ijsre vol. 1 (3), march, 2017 international journal of ... · taylor forge, “modern flange...

FLANGE DESIGN FOR FILTER VESSEL

Jay Kumar Patel1, Yashkumar Gandhi

2, Rahul Mishra

3, Amrezalam Chaudhary

4

Student, Mechanical department, Laxmi institute of Technology, Sarigam-Valsad. Gujarat

Corresponding Author Detail:

Jay Kumar Patel

Student, Mechanical department,

Laxmi institute of Technology,

Sarigam-Valsad, Gujarat.

Internal Guide Detail:

Mr. Vinit Patel

Assistant Professor, Mechanical department,

Laxmi institute of Technology,

Sarigam-Valsad. Gujarat.

ABSTRACT

A flange is a method of connecting the cylindrical shell and ellipsoidal head of the filter

assembly. It provides easy access for cleaning, inspection and modification. The objective of

this paper is to study the design analysis of ring flange for filter vessel. Through this we shall

get the proper dimension for the flange, bolt and gasket by following the standard design

procedure of flange design.

KEYWORDS: Flange, Ring Flange, Gasket, Bolt, Filter Vessel, Design Calculation.

INTRODUCTION

Filter is made by the assembly of pressure vessel, gasket, flange, nuts &bolt, piping, filter

element, nozzles, etc. We are designing the flange dimensions, so in this paper we will

discuss in detail about the flange, gasket and bolt design. Flanges are relatively simple

mechanical connectors that have been used successfully for high pressure piping applications.

They are well understood, reliable, cost-effective, and readily available. In addition the

moment carrying capacity of flange is significant compared to other mechanical connectors.

This is an important feature for the system that experience pipe-walking or lateral buckling

from temperature and pressure variation. Flanges can be designed to meet a wide range of

application requirement such as high temperature and corrosion resistance. Flanges, gaskets,

bolts and rings are used to seal, prevent the leakage and absorb vibration around the filter

vessel shell.

The filter discussed here are the industrial filter used in chemical, pharmaceutical,

biotechnology healthcare, etc for filtration, clarification, fermentation broth, cake forming,

etc. These filters need proper sealing so that it doesn’t fail or leak. So selection of material for

sealing and its designing needs to be done precisely. There are various types of flanges used

for joining pipes, vessels and other equipments. These are slip-on flange, threaded ring flange,

weld neck flange, ring flange, blind flange, lap type ring flange. Flanges are usually weld

onto pipes or screwed onto a threaded pipe end and then joined with bolt to make the

connection. For sealing purpose generally ring flange is used which is an easy way to join the

two parts of vessel. The ring flange uses gasket for sealing which prevents the leakage and

pressure drop at the joining surface. Here we will also discuss about the material selection of

the flange and gasket.

MATERIAL SELECTION

International Journal of Scientific Research in Engineering (IJSRE) Vol. 1 (3), March, 2017

IJSRE Vol. 1 (3), March, 2017 www.ijsre.in Page 64

A. Gasket Material

Gasket: A gasket is a device used to create and maintain a barrier against transfer of fluid

across the mating surfaces of mechanical assembly.

Generally there are 2 types of gasket:

1. Metallic- Eg. Lead, Copper, Aluminum, etc

2. Non-Metallic.- Rubber, Plastic, Asbestos, etc

Physical properties are important factors when considering gasket design and the primary

selection of a gasket type is based on the following:

• Temperature of the media to be contained

• Pressure of the media to be contained

• Corrosive nature of the application

• Criticality of the application

Figure-1 Gasket factor and minimum gasket seating force

B. Bolt & Fastener Selection

Metals used in fastener manufacture are elastic materials which will stretch under applied

loads and return to their original shape when the load is removed. However, if sufficient load

is applied, the material will stretch beyond its yield point and enter a plastic zone, losing its

elasticity and becoming permanently stretched. Further increased load on the material will

stretch it to its ultimate tensile strength at which point the material will fracture.

The materials of our particular concern are:

Steels - low tensile (mild steel)

- high tensile

- stainless steel

The major factor in determining the load a material can carry is its tensile strength, which is

related to its hardness.

1. Tensile Strength - is an expression of the maximum capacity of a particular material to

stretch under tension load, prior to failure.

2. Yield Stress (yield point) - is an expression of the theoretical point of stress (pressure)

beyond which the material loses its elasticity and becomes permanently stretched;

(realistically, a range rather than a single point).

3. Proof Load Stress - is an expression of the minimum stress a material must achieve,

prior to permanent elongation and, the stress which would be applied to test and re-



measure a specific fastener to prove it had not permanently stretched and that it will

carry the required load.

4. Ultimate Tensile Stress - is the theoretical minimum point at which the material will

fracture. It is expressed in the same terms as yield stress and proof load stress.

Figure-2 Dimensional data for bolt

C. Flange Material

Flanges shall be forged in accordance with material specifications ASTM A 105, A 181, A

182, A 350, A 387, A 694 and nickel base alloys. Forging to other standards may be used

only subject to the approval of the Purchaser. Slip-on flanges made from plate shall not be

used except for low pressure duties and for reducing flanges and then only subject to the

approval of the Purchaser. Flange material with yield strengths 331 mPa (48 ksi) and higher

shall be killed steel (A 350 gr LF-1 or gr LF-2). All flanges shall be furnished in a heat-

treated condition. Heat treatment shall consist of normalizing, normalizing and tempering, or

quenching and tempering.

Figure-3 Material Strength

DESIGN COMPONENT

Design pressure of a vessel is the gage pressure at the top of the filter vessel. This pressure is

used to determine the minimum wall thickness of the various pressure parts. The IS: 4503



species that the design pressure should at least 5% greater than the maximum allowable

working pressure. Usually a 10% higher value is used. The maximum allowable working

pressure is the gage pressure for a specified operating temperature that is permitted for the

service of the filter vessel units. According the IS: 4503, the shell and tube sides pressure

should be specified individually. The design pressure specification is at 250, 120 and 65ºC

for carbon steel, stainless steel and non-ferrous metals respectively. The maximum

permissible stresses for various vessel components should not be exceeded at the allowable

pressure. The design temperature is used to determine the minimum wall thickness of various

parts of the vessel for a specified design pressure. It is normally 10ºC greater than the

maximum allowable temperature

A. Gasket

A preliminary estimation of gaskets is done using following expression:

Residual gasket force = Gasket seating force – Hydrostatic pressure force

The residual gasket force should be greater than that required to prevent the leakage of the

internal fluid. This condition results the final expression in the form of:

(1)

𝐷𝑂𝐺=outside gasket diameter [mm]

𝐷𝐼𝐺=inside gasket diameter [mm];

Usually, 𝐷𝐼𝐺=𝐷𝑠+0.25

p=design pressure Y= minimum design seating stress

𝑚= gasket factor

Calculate the width of the gasket width,

𝑁= (𝐷𝑂𝐺−𝐷𝐼𝐺)/2 (2)

[The IS:4503 specifies that the minimum width of peripheral ring gaskets for external joints

shall be 10 mm for shell sizes up to 600 mm nominal diameter and 13 mm for all larger shell

sizes]

B. Bolt Design

The bolt design procedure is as follows:

The minimum initial bolt load (𝑊𝑚1) at atmospheric pressure and temperature is given by:

(3)

The gasket is compressed under tight pressure. The required bolt load (𝑊𝑚2) is given by:

(4)

Where, mean gasket diameter,

(5)

Total hydrostatic end force,

H=πG2p/4 (6)

Total joint contact surface compression load,

𝐻𝑃 = 2𝜋𝑏𝐺𝑚𝑝 (7)

Effective gasket seating width, 𝑏=𝑏𝑜 for 𝑏𝑜 < 14inch (6 mm) and 𝑏=0.5 𝑏𝑜 for 𝑏𝑜 > 14inch

(6 mm)

)1(

DOG

mpY

pmY

DIG

bGYwm 1

bGmppGHHw Pm

24

22

2

IGOG DDG



Basic gasket seating width 𝑏𝑜 = 𝑁/2 for flat flange

Determine the controlling load: the greater value of 𝑊𝑚2 or 𝑊𝑚1

Calculate the required (minimum) bolt cross sectional area, 𝐴𝑚 based on the controlling

load:

(8)

𝑓𝑏= allowable bolt stress at design temperature,

𝑓𝑎= allowable bolt stress at ambient temperature

Select the number of bolts (usually a multiple of 4 is used), bolt circle diameter (𝐶𝑏), root

diameter (𝑑𝑏𝑟) and bolt edge distance (𝐸)(follow IS: 4864-1968, to select bolts details).

From the number of bolts chosen, find out the actual bolt area (𝐴𝑏).

Always𝑨𝒃 should be greater than 𝑨𝒎.

C. Flange Design

Calculation of flange forces:

Hydrostatic end force on area inside of the flange is given,

𝐻𝐷=𝜋𝐵2𝑝4 (9)

Where, 𝐵 is the centre line to centre line bolt-spacing can be taken same as outside shell

diameter) Pressure force on the flange face,

𝐻𝑇=𝐻−𝐻𝐷 (10)

Gasket load under operating conditions,

𝐻𝐺=𝑊−𝐻 (11)

For gasket seating condition,

𝐻𝐺=𝑊 (12)

Calculation of flange moment: Calculate the summation of flange moments for the

operating condition,

𝑀𝑓=𝑀𝐷+𝑀𝑇+𝑀𝐺 (13)

Moment due to𝐻𝐷,

𝑀𝐷=𝐻𝐷h𝐷; where h𝐷= (𝐶𝑏−𝐵)/2 (14)

Moment due to 𝐻𝑇,

𝑀𝑇=𝐻𝑇h𝑇; where h𝑇= (h𝐷+h𝐺)/2 (15)

Moment due to 𝐻𝐺,

𝑀𝐺=𝐻𝐺h𝐺; where h𝐺= (𝐶𝑏−𝐺)/2 (16)

The flange bolt load, 𝑊= (𝐴𝑚+𝐴𝑏).𝑓𝑎/2 for gasket seating condition and,

𝑊=𝑊𝑚2for the operating condition

Calculate the flange moment for the gasket seating condition:

(17)

Calculate the flange thickness (𝑡𝑓) based on the maximum value for the gasket seating

condition or operating condition given by:

(18)

Which one is greater

a

m

b

mm

f

Wor

f

WA

12

Bf

YMor

Bf

YM

fa

f

f

fft

*

** 0

*

2

)(0 GCWM

b

f



𝑓𝑓 = allowable flange stress at design temperature,

𝑓𝑓𝑎 = allowable flange stress at ambient temperature.

You can determine Y as a function of 𝐾. The value 𝐾 is available in standard pressure vessel

design book.

𝐾=𝐴𝐵; where flange OD, 𝐴 =bolt circle (𝐶𝑏) diameter + 2𝐸

CONCLUSION

Through this paper one can prepare the accurate dimension for the flange and other parts. By

studying the designing flange we can design the flange as per our requirement and select the

appropriate flange. Without calculations one may select inappropriate flange which may fail

but through this we have the calculated design of flange. The designing is based on standard

and calculations so there are no chances of any failure of the part. Also the data match with

the various other author mentioned in references so they are more likely to be standard. Not

only design but the material selection can also be depending upon the area of application.

There are various materials of flange and gasket and its selection depends on its application

and their properties.

REFERENCES

1. Taylor Forge, “Modern Flange Design,” in Taylor Forge Engineered Sys. Inc., Paola,

Kansas, Feb. 2010.

2. ASME B16.5-2003

3. Dennis Moss, “Pressure vessel design manual”, third edition.

4. San Gabriel, “Mechanical engineering design criteria.”

5. ISO flanges and fittings

6. “Loads on Flange”, Pressure vessel engineering ltd., Ontario, Canada.

7. Larsen, H. A., G. R. de Hoff and N.W. Todd, “Modern Plastics”.

8. Press, I. D., “Material & Methodology”.

9. Basic gasket Application guide & material selection.

10. David P., Rowlands, BSC Eng, “The Mechanical properties of stainless steel”.


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