard SP-97 –

Integrally Reinforced Forged Branch Outlet Fittings -

Socket Welding, Threaded and Buttwelding Ends.

Wrought Fittings

Wrought Steel Butt Weld Fittings under ASME B16.9

(standard radius 1.5D elbows and other fittings) are available

in sizes 1/2” through 48”. Wrought Steel Butt Weld Fittings

under B16.28 (short radius 1D elbows), are available in sizes

1/2” through 24”. There is no pressure/temperature rating

classification for these fittings. In lieu of fitting pressure

classifications both B16.9 and B16.28 require that the fitting

material be the same as or comparable to the pipe material

specification and wall thickness. Under ASME B16.9, given

the same material composition, the fittings will have the

same allowable pressure/temperature as the pipe. ASME

requires that the fittings under B16.28, short radius elbows,

be rated at 80% of that calculated for straight seamless pipe

of the same material and wall thickness.

These fittings can be manufactured from seamless or

welded pipe or tubing, plate or forgings. Laterals, because of

the elongated opening cut from the run pipe section are rated

at 40% of that calculated for straight seamless pipe of the

same material and wall thickness. If a full strength lateral is

required either the wall thickness of the lateral itself can be

increased or a reinforcement pad can be added at the branch

to compensate for the loss of material at the branch opening.

Wrought copper solder joint fittings, under ASTM B88

and ASME B16.22, are available in sizes 1/4” through 6”.

These fittings can be used for brazing as well as soldering.

The pressure/temperature rating for copper fittings are

based on the type of solder or brazing material and the

tubing size. It will vary too, depending on whether the fitting

is a standard fitting or a DWV (Drain, Waste, Vent) fitting,

which has a reduced pressure rating.

As an example, using alloy Sn50, 50-50 Tin-Lead

Solder, at 100ºF, fittings 1/2” through 1” have a pressure

rating of 200 psig and fittings 1½” through 2” have a

pressure rating of 175 psig. DWV fittings 1½” through 2”

have a pressure rating of 95 psig.

Using alloy HB, which is a Tin-Antimony-Silver-

Copper-Nickel (Sn-Sb-Ag-Cu-Ni) solder, having 0.10%

maximum Lead (Pb) content, at 100ºF, fittings 1/2” through

1” have a pressure rating of 1035 psig and fittings 1½”

through 2” have a pressure rating of 805 psig. DWV fittings

1½” through 2” would have a pressure rating of 370 psig.

As you can see, within the same type of fitting, there is

a significant difference in the pressure ratings of soldered

joints depending on the type of filler metal composition.

Much of the difference is in the temperature at which the

solder or brazing filler metal fully melts. This is referred to

as its liquidus state. The temperature at which it starts to

melt is referred to as its solidus temperature, the higher the

liquidus temperature the higher the pressure rating of the

joint.

Pipe and Tubing

The catch-all terminology for pipe and tubing is tubular

products. This includes pipe, tube and their respective

12

fittings. Piping itself refers to a system of pipe, fittings,

flanges, valves, bolts, gaskets and other in-line components

that make up an entire system used to convey a fluid. The

simple distinction between pipe and tubing is that tubing is

thin-walled pipe with a different size for size diameter.

Tubular products can basically be grouped into three

broad classifications: pipe, pressure tube and mechanical

tube.

Based on user requirements the above classifications

come in various types such as Standard Pipe, Pressure Pipe,

Line Pipe, Water Well Pipe, Oil Country Tubular Goods,

Conduit, Piles, Nipple Pipe and Sprinkler Pipe. The two

types that we are mainly interested in are Standard and

Pressure Pipe. Distinguishable only from the standpoint of

use, Standard Pipe is intended for low pressure, non-volatile

use, whereas Pressure Pipe is intended for use in higher

integrity services. These are services in which the pipe is

required to convey high pressure volatile or non-volatile

liquids and gases at sub-zero or elevated temperatures.

The following represents a combined description of

Standard and Pressure Pipe.

Pipe: Pipe is manufactured to a NPS in which the OD

of a given nominal size remains constant while any change

in wall thickness is reflected in the pipe ID. Pipe wall

thicknesses are specified by Schedule (Sch.) numbers 5, 10,

20, 30, 40, 60, 80, 100, 120, 140 and 160. Add the suffix „s‟

when specifying stainless steel or other alloys. Wall

thickness is also specified by the symbols Std. (Standard),

XS (Extra Strong) and XX (Double Extra Strong).

Pipe NPS 12” and smaller has an OD that is nominally

larger than that specified. Pipe with a NPS 14” and larger

has an OD equal to the size specified.

Tubing: Steel and alloy tubing is manufactured to an

OD equal to that specified. Meaning that 1/4” tubing will

have a 1/4” OD, 2” tubing will have a 2” OD. Copper

tubing, accept for ACR (Air-Conditioning & Refrigeration)

tubing, which has an OD equal to that specified, has an OD

that is always 1/8” larger than the diameter specified. As an

example, 1/2” tubing will have a 5/8” OD, 1” tubing will

have a 1 1/8” OD.

Wall thickness for tubing is specified in the actual

decimal equivalent of its thickness.

Pipe is manufactured in three basic forms: cast, welded

and seamless. Tubing is manufactured in two basic forms:

welded and seamless.

Cast Pipe: Cast pipe is available in four basic types:

white iron, malleable iron, gray iron and ductile iron. White

iron has a high carbon content in the carbide form. The lack

of graphite gives it its light colored appearance. Carbides

give it a high compressive strength and a hardness that

provides added resistance to wear, but leave it very brittle.

Malleable iron is white cast iron that has been heat

treated for added ductility. By reheating white cast iron in

the presence of oxygen containing materials such as iron

oxide, and allowing it to cool very slowly, the free carbon

forms small graphite particles. This gives malleable iron

excellent machinability and ductile properties along with

good shock resistant properties.

Gray iron is the oldest form of cast iron pipe and is

synonymous with the name cast iron. It contains carbon in

the form of flake graphite, which gives it its gray identifying

color. Gray cast iron has virtually no elastic or plastic

properties, but has excellent machining and self-lubricating

properties due to the graphite content

Ductile iron is arguably the most versatile of the cast

irons. It has excellent ductile and machinable properties

while also having high strength characteristics.

Welded Steel Pipe and Tubing: Referring to pipe in

the following also includes tubing.

Welded steel pipe is manufactured by Furnace Welding

or by Fusion Welding. Furnace Welding is achieved by

heating strip steel, also referred as skelp, to welding

temperature then forming it into pipe. The continuous weld,

or buttweld, is forged at the time the strip is formed into

pipe. This is a process generally used to manufacture low

cost pipe 3 ½” and below.

Fusion Welded pipe is formed from skelp that is cold

rolled into pipe and the edges welded together by resistance

welding, induction welding or arc welding. Electric

resistance welding (ERW) can be accomplished by flash

welding, high-frequency or low-frequency resistance

welding. A scarfing tool is used to remove upset material

along the seam of flash-welded pipe.

Flash welding produces a high strength steel pipe in

NPS 4” through 36”. Low-frequency resistance welding can

be used to manufacture pipe through NPS 22”. High-

frequency resistance welding can be used to manufacture

pipe through NPS 42”.

High-frequency induction welding can be used for high

rate production of small NPS pipe. This is a cleaner form of

welding in which scarfing, or the cleaning of upset material

along the seam, is normally not required.

Arc welding the longitudinal seam of production pipe is

accomplished with submerged arc welding (SAW), inert gas

tungsten arc welding (GTAW) also called tungsten inert gas

welding (TIG), or gas shielded consumable metal arc

welding (MIG).

13

As you will see in Part II, the type of weld seam used in

the manufacture of pipe is a factor when calculating the

Pressure Design Thickness (t) of the pipe wall. It reduces the

overall integrity of the pipe wall by a percentage given in

ASME B31.3 based on the type of longitudinal seam weld.

Seamless Steel Pipe and Tubing: Referring to pipe in

the following also includes tubing.

Seamless steel pipe, using various extrusion and

mandrel mill methods, is manufactured by first creating a

tube hollow from a steel billet, which is a solid steel round.

The billet is heated to its hot metal forming temperature then

pierced by a rotary piercer or by a press piercer creating the

tube hollow, which will have a larger diameter and thicker

wall than its final pipe form. The tube hollow is then hot-

worked by the Mandrel Mill Process, Mannesmann Plug-

Mill Process, or Ugine Sejournet Extrusion Process.

Upon completion of these processes the pipe is referred

to as hot-finished. If further work is required to achieve

more accuracy in the diameter, wall thickness or improve its

finish the pipe can be cold-finished, or cold-worked. When

the pipe is cold-finished it will require heat treating to

remove stress in the pipe wall created when worked in its

cold state.

There are also two forging processes used in the

manufacture of large diameter (10 to 30 inch) pipe with

heavy wall thickness (1.5 to 4 inch). The two forging

methods are called Forged and Bored, and Hollow Forged.

Other Material and Systems

We have touched on just some of the key points of steel

pipe and fittings. What I have not touched on are plastic

lined pipe systems and non-metallic piping including

proprietary piping systems. The area of non-metallic piping

is certainly worth including in the context of piping.

However, we will keep these articles focused on metallic

piping material. Non-metallic piping merits a discussion on

its own, and should not be relegated to a paragraph or two

here.

However, since plastic lined pipe is steel pipe with a

liner and is so widely used in the various industries I will

touch on some of its key points.

Lined Pipe Systems: Lined flex hoses were first

developed in 1936 by Resistoflex followed by lined pipe,

which did not come to the industry until 1956 by way of the

same company. When first introduced, plastic line pipe filled

a large fluid handling gap in industry, but brought with it

some technical issues.

As other manufacturers such as Dow and Peabody

Dore‟ began producing lined pipe and fittings industry

standards for lined pipe did not exist. Consequently, there

were no standard fitting dimensions and the availability of

size and type of fittings would vary from one company to

another, and still, to a much lesser degree, does to this day.

Due to the autonomous nature of lined pipe

manufacturing during its initial stages the pipe designer

would have to know early in the design process which

manufacturer they were going to use. Particularly in fitting

make-up situations, you needed to know in advance what

those make-up dimensions were going to be, and thus the

fitting manufacturer.

While not having industry standard dimensions was a

design problem other operational type problems existed as

well. Some of the fluid services these line pipe systems were

specified for, and still are, would normally be expected to

operate under a positive pressure, but at times would phase

into a negative pressure. The liners in these early systems

were not necessarily vacuum rated and at times would

collapse under the negative internal pressure, plugging the

pipeline.

There was an added problem when gaskets were thrown

into the mix. Gaskets were not normally required unless

frequent dismantling was planned, and many firms, both

engineers and manufacturers, felt more secure in specifying

gaskets at every joint. When required, the gasket of choice,

in many cases, was an envelope type gasket made of PTFE

(polytetrafluoroethylene) with an inner core of various filler

material,Viton (a DuPont trade name) or EPDM.

These gaskets had a tendency to creep under required

bolt torque pressure at ambient conditions. From the time a

system was installed to the time it was ready to hydrotest the

gaskets would, on many occasion, creep, or relax to the point

of reducing the compressive bolt load of the joint enough to

where it would not stand up to the hydrotest pressure. Quite

often leaks would become apparent during the fill cycle prior

to testing.

There also exists the problem of permeation with regard

to PTFE liner material and of Internal and External

Triboelectric Charge Generation and Accumulation (static

electricity). But, due to the diligent efforts of the line pipe

and gasket industries these types of problems have either

been eliminated or controlled, and some are still being

pursued.

Fitting dimensions have been standardized through

ASTM F1545 in referencing ASME B16.1 (cast iron

fittings), B16.5 (steel fittings) and B16.42 (ductile iron

fittings). You will need to read Note 3 under Sub-Para. 4.2.4,

which states, “Center-to-face dimensions include the plastic

lining.” Meaning, the dimensions given in the referenced

ASME standards are to the bare metal face of the fittings.

However, when lined fittings are manufactured the metal

casting is modified to accommodate the liner thickness being

included in that same specified center-to-face dimension.

14

With regard to vacuum rating, liner specifications are

greatly improved, but you will need to check the vacuum

ratings of available pipe and fittings with each tentative

manufacturer. This provision will vary from manufacturer to

manufacturer depending on size, fitting, liner type, pressure

and temperature.

Gasket materials such as Garlock‟s Gylon gasket, which

is a PTFE/Silicate composite, and W. L. Gore‟s Universal

Pipe Gasket, which is a 100% expanded PTFE, have been

developed to reduce the creep rate in a gasket material that is

compatible with virtually the same fluid services that lined

pipe systems are usually selected for.

Permeation issues with PTFE liners (it also exists, to a

lesser extent, with other liner material) have been

accommodated more than resolved with the use of vents in

the steel pipe casing, the application of vent components at

the flange joint, and increased liner thickness.

Internal and external charge accumulation, known as

static electricity, or triboelectric charge accumulation, is the

result of an electrical charge generation unable to dissipate.

If the electrical charge generation is allowed to continually

dissipate to ground then there is no charge build-up and no

problem. This is what occurs with steel pipe in contact with

a flowing fluid. Charge generation has a path to ground and

does not have an opportunity to build up.

With regard to thermoplastic lined pipe there are two

issues to be considered: external charge accumulation and

internal charge accumulation.

This is an issue that requires experience and expertise in

order to analyze a particular situation. What we will do in

Part II of this series is provide you with basic information

that will at least allow you to be familiar with the subject,

and help you to understand the issues.

Standard sizes of plastic lined pipe and fittings range

from NPS 1” through 12”. Edlon, a lined pipe manufacturer,

also manufactures larger diameter pipe and fittings from

NPS 14” through 24”, and when requested can manufacture

spools to 144” diameter.

Hygienic Piping

Hygienic is a term defined in ASME-BPE as: “of or

pertaining to equipment and piping systems that by design,

materials of construction, and operation provide for the

maintenance of cleanliness so that products produced by

these systems will not adversely affect animal or human

health.”

While system components such as tube, fittings, valves

and the design itself, with regard to hygienic conditions, can

translate to the Semi-Conductor industry the term hygienic

does not. It pertains strictly to the health aspects of a clean

and cleanable system for the pharmaceutical industry. The

semi-conductor industry requires a high, or in some cases

higher, degree of cleanliness and cleanability than hygienic

systems in the pharmaceutical industry, for altogether

different reasons.

A term that can more appropriately be interchanged

between these two industries is high-purity. This implies a

high degree of cleanliness and cleanability without being

implicitly connected with one industry or the other.

For what is referred to as product contact material, the

surface roughness, dead-leg minimums and an easily

cleanable system are all imperative. Because of this the

pharmaceutical industry had to make a departure from the 3-

A standards it plagiarized early on in order to develop a set

of guidelines and standards that better suit its industry. Enter

ASME-BPE.

ASME-BPE has taken on the task of providing a forum

for engineers, pharmaceutical manufacturers, component and

equipment manufacturers, and inspectors in an effort to

develop consensus standards for the industry where none

existed before. I won‟t go further with this except to say that,

to the handful of engineers undaunted by the task ahead of

them, in approaching ASME about the need to create

another standards committee, and the perseverance to see it

through; my hat goes off to you.

Hygienic piping was, up until just recently, referred to

as sanitary piping. Because this term has been so closely

associated with the plumbing industry and sanitary drain

piping it is felt by the pharmaceutical industry that the

change in terminology to hygienic is more appropriate.

In both the pharmaceutical and semiconductor industries

the need for crevice free, drainable systems is a necessity.

This translates into weld joint quality, mechanical joint

design requirements, interior pipe surface roughness limits,

system drainability and dead-leg limitations.

Slope, welding, dead-legs and surface roughness will be

discussed in Part II. This article will concentrate on the basic

aspects of the fittings.

Fittings

There are two basic types of fitting joints in hygienic

piping: welded and clamp. Welded fittings, unlike standard

buttweld pipe fittings, have an added tangent length to

accommodate the orbital welding machine. The orbital

welding machine allows the welding operator to make

consistent high quality autogenous welds. Autogenous welds

are welds made without filler metal. Fusion is made between

the parent metals of the two components being welded by

means of tungsten inert gas welding; more on welding in

Part II.

15

Figure 11 - Fittings Ready To Be Orbital Welded

Compliments of ARC Machines, Inc.

Figure 11 is an example of an orbital, or automatic,

welding machine mounted on its work-piece. In this example

it happens to be a 90° elbow being welded to a cross. You

can see by this example why the additional straight tangent

section of automatic weld fittings is needed. That extra

length provides a mounting surface for attaching the

automatic welding machine.

The clamp connection is a mechanical connection

whose design originated in the food and dairy industry, but

whose standardization has been under development by

ASME-BPE. Due to a lack of definitive standardization most

companies that use this type connection require in their

specifications that both the ferrule, the component that the

clamp fits on, and the clamp itself come from the same

manufacturer. This is to ensure a competent fit.

There are no specific dimensions and tolerances for the

clamp assembly, except for that which is being developed by

ASME-BPE. Currently it is possible to take a set of ferrules

from one manufacturer, mate them together with a gasket,

attach a clamp from a different manufacturer and tighten up

on the clamp nut. In some cases you can literally rotate the

clamp by hand about the ferrules. Meaning, there is no force

being applied on the joint seal.

For those of you unfamiliar with the clamp joint, it is

the clamp that applies the force that holds the ferrules

together. The fact that this can occur begs the need for

standardization to a greater degree than what currently

exists.

We‟ll get into this in greater detail in Part II, but another

issue that currently exists with the clamp joint is gasket

intrusion into the pipe ID due to inadequate compression

control of the gasket.

Gasket intrusion is a problem in pharmaceutical service

for two reasons: 1. Depending on the hygienic fluid service

and the gasket material the gasket protruding into the fluid

stream can break down and slough off into the fluid flow,

contaminating the hygienic fluid. 2. The intrusion of the

gasket into pipe ID on a horizontal line can also cause fluid

hold-up. This can result in the loss of residual product, cause

potential cross-contamination of product, and promote

microbial growth.

The reason I mention this here, and I won‟t go into it

any further until Part II, is because there are manufacturers

that are attempting to overcome these issues by improving

on the concept of the clamp joint.

Two manufactures, Swagelok and The Neumo

Ehrenberg Group, represented in the US by VNE, have,

what I would consider, well developed re-designs of the

standard hygienic clamp assembly.

Figure 12 – Swagelok TS Series Profile

Compliments Swagelok Company

Swagelok has developed what they call their TS series

fittings. These ferrules (Fig. 12) have a design that provides

compression control of the gasket while also controlling the

creep tendency inherent in, arguably, the most prevalent

gasket material used in high purity piping, Teflon.

Figure 13 – Maxpure Connect S

Compliments Neumo Ehrenberg Group

The Neumo Ehrenberg Group manufactures a clamp

joint (also provided as a bolted connection) that does not

require a gasket (Fig. 13). This type of joint, called the

Connect-S under their newly formed MaxPure label of

fittings, is currently in use in Europe. While this connection

alleviates the issues that are present with a gasketed joint

16

added care would need to be applied in its handling. Any

scratch or ding to the faced part of the sealing surface could

compromise its sealing integrity. Nevertheless this is a

connection design worth consideration.

In this first article we have covered a few of the basics,

which will provide us with a little more insight when we

discuss the more in-depth topics of piping Codes, piping

design, and fabrication of pipe in Part II.

Future Articles

What we have discussed so far is just some of the basics

of general piping. While there is a great deal left unsaid we

will provide further clarification as we move through the

next two articles.

The next article, titled “Piping Design Part II – Code,

Design and Fabrication”, will cover the more specific

aspects of Code governance, engineering in pipe design and

fabrication as it relates to welding, assembly and installation.

The third article in this series, titled “Piping Design Part

III – Installation, Cleaning, Testing and Verification”, will

wrap up the series by discussing the four title points.

Acknowledgement:

I wish to thank Earl Lamson, senior Project Manager with

Eli Lilly and Company, for taking time out of a busy

schedule to read through the draft of this article. He obliged

me by reviewing this article with the same skill, intelligence

and insight he brings to everything he does. His comments

kept me concise and on target.

About the author:

W. M. (Bill) Huitt has been

involved in industrial piping

design, engineering and

construction since 1965.

Positions have included

design engineer, piping design

instructor, project engineer,

project supervisor, piping

department supervisor,

engineering manager and

president of W. M. Huitt Co. a

piping consulting firm

founded in 1987. His

experience covers both the engineering and construction

fields and crosses industrial lines to include petroleum

refining, chemical, petrochemical, pharmaceutical, pulp &

paper, nuclear power, biofuel, and coal gasification. He has

written numerous specifications, guidelines, papers, and

magazine articles on the topic of pipe design and

engineering. Bill is a member of ISPE (International Society

of Pharmaceutical Engineers), CSI (Construction

Specifications Institute) and ASME (American Society of

Mechanical Engineers). He is a member of three ASME-

BPE subcommittees, several Task Groups, an API Task

Group, and sets on two corporate specification review

boards. He can be reached at:

W. M. Huitt Co.

P O Box 31154

St. Louis, MO 63131-0154

(314)966-8919

wmhuitt@aol.com

www.wmhuitt.com

As published in the June and July 2007 issues of Chemical Engineering Magazine

There is not a reason sufficiently good enough not to comply with appropriate industry Standards and

Codes. W. M. (Bill) Huitt

W. M. Huitt Co.

A request was put to me a few years back asking if I

would respond in writing to the question, “Why do we, as a

company, need to comply with a piping Code?” The

question was in regard to the building of industrial facilities,

and was in preparation for a meeting that was about to take

place for which the main topic was going to be the issue of

Code compliance.

If you considered the question while reading it you may

have noticed that there is, although unintentional, a trick to

it. Code, by definition is law with statutory force. Therefore

the reason for complying with a Code is because you

literally have to, or be penalized for non-compliance.

The question actually intended was, “why comply with

or adopt a piping consensus standard?” When a question like

the one above is phrased as it is it supports my contention

that many people, referring to engineers and designers in our

case, do not fully understand the difference between a Code

and a Standard. And it doesn‟t help matters when some

Standards are published as a Code, and some Codes are

published as a Standard. This is certainly nothing to get

excited about, but it is something worth pointing out.

My take on the reason for the misunderstanding of these

two closely related terms, Standard and Code, is that they

get bounced around so often in the same context that

designers and engineers simply begin interchanging the two

terms without much consideration for their different

meanings. I‟m going to explain the difference between a

Standard and a Code, but before I do, here‟s the written

response I gave to the above question:

Consensus Standards such as those published by ASME,

ANSI, API, NFPA, ASTM, International Plumbing Code and

others are not mandatory in and of themselves. However,

federal, state, city and other local Codes are mandatory. In

these municipal Codes you will find regulations that

establish various requirements taken in whole, or in part

from the Standards published by the above listed

organizations, and others, as legally binding requirements.

These Standards, as adopted, then become Code, which is

enforceable by law.

When not addressed on a municipal level, but included

in corporate specifications, the Standard becomes a legal

Code on a contractual basis.

To comply with these Codes, irrespective of government

regulations or corporate requirements, doesn't cost the

builder any more than if they didn't comply. It does,

however, cost more to fabricate and install piping systems

that have a high degree of integrity as opposed to a system

that doesn't.

By hiring non-certified welders and plumbers, by-

passing inspections, examinations and testing, using

material that may potentially not withstand service pressures

and temperatures, and supporting this type of system with

potentially inadequate supports is less costly but there's too

much at risk. I don't think anyone in good conscience would

Piping Design

Part 2: Code, Design and

Fabrication

2

intentionally attempt to do something like that in order to

save money, but then again the world is full of unscrupulous

individuals and corporations.

If anyone intending on fabricating and installing a

piping system plans to:

1. Use listed material,

2. Specify material that meets the requirements for fluid

service, pressure and temperature,

3. Inspect the material for MOC, size and rating,

4. Use certified welders and plumbers,

5. Inspect welds and brazing,

6. Adequately support the pipe,

7. Test the pipe for tightness;

Then they are essentially complying with Code. The Code

simply explains how to do this in a formal, well thought-out

manner.

There is not a reason sufficiently good enough not to

comply with appropriate industry Standards and Codes. If

there was a fee involved for compliance this might be a

stimulus for debate. But there is no fee, and there is usually

just too much at stake. Even with utility systems in an admin

building or an institutional facility, the potential damage

from a ruptured pipeline, or a slow leak at an untested joint

could easily overshadow any savings gained in non-

compliance. That's without considering the safety risk to

personnel.

The first thing that someone should do, if they are

considering to do otherwise, is check local and state Code.

They may find regulations that require adherence to ASME,

the International Plumbing Code or some of the other

consensus Standards. If not already included, this should be

a requirement within any company’s specifications.

Just a bit of trivia:

ASME published the first edition of the Boiler and

Pressure Vessel Code in 1914-15. Prior to creation of the

Code, and what played a large part in instigating its

creation, was that between 1870 and 1910 approximately

14,000 boilers had exploded. Some were devastating to both

people and property. Those numbers fell off drastically as

the Code was adopted.

Uniformity and regulation does have its place.

PIPING CODE

In a piping facility, defined here as an industrial facility

requiring a significant amount (apply your own order of

magnitude here) of pipe, the three key factors in its

development are the governing Code, the design (includes

specifications and engineering), and pipe fabrication

(includes installation). These are the three topics we will

discuss on a broad, but limited basis in this article.

Like the seatbelt law Code compliance is not just the

law, it makes good sense. A professional Consensus

Standard is, very simply put, a Code waiting to be adopted.

Take the ASME Boiler and Pressure Vessel Code (BPVC),

since its first publication in 1915 it has been adopted by 49

states, all the provinces of Canada, and accepted by

regulatory authorities in over 80 countries.

On May 18, 2005 it was finally adopted by the 50th

state, South Carolina. And this doesn‟t mean the BPVC is

adopted in its entirety. A state, or corporation for that matter,

can adopt a single section or multiple Sections of the BPVC,

or they can adopt it in its entirety. Until South Carolina

adopted the BPVC it was actually no more than a Standard

in that state and only required compliance when stipulated in

a specification. However, in all honesty you would not get a

US boiler or pressure vessel manufacturer to by-pass Code

compliance. That is, unless you wanted to pay their potential

attorneys fees.

With regard to Code compliance, the question I get

quite often is, “How do I determine which piping Code, or

Standard, I should comply with for my particular project?”

Determining proper Code application is relatively

straightforward while at the same time providing a certain

degree of latitude to the Owner in making the final

determination. In some cases that determination is made for

the Engineer or Contractor at the state level, the local level

or by an Owner company itself. Providing guidelines for

Code adoption on a project basis is direction that should be

included in any company‟s set of specifications, but quite

often is not. This can cause a number of disconnects through

design and construction.

In order to answer the question about Code assignment

some history has to be told. In keeping this brief I will just

touch on the high points. In 1942, ASA B31.1 – American

Standard Code for Pressure Piping was published by the

American Standards Association. This would later change to

B31.1 - Power Piping. In the early 1950‟s the decision was

made to create additional B31 Codes in order to better define

the requirements for more specific needs. The first of those

Standards was ASA B31.8 – Gas Transmission and

Distribution Piping Systems, which was published in 1955.

In 1959 the first ASA B31.3 – Petroleum Refinery Piping

Standard was published.

After some reorganization and organizational name

changes the ASA became ANSI, American National

Standards Institute. Subsequent Code revisions were

designated as ANSI Codes. In 1978, ASME was granted

accreditation by ANSI to organize the B31 Committee as the

ASME Code for Pressure Piping. This changed the Code

designation to ANSI/ASME B31.

3

Since 1955 the B31 Committee has continued to

categorize, create and better define Code requirements for

specific segments of the industry. Through the years since

then they have created, not necessarily in this order, B31.4 –

Liquid Transportation Piping, B31.5 – Refrigeration Piping,

B31.9 – Building Services Piping, and B31.11 – Slurry

Transportation Piping. Each of these Standards is considered

a stand-alone Section of the ASME Code for Pressure

Piping, B31.

What the B31 committee has accomplished, and is

continuing to improve upon, are Standards that are better

focused on specific segments of industry. This alleviates the

need for a designer or constructor building an institutional

type facility from having to familiarize themselves with the

more voluminous B31.3 or even a B31.1. They can work

within the much less stringent and extensive requirements of

B31.9, a Standard created for and much more suitable for

that type of design and construction.

As mentioned above, ASME B31.1 – Power Piping, was

first published in 1942. Its general scope reads: “Rules for

this Code Section have been developed considering the

needs for applications which include piping typically found

in electric power generating stations, in industrial and

institutional plants, geothermal heating systems, and central

and district heating and cooling systems.”

The general scope of ASME B31.3 – Process Piping,

reads: “Rules for the Process Piping Code have been

developed considering piping typically found in petroleum

refineries, chemical, pharmaceutical, textile, paper,

semiconductor and cryogenic plants; and related processing

plants and terminals.”

ASME B31.5 – Refrigeration Piping, applies to

refrigerant and secondary coolant piping systems.

Closely related to B31.1, but not having the size,

pressure or temperature range, B31.9 was first published in

1982. It was created to fill the need for piping in limited

service requirements. Its scope is narrowly focused on only

those service conditions that may be required to service the

utility needs of operating a commercial, institutional or

residential building.

From its shear scope of responsibility, B31.3

encompasses virtually all piping, including those also

covered by B31.1 (except for boiler external piping), B31.5

and B31.9. The difference, and distinction, as to which Code

should apply to a particular project, lies with the definition

and scope of the project itself.

If a project includes only the installation of perhaps a

refrigeration system, B31.5 would apply. If a project's scope

of work consists of an office, laboratory, research facility,

institutional facility or any combination thereof, B31.1 or

B31.9 and possibly B31.5 would apply. A laboratory or

research facility could possibly require fluid services beyond

the fluid service limits of B31.9. In that case, B31.3 would

be adopted for those services.

In the case of a process manufacturing facility, B31.3

would be the governing Code. Since B31.3 covers all piping,

B31.5 or B31.9 would not need to be included, not even

necessarily with associated lab, office and research facilities.

The only time B31.5 or B31.9 would become governing

Codes, in association with a manufacturing facility, is if a

refrigeration unit, or an office, lab and/or research facility

were under a separate design/construct contract from the

process manufacturing facility. Or they were a substantial

part of the overall project.

As an example, project XYZ consists of a process

manufacturing facility, related office building and lab

facilities. If the utility service piping for the office and lab

facilities is a small percentage of the overall project, and/or

the design and construction contracts for those facilities are a

part of the overall process manufacturing facility, all piping,

with Code exclusions, could be governed by B31.3.

If, however, the office and lab facilities were a

substantial part of the overall project, or they were to go to a

separate constructor it may be more beneficial to determine

battery limits for those facilities and designate anything

inside those battery limits as B31.1 or B31.9 and/or B31.5.

In such a case, separate pipe specifications may have to be

issued for those portions of the project designated as being

governed by B31.9. This is due to the range of fluid services

and the corresponding pressure and temperature limits of

B31.9 compared to those of B31.3. These differences in

Code assignment and battery limits may be a driver for the

project‟s contracting strategy.

Many piping service requirements such as steam, air,

chilled water, etc. can come under the auspices of multiple

Codes. These fluid services, which fall within the definition

of B31.3 Category D fluid services, can just as easily fall

within the requirements of B31.1 or B31.9 as well. In an

effort at maintaining a high degree of continuity in the

process of making the determination of which Code to apply

to a project, company guidelines should be well defined.

The final determination as to what constitutes a

governing Code, within the purview of the above mentioned

Codes, is left to the Owner and/or to the local governing

jurisdiction. Engineering specs should clarify and reflect the

intent of the Owner and the respective Codes in an attempt

to provide consistency and direction across all projects

within a company.

PIPING DESIGN

Piping design is the job of configuring the physical

aspects of pipe and components in an effort to conform with

P&ID‟s, fluid service requirements, associated material

4

specifications, equipment data sheets, and current Good

Manufacturing Practice while meeting Owner expectations.

All of this has to be done within a pre-determined three-

dimensional assigned space while coordinating that activity

with that of the architecture, structural steel, HVAC,

electrical, video, data & security conduit and trays, and

operational requirements.

Pulling together and coordinating the above mentioned

discipline activities to achieve such a compilation of design

requires a systematic methodology, planning, technical

ability, coordination, foresight, and above all experience.

A note of omission here: CAD (Computer Aided Design)

is such an integral part of piping design that it’s difficult, if

not impossible, to discuss design without including CAD in

the discussion. It plays such a large part that, rather than

enter into it here, I will dedicate an entire article to it at a

later date. That article will discuss the integration of CAD

into the industry including its merits, and how, in many

respects, its method of implementation and integration has

inversely diminished the quality of design with respect to

industrial piping. The article will also discuss industry’s

reaction to this unexpected result, and the issues we are still

dealing with today in the use of CAD.

PIPING SPECIFICATIONS

One of the first activities the piping engineer will be

involved with is development of piping specifications,

design guidelines and construction guidelines. Piping

specifications, as an overview, should provide essential

material detail for design, procurement and fabrication.

Guidelines, both design and construction, should provide

sufficient definition in a well organized manner to allow the

designer and constructor the insight and direction they need

in order to provide a facility that will meet the expectation of

the Owner with minimal in-process direction from the

Owner or Construction Manager.

Piping Specifications

A Piping Specification is the document that will

describe the physical characteristics and specific material

attributes of pipe, fittings and manual valves necessary to the

needs of both design and procurement. These documents

also become contractual to the project and those contractors

that work under them.

Design will require a sufficient degree of information in

a specification that will allow for determining the service

limitations of the specification and what fluid services the

specification‟s material is compatible with. That is, a project

may have, among other fluid services, sulfuric acid and

chilled water. The economic and technical feasibility of the

material selection for chilled water service would not be

technically feasible for sulfuric acid. Inversely, the economic

and technical material selection for sulfuric acid service

would not be economically feasible for chilled water service.

Procurement too, will need detailed specifications to

limit the assumptions they will have to make or the

questions they will have to ask in preparing purchase orders.

The piping specification should make clear exactly what the

material of construction is for each component, and what

standard that component is manufactured to. Also included

in the component description should be pressure rating, end

connection type and surface finish where required.

There are a few rather consistent mistakes that

companies make in developing or maintaining specs: 1.

within the spec itself they are either not definitive enough or

they are too definitive; 2. they are not updated in a timely

manner; and/or 3. The specs are too broad in their content.

In defining the above issues we‟ll begin with:

Point #1: When defining pipe and components in a

specification you should provide enough information to

identify each component without hamstringing yourself or

procurement in the process. What I mean by that is, do not

get so specific or proprietary with the specification that only

one manufacturer is qualified to provide the component,

unless you intend to do just that. With standard pipe and

fittings it‟s difficult to provide too much information.

However, with valves and other inline equipment it can

happen quite easily.

A common practice of spec writers is to write a

specification for a generic type valve, one that can be bid on

by multiple potential suppliers, by using the description of

one particular valve as a template. What happens is that

proprietary manufacturer trade names, such as some of the

trim materials, are carried over to the generic valve spec.

When the procurement person for the mechanical contractor,

or whoever is buying the valves for the project, gets ready to

buy this valve the only manufacturer that can supply it with

the specified proprietary trim is the one from which the spec

was copied.

You would think that, in doing this, it would eliminate

multiple bids for the valve based on the unintentional

proprietary requirements in the spec. In actuality it creates

confusion and propagates questions. The valve bidders, other

than the one the spec was based on, will bid the valve with

an exception to the proprietary material, or they will contact

the purchasing agent for clarification. Since the purchasing

agent won‟t have the answer, the question, or actually the

clarification, then goes back to the engineer and/or the

Owner. The time necessary in responding to these types of

issues is better spent on more pressing matters.

When developing a spec be specific, but try not to

include proprietary data unless you intend to. As an example

when specifying Viton you are specifying a generic DuPont

5

product. Generic in that there are several different types of

Viton such as Viton A, Viton B, Viton GF, Viton GFLT, etc.

Each of these has specific formulations, which gives them

different fluid service compatibility and pressure/

temperature ranges. Viton is a type of fluorocarbon.

Fluorocarbons are designated FKM under ASTM D-1418.

So when specifying “Viton” you are identifying a specific

product from a specific manufacturer…almost.

If, in developing a specification, you wish to establish

minimum requirements for a component or a material it is

certainly acceptable to identify a specific proprietary item as

a benchmark. In doing this, and we‟ll stay with the

fluorocarbon gasket or seal material example, you could

identify Viton GF or equal, which would indicate that a

comparable material from one of the other fluorocarbon

manufacturers would be acceptable so long as the fluid

service compatibility and pressure/temperature ranges were

equal to or greater than the Viton GF material.

In saying “almost” above what I meant by that is, if you

write the spec as Viton you would most likely get the

original formulation, which is Viton A. The fluid service

may be more suited for an FKM with

polytetrafluoroethylene in it. That would be a Viton GF. Or

an FKM suitable for colder temperatures may be a better

choice. That would be a Viton GFLT. Be specific for those

that have to use the specs to design from and those that have

to purchase the material.

Point #2: All too often after a specification is developed

it will reside in the company‟s database without being

periodically reviewed and updated. Industry standards

change, part numbers change, manufacturers are bought and

sold; manufacturers improve their products, etc. All of these

things constitute the need and necessity to review and revise

specifications on a timely basis.

A company that houses their own set of specifications

should review those specifications at least every two years.

This timing works out for a couple reasons: 1. industry

standards, on average, publish every two years, and 2.

capital projects, from design through close-out, will arguably

have an average duration of two years. Lessons-learned from

projects can then be considered for adoption into company

specs, prompting a new revision.

Point #3: Specs being too broad in their content refers to

an attempt at making the specs all-inclusive. A piping

specification should contain only those components and

information that would typically be used from job to job.

That would include the following (as an example):

1. Pressure/Temperature limit of the spec

2. Limiting factor for Pressure/Temperature

3. Pipe material

4. Fitting type, rating and material

5. Flange type, rating and material

6. Gasket type, rating and material

7. Bolt & nut type and material

8. Manual valves grouped by type

9. Notes

10. Branch chart matrix with corrosion allowance

The ten line items above provide the primary

component information and notations required for a typical

piping system. Some specifications are written to include

such components as steam traps, sight glasses, 3-way or 4-

way valves, strainers, and other miscellaneous type items.

Those miscellaneous items are better referred to as specialty

items (or some other similar descriptive name) and are sized

and specified for each particular application. This does not

make them a good candidate for inclusion into a basic pipe

specification.

To explain the above we can use, as an example, a

carbon steel piping system that is specified to be used in a

150 psig steam service. The pipe, flanges, fittings, bolts,

gaskets and valves can all be used at any point in the system

as specified. The specification for a steam trap, however,

will vary depending on its intended application. And

depending on its application the load requirements for each

trap may vary.

As an example, a steam trap application at a drip leg

will have a light steady load, whereas a steam trap

application at a shell & tube heat exchanger may have a

heavier modulating load. And that doesn‟t take into account

the need for the different types of traps, e.g. F&T, inverted

bucket, thermodynamic, etc.

You could, depending on the size of the project, have

multiple variations of the four basic types of steam traps

with anywhere from 30 to 300 or more traps in multiple

sizes and various load requirements. I think you can see why

this type of requirement needs to be its own specification

and not a part of the piping specification.

A piping specification should be concise, definitive and

repeatable. Adding specialty type items to the specification

makes it convoluted and difficult to control and interpret.

Users of these specifications are designers, bidders,

procurement personnel, fabricators, receipt verification

clerks, validation and maintenance personnel.

With that in mind you can better understand, or at least

value the fact, that these documents have to be interpreted

and used by a wide range of personnel. Those personnel are

looking for particular information, written in a concise

manner that will allow them to design and order or verify

components within that specification. In attempting to

include the specialty type items it will, at the very least,

complicate and exacerbate the process.

DESIGN AND CONSTRUCTION GUIDELINES

6

Design and construction guidelines, working in

conjunction with the piping specifications, should convey to

the designer and constructor point by point requirements as

to how a facility is to be designed and constructed. The

guidelines should not be a rhetorical essay, but instead

should follow an industry standard format, preferably a CSI

(Construction Specifications Institute) format.

Look at it this way, the material specifications tell the

designer and constructor what material to use; the guidelines

should tell them how to assimilate and use the material

specifications in applying them to Good Design Practice.

Without these guidelines as part of any bid package or

Request For Proposal package, the Owner is essentially

leaving it up to the Engineer and/or Constructor to bring

their own set of guidelines to the table. And this may or may

not be a good thing. Leaving the full facilities delivery to the

Engineer and Constructor depends a great deal on the

qualifications of the Engineer and the Constructor, and

whether or not consistency from plant to plant and project to

project is an issue.

If the Owner approaches a project with expectations as

to how they would like their plant or facility designed and

built then some preparation, on the Owner‟s part, is in order.

Preparation should include, not only material specifications

as described earlier, but also the guidelines and narratives

(yes, narratives) necessary to define the design and

construction requirements.

I mention the use of narratives here because it helps

facilitate the understanding and convey the magnitude of the,

in most cases, reams of specifications and guidelines

necessary to build an industrial facility of any appreciable

size.

A narrative, in general, should explain in simple,

straight-forward language, for each discipline, the

numbering scheme used for the specifications and

guidelines; association between the material specifications

and the guidelines; an explanation as to why the project is

governed by a particular Code or Codes; and a brief

description of expectation.

The narrative allows you to be more explanatory and

descriptive than a formal point-by-point specification. It

gives the bidder/Engineer a Readers Digest version of the

stacks of specifications and guidelines they are expected to

read through and assimilate within a matter of a few weeks

How piping specifications are delivered to a project can

have a significant impact on the project itself. There are,

generally speaking, three scenarios in which project

specifications and guidelines are delivered to a project:

1. In scenario 1 the Owner, or Customer, has

developed, throughout their existence, a

complete arsenal of specifications and

guidelines. In the older, more established

petroleum refining and chemical companies you

will see entire departments whose mission is to

create, maintain and refine all of the

specifications and guidelines necessary to

execute a project. When a project is approved to

go out for bid to an Engineer the necessary

specifications and guidelines, along with the

requisite drawings, are assembled, packaged and

provided to the Engineer as bid documents, and

beyond that as working documents in the design,

engineering and construction efforts.

2. In scenario 2 the Owner, or Customer, has some

specifications and guidelines that have possibly

not been updated for several years. These are

provided to the Engineer with the understanding

and stipulation that any errors or omissions in

the documents should be addressed and

corrected by the Engineer. These too would be

used in the bid process as well as on the project

itself.

3. In scenario 3 the Owner, or Customer, brings no

specifications or guidelines to the project table.

Specification development becomes part of the

overall project engineering effort.

Scenarios 1 and 3 are at opposite ends of the spectrum,

but afford the best situation for both the Owner and

Engineer/Constructor. By providing the Engineer and

Constructor, as in scenario 1, with a full set of current

specifications and well articulated guidelines, making the

assumption that both the engineer and constructor are

qualified for the level of work required, they can very

effectively execute the design, engineering and construction

for the project.

Scenario 3 allows the Engineer and Constructor to bring

their own game-plan to the project. This too is effective, due

only to the fact that the learning curve is minimal. Most

engineering firms will be prepared to execute a project with

their own set of specifications and guidelines. This applies to

qualified Constructors as well. The down-side of this is the

project to project inconsistency in specifications and

methodology when using different engineers and

constructors.

Scenario 2 is a worse case situation. Ineffective and

outdated Owner specifications create confusion and

inefficient iterations in both the bid process and the

execution of a project. It additionally creates the greatest

opportunity for conflicts between Owner documents and the

Engineer‟s documents. For Project Management, this

translates into change orders at some point in a project.

A guideline should explain to the engineering firm or

constructor, in a concise, definitive manner, just what it is

the Owner expects of them in executing the design and

construction of a facility. By actively and methodically

developing a set of guidelines an Owner/Customer does not

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have to rely on an outside resource, such as an engineering

firm or constructor, to hopefully provide them with the

facility they require and hope to get.

Developing guidelines to convey your company‟s

requirements and expectations can be accomplished using

one or both of the following two basic methods:

1. A formal point-by-point format that covers

all necessary criteria that you, as the Owner,

require on a proprietary basis, plus a listing

and description of the necessary Code and

cGMP requirements.

2. A narrative, for each discipline, that allows

the writer to expand and define, in a much

more descriptive manner, the points that

aren‟t made clear enough, or readily

apparent in the more formal format.

The guideline itself can be structured based on one of

the CSI formats. The format examples provided by CSI give

a company sufficient flexibility in writing guidelines, or

specifications for that matter, to allow the document to

conform to their own particular brand of requirements and

nuances. It also lends a degree of intra-industry conformity

to the guidelines and specifications, providing a degree of

familiarity to the engineers and constructors that will have to

adhere to them.

Design Elements

In the first paragraph of this segment of the article,

“Piping Design”, I described the act of designing piping

systems for a facility as bringing a number of technical

components together to make the pipe conform to a specific

set of requirements, within a prescribed area.

That‟s pretty simplistic, and does not really convey the

magnitude of the experience, technical background or the

imagination required to execute such a task. Experience is

the essential component here. And that is simply because,

aside from whatever innate ability a good designer might

possess, the knowledge required is not taught through formal

education, but is instead learned by being involved in the

process of hands-on design over a period of time

accompanied by ongoing learning.

Ongoing learning can be in the form of organized

classes, a mentor and/or any other means available to help

learn and understand the physical requirements and restraints

of the various systems you will be designing and industries

you will be serving.

Since we do not have enough space here to cover all of

the design elements I would like to, I will key in on a few

topics that generally find their way to me for clarification.

And this doesn‟t even scratch the surface. We will discuss

flanges, pipe internal surface finish, weld seam factor, pipe

wall thickness, MAWP/MADP, design pressure/temperature,

and charge accumulation.

Flanges

In the learning process, some designers (I include

engineers as well) will gloss over some of the primary basics

of design and go directly to the bottom line information they

need. Case in point: In Part I, of this series of articles, we

discussed ASME flanges and their Classifications. Most

designers are familiar with ASME flange Classifications

such as 150, 300, 400, etc. And even though verbally stating

150 pound flange (we discussed the origin of this term in

Part I) rolls off the tongue much easier and is still an

industry accepted term; Class 150 is the proper terminology

and designation.

What you may not know is that the Class designation is

a factor in the calculation for determining the rated working

pressure of a flange. That calculation is:

(eq. 1)

Where:

Pc = ceiling pressure, psig, as specified in

ASME B16.5, para. D3 at temperature T

PT = Rated working pressure, psig,for the

specified material at temperature T

Pr = Pressure rating class index, psi1 (e.g., Pr =

300 psi for Class 300)

S1 = Selected stress, psi, for the specified

material at temperature T. See ASME

B16.5, paras. D2.2, D2.3 and D2.4. 1 This definition of Pr does not apply to Class 150. See ASME

B16.5, paras. D2.2, D2.3 and D2.4.

Pipe Internal Surface Finish

Internal surface roughness is a topic that is specific to

the pharmaceutical, bio-pharmaceutical and semiconductor

industries, but can also be an issue in the chemical industry.

Quantifying and specifying a maximum surface

roughness for internal pipe wall for use in, what is referred

to as direct impact fluid services, is a necessity in the above

mentioned industries.

Direct impact piping systems are those systems that

carry product or carry a fluid service that ultimately comes

in contact with product.

The need for a relatively smooth internal pipe wall is

predicated on three primary issues as it relates to the

industries mentioned above. Those issues are: 1.

Cleanability/Drainability, 2. The ability to hinder the growth

(we don‟t yet have the ability to control it) of biofilm and to

enhance the ability to remove it once it does appear, and 3.

To reduce, to a microscopic level, crevices in which

8

)(2 PYSE

PDt

microscopic particles can reside and at some point dislodge

and get carried along in the fluid stream to damage product.

Regarding the first point, cleanability and drainability

are associative in this context. Meaning that, in order for a

system to be fully cleanable it has to be designed and laid

out in a manner that will eliminate any pockets and provide

enough slope to eliminate any residual liquid (drainable).

Not only is this residual liquid, or hold-up, a contaminant,

from both a bacterial standpoint and as a cross batch

contaminant, it can also be costly due to the high cost of

some drug products. Along those lines, the ASME-BPE

Standard provides criteria for minimum slope, maximum

deadleg, gasket intrusion, gasket concavity, and many other

criteria for design of cleanable and drainable hygienic piping

systems.

Regarding the second point, biofilm (Fig. 1) is defined

as a bacterial population composed of cells which are firmly

attached as microcolonies to a solid surface.

A paper titled, “Microbial Biofilms – are they a problem

in the Pharmaceutical Industry?”, was delivered at an

ASME-BPE symposium in Cork, Ireland, June 2004 by

Frank Riedewald, a Senior Process Engineer with

Lockwood-Greene IDC Ltd. In it he explains the results of

testing that was performed to determine the relative

association between the formation of biofilm, pipe wall

surface finish and pipe wall surface cleanability.

Fig. 1 – Biofilm magnified ≈2000X

(Courtesy of Mr. Riedewald)

One of the many interesting factors that came from the

studies mentioned in this paper is the fact that the internal

surface of the pipe wall can actually be too smooth.

Referring to the graph in Fig. 2, results of the studies in the

above mentioned paper indicate that the surface finish range

best suited to reduce biofilm adherence to the internal pipe

wall surface is from 0.4Ra µm to 1.Ra µm (15.7Ra µin to

58.8Ra µin). What this implies is that while we currently do

not have the means to prevent the onset of biofilm on the

internal walls of hygienic or semiconductor piping systems

we can facilitate its removal in the cleaning process by

specifying the proper surface finish of the internal pipe

walls.

The accepted max surface finish in the pharmaceutical

and bio-pharmaceutical industries is 25Ra µin (0.6 µm). In

the semiconductor industry you might typically see surface

finishes in the 7Ra µin to 15Ra µin, particularly in gas

delivery systems. While the pharmaceutical industry is

concerned with bacterial growth and cross contamination,

the semiconductor industry is concerned more with

particulate damage to product, on the microscopic level.

This pertains to point three above.

Fig. 2 – Biofilm Attachment vs Surface Roughness

(Courtesy of Mr. Riedewald)

Pipe Weld Seam Factor

Part I, of this series of articles, mentioned the fact that

the weld seam in longitudinally welded pipe is a factor in the

pipe wall pressure design thickness calculation.

In ASME B31.3 there are two pipe wall thicknesses to

calculate for. One is pressure design thickness (t) and the

other is minimum required thickness (tm).

There are two equations for finding pressure design

thickness (t) for straight pipe under internal pressure. One is

where t < D/6. This calculation (eq. 2) is based on internal

pressure, actual (not nominal) OD of the pipe, stress value of

the material at design temperature, joint efficiency factor,

and the coefficient Y [a factor used to adjust internal

pressure (P) for a nominal material at temperature].

The other calculation used is that in which t ≥ D/6. This

calculation (eq. 3) is based on the above listed criteria except

for the OD and uses instead ID of the pipe, and the sum of

all mechanical allowances.

The two equations look like this:

Where t < D/6:

(eq. 2)

Where t ≥ D/6:

9

)]1([2

)2(

YPSE

cdPt

cttm

(eq. 3)

Where:

t = Pressure design thickness

tm = Minimum required thickness, including

mechanical, corrosion, and erosion

allowances

c = Sum of the mechanical allowances (thread

or groove depth) plus corrosion and

erosion allowances. For threaded

components, the nominal thread depth

(dimension h of ASME B1.20.1, or

equivalent) shall apply. For machined

surfaces or grooves where the tolerance is

not specified, the tolerance shall be

assumed to be 0.02 in. (0.5 mm) in

addition to the specified depth of the cut.

D = Actual pipe OD

d = Pipe ID

P = Internal design gage pressure

S = Stress value for material from ASME

B31.3 Table A-1, at design temperature

E = Quality factor, or joint efficiency factor

Y = Coefficient from ASME B31.3 Table

304.1.1, valid for t < D/6.

The minimum required thickness (tm) is simple enough:

(eq. 4)

To determine wall thickness for pipe under external

pressure conditions refer to the Boiler and Pressure Vessel

Code (BPVC) Section VIII, Division 1, UG-28 through UG-

30 and ASME B31.3, Para. 304.1.3.

Keep in mind that for seamless pipe E will be removed

from equations eq. 2 & eq. 3.

Taking a page from the BPVC we will go through a few

brief steps to determine Maximum Allowable Working

Pressure (MAWP) for straight pipe. But let me begin by

saying that MAWP is not a B31.3 expression, it comes from

the BPVC. We will instead transpose this term to MADP

(Maximum Allowable Design Pressure), which is also not a

B31.3 term, but more closely relates to piping.

When a vessel goes into design it is assigned a

coincidental design pressure and temperature. These are the

maximum conditions the vessel is expected to experience

while in service, and what the vessel engineers will design

to. The material, material thickness, welds, nozzles, flanges,

etc. are all designed predicated on this predetermined design

criteria.

Throughout design the vessel‟s intended maximum

pressure is referred to as its design pressure. All calculations

are based on specified material and component tolerances

along with fabrication specifics, meaning types and sizes of

welds, reinforcement, etc. Not until after the vessel is

fabricated can the engineer know what the actual material

thickness is, the type and size of each weld, thickness of

each nozzle neck, etc. Only when all of the factual data of

construction is accumulated and entered into vessel

engineering programs can the MAWP be determined. This

value, once determined, then replaces the design pressure,

and is calculated based on the installed configuration of the

vessel. That is, mounted vertically or horizontally; mounted

on legs; or mounted on lugs.

The difference between the design pressure and the

MAWP is that the engineer will design to the design

pressure, but the final MAWP is the limiting pressure of the

vessel, which may exceed the design pressure; it can never

be less than the design pressure.

In applying this to piping we will first calculate the

burst pressure of the pipe and then determine the MAWP, or,

as was mentioned earlier, a term more closely related to

piping, the Maximum Allowable Design Pressure (MADP).

There are three equations generally used in calculating

burst pressure for pipe. They are:

The Barlow formula;

(eq. 5)

The Boardman formula:

(eq. 6)

The Lame` formula:

(eq. 7)

Where:

PBA = Burst Pressure, psig (Barlow Formula)

PBO = Burst Pressure, psig (Boardman Formula)

PL = Burst Pressure, psig (Lame` Formula)

D = Actual pipe OD, inches

d = Pipe ID, inches

TF = Wall thickness, inches, minus factory

tolerance

ST = Minimum tensile strength, psi, from

D

STP TF

BA

2

)8.0(

2

TD

STP TF

BO

)(

)(22

22

dD

dDSP T

L

)8.0(

2

TD

STP TF

BO

10

B31.3 Table A-1

Sf = Safety factor, a factor of 3 or 4 is applied

to burst pressure to determine MADP

M = Maximum Allowable Design Pressure

(MADP)

Using the results from any one of the above equations

we can then solve for MADP as follows:

(eq. 8)

** = BA, BO, or L subscript

Design Pressure and Temperature

The ASME B31.3 definition for Design Pressure and

Design Temperature is stated as two separate definitions. I

will integrate them into one by stating: The design pressure

and temperature of each component in a piping system shall

be not less than the most severe condition of coincident

internal or external pressure and temperature (minimum or

maximum) expected during service.

It goes on to state: The most severe condition is that

which results in the greatest required component thickness

and the highest component rating.

How do you determine these values and where do you

apply them? We‟ll cover the where first. What we did earlier

in determining pipe wall thickness was based on design

conditions, in which P = Internal Design Gage pressure and

S = Stress value at design temperature. Design conditions are

also used to determine component rating and as a basis for

determining leak test pressure, which we will get into in the

final article of this series.

There is no published standard, or real industry

consensus on how to determine design conditions. It

basically comes down to an Owner‟s or engineer‟s

experience. What I will provide here is a resultant

philosophy developed from many sources along with my

own experiences.

In understanding what constitutes design conditions we

first of all need to define them. Following is some accepted

terminology and their definitions:

System Operating Pressure: The pressure at which a

fluid service is expected to normally operate at.

System Design Pressure: Unless extenuating process

conditions dictate otherwise, the design pressure is the

pressure at the most severe coincident of internal or external

pressure and temperature (minimum or maximum) expected

during service, plus the greater of 30 psi or 10%.

System Operating Temperature: The temperature at

which a fluid service is expected to normally operate at.

System Design Temperature: Unless extenuating

process conditions dictate otherwise, the design

temperature, for operating temperatures between 32°F and

750°F, shall be equal to the maximum anticipated operating

temperature, plus 25°F rounded off to the next higher 5°.

Applying a sort of philosophy created by the above

definitions is somewhat straight forward for utility services

such as steam, water, non-reactive chemicals, etc. However,

that part of the above definitions for design conditions that

provide the caveat, “…extenuating process conditions…”

implies a slightly different set of rules for process systems.

Extenuating process conditions can mean increased

pressure and temperature, beyond that defined above, due to

chemical reaction, loss of temperature control in heat

transfer, etc.

Charge Accumulation of Lined Pipe

Clarification

Internal and external charge accumulation, known as

static electricity, or more technically known, as triboelectric

charge accumulation, is the result of charge generation

unable to dissipate. If a charge generated in a flowing fluid

is allowed to dissipate to ground, as it does in grounded

metallic pipe, then there is no problem. However, if a charge

cannot dissipate and is allowed to accumulate, it now

becomes a problem by potentially becoming strong enough

to create an Electrostatic Discharge (ESD). With regard to

thermoplastic lined pipe there are two forms of this to be

considered: External Charge Accumulation (ECA) and

Internal Charge Accumulation (ICA).

External Charge Accumulation

ECA is a concern with lined pipe due to the possibility

of not achieving spool-to-spool continuity during installation

due, in large part, to improved paint primer on flanges.

To explain the loss of spool-to-spool continuity: this

lack of integral continuity is, as mentioned above, the result

of the prime paint coat that is applied by the manufacture.

When pipe spools, lined or un-lined, are joined by flanges

using non-metallic gaskets the only thing that completes the

Spool-to-spool continuity is the bolting. The improved paint

primer on lined pipe flanges makes this more difficult to

achieve because normal bolt tightening doesn‟t guarantee

metal-to-metal contact between the nut and the flange.

Pipe generally does not come with a prime coat of paint,

however lined pipe does. Since flange bolts are used to

complete continuity from spool to spool the installer has to

make certain, when installing lined pipe, that the bolts, at

least one of the bolts, has penetrated the primer and made

contact with bare metal. This was achieved in the past by

fS

PM **

11

using star washers on at least one flange bolt while assuming

possible bare metal contact with the other bolts allowing the

washers, as they were tightened, to scrape away the prime

coat so that contact was made with the bare metal of the

flange. With improved prime coat material this is no longer a

guarantee.

If continuity from spool to spool is not achieved any

charge generation resulting from an internal or an external

source cannot readily dissipate to ground. The voltage in

triboelectric charge generation will build until it is strong

enough to jump to the closest grounded object creating an

undesired spark of electricity in doing this (Electrostatic

Discharge).

Internal Charge Accumulation

ICA, with regard to pipe, is unique to thermoplastic

lined pipe and solid thermoplastic pipe. Without being

impregnated with a conductive material, thermoplastics are

not good conductors of electricity. PTFE

(Polytetrafluoroethylene), as an example, used as a pipe

liner, has a high (>1016

Ohms/Square), resistivity factor. This

is a relatively high resistance to conductivity. This means

that any charge created internally to the pipe cannot readily

be conducted away to ground by way of the PTFE liner.

Instead the charge will be allowed to build until it exceeds

its total dielectric strength and burns a pinhole in the liner to

the internal metal wall of the casement pipe. It isn‟t charge

generation itself that is the problem, it‟s the charge

accumulation. When the rate of charge generation is greater

than the rate of charge relaxation (the ability of material to

conduct away the generated charge), charge accumulation

occurs.

The dielectric strength of PTFE is 450 to 500 volts/mil.

This indicates that for every 0.001” of PTFE liner 450 volts

of triboelectric charge will be required to penetrate the liner.

For a 2” pipeline with a 0.130” thick liner this translates into

58500 volts of triboelectric charge to burn through the liner

thickness.

When the liner is penetrated by an accumulated charge

two additional problems (time bombs) are created: 1.

Corrosive fluid (a major user of lined pipe) is now in contact

with and corroding the metal pipe wall and at some point,

depending on rate of corrosion, will fail locally causing fluid

to leak to the environment, and 2. The initial charge that

burned through the liner is now charging the outer metal

pipe, which, if continuity has not been achieved for the outer

pipe, a spark of triboelectric charge is, at some point, going

to jump to ground causing a spark.

Corrective Action

External Charge Generation

The simplest method to ensure continuity is to sand

away any primer on the back side of each flange to ensure

good metal-to-metal contact between nut and flange. Aside

from that or the use of a conductive prime paint, the current

ready-made solution to the external continuity problem is the

addition of stud bolts located in close proximity to flanges

on both pipe spools and fittings (see Fig. 3). These studs can

be applied at the factory or in the field. At each flange joint a

grounding strap (jumper) is then affixed to a stud on one

spool with a nut, extended over the flange joint and attached

to a stud on the connecting spool completing continuity

throughout the chain of connecting spools and fittings.

Figure 3 – Grounding Lug Location

Another method of creating continuity at flange joints,

while being less obtrusive and more integral, is described as

follows and represented in Fig. 4:

Referring to Fig. 4, flanges would be purchased pre-

drilled and tapped in the center of the outer edge of the

flange between the backside of the flange and the face side

of the flange. The drilled and tapped hole in each flange will

need to be centered between boltholes so that they line up

after the flange bolts are installed. The tapped hole is 1/4”

dia. x 1/2” deep.

After a flange set is installed and fully bolted the

Continuity Plate (Fig. 4) can be installed using two 1/4”

x1/2” long hex head screws and two lock washers. The

Continuity Plate has two 0.312” slotted boltholes allowing

for misalignment and movement.

The entire continuity plate assembly is relatively simple

to install, unobtrusive and establishes integral contact with

the pipeline.

12

Figure 4 – Continuity Flange Plate

Internal Charge Generation

One of the first options in preventing Internal Charge

Accumulation is by minimizing charge generation. This can

be done by adjusting the flow velocity relative to the liquid‟s

conductivity. To minimize design impact, cost and even

schedule impact on a project this needs to be evaluated early

in the project due to the possibility of a change in line size.

To retard charge generation by reducing flow velocities

British Standard (BS) suggests the following as represented

in Table 1 per BS 5958:

TABLE 1 - RECOMMENDED VELOCITIES

Liquid Conductivity BS 5958 Recommended Flow

Velocity

>1000 pS/m No restriction

50 – 1000 pS/m Less than 7 m/s

Less than 50 pS/m Less than 1 m/s

pS/m (picosiemens/meter)

If velocity reduction is not an option, or if further

safeguards against charge accumulation are warranted then a

mechanical solution to provide a path to ground for Internal

Charge Generation might be called for.

One method for conducting charge accumulation from

the interior of the pipe to ground is indicated in Figures 5 &

6. What is shown is an orifice plate made of conductive

(static dissipative) material that is compatible with the fluid

service. The orifice itself is off center to the OD of the plate

and the pipeline itself. With the shallow portion of the ID at

the invert of the pipe it allows the piping to drain in

horizontal runs.

The tab portion of the plate extends beyond the flange

OD. On the tab is a bolthole for attaching the modified

Continuity Flange Plate. The plate is designed to come in

contact with the interior surface of the liner wall as well as

protrude into the flowing fluid providing a conduit for

internally generated charge. Continuity is achieved by

attaching the plate to the flange OD that is in contact with

the piping, which is, in turn, grounded through equipment.

Figure 5 – Conductive Orifice Plate Assembly

Figure 6 – Conductivity Orifice Plate Assembly Section

Conclusion and Recommendations

It is difficult to pre-determine what fluid services and

systems will be candidates for charge accumulation

prevention and Electrostatic Discharge protection. The

simplest and most conservative answer to that is to assume

that all fluid services in lined pipe systems are susceptible.

In saying that, we then have to declare that a company‟s pipe

specifications need to reflect a global resolution that will

affect all installations.

With regard to External Charge Accumulation, the

recommendation for future installations with the least impact

would be to specify pipe with no prime coat or at least no

primer on the flanges, or a prime coat using a conductive

paint. The un-primed pipe would be primed prior to

installation with care given to primer touchup on flanges

after installation by the installing contractor or their sub.

This would better ensure spool-to-spool external continuity.

For existing installations either the studs or the

continuity plate installation would work. It can also be

suggested that the continuity plates can be tacked on to one

flange rather than drilling and tapping both flanges.

For dissipating internal charge generation the orifice

plate, as shown in Figures 5 & 6, is the only

recommendation.

PIPE FABRICATION

Entering this part of the article on fabrication does not

mean that we leave engineering behind. Indeed, the majority,

if not all, fabricators (referring to the fabricators that are

qualified for heavy industrial work) will have an engineering

staff.

13

As a project moves from the design phase into the

construction phase anyone with a modicum of project

experience can acknowledge the fact that there will most

certainly be conflicts, errors and omissions, no matter how

diligent one thinks they are during design. This is inherent in

the methodology of today‟s design/engineering process.

There are methods and approaches to design in which this

expected result can be minimized. It‟s actually a

retrospective concept, but we will save that for a future

article.

The preparation for such errors and omissions is always

prudent. If, on the other hand, the assumption is made that

the Issued for Construction design drawings will facilitate

fabrication and installation with minimal problems, then you

can expect to compound whatever problems do occur

because you weren‟t prepared to handle them. The greatest

asset a project manager can have is the ability to learn from

past experience and the talent to put into practice what they

have learned.

Fabrication

Pipe fabrication, in this context, is the construction of

piping systems by forming and assembling pipe and

components with the use of flanged, threaded, clamped,

grooved, crimped and welded joints.

In Article I we discussed the flange joint, we will

discuss the others here. There are various factors, or

considerations, that prompt the decision as to which type of

connection to use in the assembly of a piping system. To

start with, any mechanical joint is considered a potential leak

point and should be minimized. Also, the decision as to

which type of joint should be specified comes down to

accessibility requirements, installation requirements and

joint integrity. Using that as our premise we can continue to

discuss the various joining methods.

Threaded Joints

Pipe thread, designated as NPT (National Pipe Taper)

under ASME B1.20.1, is the type of thread used in joining

pipe. This is a tapered thread that, with sealant, allows the

threads to form a leak-tight seal by jamming them together

as the joint is tightened.

I described the threaded flange joint in Article I. Those

same criteria apply also to threaded fittings, in which the

benefits of the threaded joint is both in cost savings and in

eliminating the need for welding. In this regard, to

paraphrase Article I, threaded components are sometimes

used in high-pressure service in which the operating

temperature is ambient. They are not suitable where high

temperatures, cyclic conditions or bending stresses can be

potential concerns.

Hygienic Clamp Joint

The clamped joint, as mentioned in Article I, refers to

the sanitary or hygienic clamp. As you can see in Fig. 7

there are issues with this type clamp.

Figure 7 – Hygienic Clamp Joint

(Courtesy Rubber Fab Technologies Group)

Represented in Fig. 7 are three installed conditions of

the hygienic joint, minus the clamp. Joint „A‟ represents a

clamp connection that has been over tightened causing the

gasket to intrude into the ID of the tubing. This creates a

damming effect, preventing the system from completely

draining.

In joint „B‟ the clamp wasn‟t tightened enough and left

a recess at the gasket area. This creates a pocket where

residue can accumulate and cleanability becomes an issue.

Joint „C‟ represents a joint in which the proper torque

was applied to the clamp leaving the ID of the gasket flush

with the ID of the tubing.

The clamp „C‟ representation is the result that we want

to achieve with the hygienic clamp. The problem is that this

is very difficult to control on a repeatable basis. Even when

the gasket and ferrules are initially lined up with proper

assembly and torque on the joint, some gasket materials

have a tendency to creep (creep relaxation), or cold flow.

Creep relaxation is defined as: A transient stress-strain

condition in which strain increases concurrently with the

decay of stress. More simply put, it is the loss of tightness in

a gasket, measurable by torque loss.

Cold Flow is defined as: Permanent and continual

deformation of a material that occurs as a result of

prolonged compression or extension at or near room

temperature.

There have been a number of both gasket and fitting

manufacturers that have been investing a great deal of

research in attempting to resolve this issue with the clamp

joint. Some of the solutions regarding fittings were

14

addressed in Article I. Additionally, gasket manufacturers,

and others have been working on acceptable gasket materials

that have reduced creep relaxation factors, as well as

compression controlled gasket designs.

When mentioning acceptable gasket material in the

previous paragraph, what I am referring to is a gasket that is

not only compatible with the hygienic fluid service, but also

meets certain FDA requirements. Those requirements

include Gasket material that complies with USP Biological

Reactivity Test #87 & 88 Class VI for Plastics and FDA

CFR Title 21 Part 177.

Grooved Joint

The grooved joint (Fig. 8), from simply a static internal

pressure containment standpoint, is as good as or, in some

cases superior to the ASME Class 150 flange joint. In the

smaller sizes, 1” through 4” the working pressure limit will

be equal to that of a Class 300, carbon steel, ASTM A105,

ASME B16.5 flange.

Its main weakness is in its allowable bending and

torsional stress at the coupling. This can be alleviated with

proper support. Because of this design characteristic the

manufacturers of grooved joint systems have focused their

efforts and created a niche in the fire protection and utility

fluid service requirements, with the exception of steam and

steam condensate.

This type of joint is comparatively easy to install and

enhances that fact in areas that would require a fire card for

welding. Since no welding is required modifications can be

made while operation continues. Some contractors choose to

couple at every joint and fitting, while others choose to

selectively locate couplings, much as you would selective

locate a flange joint in a system. It‟s a decision that should

be made based on the particular requirements or preference

of a project or facility.

Figure 8 – Grooved Pipe & Coupling

(Courtesy Victaulic)

Pressed Joint

The pressed joint is actually a system that uses thin wall

pipe, up through 2” NPT, to enable the joining of pipe and

fittings with the use of a compression tool. Welding is not

required and threading is only necessary when required for

instrument or equipment connection.

Figure 9 – Pressed Joint

(Courtesy Victaulic)

These types of systems are available from various

manufacturers in carbon steel, 316 and 304 stainless steel

and copper. Because of the thin wall pipe corrosion

allowance becomes a big consideration with carbon steel.

While the static internal pressure rating of these systems

is comparable to an ASME Class 150 flange joint there are

additional fluid service and installation characteristics that

need to be considered. With axial and torsional loading

being the weak spot in these systems they are not practical

where water hammer is a potential, such as in steam

condensate. The axial load consideration carries over to

supporting the pipe as well. Ensure that vertical runs of this

pipe are supported properly from beneath. Do not allow

joints in vertical runs to be under tension. They must be

supported properly from the base of the vertical run.

Welded Joint

The welded joint is by far the most integrated and

secure joint you can have. When done properly it is as strong

as the pipe itself. The key to a weld‟s integrity lies in the

craftsmanship of the welder or welding operator, the

performance qualification of the welder or welding operator,

and the weld procedure specification.

Before I go further I want to explain the difference

between the terms welder and welding operator. A welder is,

as you might have guessed, someone who welds. To be more

precise, it is someone who welds by hand, or manually. A

welding operator is someone who operates an automatic

welding machine. The ends of the pipe still have to be

prepared and aligned, and the automatic welding machine

has to be programmed.

The advantage of machine welding is apparent in doing

production welds. This is shop welding in which there is a

quantity of welds to be made on the same material type, wall

thickness and nominal pipe size. Once the machine is set up

15

for a run of typical pipe like this it is very efficient and

consistent in its weld quality.

This is another topic that could easily stand alone as an

article, but we won‟t do that here. Instead we will focus on

some of the primary types of welding used with pipe. Those

types include:

1. GMAW (Gas Metal Arc Welding) or MIG

2. GTAW (Gas Tungsten Arc Welding) or TIG

3. SMAW (Shielded Metal Arc Welding) or MMA or

Stick Welding

4. FCAW (Flux Cored Automatic welding)

GMAW: Most often referred to as MIG, Metal Inert

Gas welding, GMAW (Gas Metal Arc Welding) can be an

automatic or semi-automatic welding process. It is a process

by which a shielding gas and a continuous, consumable wire

electrode is fed through the same gun (Fig. 10). The

shielding gas is an inert or semi-inert gas such as argon or

CO2 that protects the weld area from atmospheric gases,

which can detrimentally affect the weld area.

There are four commonly used methods of metal

transfer used in GMAW. They are:

1. globular,

2. short-circuiting,

3. spray, and

4. pulsed-spray

With the use of a shielding gas the GMAW process is

better used indoors or in an area protected from the wind. If

the shielding gas is disturbed the weld area can be affected.

Figure 10 – GMAW (MIG) Welding

(Courtesy The Welding Institute)

GTAW: Most often referred to as TIG, Tungsten Inert

Gas welding, GTAW (Gas Tungsten Arc Welding) can be

automatic or manual. It uses a nonconsumable tungsten

electrode to make the weld (Fig. 11), which can be done

with filler metal or without filler metal (autogenous). The

TIG process is more exacting, but is more complex and

slower than MIG welding.

In Article 1 I mentioned the use of orbital welding for

hygienic tube welding. Orbital welding uses the GTAW

method. Once the orbital welder is programmed for the

material it is welding it will provide excellent welds on a

consistent basis. Provided, that is, that the chemistry of the

base material is within allowable ranges.

Figure 11 – GTAW (TIG) Welding

(Courtesy The Welding Institute)

A wide differential in sulfur content between the two

components being joined can cause the weld to drift into the

high sulfur side. This can cause welds to be rejected due to

lack of full penetration.

SMAW: Also referred to as MMA, Manual Metal Arc

welding, or just simply Stick welding, SMAW (Shielded

Metal Arc Welding) is the most common form of welding

used. It is a manual form of welding that uses a consumable

electrode, which is coated with a flux (Fig. 12). As the weld

is being made the flux breaks down to form a shielding gas

that protects the weld from the atmosphere.

The SMAW welding process is versatile and simple,

which allows it to be the most common weld done today.

Figure 12 – SMAW (Stick) Welding

(Courtesy The Welding Institute)

FCAW: Flux Cored Arc Welding is a semiautomatic or

automatic welding process. It is similar to MIG welding, but

the continuously fed consumable wire has a flux core. The

flux provides the shielding gas that protects the weld area

from the atmosphere during welding.

Welding Pipe

The majority of welds you will see in pipe fabrication

will be full penetration circumferential buttwelds, fillet

16

welds or a combination of the two. The circumferential

buttwelds are the welds used to weld two pipe ends together

or other components with buttweld ends. Fillet welds are

used at socketweld joints and at slip-on flanges. Welds in

which a combination of the buttweld and fillet weld would

be used would be at a stub-in joint or a joint similar to that.

A stub-in joint (not to be confused with a stub-end) is a

connection in which the end of a pipe is welded to the

longitudinal run of another pipe (Fig. 13). Depending on

what the design conditions are this can be a reinforced

connection or an unreinforced connection. The branch

connection can be at 90º or less from the longitudinal pipe

run.

Figure 13 – Sample Stub-In Connections

(Courtesy ASME B31.3)

Hygienic Fabrication and Documentation

Hygienic and semiconductor pipe fabrication uses

automatic autogenous welding in the form of orbital

welding. This, as explained in Article I, is a weld without the

use of filler metal. It uses the orbital welding TIG process. In

some cases hand welding is required, but this is kept to a

minimum, and will generally require pre-approval.

When fabricating pipe for hygienic services it will be

necessary to comply with, not only a specific method of

welding, but also an extensive amount of documentation. As

mentioned in Article I, developing and maintaining the

required documentation for hygienic pipe fabrication and

installation can add an additional 30% to 40% to the piping

cost of a project.

The documentation needed, from the fabrication effort

for validation, may include, but is not limited to:

1. Incoming Material Examination Reports

2. Material Certification

a. MTR‟s

b. Certification of Compliance

3. Weld Gas Certification

4. Signature Logs

5. WPQ‟s (Welder & Welding Operator Performance

Qualification)

6. Welder & Welding Operator Inspection Summary

7. Mechanical and electropolishing procedures

8. Examiner Qualification

9. Inspector Qualification

10. Welder Qualification Summary

11. Gage Calibration certifications

12. Weld Continuity Report

13. WPS‟s (Weld Procedure Specifications)

14. PQR‟s (Procedure qualification Record)

15. Weld Coupon log

16. Weld Maps

17. Slope Maps

18. Weld Logs

19. Leak Test Reports

20. Inspection reports

21. Passivation Records

22. Detail mechanical layouts

23. technical specifications for components

24. As-Built Isometrics

25. Original IFC isometrics

26. Documentation recording any changes from IFC to

As-Build isometrics

The above listed documentation, which closely parallels

the list in ASME-BPE, is that which is generally required to

move an installed hygienic system through validation,

commissioning and qualification (C & Q). And this isn‟t all

that‟s required. There is additional supporting

documentation such as P&ID‟s, procedural documents, etc.

that are also required. Depending on the size and type of a

project it can be a massive undertaking. If not properly set

up and orchestrated it can become a logistical nightmare.

What you do not want to do is discover during C&Q

that you are missing a portion of the required

documentation. Resurrecting this information is labor

intensive and can delay a project‟s turn-over significantly. I

cannot stress it strongly enough just how imperative it is that

all necessary documentation be identified up front. It needs

to be procured throughout the process and assimilated in a

turnover package in a manner that makes it relatively easy to

locate needed information while also allowing the

information to be cross indexed and traceable within the TO

package.

The term validation is a broad, generalized, self-

defining term that includes the act of commissioning and

qualification. Commissioning and qualification, while they

go hand in hand, are two activities that are essentially

distinct within themselves.

For this article I will go no further with the topic of

Validation, Commissioning and Qualification. This is a topic

that I will touch on again in Article III.

Future Articles

The third and final article in this series, titled “Piping

Design Part III – Installation, Cleaning, Testing and

Verification”, will wrap up the series by discussing the four

title points.

Acknowledgement:

17

I wish to thank Earl Lamson, Senior Project Manager

with Eli Lilly and Company, for being kind enough in taking

time out of a busy schedule to read through the draft of this

second article. Earl has a remarkable set of project and

engineering skills that set him apart from many I have

worked with. That and the fact that I value his opinion are

the reasons I asked him to review this article.

About the author:

W. M. (Bill) Huitt has

been involved in industrial

piping design, engineering

and construction since 1965.

Positions have included

design engineer, piping design

instructor, project engineer,

project supervisor, piping

department supervisor,

engineering manager and

president of W. M. Huitt Co. a

piping consulting firm

founded in 1987. His experience covers both the engineering

and construction fields and crosses industrial lines to include

petroleum refining, chemical, petrochemical,

pharmaceutical, pulp & paper, nuclear power, biofuel, and

coal gasification. He has written numerous specifications,

guidelines, papers, and magazine articles on the topic of pipe

design and engineering. Bill is a member of ISPE

(International Society of Pharmaceutical Engineers), CSI

(Construction Specifications Institute) and ASME

(American Society of Mechanical Engineers). He is a

member of three ASME-BPE subcommittees, several Task

Groups, an API Task Group, and sets on two corporate

specification review boards. He can be reached at:

W. M. Huitt Co.

P O Box 31154

St. Louis, MO 63131-0154

(314)966-8919

wmhuitt@aol.com

www.wmhuitt.com

As published in the September and October 2007 issues of Chemical Engineering Magazine

Efficiency, quality and safety are the imperatives that are factored in when considering field fabrication, but

don’t forget cost. W. M. (Bill) Huitt

W. M. Huitt Co.

As the title implies this article will discuss the

Installation, Cleaning, Testing and, to a lesser degree,

Validation of piping systems. I say to a lesser degree with

Validation because Validation is a very complex, often

proprietary and exceedingly difficult-to-define topic. Rather

than delve into it in great detail as part of a multi-topic

article I will attempt to simply provide some understanding

as to its function and need.

PIPE INSTALLATION

But first things first, the installation of pipe follows its

fabrication and is very frequently a part of it. The installation

of pipe can be accomplished in the following four primary

ways, or combinations thereof:

1. Field fabricate and install,

2. Shop fabricate and field erected,

3. Skid fabrication, assembly & installation, and

4. Modular construction

I would like to assure you that I am not going to diverge

off into fabrication again since we discussed it, although

somewhat briefly, in Article II. I am including fabrication in

this article simply because fabrication is such an integral part

of pipe installation.

FIELD FABRICATE AND INSTALL

Field fabrication and installation is just what it implies.

The pipe is fabricated on site either in place or in segments

at an on-site field fabrication area and then erected. A

number of factors will dictate whether or not it is feasible to

field fabricate: The size and type of the project, pipe size and

material, the facility itself, weather conditions, availability

of qualified personnel, existing building operations,

cleanliness requirements, time available to do the work, etc.

Efficiency, quality and safety are the imperatives that

are factored in when considering field fabrication. And

before you think I missed it, cost is the fallout of those

factors. Logistically speaking, if all pipe could be fabricated

on-site in a safe and efficient manner, maintaining quality

while doing so, it would make sense to do it in that manner.

However, before making that final decision, let’s look at

some of the pros and cons of field fabrication:

Pros:

1. Only raw material (pipe, fittings, valves, etc.)

need to be shipped to the site location. This is

much easier to handle and store than multi-plane

configurations of pre-fabricated pipe.

2. No time-consuming need to carefully crib, tie-

down and chock pre-fabricated *spool pieces for

transport to the job site.

3. Reduced risk of damage to spool pieces.

4. More efficient opportunity to fab around

unexpected obstacles (structural steel, duct,

cable tray, etc.)

5. Fabricate-as-you-install reduces the rework risk

assumed when pre-fabricating spools, or the cost

Piping Design Part 3:

Installation, Cleaning,

Testing & Verifification

2

related to field verification prior to shop

fabrication.

6. The field routing installation of pipe through an

array of insufficiently documented locations of

existing pipe and equipment, on a retrofit

project, is quite frequently more effective than

attempting to pre-fabricate pipe based on

dimensional assumptions. *Spool pieces are the pre-fabricated sections of pipe that are fabricated and numbered in the fab shop then shipped to the job site

for installation.

Cons:

1. Weather is arguably the biggest deterrent. If the

facility under construction is not enclosed then

protection from the elements will have to be

provided.

2. When welding has to be done in conditions that

are not environmentally controlled then pre-

heating will be required if the ambient

temperature (not the metal surface temperature)

is 0° F or below.

3. In a new facility, as opposed to having to route

piping through an array of poorly located

existing pipe and equipment, field fabrication of

buttwelded pipe is not as efficient and cost

effective as shop fabrication.

4. Concerns about safety and efficiency when

working in a facility while it is in operation in

advance of a turnaround or to begin advance

work on a plant expansion.

Generally speaking, threaded, socketweld, grooved, and

other proprietary type joints that do not require buttwelding

are field fabricated and installed. Buttwelding of small, 1

1/2” NPS and less, are very often field fabricated and

installed because of the added risk of damage during

transport, in pre-fabricated form, from the shop to the site.

SHOP FABRICATE AND INSTALL

Shop fabrication is, generally speaking, any pipe,

fittings and components that are assembled by welding into

spool assemblies at the fabricator’s facility. The spools are

then labeled with an identifier and transported to the job site

for installation.

Each spool piece needs its own identifier marked on the

piece itself in some fashion that will make it easy to know

where its destination is in the facility and/or where it belongs

in a multi-spool system of pipe. This will allow the installer

to efficiently stage the piece and ready it for installation.

As part of the process of developing spool sections

field-welded joints need to be designated. These are welded

joints that connect the pre-fabricated spools. In doing this

the designer or fabricator will identify two different types of

field-welded joints.

One is a Field Weld (FW) and the other is a Field

Closure Weld (FCW). The FW indicates a joint in which the

end of a pipe segment is prepared for the installer to set in

place and weld to its connecting joint without additional

modification in the field. This means that the length of pipe

that is joined to another in the field is cut precisely to length

and the end prepared in the shop for welding.

The FCW provides the installer with an additional

length of pipe, usually 4” to 6” longer than what is indicated

on the design drawings, to allow for field adjustment.

What has to be considered, and what prompts the need

for a FCW, is the actual, as-installed, location of both the

fixed equipment that the pipe assemblies may connect to and

the actual installed location of the pipe assembly itself. Odds

are that all equipment and piping will not be installed

exactly where indicated on design drawings.

The dimensional location of the equipment items given

on design drawings is not a finite location, they are merely

intended locations, as are drawings for building steel, pipe

supports and others. What factors into the installation of

shop fabricated pipe is the actual location of the equipment

nozzle it will be connecting to in relation to the pipe’s

installed location.

In connecting to equipment there is a build-up, or stack-

up, of tolerances that will effectively place the actual, or

final, location of the nozzle at some point in the xyz

geometry of three-dimensional space, other than where the

design drawing indicates. The tolerance stack-up comes

from the following:

1. Manufacturing tolerances in material forming,

nozzle location, and vessel support location.

2. The actual set-in-place location of the vessel.

3. Load cell installation (when applicable).

4. The actual set-in-place pipe run-up location.

In order to allow for these inevitable deviations between

the drawing dimensions used to fabricate the vessel, set the

vessel, and install the pipe assembly, and the actual installed

location of the connecting points, a field closure piece, or

two, will be required for that final adjustment.

The field closure piece is a designated section of the

pipe assembly in which a field weld has been indicated. The

section with the field closure weld would be the length

required to agree with that indicated on the design drawing,

plus an additional 4” to 6” (more or less depending on

fabricator’s comfort level with the equipment locations).

What this does is allow the field to make the final

determination in the adjustments when connecting to fixed

equipment.

SKID (SUPER SKID) FABRICATION

3

A skid is a pre-packaged assembly that may contain all

or some of the following that make up an operating system:

vessels, rotating equipment, piping, automation components,

operator interfaces, instrumentation, gages, electrical panels,

wiring and connectors, framework, supports, in-line piping

components, and insulation. A single process or utility

system may fit onto one skid or, depending on size

restraints, may comprise multiple skids.

After fabrication of a skid is complete it will typically

go through Factory Acceptance Testing (FAT) at the

fabricator’s facility. The skid is then shipped to the job site

where it is installed in its final location. After installation it

would typically go through a follow-up Site Acceptance Test

(SAT), including additional hydro-testing. This is basically a

system shake-down to determine that everything is intact,

and that those things that did not remain intact during

transport are discovered and repaired.

Logistics and the necessary skill-set required for the

installation, connection and start-up of a particular skid

package will dictate to what extent the skid fabricator will be

involved after it is shipped to the job site.

MODULAR CONSTRUCTION

The term module or modular construction is quite often,

in this context, interchanged with the term skid fabrication.

A module can refer to pre-fabricated units that actually form

the structure of a facility as each is installed. Or, the units

may be smaller sub-assemblies that, when combined, make

up a complete process or utility system.

Modules too consist of all or some of the following:

vessels, rotating equipment, piping, automation components,

HVAC, instrumentation, electrical wiring and connectors,

framework, walls, architectural components, lighting,

supports, in-line piping components, and insulation. This, as

an example, allows a complete locker room module to be

placed and connected to a complete water treatment module.

The smaller sub-assembly modules, in many cases, are

interchanged with the term skid. It saves on misperception

when a company defines these terms, both for internal

discussion and for the purpose of making it clear to outside

contractors, as to what is meant when using the term

module.

INSTALL APPROACH

Now that we have a general idea of the four primary

approaches to piping installations how do we decide which

is the best method, or combination of methods, to use for a

particular project? But there is one major caveat I would like

to address before launching into this subject.

Each project is individualized with its own particular set

of decision drivers with regard to a selected execution

approach. There are no hard and fast rules for determining a

best approach at job execution. It requires experienced

personnel assigning values to the various aspects of project

execution, overlaying a timeline, and then assessing

logistics. Sounds simple, but is in actuality can be a very

complex process.

What I am attempting to say here is, that the following

is a guideline and not hard and fast rules. There are simply

too many project variables and complexities to allow it.

In approaching this decision keep in mind that the

method of installation needs to be weighed against a

contractor’s preferred methodology. In saying that I am not

implying that the contractor’s preferred methodology should

drive your decision on how to execute a job. On the

contrary, once you determine how the job needs to be

executed you then look to only those contractors whose

preferred methodology agrees with your project execution

plans.

Some contractors prefer to do most, if not all fabrication

in the shop, others prefer to set up at the job-site, while

others are flexible enough to utilize the best of both

methods.

The three main criteria, efficiency, quality and safety

indicated earlier under “Field Fabricate and Install”, would

apply here as well. Using those three elements as a basis for

making our determination let us look at some common

variables:

1. Environment

a. Controlled environment

b. Open to the elements

2. Industry

a. Pharmaceutical

b. Biopharmaceutical

c. Semiconductor

d. Food & Dairy

e. Petroleum refining

f. Bulk chemical

g. Pulp & paper

h. Off-Shore

i. Pipeline

j. Power generation

3. Type of project

a. Retrofit

b. Fast track approach

c. New (Grassroots/Greenfield) project

d. Clean-build

e. Single level

f. Multi-level

g. Room repetition

4. Range of pipe material and sizes

a. Small percentage of alloy pipe

b. Large percentage of alloy pipe

c. Large % of large pipe sizes

4

d. Large % of small pipe sizes

e. Mix of small and large pipe sizes

5. Location

a. Close to metropolitan area

b. Remote location

c. Country with limited resources

Environment

The environment is only a factor when work has to be

done in an open-air structure or other outdoor installation

(tank farm, pipeline, pipe rack or yard piping, etc.). Working

in an open air structure will require protection from the

elements (rain, snow, wind, cold, etc.). There may

additionally be a requirement to work in elevated areas on

scaffolding and otherwise. All of this can have a potential

impact on safety and efficiency.

Pipe rack installation consists mainly of straight runs of

pipe, and will not necessarily have a requirement or need for

pre-fabrication. That is, unless it is pre-fabricated as modular

skid units. Depending on the project it could be cost

effective on an overall strategic basis to modularize the pipe

rack, steel and all.

The big advantage to shop fabrication is the controlled

environment in which it’s done. This includes the Quality

Control aspect, better equipment (generally speaking), a

routine methodology of how a piece of work progresses

through the shop, and better control, through a developed

routine, of required documentation.

Industry

I know this is generalizing, but we can group the

various industries into clean/indoor build and non-

clean/outdoor build. There are exceptions to this, but under

clean/indoor build we can list the following;

Clean/Indoor build

a. Pharmaceutical

b. Biopharmaceutical

c. Semiconductor

d. Food & Dairy

Under non-clean/outdoor build we can list the

following;

Non-Clean/Outdoor Build

a. Petroleum refining

b. Bulk chemical

c. Pulp & paper

d. Off-Shore

e. Pipeline

f. Power generation

The clean build philosophy comes from the need to

construct certain facilities with a more stringent control on

construction debris. Those industries listed above under

Clean/Indoor Build often require a facility, at least a portion

of a facility, to be microbial and particulate free, as

stipulated by the design.

There can be no debris, organic or inorganic, remaining

after construction in accessible or inaccessible spaces of the

facility. Of particular concern with the pharmaceutical,

biopharm and food 7 dairy is food waste and hidden

moisture. Food waste can entice and support rodents and

insects, and hidden moisture can propagate mold, which can

eventually become airborne. If not discovered until the

facility is in operation the impact, upon discovery, can

potentially be devastating to production.

Such contamination can be discovered in one of two

ways. Discovery at the source, possibly behind a wall or

some other out-of-the-way place, means that not only does

current production have to cease, but product will have to be

analyzed for possible contamination. Once found it hen has

to be remediated.

The other method of discovery comes from the

continuous testing and validation of the product stream. If a

contaminant is discovered in the product the production line

is stopped and the problem then becomes an investigation in

to finding the source of the contamination.

The clean-build philosophy therefore dictates more

stringent and strict requirements for controlling and

inspecting for debris on an ongoing basis throughout

construction and start-up.

It will be necessary, on a clean-build site, to follow

some rather simple rules:

1. Smoking or smokeless tobacco products of any

kind are not allowed on the site property,

2. Off site break and lunch areas, no food or drink,

other than water, allowed on the site premises,

3. Do not begin installing pipe, duct or equipment

until, at the very least, a roof is installed,

4. After roof and walls are installed ensure that

there is no standing water remaining in the

facility,

5. Prior to and during the construction of hollow

walls, such as those framed and dry-walled,

ensure on a daily basis that there is no moisture

or debris in the wall cavity,

6. Duct work delivered to the job site shall have the

ends covered with a plastic sheet material, which

shall remain on the ends until connected in place,

7. Fabricated pipe delivered to the job site shall

have the ends covered in a suitable fashion with

suitable material, and shall remain on the ends

until connected in place,

8. During and after flushing and testing of pipelines

all water spills shall be controlled to the extent

possible and shall be cleaned up after flushing

and testing or at the end of the work day,

5

Type of Project

While the type of project is not the main influence in

determining how you approach the execution of a project it

does play a key role. It will help drive the decision as to how

the piping should be fabricated and installed.

As an example, if the project is a retrofit it will require

much of the pipe, regardless of size and joint connection, to

be field fabricated and installed. This is due simply to the

fact that the effort and cost necessary to verify the location

of all existing pipe, equipment, walls, columns, duct, etc. in

a somewhat precise manner, would not be very practical.

You would be better served by field verifying the

approximate location of the above items with existing

drawings, for planning and logistic purposes, then shop or

field fabricate, verify and install as you go.

A fast track project, one that has a compressed schedule,

will require parallel activities where possible. Whereas shop

and skid fabrication would be utilized as much as possible

simply to expend more man-hours over a shorter time period

while attempting to maintain efficiency. Even though there

may be added cost to this approach. This approach is time

driven and not budgetary driven.

A new grassroots facility still requires routing

verification as you go, but certainly not the much more

involved need to locate previously installed obstructions as

needs to be done when working with an existing facility.

If the project is a clean-build project (typical for the

pharmaceutical, biopharmaceutical, semiconductor and food

& dairy industries) inside an environmentally controlled area

it will be more practical to shop fabricate or utilize skid or

modular fabrication for most, if not all of the piping. This

will reduce the number of personnel and the amount of

fabrication debris in the facility, and provide better control

for keeping it out of the pipe itself. With personnel you

could have food wrappers, drink cans and bottles, food

waste, and clothing items. Fabrication debris could include

metal filings, cutting oil, pieces of pipe, weld rod and weld

wire remnants, etc.

If the project is not a clean-build, but is still inside an

environmentally controlled facility the same logic does not

necessarily apply. The decision to shop fab and install or to

field fab and install becomes one based on efficiency rather

than how best to maintain a clean area. And that’s not to say

that if it doesn’t qualify as a clean-build project then the

construction debris can just be allowed to pile up.

There is still safety and efficiency to be concerned with

on any project and a clean job site is a major part of that.

Maintaining a clean job site is an integral component of

good project execution.

Keeping personnel and equipment to a minimum at the

job site is not an absolute, but is one of the key

considerations to the efficiency of pipe installation.

Following that logic most of the buttwelded pipe should be

shop fabricated. A couple of things to consider, when

determining which buttwelded pipe to shop fabricate, is size

and material.

Range of Pipe Material and Sizes

Shop fabricated spools need to be transported to the job

site. This requires handling. Handling and transporting small

diameter pipe and/or thin-wall tubing spools creates the

potential for damage to those spools.

If you are shop fabricating everything and the distance

from shop to site is simply across town the risk to damaging

small diameter pipe spools is a great deal less than if they

have to be shipped half way across the US, Europe or Asia.

Or even across an ocean.

In transporting spools over long distances, unless there

is a great deal of thought and care given to cribbing the load

of spools, it may not be beneficial to transport buttwelded

pipe spools NPS 1 ½” and less. It may be more practical to

fabricate these sizes on site, unless you are fabricating

hygienic or semi-conductor piping. These types of systems

require a great deal more control and a cleaner fabrication.

Meaning that pipe fabrication will require a clean shop area

on-site, or the pipe will need to be fabricated at an off-site,

better controlled shop facility.

A practical rule of thumb in determining what to shop

fab and what to field fab follows in Table 3-1:

Table 3-1 Shop and Field Fabrication

Size (in) Material Joint Shop/Field

≤ 1 ½ Pipe 1, 2, 3, 6 Field

≤ 1 ½ Pipe 4 & 5 Shop

≥ 2 Pipe 3 & 6 Field

≥ 2 Pipe 4 & 5 Shop

≤ 1 Tubing 5 Field

≤ 1 Tubing 5 Shop (a, b)

≥ 1 ½ Tubing 5 Shop Joint Type:

1 = Socketweld

2 = Threaded 3 = Grooved – Fully (Grooved fittings and pipe ends.)

4 = Grooved – Partially (Shop-welded spools with grooved ends.)

5 = Buttweld 6 = Flanged – Lined or unlined Pipe

Notes:

a. Hygienic tubing b. Special cribbing and support for transport

The above Table 3-1 is a general methodology. Dictates

of the project and a contractors SOP will determine how best

to define what gets shop fabricated and what gets field

fabricated.

6

Petroleum refining and bulk chemical projects are

generally open air projects in which field fabrication and

installation of pipe is exposed to the elements. While a clean

build is not a requirement on these types of projects

efficiency and, above all, safety is, as it is on any type

project. Because of this, it would make sense to utilize shop

fabrication as much as possible.

Fabricating pipe spools under better controlled shop

conditions will provide improved efficiency and safer per

hour working conditions over what you will generally find in

the field. This translates into fewer accidents.

Referring back to Table 3-1, with respect to the

potential for damage during transport, pipe sizes NPS 2” to

3” and larger ship much better than smaller pipe sizes.

Particularly when working with thin-wall tubing. This is a

consideration when determining what to shop fab and what

to field fab.

Location

Job site location is one of the key markers in

determining shop or field fabrication. In many cases building

a facility in a remote location will be a driver for utilizing a

disproportionate amount of skid or module fabrication.

Disproportionate in the sense that project management may

look at modularizing the entire job, rather than mobilize the

staffing and facilities needed to fab and install on or near the

job site. This would constitute a larger amount of

modularization over what might normally be expected for

the same type project in a more metropolitan region, or an

area with reasonable access to needed resources.

To expand on that thought; it was pointed out to me by

Earl Lamson, Senior Project Manager with Eli Lilly and

Company, an observation I fully agree with, that project

resources, even in metropolitan areas, are quite frequently

siloed around a specific industry. In certain regions of the

US for example, you may discover that there are an

abundance of craftsman available when building a refinery,

but that same region may have difficulty, from a trained and

experienced personnel perspective, in supporting the

construction of a semiconductor facility.

Consequently when building a pharmaceutical facility in

another region you may find a sufficient population of

trained and experienced craftsman for that industry, but may

not find that resource adequate when building a chemical

plant.

Building a project in a remote location requires the

project team to rethink the job-as-usual methodology. From

a logistics standpoint mobilization of personnel and material

become a major factor in determining the overall execution

of such a project. Project planning is a big component in

project execution, but is more so when attempting to build in

remote areas. And this doesn’t even touch on the security

aspect.

Nowadays, when constructing in any number of remote

areas, security is a real concern that requires real

consideration and real resolution. Reduced on-site staffing is

a good counter-measure in reducing risk to personnel when

building in remote or even non-remote third-world areas.

PIPE SYSTEM CLEANING

While there are requirements in ASME for leak testing

cleaning requirements do not exist. In ASTM A 380 & 967

you will find Standards on cleaning, descaling and

passivation, but nothing in ASTM on simply flushing and

general cleaning. Defining the requirements for the internal

cleaning of piping systems falls within the responsibilities of

the Owner.

The term “cleaning”, in this context, is a catch-all term

that also includes flushing, chemical cleaning, and

passivation. So before we go further let me provide some

definition for these terms as they apply in this context. I say,

“as they apply in this context”, because these terms are

somewhat flexible in their meaning, depending on source

and context, and could be used to describe activities other

than what is intended in this dialog.

Definitions

Cleaning: A process by which water, solvents, acids or

proprietary cleaning solutions are flushed through a piping

system to remove contaminants such as cutting oils, metal

filings, weld spatter, dirt, and other unwanted debris.

Flushing: A process by which water, air or an inert gas

is forced through a piping system either in preparation for

chemical cleaning or as the only cleaning process. Flushing

can be accomplished by using dynamic pressure head or

released static pressure head, as in a fill-and-dump

procedure. Blow-down can be considered as flushing with a

gas.

Passivation: A process by which a chemical solution,

usually with a base of nitric, phosphoric, citric acid or other

mild oxidant, is used to promote or accelerate the formation

of a thin (25 to 50 Angstroms) protective oxide layer (a

passive layer) on the internal surface of pipe, fittings and

equipment. In stainless steels, the most commonly used alloy

at present, it removes any free iron from the pipe surface to

form a chromium-rich oxide layer to protect the metal

surface from aggressive liquids such as high purity waters.

Note: Cleaning and Flushing can be interchanged when the process

only requires water, air or an inert gas to meet the required level of

cleanliness. When the term “cleaning” is used in this context it may

infer what is defined as flushing.

Cleaning and Testing

7

With regard to cleaning and leak testing, and which to

do first, there are drivers for both and different schools of

thought on the overall process. Each contractor will have

their preference. It is in the Owner’s best interest to

determine their preference or be at risk in just leaving it to

the contractor. In either case you should have a line of

thought on the process, if for no other reason than to be able

to understand what it is the contractor is proposing to do.

At the very least, in advance of leak testing, perform

either a basic flush of a *test circuit, or perform an internal

visual examination as the pipe is installed. A walk-down of

the test circuit should be done just prior to filling the system

with any liquid. The last thing you want to happen is to

discover too late that a joint wasn’t fully connected or an in-

line component was taken out of the pipeline. In a facility

that is not a clean-build it can simply be a mess that has to

be cleaned up. In a clean-build facility an incident such as

this can potentially be costly and time-consuming to

remediate.

Note: *refer to the following section on “Leak Testing”

Before getting into further specifics of this discussion

we need to define some general cleaning and testing

procedures and assign them some easy to use indicators. In

this way it will be much easier to discuss the various

processes. We can then work through some general

scenarios and see which sequencing works best.

Following is a list of cleaning requirements:

Table 3-2 – General Cleaning Scenarios

Category Description

C-1 Flush only (water, air or inert gas)

C-2 Flush, clean with cleaning solution, flush

C-3 Clean with cleaning solution, flush

C-4 Flush, clean, passivate, flush

Following is a list of leak testing requirements:

Table 3-3 – General Leak Testing Scenarios

Category Description

T-1 Initial service leak test

T-2 Hydrostatic leak test

T-3 Pneumatic leak test

T-4 Sensitive leak test

T-5 Alternative leak test

While the cleaning descriptions are self explanatory the

leak testing descriptions may not be. Please refer to the

following section on “Leak Testing” to find clarification of

the terms used in Table 3-3.

One other thing I would like to mention before we go

on. Since we are discussing new pipe installation we will not

include steam-out cleaning or pipeline pigging. These are

cleaning procedures that are used on in-service piping to

clean the fluid service residue build-up from interior pipe

walls after a period of use.

Before subjecting the system to an internal test pressure

the piping should first be walked down to make certain, as

mentioned earlier, that there are no missing or loose

components. The system is then flushed with water or air to

make sure that there are no obstacles in the piping. Over the

years we have discovered in installed piping systems

everything from soda cans to shop towels, work gloves, nuts

& bolts, weld rod, Styrofoam cups, candy wrappers, and

other miscellaneous debris including dirt and rocks.

After this initial flush, which could also be the only

flush and cleaning required, the system is ready for chemical

cleaning or to leak test. In large systems it may be beneficial

to leak test smaller test circuits and then perform a final

cleaning once the entire system is installed and tested. This

would include a final completed system leak test that would

test all of the joints that connect the test circuits. That is,

unless these joints were tested as the assembly progressed.

If it is decided, on large systems, to leak test smaller

segments, or test circuits as they are installed, prior to

flushing the entire system, the piping needs to be examined

internally as it is installed. This is to prevent any large debris

items, as listed above, from remaining in the piping during

the test.

Now that we have touched on those generalities let’s

take a look at each of the cleaning Categories listed in Table

3-2 and see how to apply them.

Cleaning Category C-1 is simply a flush with water, air

or inert gas. The one non-manual assist that water requires in

order for it to clean the inside of a piping system is velocity.

But what velocity is necessary?

The main concept behind flushing a pipeline is to

dislodge and remove suspected debris. In order to dislodge,

suspend and remove this unwanted material in the piping

system it is necessary that water or air be forced through the

piping system at a velocity sufficient to suspend the heaviest

suspected particles and move them along the pipeline.

The velocity required to suspend the particles and move

them along the pipeline for removal is dependent upon their

size and weight, and the flush medium. Metal filings,

arguably the heaviest particles normally found in newly

fabricated pipe, will have a terminal mid-range settling

velocity, in water, of approximately 10 feet per second.

Therefore, a flushing velocity of approximately 10 feet per

second should be achieved during the flush. (This does not

apply to acid cleaning.)

8

The following Table 3-4 indicates the rate of flow

required to achieve approximately 10 feet per second of

velocity through various sizes and schedules of pipe.

Table 3-4 – Rate of Flushing Liquid Needed to Maintain

Approximately 10 FPS Velocity (GPM)

Pipe Pipe Sizes (inches)

Sch. ½ ¾ 1 1 ½ 2 3 4

5s 12 20 34 77 123 272 460

40 10 16 27 64 105 230 397

80 7 13 22 55 92 ─ ─

Purging a piping system clear of debris with air requires

a velocity of approximately 25 feet per second. The

following Table 3-5 indicates the rate of air flow required to

achieve approximately 25 feet per second of velocity through

various sizes and schedules of pipe.

Table 3-5 – Rate of Air Flow to Maintain Approx 25 FPS Velocity

(SCFS)

Pipe

Sch

Pipe Sizes (inches)

½ ¾ 1 1 ½ 2 3 4

Press

15

psig

5s 0.14 0.23 0.39 0.86 1.39 3.06 5.17

40 0.11 0.19 0.30 0.71 1.18 2.59 4.47

80 0.08 0.15 0.25 0.62 1.04 2.32 4.03

Press

50

psig

5s 0.30 0.51 0.84 1.88 3.02 6.67 11.3

40 0.23 0.41 0.66 1.56 2.56 5.65 9.73

80 0.18 0.33 0.55 1.35 2.26 5.05 8.79

One thing you might notice is that the size range only

extends to 4” NPS for both the liquid flush and for the air or

gas blow-down. The reason for that is the volume of liquid

or gas required to achieve the necessary velocity through the

larger pipe sizes is quite significant.

As an example a 6” NPS pipeline would require

approximately 900 to 1000 GPM, depending on wall

thickness of the pipe, to achieve a velocity of 10 FPS. This

gets a little cumbersome and costly. That is unless you have

pumps or compressors in place that can achieve the

necessary flow rate.

The alternative for liquid flushing the larger pipe sizes

other than using source line pressure or a pump is to perform

a fill-and-dump. In this process the pipe system is

completely filled with liquid and then drained through a full

line size, quick opening valve.

In doing this there has to be enough static head to

generate sufficient force and velocity to achieve essentially

the same result as the pumped or line pressure liquid.

Cleaning Category C-2 is a three-step process by which

the piping system is initially flushed out with a liquid to

remove most of the loose debris. This is followed by the

circulation of a cleaning solution, which is then followed by

a final flush of water.

Cleaning solutions are, in many cases, proprietary

detergent or acid-based solutions each blended for specific

uses. Detergent-based solutions are generally used for

removing dirt, cutting oils and grease. Acid-based solutions

are used to remove the same contaminants as the detergent-

base plus weld discoloration and residue. The acid based

solution also passivates the pipe wall.

As defined earlier, passivation provides a protective

oxide barrier against corrosion. The acids used in some

cleaning solutions for ferrous and copper materials leave

behind a passivated interior pipe surface as a result of the

cleaning process. In utility water services such as tower

water, chilled water, etc., this barrier against corrosion is

maintained with corrosion inhibitors that are injected into

the fluid stream on an ongoing basis.

And keep in mind that when I talk about passivated

surfaces this is a natural occurrence with metals in an

oxygen environment. The acid merely initiates and speeds

up the process.

When using stainless alloys, usually 316L, in hygienic

water services such as Water For Injection (WFI), Purified

Water, Deionized (DI) Water and in some cases Soft Water,

passivation is a final intended step in the preparation for

service of these pipelines.

Passivation is also a periodic ongoing preventative

maintenance procedure. To explain: High purity water is

very corrosive and attacks any free iron found on the surface

of stainless pipe. Free iron has a tendency to come out of

solution when material is cold worked, as in bending or

forming pipe without the benefit of heat. It also occurs with

the threading of alloy bolts, which are solution annealed

(heat treated) after threading. Passivation removes this free

iron while also accelerating, in the presence of O2, the

oxidation rate of the stainless steel providing a chromium

rich oxide corrosion barrier as defined above.

Over time (and this is one hypothetical thought on the

subject), this very thin corrosion barrier tends to get depleted

or worn off, particularly at high impingement areas of the

piping system (elbows, tees, pump casings, etc.). Once the

passive layer wears through any free iron exposed to the

high purity water will oxidize, or rust. This will show up as

surface rouge.

Rouging is an unwanted surface discoloration which is

periodically removed by means of a derouging process. This

is an operational, as-needed chemical cleaning process that

will remove all or most of the rouge and also re-passivate the

internal pipe surface.

9

Discussions and research on the topic of rouging

continues. This is a subject that has more questions than

answers at the present time. Currently the ASME-BPE is

looking into this issue. One of the questions to be answered

is whether or not rouge is actually detrimental to product

streams.

Cleaning Category C-3 is a two-step cleaning process

that uses a detergent or acid based solution to clean the pipe

interior of any unwanted residue or debris. This is then

followed by a final flush of water.

Cleaning Category C-4 is a three or four-step process

generally used in hygienic service piping. In most cases,

simply due to the clean fabrication approach used in

hygienic pipe fabrication, only a water flush with Deionized

(DI) quality water or better would be necessary for cleaning

followed by passivation of the piping system, then a final

flush of water.

There are variations to each of these primary cleaning

functions and it would be in an Owner’s best interest to

define these requirements, by fluid service, in advance of the

work to be done.

LEAK TESTING

Pressure testing is a misnomer that is quite often used

when referring to leak testing of piping systems. And as long

as all parties understand what is meant by that, then that’s

fine. However, in a true sense a pressure test is a test you

perform on a relief valve to test its set point pressure. The

intent, when pressure testing a relief valve, is not to check

for leaks, but to test the pressure set point of the valve by

gradually adding pressure to the relief valve until it lifts the

valve off of the seat.

A leak test, on the other hand, is performed to check the

sealing integrity of a piping system by applying internal

pressure to a pre-determined limit, based on design

conditions, then checking joints and component seals for

leaks. It is not intended that the MAWP of a piping system

be verified or validated.

Before discussing the various types of leak tests and

leak test procedures I would like to briefly talk about

controlling and tracking this activity.

Cleaning and testing, like many aspects of a project,

should be a controlled process. Meaning, there should be a

formal method of documenting and tracking this activity as

the Contractor proceeds through the leak testing process..

In documenting the leak testing activity there are certain

forms that will be needed. They consist of the following:

1. A dedicated set of P&ID’s to identify the limits

and number the test circuits;

2. A form to record components that were either

installed or removed prior to testing;

3. A checklist form for field supervision to ensure

that each step of the test process is

accomplished; and

4. Leak test data forms

The two sets of documents, from those listed above, that

need to be retained are the P&ID’s (#1) and the Leak Test

Data Forms (#4). The other two sets of forms are procedural

checklists.

The Leak Test Data forms should contain key data such

as:

1. Test circuit number

2. P&ID number(s)

3. Date of test

4. Project name and/or number

5. Location within facility

6. Line number(s)

7. Design pressure

8. Test pressure

9. Test fluid

10. Test fluid temperature

11. Time (military) recorded test begins

12. Pressure at start of test

13. Time (military) recorded test ends

14. Pressure at end of test

15. Total elapsed time of test

16. Total pressure differential (plus or minus) from

beginning to end of test period

17. Comment section (indicate if leaks were found and

system was repaired and retested or if system

passed)

18. Signatures & dates

Also make certain that the testing contractor has current

calibration logs of their test instruments, such as pressure

gages.

To continue with the leak testing, ASME B31.3 defines

five primary leak tests as follows:

Initial Service Leak Test: This applies only to those

fluid services meeting the criteria as defined under ASME

B31.3 Category D fluid service. This includes fluids in

which the following apply:

(1) the fluid handled is nonflammable, nontoxic,

and not damaging to human tissue;

(2) the design gage pressure does not exceed 1035

kPA (150 psi); and

(3) the design temperature is from -29°C (-20°F)

through 186°C (366°F).

The Initial Service leak test is a process by which the

test fluid is the fluid that is to be used in the intended piping

system at operating pressure and temperature. It is

accomplished by connecting to the fluid source with a

10

valved connection and then gradually opening the source

valve and filling the system. In liquid systems air is purged

during the fill cycle through high point vents. A rolling

examination of all joints is continually performed during the

fill cycle and for a period of time after the system is

completely filled and is under line pressure.

In a situation in which the distribution of the pipeline

that is being tested has distribution on multiple floors of a

facility there will be pressure differentials between the floors

due to static head differences. This will occur in operation

and is acceptable under initial service test conditions.

The test pressure achieved for initial service testing

pressure is what it is. Meaning that what you achieve in the

test is what it will be in operation. The only difference is that

the flowing fluid during operation will incur an amount of

pressure drop that will not be present during the static test.

Hydrostatic leak test: This is the most commonly used

leak test and is performed by using a liquid, normally water,

and in some cases with additives to prevent freezing, under a

calculated pressure.

(eq. 1)

(eq. 1.1)

Eq. 1 represents the equation for that calculated

pressure. However, as long as the metal temperature of ST

remains below the temperature at which the allowable stress

value for ST begins to diminish and the allowable stress

value of S and ST are equal then ST and S cancel each other

leaving the simpler eq. 2:

(eq. 2)

Unlike initial service testing, pressure variations due to

static head differences in elevation have to be

accommodated in hydrostatic testing. What I mean by that is

the calculated test pressure is the minimum pressure required

for the system. When hydrostatically testing a multi-floor

system the minimum calculated test pressure shall be

realized at the highest point. This is not stated, but is inferred

in B31.3.

Pneumatic leak test: This test is performed using air or a

preferred inert gas. This is a relatively easy test to perform

simply from a preparation and cleanup standpoint. However,

this test has a hazardous potential because of the stored

energy in the pressurized gas. And for that reason alone it

should be used very selectively.

When pneumatic testing is performed it must be done

under a strictly controlled procedure with on-site supervision

in addition to coordination with all other crafts and

personnel in the test area.

(eq. 3)

(eq. 4)

(eq. 5)

The test pressure for pneumatic leak testing under B31.3

is calculated using eq. 3, for B31.9 it is calculated using eq.

4, and for B31.1 it is calculated using eq. 5.

One misconception I need to address here with

pneumatic leak testing is in its procedure, as described in

B1.3. There is a misconception that the test pressure should

be maintained while the joints are examined. This is not

correct. As B31.3 explains, pressure is increased gradually

until the test pressure is reached. At that point the test

pressure is held until piping strains equalize throughout the

system.

After allowing a sufficient amount of time for piping

strains to equalize the pressure is then reduced to the design

pressure (refer to article II for design pressure). While

holding design pressure all joints are examined for leaks. It

is not required that the examination take place while holding

test pressure.

There is more to the entire procedure that I did not

include here. Please refer to B31.3 or B31.1 for full details

on pneumatic leak testing.

Sensitive leak test: This leak test is performed when

there is a higher than normal potential for fluid leakage, such

as for hydrogen. I also recommend its use when a fluid is

classified as a Category M fluid service. B31.1 refers to this

test as Mass-Spectrometer and Halide Testing.

In B31.3 the process for sensitive leak testing is as

follows:

The test shall be in accordance with the gas and bubble

test method specified in the BPV Code, Section V, Article 10,

or by another method demonstrated to have equal sensitivity.

Sensitivity of the test shall be not less than 10-3

atm-ml/sec

under test conditions.

(a) The test pressure shall be at least the lesser of

105kPa (15 psi) gage, or 25% [of] the design pressure.

Where:

PT = Test Pressure, psi

P = Internal design gage pressure, psig

ST = Stress value at test temperature, psi (see B31.3 Table A-1)

S = Stress value at design temperature, psi (see B31.3 Table A-1

S

PSP T

T

5.1

PPT 5.1

PPT 1.1

PPT 4.1

PPtoPT 5.12.1

11

12)(K

UL

Dy

(b) The pressure shall be gradually increased until a

gage pressure the lesser of one-half the test pressure or 170

kPa (25 psi) gage is attained, at which time a preliminary

check shall be made. Then the pressure shall be gradually

increased in steps until the test pressure is reached, the

pressure being held long enough at each step to equalize

piping strains.

In testing fluid services that are extremely difficult to

seal against, or fluid services classified as a Category M

fluid service I would suggest the following in preparation for

the process described under B31.3: prior to performing the

sensitive leak test perform a low pressure (15 psig) test with

air or an inert gas using the bubble test method. Check every

mechanical joint for leakage.

After completing the preliminary low pressure

pneumatic test, purge all of the gas from the system using

helium. Once the system is thoroughly purged, and contains

no less than 98% helium, continue using helium to perform

the sensitive leak test with a helium mass spectrometer.

Helium is the trace gas used in this process and has a

molecule that is close to the size of the hydrogen molecule

making it nearly as difficult to seal against as hydrogen

without the volatility. Test each mechanical joint using the

mass-spectrometer to determine leak rate, if any.

Alternative leak test: In lieu of performing an actual

leak test, in which internal pressure is used, the alternative

leak test takes the examination and flexibility analysis

approach.

This test is conducted only when it is determined that

hydrostatic or pneumatic testing would be detrimental to the

piping system and/or the fluid intended for the piping

system, an inherent risk to personnel, or impractical to

achieve.

As an alternative to testing with internal pressure it is

acceptable to qualify a system through examination and

flexibility analysis. The process calls for the examination of

all groove welds, and includes longitudinal welds used in the

manufacture of pipe and fittings that have not been

previously tested hydrostatically or pneumatically. It

requires a 100% radiograph or ultrasonic examination of

those welds. Where applicable, the sensitive leak test shall

be used on any untested mechanical joints. This Alternative

leak test also requires a flexibility analysis as applicable.

Very briefly, a flexibility analysis verifies, on a

theoretical basis, that an installed piping system is within the

allowable stress range of the material and components under

design conditions if a system: (a) duplicates or replaces

without significant change, a system operating with a

successful service record; (b) can be judged adequate by

comparison with previously analyzed systems; and (c) is of

uniform size, has no more than two points of fixation, no

intermediate restraints, and falls within the limitations of

empirical equation (eq. 6).

(eq. 6)

Where:

D = outside diameter of pipe. in. (mm)

y = resultant of total displacement strains to be

absorbed by piping system, in. (mm)

L = developed length of piping between anchors, in.

(mm)

U = anchor distance, straight line between anchors,

ft. (m)

K1 = 208,000 SA/Ea, (mm/m)2

= 30 SA/Ea, (in./ft.)2

SA = allowable displacement stress range per

equation (1a) of ASME B31.3, ksi (MPa)

Ea = reference modulus of elasticity at 70°F

(21°C), ksi (MPa)

One example in which an alternative leak test might be

used is in making a branch tie-in to an existing, in-service

line using a saddle with an o-let branch fitting with a weld

neck flange welded to that and a valve mounted to the

flange. Within temperature limitations, the fillet weld used

to weld the saddle to the existing pipe can be examined

using the dye penetrant or magnetic particle method. The

circumferential butt or groove weld used in welding the weld

neck and the o-let fitting together should be radiographically

or ultrasonically examined. And the flange joint connecting

the valve should have the torque of each bolt checked after

visually ensuring correct type and placement of the gasket.

There are circumstances, regarding the tie-in scenario

we just discussed for alternative leak testing, in which a

hydrostatic or pneumatic test can be used. It depends on

what the fluid service is in the existing pipeline. If it is a

fluid service that can be considered a Category D fluid

service then it is quite possible that a hydrostatic or

pneumatic leak test can be performed on the described tie-in.

By capping the valve with a blind flange modified to

include a test rig of valves, nipples and hose connectors, you

can perform a leak test rather than an alternative leak test.

As mentioned this does depend on the existing service fluid.

If the existing fluid service is steam or a cryogenic fluid then

you might want to consider the alternative leak test.

Cleaning and Leak Testing Procedures

As you can see by equations eq. 1 through eq. 5 above,

the leak test pressure, except for initial service testing, is

based on design pressure and design temperature. In Article

2 we described design pressure and temperature. What we

will do here is apply that understanding and describe a few

general procedures for cleaning and testing.

12

As in all other project functions control and

documentation is a key element in the cleaning and testing

of piping systems. It does, however, need to be handled in a

manner that is dictated by the type of project. Meaning that

you don’t want to bury yourself in unwarranted paperwork

and place an unneeded burden on the contractor when it isn’t

necessary.

Building a commercial or institutional type facility will

not require the same level of documentation and stringent

controls that an industrial type facility would require. But

even within the industrial sector there are varying degrees of

required testing and documentation.

To begin with, documentation requirements in industry

standards are simplistic and somewhat generalized, as is

apparent in ASME B31.3, which states in Para. 345.2.7:

Records shall be made of each piping system during the

testing, including:

(a) date of test

(b) identification of piping system tested

(c) test fluid

(d) test pressure

(e) certification of results by examiner

These records need not be retained after completion of

the test if a certification by the inspector that the piping has

satisfactorily passed pressure testing as required by this

Code is retained.

ASME B31.3 goes on to state, in Para. 346.3:

Unless otherwise specified by the engineering design,

the following records shall be retained for at least 5 years

after the record is generated for the project:

(a) examination procedures; and

(b) examination personnel qualifications.

Standards, that cover such a broad array of industrial

manufacturing, do not, as a rule, attempt to get too specific

in some of their requirements. Beyond the essential

requirements, such as those indicated above, the Owner,

engineer or contractor has to assume responsibility and

know-how for providing more specific and proprietary

requirements for a particular project specific to the particular

needs of the Owner. The following will help, to some extent,

fill that gap.

Cleaning Procedures

This section will describe some fundamental cleaning

procedures as they might appear in a specification or

guideline, and this includes the leak test procedures that

follow. This will give you some idea as to what you might

consider developing for your own set of specifications.

Assuming that if your company repeatedly executes projects

you will have cleaning and testing guidelines, in some form,

prepared for your contractor. If not you may not get what

you expect. It’s better to give some forethought to these

activities rather than be surprised at the results.

Once a menu of these cleaning and testing procedures

are developed, using pre-assigned symbols, much as those

given in the following, they can then be specified in the line

list with the respective fluid services as you require. In this

manner there is no second guessing during construction.

Each piping circuit is assigned a specific clean and test

protocol in advance.

Many pre-developed procedures I have seen over the

years, those developed by Owners in particular, have been

very simplistic, and typically out of date. This is an indicator

to most contractors that the Owners Rep will most likely not

attempt to enforce them. The contractor, in making that

assumption, may simply ignore them and perform their own

procedures.

What your procedural guidelines should do is be explicit

enough and current to the point where the contractors know

that someone has given some thought as to how they want

that work accomplished. Making it far more likely they (the

contractors) will execute your procedure instead of their’s.

It is certainly acceptable to accommodate suggestions to

a procedure from a contractor when it doesn’t compromise

the intent of the Owner’s requirements and improves the

efficiency of the contractor. If a submitted alternate

procedure does not compromise the intent of the Owner it is

recommended that they be accepted. This will allow the

Owner to see if that efficiency is really there. With that in

mind let’s create a couple of general cleaning procedures.

A general practice in the flushing and cleaning process,

also indicated in leak testing, is the evacuation of air when

using liquids. Always provide high point vents for

evacuating air during the fill cycle and low point drains for

clearing out all of the liquid when the process is complete.

Using the same symbology indicated in Table 3-2 these

cleaning procedures will be categorized as follows:

Category C-1: Flush or Blow Down only (water, air or inert

gas)

C-1.1 These systems shall be flushed with the fluid that the

system is intended for. There shall be no hydrostatic

or pneumatic leak test. An Initial Service leak test will

be performed. Refer to test Category T-1.

a. Connect system to its permanent supply line.

Include a permanent block valve at the supply line

connection. All outlets shall have temporary hoses

run to drain. Do not flush through coils, plates,

strainer or filter elements.

13

b. Using supply line pressure, flush system through all

outlets until water is clear and free of any debris at

all outlet points. Flush a quantity of fluid through

each branch not less than three times that contained

in the system. Use Table 3-6 to estimate volume of

liquid in the system.

c. These systems are required only to undergo an

Initial Service leak test. During the flushing

procedure, and as the system is placed into service,

all joints shall be checked for leaks.

d. Any leaks discovered during the flushing process,

or during the process of placing the system into

service, will require the system to be drained and

repaired. After which the process will start over

with step 2.

C-1.2 These systems shall be flushed clean with Potable

Water.

a. Connect a flush/test manifold at a designated inlet

to the system, and a temporary hose or pipe on the

designated outlet(s) of the system.

b. Route temporary hose or pipe from potable water

supply, approved by Owner, and connect to

flush/test manifold. Route outlet hose or pipe to

sewer, or as directed by Owner rep. Secure end of

outlet.

c. Using a Once through procedure (not a re-

circulation), and the rate of flow in Table 3-4,

perform an initial flush through the system with a

quantity of potable water not less than three times

that contained in the system. Use Table 3-6 to

estimate volume of liquid in the system. Discharge

to sewer, or as directed by Owner rep.

d. After the initial flush, insert a conical strainer into

a spool piece located between the discharge of the

piping system and the outlet hose. Perform a second

flush with a volume of potable water not less than

that contained in the system.

e. After the second flush (step 4), pull the strainer

and check for debris; if debris is found repeat step 3.

If no debris is found the system is ready for leak

testing.

Category C2: Flush then clean with cleaning solution,

followed by a neutralization rinse. Because of the

thoroughness of the flush, clean and rinse process there

should be no need to check for transient debris, only for

neutralization. However, if circumstances dictate otherwise

then a final check for debris may be warranted.

C-2.1 These systems shall be pre-flushed with potable water,

cleaned with (indicate cleaning agent) then a

rinse/neutralization followed by leak testing with

potable water. If it is determined that the system will

be installed and tested progressively in segments, the

sequence of cleaning and testing can be altered to

follow the segmented installation. Thereby leak

testing segments of a piping system as they are

installed without cleaning. The entire system would

then cleaned once installed and tested.

a. Hook up flush/test manifold at a designated

temporary inlet to the system between the

circulating pump discharge and the system inlet.

Install a temporary hose or pipe on the designated

outlet(s) of the system.

b. Route temporary hose or pipe from potable water

supply, approved by Owner, and connect to

flush/test manifold. Route outlet hose or pipe to

sewer, or as directed by Owner’s Rep.

c. Close valve between the circulating pump (if no

valve included in the system design insert a line-

blind or install a blind flange with a drain valve)

discharge and flush/test rig. Open valve between

flush/test manifold and piping system.

d. Using the once through procedure (meaning the

cleaning fluid is not re-circulated), and the rate of

flow in Table 3-4, perform an initial flush through

the system, by-passing the circulation pump, with a

quantity of potable water equal to not less than three

times that contained in the system. Use Table 3-6 to

estimate volume of liquid in the system.

(Note: During the water flush check the system for

leaks. Verify no leaks prior to introducing chemical

cleaning solution to the piping system.)

Table 3-6 – Volume of Water Per Lineal Foot of Pipe (gal.)

Pipe Sizes (inches)

Sch. 1/2 3/4 1 11/2 2 3 4 6 8 10 12 14 16 18 20 24

5s .021 .035 .058 .129 .207 .455 .771 1.68 ─ ─ ─ ─ ─ ─ ─ ─

20 ─ ─ ─ ─ ─ ─ ─ ─ 2.71 4.31 6.16 7.34 9.70 12.4 15.2 22.2

40 .016 .028 .045 .106 .176 .386 .664 1.51 2.61 4.11 5.84 9.22 9.22 14.5 14.5 ─

80 .012 .023 .037 .093 .154 .345 .60 1.36 ─ ─ ─ ─ ─ ─ ─ ─

14

e. Discharge to sewer, or as directed by Owner’s

Rep.

f. After completing the initial flush, drain remaining

water in the system. Or, retain water if cleaning

chemicals will be added to the circulating water.

g. Configure valves and hoses to circulate through

pump. Connect head tank, or other source

containing cleaning agent, to connection provided

on circulation loop.

h. Fill the system with the pre-measured (indicate

preferred cleaning agent and mixing ratio or % by

volume) and circulate through the system for 48

hours. To minimize corrosion, if anticipated,

circulate cleaning agent at a low velocity rate

prescribed by the cleaning agent manufacturer.

i. Drain cleaning agent to sewer or containment, as

directed by Owner.

j. Reconnect as in step #1 for the once through

flush/neutralization, and flush system with potable

water using a quantity not less than three times that

of the system volume. Since the (name cleaning

agent) solution has a neutral pH the rinse water will

have to be visually examined for clarity. Rinse until

clear. The rinse must be started in as short as

quickly after the cleaning cycle as possible. If

cleaning residue is allowed to dry on the interior

pipe wall, it will be more difficult to remove by

simply flushing. The final rinse and neutralization

must be accomplished before any possible residue

has time to dry.

k. Test pH for neutralization. Once neutralization is

achieved proceed to step #12.

l. Remove pump and temporary circulation loop

then configure the system for leak testing. This may

include removal of some components, insertion of

line-blinds, installation of temporary spools pieces,

etc.

Those three examples should provide an idea as to the

kind of dialog that needs to be created in providing guidance

and direction to the contractor responsible for the work.

And, as I stated earlier, these procedures, for the most part,

are flexible enough to accommodate suggested

modifications from the contractor.

Leak Test Procedures

As in the cleaning procedures we will keep this general,

but provide enough specifics for you to develop leak testing

procedures that will suit your company’s own particular

needs.

In Article 1 I stated the B31.3 definition for Category D

fluid services. I then indicated that while Category D fluid

services qualified for initial service leak testing there are

caveats that should be considered.

Again, this is a situation in which ASME provides

some flexibility in testing by lowering the bar on

requirements where there is reduced risk in failure.

Provided, that if failure should occur the results would not

cause catastrophic damage to property or irreparable harm to

personnel.

The Owner’s responsibility, for any fluid service

selected for initial service leak testing lies in determining

what fluid services to place into each of the fluid service

Categories. Those Categories being: Normal, Category D,

Category M, and High Pressure.

Acids, caustics, volatile chemicals and petroleum

products are usually easy to identify as those not qualifying

as a Category D fluid service. Cooling tower water, chilled

water, air, and nitrogen are all easy to identify as qualifyiers

for Category D fluid services. The fluid services that fall

within the acceptable Category D guidelines, but still have

the potential for being hazardous to personnel are not so

straight forward.

Using water as an example, at ambient conditions water

will simply make you wet if you get dripped or sprayed on.

Once the temperature of water exceeds 140°F (60°C), by

OSHA standards, it starts to become detrimental to

personnel upon contact. At this point the range of human

tolerance becomes a factor. However, as the temperature

continues to elevate it eventually moves into a range that

increasing becomes scalding upon human contact and human

tolerance is no longer a factor because it is now hazardous

and the decision is made for you.

Before continuing I need to be clear on the above

subject matter. The 140ºF temperature mentioned above is

with respect to simply coming in contact with an object at

that temperature. Brief contact at that temperature would

not be detrimental. In various litigation related to scalding it

has been determined that an approximate one-second

exposure to 160°F water will result in third degree burns.

An approximate half-minute exposure to 130°F water will

result in third degree burns. And an approximate ten minute

exposure to 120°F water can result in third degree burns.

With the maximum temperature limit of 366°F

(185.5°C) for Category D fluid services what the Owner

needs to consider here are three factors: within that range of

140°F (60°C), the temperature at which discomfort begins to

set in, to 366°F (185.5°C), the upper limit of Category D

fluids, what do we consider hazardous; what is the level of

15

opportunity for risk to personnel; and what is the level of

assured integrity of the installation.

What I mean by assured integrity is this: if there are

procedures and protocols in place that require, validate and

document third-party inspection of all pipe fabrication,

installation and testing, then there is a high degree of assured

integrity in the system. If some or all of these requirements

are not in place then there is no assured integrity.

All three of these factors: temperature, risk of contact,

and assured integrity, have to be considered together to

arrive at a reasonable determination for borderline Category

D fluid services. If, for instance, a fluid service is hot

enough to be considered hazardous, but is in an area of a

facility that sees very little personnel activity then the fluid

service could still be considered as a Category D fluid

service.

One factor I have not included here is the degree of

relative importance of a fluid service, or in other words, if a

system failed how big of a disruption would it cause in plant

operation, and how does that factor into this process.

As an example, if a safety shower water system has to

be shut down for leak repair the down-time to make the

repairs has little impact on plant operations. This system

would therefore be of relative low importance and not a

factor in this evaluation process.

If on the other hand a chilled water system has to be

shut down for leak repair to a main header, this could have a

significant impact to operations and production. This could

translate into lost production and could be considered a high

degree of importance.

You could also extend this logic a bit further by

assigning normal fluid service status to the primary headers

of a chilled water system and assigning Category D status to

the secondary distribution branches then leak test

accordingly. You need to be cautious in considering this. By

applying different Category significance to the same piping

system it could cause more confusion than it is worth. In

other words it may be more value added to simply default to

the more conservative Category of Normal.

Continuing; if we can consider that there is a high

assured integrity value for these piping systems there are two

remaining factors to be considered. The first would be:

within the above indicated temperature range at what

temperature should a fluid be considered hazardous; and

secondly, how probable is it that personnel could be in the

vicinity of a leak, should one occur.

For our purpose here let us determine that any fluid

160°F (71°C) and above is hazardous upon contact with

human skin. If the fluid you are considering is within this

temperature range then it has the potential of being

considered a normal fluid, as defined in B31.3, pending its

location as listed in Table 3-7.

Table 3-7 – Areas Under Consideration For Cat. D

Group Description Yes No

1 Personnel Occupied Space √

2 Corridor Frequented by

Personnel

√

3 Sensitive Equipment (MCC,

Control Room, etc.) √

4 Corridor Infrequently Used by

Personnel √

5 Maintenance & Operations

Personnel Only Access √

As an example, if you have a fluid that is operating at

195°F (90.6°C) it would be considered hazardous in this

evaluation. But, if the system is located in a Group 5 area

(ref. Table 3-7) it could still qualify as a Category D fluid

service.

After the above exercise in evaluating a fluid service we

can now continue with a few examples of leak test

procedures. Using the same symbology indicated in Table 3-

3 these leak test procedures will be categorized as follows:

Category T-1: Initial Service Leak Test

T-1.1 This Category covers liquid piping systems

categorized by ASME B31.3 as Category D Fluid

service and will require Initial Service Leak Testing

only.

1. If the system is not placed into service or tested

immediately after flushing and cleaning, and has set

idle for an unspecified period of time it shall require

a preliminary pneumatic test at the discretion of the

Owner. In doing so, air shall be supplied to the

system to a pressure of 10 psig and held there for 15

minutes to ensure that joints and components have

not been tampered with, and that the system is still

intact. After this preliminary pressure check

proceed.

2. After completion of the flushing and cleaning

process, connect the system, if not already

connected, to its permanent supply source and to all

of its terminal points. Open the block valve at the

supply line and gradually feed the liquid into the

system.

3. Start and stop the fill process to allow proper high

point venting to be accomplished. Hold pressure to

its minimum until the system is completely filled

and vented.

4. Once it is determined that the system has been filled

and vented properly, gradually increase pressure

16

until 50% of operating pressure is reached. Hold

that pressure for approximately 2 minutes to allow

piping strains to equalize. Continue to supply the

system gradually until full operating pressure is

achieved.

5. During the process of filling the system, check all

joints for leaks. Should leaks be found at any time

during this process drain the system, repair leak(s)

and begin again with step 1. (Caveat: Should the

leak be no more than a drip every minute or two on

average at a flange joint, it could require simply

checking the torque on the bolts without draining

the entire system. If someone forgot to fully tighten

the bolts then do so now. If it happens to be a

threaded joint you may still need to drain the

system, disassemble the joint, clean the threads, add

new sealant and reconnect the joint before

continuing.)

6. Record test results and fill in all required fields on

the leak test form.

T-1.2.This Category covers pneumatic piping systems

categorized by ASME B31.3 as Category D Fluid

service and will require Initial Service Leak Testing.

1. After completion of the blow-down process, the

system shall be connected to its permanent supply

source, if not already done so, and to all of its

terminal points. Open the block-valve at the supply

line and gradually feed the gas into the system.

2. Increase the pressure to a point equal to the lesser of

one-half the operating pressure or 25 psig. Make a

preliminary check of all joints by sound or bubble

test. If leaks are found release pressure, repair

leak(s) and begin again with step 1. If no leaks are

identified continue to step 3.

3. Continue to increase pressure in 25 psi increments,

holding that pressure momentarily (approximately 2

minutes) after each increase to allow piping strains

to equalize, until the operating pressure is reached.

4. Check for leaks by sound and/or bubble test. If leaks

are found release pressure, repair leak(s) and begin

again with step 2. If no leaks are found the system is

ready for service.

5. Record test results and fill in all required fields on

the leak test form.

Category T-3.1: Hydrostatic Leak Test

T-3.1.This Category covers liquid piping systems

categorized by ASME B31.3 as Normal Fluid service.

1. If the system is not placed into service or tested

immediately after flushing and cleaning, and has set

idle for an unspecified period of time it shall require

a preliminary pneumatic test at the discretion of the

Owner. In doing so, air shall be supplied to the

system to a pressure of 10 psig and held there for 15

minutes to ensure that joints and components have

not been tampered with, and that the system is still

intact. After this preliminary pressure check

proceed.

2. After completion of the flushing and cleaning

process, with the flush/test manifold still in place

and the temporary potable water supply still

connected (reconnect if necessary), open the block

valve at the supply line and complete filling the

system with potable water.

3. Start and stop the fill process to allow proper high

point venting to be accomplished. Hold pressure to

its minimum until the system is completely filled

and vented.

4. Once it is determined that the system has been filled

and vented properly, gradually increase pressure

until 50% of the test pressure is reached. Hold that

pressure for approximately 2 minutes to allow

piping strains to equalize. Continue to supply the

system gradually until test pressure is achieved.

5. During the process of filling the system, and

increasing pressure to 50% of the test pressure,

check all joints for leaks. Should any leaks be found

drain system, repair leak(s) and begin again with

step 1.

6. Once the test pressure has been achieved, hold it for

a minimum of 30 minutes or until all joints have

been checked for leaks. This includes valve and

equipment seals and packing.

7. If leaks are found evacuate system as required,

repair and repeat from step 2. If no leaks are found,

evacuate system and replace all items temporarily

removed.

8. Record all data and activities on leak test forms.

Those three examples should provide an idea as to the

kind of guideline that needs to be created in providing

direction to the contractor responsible for the work.

For leak testing to be successful on your project, careful

preparation is key. This preparation starts with gathering

information on test pressures, test fluids, and the types of

tests that will be required. The most convenient place for this

information to reside is the piping line list or piping system

list.

17

A piping line list and piping system list achieve the

same purpose only to different degrees of detail. On some

projects it may be more practical to compile the information

by entire service fluid systems. Other projects may require a

more detailed approach by listing each to and from line

along with the particular data for each line.

The line list itself is an excellent control document that

might include the following for each line item:

1. Line size

2. Fluid

3. Nominal material of construction

4. Pipe Spec

5. Insulation spec

6. P&ID

7. Line sequence number

8. from and to information

9. Pipe code

10. Fluid Service Category

11. Heat Tracing

12. Operating Pressure

13. Design Pressure

14. Operating Temperature

15. Design Temperature

16. Type of Cleaning

17. Test Pressure

18. Test Fluid

19. Type of Test

Developing this type of information on a single form

provides everyone involved with the basic information

needed for each line. Having access to this line-by-line

information in such a concise well organized manner

reduces guess-work and errors during testing.

Test results, documented on the test data forms, will be

maintained under separate cover. Together the line list

provides the required information on each line or system and

the test data forms provide signed verification of the actual

test data of the test circuits that make up each line or system.

VALIDATION

The process of Validation has been around for longer

than the 40 plus years I have been in this business. You may

know it by its less formal namesakes walk-down and

checkout. Compared to validation, walk-down and checkout

procedures are not nearly as complex, stringent, or all

inclusive.

Validation is actually a subset activity under the

umbrella of Commissioning and Qualification (C&Q). It is

derived from the need to authenticate and document

specifically defined requirements for a project and stems

indirectly from, and in response to, the Code of Federal

Regulation 29CFR Titles 210 and 211 current Good

Manufacturing Practice (cGMP) and FDA requirements.

These CFR Titles and FDA requirements drove the need to

demonstrate or prove compliance.

These requirements can cover everything from

verification of examination and inspection, documentation of

materials used, software functionality and repeatability to

welder qualification, welding machine qualification, etc.

The cGMP requirements under 29CFR Titles 210 & 211

are a vague predecessor of what validation has become, and

continues to become. From these basic governmental

outlines companies, and the pharmaceutical industry as a

whole, have increasingly provided improved interpretation

of these guidelines to meet many industry imposed, as well

as self-imposed requirements.

To a lesser extent, industrial projects outside the

pharmaceutical, food & drug, and semi-conductor industries,

industries not prone to require such in-depth scrutiny, could

benefit from adopting some of the essential elements of

validation. Elements such as: material verification, leak test

records, welder and welding operator qualification records,

etc.

At face value this exercise would provide an assurance

that the fabricating/installing contractor is fulfilling their

contractual obligation. The added benefit is that in knowing

that this degree of scrutiny will take place the contractor will

themselves take extra pain to minimize the possibility of any

rejects.

And I am not inferring that all contractors are out to get

by with as little as they can. Just the opposite is actually true.

Most contractors qualified to perform at this level of work

are in it to perform well and to meet their obligations. Most

will already have their own verification procedure in place.

The bottom line is that the Owner is still responsible for

the end result. No one wants to head for the litigation table at

the end of a project. And the best way to avoid that is for the

Owner to be proactive in developing their requirements prior

to initiating a project. This allows the spec writers and

reviewers the benefit of having time to consider just what

those requirements are and how they should be defined

without the time pressures imposed when this activity is

project driven.

Performing this kind of activity while in the heat of a

project schedule tends to force quick agreement to

specifications and requirements written by parties other than

those with the Owner’s best interest at heart.

Validating a piping system to ensure compliance and

acceptability is always beneficial and money well spent.

Wrapping Up

18

Before closing out this last of three articles there are just

a couple of things I would like to touch on. We had

discussed industry Standards earlier and how they are

selected and applied on a project. What I didn’t cover is the

fact that most projects will actually have a need to comply

with multiple industry Standards.

In a large grass-roots pharmaceutical project you may

need to include industry compliance Standards for much of

the underground utility piping, ASME B31.1 for boiler

external piping (if not included with packaged boilers),

ASME B31.3 for chemical and utility piping throughout the

facility, and ASME-BPE for any hygienic piping

requirements.

These and other Standards, thanks in large part to the

cooperation of the standards developers and ANSI, work

hand-in-hand with one another by referencing each other

where necessary. These Standards committees have enough

work to do within their defined scope of work without

inadvertently duplicating work done by other Standards

organizations.

An integrated set of American National Standards is the

reason that, when used appropriately, these Standards can be

used as needed on a project without fear of conflict between

those Standards.

One thing that should be understood with industry

Standards is the fact that they will always be in a state of

flux; always changing. And this is a good thing. These are

changes that reflect updating to a new understanding,

expanded clarification on the various sections that make up a

Standard, staying abreast of technology, and simply building

the knowledge base of the Standard.

As an example, two new Parts are being added to the

seven Parts currently existing in ASME-BPE. There will be

a Metallic Materials of Construction Part MMOC, and a

Certification Part CR. This is all part of the ever-evolving

understanding of the needs of the industrial community and

improved clarification, through discussion and debate on

content.

Writing these articles was a form of informational triage

for me. There were definite piping topics I wanted to include

and others I would have preferred to include, but could leave

out without too much of an impact. And then there were the

extended discussions on some topics that ultimately had to

be sacrificed. This is why some topics were briefer than I

would have liked.

My attempt at covering such a wide range of discussion

on industrial piping was to provide a basic broad

understanding of some key points on this topic, not, as I said

earlier, to go into great detail on any specific topic.

I hope that in writing these articles I piqued enough

interest that some of you will dig deeper into this subject

matter to discover and learn some of the more finite points

of what we discussed here. I also hope these articles

provided enough basic knowledge of piping for you to

recognize when there is more to a piping issue than what you

are being told.

Acknowledgement:

My deep appreciation again goes to Earl Lamson, senior

Project Manager with Eli Lilly and Company, for taking the

time to review each of these three articles. His comments

help make this article, and the others, better documents than

they otherwise would have been. He obliged me by applying

the same skill, intelligence and insight he brings to

everything he does. His comments kept me concise and on

target.

About the author:

W. M. (Bill) Huitt has been

involved in industrial piping

design, engineering and

construction since 1965.

Positions have included design

engineer, piping design

instructor, project engineer,

project supervisor, piping

department supervisor,

engineering manager and

president of W. M. Huitt Co. a

piping consulting firm founded

in 1987. His experience covers both the engineering and

construction fields and crosses industrial lines to include

petroleum refining, chemical, petrochemical,

pharmaceutical, pulp & paper, nuclear power, biofuel, and

coal gasification. He has written numerous specifications,

guidelines, papers, and magazine articles on the topic of pipe

design and engineering. Bill is a member of ISPE

(International Society of Pharmaceutical Engineers), CSI

(Construction Specifications Institute) and ASME

(American Society of Mechanical Engineers). He is a

member of three ASME-BPE subcommittees, several Task

Groups, an API Task Group, and sets on two corporate

specification review boards. He can be reached at:

W. M. Huitt Co.

P O Box 31154

St. Louis, MO 63131-0154

(314)966-8919

wmhuitt@aol.com

www.wmhuitt.com