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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-
International Journal of Scientific Research in Engineering (IJSRE) Vol. 1 (3), March, 2017
IJSRE Vol. 1 (3), March, 2017 www.ijsre.in Page 65
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
International Journal of Scientific Research in Engineering (IJSRE) Vol. 1 (3), March, 2017
IJSRE Vol. 1 (3), March, 2017 www.ijsre.in Page 66
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
International Journal of Scientific Research in Engineering (IJSRE) Vol. 1 (3), March, 2017
IJSRE Vol. 1 (3), March, 2017 www.ijsre.in Page 67
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
International Journal of Scientific Research in Engineering (IJSRE) Vol. 1 (3), March, 2017
IJSRE Vol. 1 (3), March, 2017 www.ijsre.in Page 68
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”.
International Journal of Scientific Research in Engineering (IJSRE) Vol. 1 (3), March, 2017
IJSRE Vol. 1 (3), March, 2017 www.ijsre.in Page 69
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