asme vs ped.pdf

8/9/2019 ASME VS PED.pdf

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ASME Boiler and Pressure Vessel Code vs. PED and EN-standards

and nuclear safety requirements

Juha Purje

Inspecta Tarkastus Oy


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Pressure Equipment Directive (PED) or ASME


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The PED shall be applied to all pressure equipment to be used in

European Union except such pressure equipment that are critical tonuclear safety, they are excluded from PED

Article 1

Scope and definitions

…

3. The following are excluded from the scope of this Directive:

….

3.8. items specifically designed for nuclear use, failure ofwhich may cause an emission of radioactivity;

Such equipment should be designed and manufactured

in accordance with a specific code like

– ASME Boiler and Pressure Vessel Code Section III

– French RCC-M

– German KTA


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Nuclear island

Many pressure equipmentcri tical to nuclear safety

Conventional island

Equipment subject to PED


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Differences between European and American legal systems

concerning pressure equipment

Europe

• The PED (Pressure Equipment Directive) is the law for all European Union member

states

• The Essential Safety Requirements of PED are often rather general but some

requirements are very specific and those specific requirements shall be met.

• Pressure Equipment which conform to the harmonized standards is presumed to

conform to the Essential Safety Requirements of PED.

• To follow the harmonized standards is the preferred method to show compliance to thePED but they are not mandatory. The manufacturer may follow any set of rules or

standards for design and manufacturing on condition that the Essential Safety

Requirements are met.

USA• The ASME Boiler and Pressure Vessel Code is not a law but construction standard

generally accepted in USA and in many other countries.


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Most important harmonized standards

For products:

EN 13445:2009 Unfired pressure vessels – Parts 1 to 8

(with latest amendments)

EN 13480:2012 Metallic industrial piping - Parts 1 to 8

For welding procedures:

EN ISO 15614-1:2004 Specification and qualification of welding procedures for metallic

(with amendments) materials - Welding procedure test - Part 1: Arc and gas weldingof steels and arc welding of nickel and nickel alloys

For personnel qualification:

EN 287-1:2011 Qualification test of welders - Fusion welding - Part 1: Steels

EN 473:2008 Non-destructive testing - Qualification and certification of NDT

personnel - General principles


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PED and ASME Boiler and Pressure Vessel Code

There are many fundamental differences between PED and ASME Code.

The PED does not set any specific calculation equations, therefore the designcalculation may also be based on the equations of a ASME Code.

– The allowable stress specified in PED is often different from the allowable stress of

ASME Section II D ASME Code allows that the manufacturer may perform many activities by himself inaccordance with his quality manual, PED requires the involvement of a recognizedthird-party organisation in categories II, III and IV

The major differences between the essential safety requirements of PED and ASME

Code are – acceptable materials

– material properties and material certification

– approval of welding procedures

– approval of and welders and NDT-personnel

Other differences

– hazard analysis is required in PED

– pressure vessel test pressure

– PED requires that the manufacturer must prepare the operating instructions andsupply them with the pressure equipment to the user


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PED and ASME

ASME Code is mandatory in USA and Canada, a pressure vessel that will be used inUSA or Canada shall be code stamped. This requires the involvement of an AuthorizedInspection Agency and certification by an Authorized Inspector.

Many other countries have also accepted ASME Code. In these countries the ASMECode is applied in many different ways, only seldom to the full extent of ASME Code.

– the manufacturer does not have the ASME Certificate of Authorization

– there is no involvement of ASME AIA or AI, therefore no ASME stamp

– only design calculations are made in accordance with the ASME code, and this is

because the designer has suitable software.

There are many manufacturers and also some notified bodies who think that

1. The ASME Code has been widely used for many decades

2. Pressure vessels that have been designed and manufactured in accordance with

ASME Code have been proven to be safe

As they have been proven to be safe they meet the essential safety requirementsof PED

This is not true. The PED is European Union law that shall be followed to the letter.


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ASME material specifications are not harmonized material standards.The suitability of such a material shall be assessed as Particular Material Appraisal.

General rule :

Material that has been supplied in accordance with the minimum requirements of ASME-material specification does not meet the essential safety requirements of PED.

– A certificate of specific product control is not a mandatory requirement for many ASME-materials.

– The organization responsible for material certification may also be other than material manufacturer. – Material traceability is endangered because the ASME material specification may not require the

products to be marked with heat or batch number.

– Many ASME pressure vessel carbon steel specifications do not have any requirements for minimumimpact energy and even if it is specified the required value is less than 27 J.

– The tensile strength properties at elevated properties are not specified in the material specification.There are even some ASME material specifications that do not specify any minimum tensile strengthproperties.

– ASME-material specifications often allow such high amount of C, P and S that at the extreme high-quality welding would be difficult and impact strength non-existent.

If the pressure equipment manufacturer specifies an ASME material he shall set supplementaryrequirements when purchasing the material like:

– A requirement for the certificate of specific product control (EN 10204:2004 3.1 or 3.2)

– A requirement that only material manufacturer may certify the material

– A requirement of material markings to guarantee traceability with the certificate

– To specify properties that are stricter than the minimum requirements of ASME material specificationlike manufacturing methods or limitations for the amount of C, P and S


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ASME vs. ENChemical composition of some common carbon steels

Steel Rp (N/mm²) Rm (N/mm²) C max(%) P max(%) S max(%)

SA-105 250 480 - 0,35 0,035 0,040

SA-106 Grade B 240 415 - 0,30 0,035 0,035

SA-234 WPB 240 415 - 585 0,30 0,050 0,058

SA-333 Grade 6 240 415 - 0,30 0,025 0,025

SA-516 Grade 70 260 485 - 620 0,30 0,035 0,035

P280GH EN 10222-2 255 460 - 580 0,20 0,025 0,015

P265GH EN 10216-2 265 410 - 570 0,20 0,025 0,020

S235 EN 10253-1 235 360 - 500 0,16 0,030 0,025

P265NL EN 10216-4 265 410 - 570 0,20 0,025 0,020P295GH EN 10028-2 290 460 - 580 0,20 0,025 0,010


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Design calculation

The theory of stress and strain is similar everywhere but practical applications are

somewhat different depending of the code.

Minimum wall thickness of cylindrical shell is defined in the following equations

ASME Section VIII Div.1 EN 13445-3

t or e = minimum thickness

P = design pressure

R = inside radius of shell (R = Di / 2)

Di = inside diameter of shell (Di = 2•R)

E or z = weld efficiency factor or joint coefficient

S or f = stress value = maximum allowable membrane stress


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Allowable stress of ferritic steel

ASME Section VIII Division 1• Allowable stress is specified in ASME

Section II D Table 1A

• The maximum allowable stress value is

the smaller of

– the specified minimum tensile

strength at room temperature divided

by 3.5

– two-thirds of the yield strength attemperature

• The ASME-material specificationsspecify the minimum strength values atroom temperature only.

– The yield strength at elevatedtemperature is based on statisticalvalues, those values are notguaranteed minimum values

PED and EN-standardsThe smaller of the values

• 2/3 Re/t

, yield limit at design temperature

or

• 5/12 Rm/20 , ultimate strength at + 20 °C

Strength values at room temperature andat elevated temperatures are specified in

the applicable harmonized materialstandard. Those values are to beconsidered as guaranteed values buttensile testing at elevated temperature isnot mandatory


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Allowable stress of similar steels, ASME vs. EN

ASME Section VIII Div ision 1 steel SA-516 Grade 70EN 13445-3 steel P295GH EN 10028-2

0

50

100

150

200

250

300

350

Degrees C

N/mm2 Rp0,2 P295GH

P295GH PED

SA-516 Grade70

Rp0,2 P295GH 290 280 264 244 225 206 189 175 160

P295GH PED 191 191 176 163 150 137 126 117 107

SA-516 Grade70 138 138 138 138 138 138 135 129 101

20 50 100 150 200 250 300 350 400

Rm / 3,5

Rm / 2,4

N/mm²


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Yield strength of steel ASME SA-106 B (N/mm²) in accordance with Section II D

Table Y-1 vs. similar European steel specifications or previous approvals

0

50

100

150

200

250

300

A106B NGS 141 240 229 215 202 185 164 144 127 115 106

St 45.8 DIN 17175 245 195 175 155 135 130 125

P265GH EN 10216-2 265 235 226 213 192 171 154 141 134 128

A106B ASME Y-1 241 235 221 214 207 199 188 177 167 158

20 50 100 150 200 250 300 350 400 450


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ASME vs. PED in manufacturing

ASME PED

Authorized manufacturer required not required

Quality Manual required in modules D, E, H

Qualification and approval manufacturer Third party in categories

of welding procedures in accordance with II, III and IV in accordance

and welders ASME Section IX with EN-standards

Approval of manufacturer or Third party in categories

NDT-personnel NDT-subcontractor in III and IV in accordance

accordance with SNT-TC-1A with EN 473

Materials Listed in ASME Section II Listed in harmonized

or standards or

" recertification" particular material appraisal

Material certificates required for plates required for all materials

for other types of materials typically EN 10204 3.1 andthe marking as specified in material manufacturer shall

material standard is sufficient operate a quality system


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PED Annex I Essential Safety Requirements

3.1.2. Permanent joining

For pressure equipment, permanent joining of components which contribute to the pressureresistance of equipment and components which are directly attached to them must be carried out by suitably qualified personnel according to suitable operating procedures.

For pressure equipment in categories II, III and IV, operating procedures and personnel

must be approved by a competent third party which, at the manufacturer's discretion, may be:- notified body,- a third-party organization recognized by a Member State as provided for in Article 13.

To carry out these approvals the third party must perform examinations and tests as set out

in the appropriate harmonized standards or equivalent examinations and tests or must havethem performed.

3.1.3. Non-destructive tests

For pressure equipment, non-destructive tests of permanent joints must be carried out by suitablequalified personnel. For pressure equipment in categories III and IV, the personnel must be

approved by a third-party organization recognized by a Member State pursuant to Article 13.

A problem for manufacturers outside of European Union :The not ified bodies or third-party organisations are far away !


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Transfer of Welding Procedure Qualif ication Records

ASME IX:

When a manufacturer or contractor is acquired by a new owner, the PQRs and

WPSs may be used by the new owner without requalification, provided that the

new owner takes responsibi lity for the WPSs and PQRs and the source of thePQRs is identified as being from the former manufacturer.

EN 15614-1:

A qualification of a pWPS by a welding procedure test obtained by a manufacturer

is valid for welding in workshops or sites under the same technical and qualitycontrol of the manufacturer.

– Welding is under the same technical and quality control when the manufacturer

who performed the welding procedure test retains complete responsibility

for all welding carried out to it.


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Welder Qualification

The principles of welder qualification in ASME Section IX and EN 287-1 are

the same.

Each welder or welding operator shall be qualified for each welding processand material to be used in production welding.

There are some variations in the test pieces and in the range of

qualification.

EN 287-1 is a general welder qualification standard. It may be applied in

any industry, not only for welding pressure equipment.

The PED sets the additional requirement that the welder’s test shall be

witnessed and approved by a notified body or by a recognized third-party

organization.


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EN 287-1 Annex C (informative)

Job knowledge

The test of job knowledge is recommended, but it is not mandatory.

However, some countries can require that the welder undergoes a test of jobknowledge. If the job knowledge test is carried out, it should be recorded on thewelder’s qualification test certif icate.

This annex outlines the job knowledge that a welder should have to ensure thatprocedures are followed and common practices are complied with. The job knowledgeindicated in this annex is only pitched at the most basic level.

Owing to different training programmes in various countries, it is only proposed tostandardize general objectives or categories of job knowledge. The actual question used

should be drawn up by the individual country, but should include questions on areascovered in C.2, relevant to the qualification test of welders.

The actual tests of a welder’s job knowledge can be given by any of the followingmethods or combinations of these methods:

a) written objective tests (multiple choice);

b) oral questioning following a set of written questions;

c) computer testing;d) demonstration/observation testing following a written set of criteria.

The test of job knowledge is limited to the matters related to the welding process used inthe test.


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Expiration of Welder Qualification

ASME IX

The qualification of a welder is valid without time limit on condition that

– he has welded on that process during a period of 6 months

– there is no reason to question his ability to weld

EN 287-1

The welder's qualification test certificate is valid for a period of two yearson condition that the employer can confirm every six months that the

welder has been welding within the range of qualification with satisfactory

results.

Welder's qualification test certificates can be prolonged every two years

by the examiner or examining body.


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ASME vs. EN

Non-destructive testing of welds

The amount of non-destructive tests depends of the welding efficiency factor

used in design calculations

E or z ASME Section VIII Div.1 PED EN 13445-5

1,0 longitudinal transversal NDT and destructive longitudinal transversal

100 % spot tests to confirm 100 % 25 - 100 %

that no signif icant

defects exist0,85 spot spot

longitudinal transversal longitudinal transversal

m n. es - -

per 15 m 0 %

0,7 0 % 0 % 0 %


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Pressure test ASME vs. PED

ASME Section VIII Div.1

1,3 • maximum allowable pressure

– In most cases the specified

materials do not influence the

test pressure

PED and EN 13445-5

Higher of the values

− 1,43 • maximum allowable pressure

− 1,25 • maximum allowable pressure •

f a is the nominal design stress of thematerial at the test temperature;

f Td is the nominal design stress of thematerial at design temperature

Typical test pressure for a pressure vesselthat is designed to operate at elevatedtemperature is 1,5 – 2,0 • maximumallowable pressure


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ASME Boiler & Pressure Vessel Code vs.

Pressure Equipment Directive (PED)

• If a boiler or pressure vessel is to be delivered to European Union it

shall be manufactured in accordance with PED and CE-marked.

• If a boiler or pressure vessel is to be delivered to USA or Canada it shall

be manufactured in accordance with ASME Boiler & Pressure Vessel

Code and ASME-stamped.

• Both rules are in practice mandatory in their own area, there is no

possibility for a compromise. The manufacturer shall accept the

customer’s requirements.


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