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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.
6.Flange Type
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.
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.
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.
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 |
-240oC (-400oF) |
400oC to 450oC |
Compressed Elastomer- Based Fiber2 |
-40oC to -30oC |
204°C to 400°C |
Beater Addition Elastomer-Based Fiber 2 |
-40oC to -30oC |
180°C to 400°C |
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 |
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) |