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Complicated Gasket selection made easy in 10 simple steps

Operating Conditions

1. Operating Temperature and Max Temperature

A combination of various materials is used to manipulate the properties of the Gasket.

Refer to Table 1: Material Application Temperature Limits

2. Operating Pressure and Max Pressure

Operating pressure is the pressure at which the system typically operates under average conditions.

Max pressure is the system design pressure that considers system upsets, excursions, and pressure spikes.

3. Fluid Compatibility/ Flowing Media

The primary purpose of the Gasket is to contain fluid (gas or liquid) in a mechanical joint. Therefore, the Gasket material should be compatible with the fluid and must not react with each other.

4.Thickness

Gasket thickness does not alter in metallic or semi-metallic gaskets; it depends on manufacturing or handling constraints.

For non-metallic Gasket, the thicker the material, the lower the pressure and temperature ratings. The thickness should be determined for the soft Gasket based on surface irregularities. Lesser the thickness better the sealing ability

5.Stress

There is always minimum gasket stress required to compress the Gasket for better sealability; it should not go beyond the maximum stress to avoid permanent deformation of sealing material. The same should be considered while selecting the appropriate Gasket or must be provided to the gasket manufacturer.

Flanges

6.Flange Type

  • Raised Face Flanges
  • Flat Face Flanges
  • Tongue and Groove Flanges
  • Male and Female Flanges
  • Flat Face and Groove Flanges
  • Ring Joint Flanges

7.Flange Surface Finish

Based on the surface finish of the flange, the gasket surface can be adjusted or corrugated to the surface leakproof

8.Flange Compatibility with Gaskets

Electrochemical (or galvanizing) corrosion is an electrochemical process between dissimilar metals that occurs in the presence of the conductive fluid. Also, Gasket should not damage or corrode the flange.

Fasteners

9. Bolts/Nut/Washers

Considering the permissible pressure range is applied by the Bolt, Nut and Washer combination. The Fastener tightening does not achieve the maximum stress required by the Gasket to seal the failing seal system. Also, sometimes the torque required for minimum tightening of bolt nut combination goes beyond the maximum permissible stress. It is always suggested to provide data of the standard fasteners to the gasket manufacturer, or the same is considered while selecting a  Gasket.

Dimensions

10. Standards or Custom Dimension

The proper standard of the flange dimensions should be considered; often, there is confusion about the flange standards. If the flange is customized, then outer diameter, pitch circle diameter and inner diameter need to be considered.

Manufacturing capability should be considered when selecting the material of Gasket.

 

To make your selection task easy, we have developed the tool.

Gasket Material Selector

If you are not a member yet, click on request an account and follow the procedure.

Any more help or technical solution is required, you can reach us at sales@pilotgaskets.com

 

Source: Fluid Sealing Association – Gasket Handbook 1st Edition

Table 1: Material Application Temperature Limits

Material

Minimum Temperature

Maximum Temperature

Flexible Graphite 1
Non-Oxidation Inhibited
Oxidation Inhibited

-240oC (-400oF)
-240oC (-400oF)

400oC to 450oC
(752oF to 842oF)
500oC to 525oC
(932oF to 977oF)

Compressed Elastomer- Based Fiber2

-40oC to -30oC
(-40oF to -22oF)

204°C to 400°C
(400°F to 750°F)

Beater Addition Elastomer-Based Fiber 2

-40oC to -30oC
(-40oF to -22oF)

180°C to 400°C
(350°F to 750°F)

Polytetrafluoroethylene (PTFE) 6

 

 

Virgin PTFE

-210°C (-346°F)

260°C (500°F)

Expanded PTFE

-210°C (-346°F)

260°C (500°F)

Filled PTFE

-210°C (-346°F)

260°C (500°F)

Phyllosilicate8

-240oC (-400oF)

454oC to 982oC
(850oF to 1800oF)

Vegetable Fiber

-30°C (-22°F)

121°C (250°F)

Rubbers/Elastomers 4 and 7

 

 

Natural (NR)

-51°C (-60°F)

104°C (220°F)

Nitrile (NBR)

-30°C (-22°F)

100°C (212°F)

Hydrogenated Nitrile (HNBR)

-30°C (-22°F)

149°C (300°F)

Ethylene-Proplylene (EPDM)

-51°C (-60°F)

149°C (300°F)

Fluorocarbon

-15°C (-5°F)

199°C (390°F)

Chloroprene (CR)

-40°C (-40°F)

121°C (250°F)

Silicone (VMQ)

-59°C (-75°F)

232°C (450°F)

Fluorosilicone (FVMQ)

-59°C (-75°F)

232°C (450°F)

Styrene-butadiene (SBR)

-46°C (-50°F)

100°C (212°F)

Cork Composition

-30°C (-22°F)

121°C (250°F)

Metals

Common Brasses

-269°C (-452°F)

260°C (500°F)

Copper

-269°C (-452°F)

316°C (600°F)

Aluminum

-269°C (-452°F)

427°C (800°F)

Stainless Steel, Type 304

-254°C (-425°F)

760°C (1400°F)

Stainless Steel, Type 316

-254°C (-425°F)

760°C (1400°F)

Stainless Steel, Type 317

-198°C (-325°F)

760°C (1400°F)

Stainless Steel, Type 321

-254°C (-325°F)

760°C (1400°F)

Stainless Steel, Type 347

-254°C (-325°F)

871°C (1600°F)

Soft Iron, Carbon Steel

-29°C (-20°F)

538°C (1000°F)

Alloy 20 (UNS N08020)

-198°C (-325°F)

871°C (1600°F)

Titanium

-59°C (-75°F)

1093°C (2000°F)

Nickel

-198°C (-325°F)

760°C (1400°F)

Monel® 400 (UNS N04400)

-198°C (-325°F)

816°C (1500°F)

Inconel® 625 (UNS N06625)

-254°C (-325°F)

1093°C (2000°F)

Hastelloy® (UNS N10276)

-254°C (-325°F)

1093°C (2000°F)