In the gasket industry, we deal with a lot of materials. There are gasketing materials for just about every need. There are some gasket materials that can survive thousands of degrees for a few seconds. There are some that can handle hundreds of degrees continuously for their service lives. High temperature gaskets are one of NEDCs core products. Throughout this entire blog post we will be using fahrenheit. In addition, we will be discussing elastomeric materials only. That is not to say that NEDC does not deal with graphite laminates, ceramic fiber blankets or other high temperature gasketing materials.
Types of High Temperature Gasket Material
The below reflects solid rubber options for these materials. However, sponge/foam options are available that offer similiar (usually less) resistance with different specifications.
EPDM Gaskets are not the most notorious for their high-temperature resistance. However, there are sometimes where an EPDM gasket may be used for its moderate heat resistance. EPDM Rubbers temperature range is usually from -60°F to +250°F. Common specifications for EPDM include AMS-3260, and others.
Typical temperatures of silicone gaskets range from -80°F to +425°F. However, on both ends of that range the service temperature of the gasket may be able to be extended. High-Temperature compounds of silicone rubber are available that can extend that range to +600°F continuously. The main specification for silicone rubber gaskets is A-A-59588, with ZZR-765 being the old specification.
Fluorosilicone Rubber is commonly used as a high-temperature gasketing material. It is found in applications where chemical/fluid resistance is required. It has a lot of similarites to silicone rubber. In general, fluorosilicone is known as silicone rubbers cousin that happens to have great fluid resistance. Fluorosilicone rubbers temperature range is generally -103 to +400-500°F. The main specification for fluorosilicone is AMS-R-25988.
Fluorocarbon Rubbers(aka FKM/Fluorel®, Fluoroelastomer Viton®)
Fluorocarbon Rubber is chemical resistant while also being heat resistant. Most gasket manufacturers know that Viton®/Fluorel®/Fluorocarbon Rubber are the same polymer except that Viton® is the registered trademark of DuPont and Fluorel® is by 3M Company. A common specification for Fluorocarbon elastomers is MIL-R-83248. The typical temperature range for Fluorocarbon is 0°F- 400°F.
Specifications of Requirements/Rubber
Rubber products are tested for heat resistance with heat air aging. The chart below details out air aging only. Air aging works by oxidizing the material faster. The relationship between increased temperature/oxidation speeds is close to linear. Phyiscal tests such as ultimate elongation, and tensile strength are done after aging. ASTM D573 is the recognized authority on air aging testing.
|Specification||Requirement||Polymer/Type of Rubber|
|AMS-R-25988 Grades 40-80 Type II Class 1||Aging 70 hours @ 392°F||Fluorosilicone Rubber|
|A-A-59588 Class 1A/1B/2A/2B||Aging 70 hours @ 437°F||Silicone Rubber|
|A-A-59588 Class 3A/3B||Aging 70 hours @ 392°F||Silicone Rubber|
|MIL-R-83248 Class 1(75 Hardness)||Aging 70 hours @ 518°F||Fluorocarbon/Viton® Rubber|
|MIL-R-83248 Class 1(90 Hardness)||Aging 70 hours @ 518°F||Fluorocarbon/Viton® Rubber|
|AMS-3260 (40-50 Hardness)||Aging 70 hours @ 212°F||EPDM(ethylene propylene terpolymer) Rubber|
These specifications detail a significant amount more of requirements, so be sure to review them individually.
For more information on high temperature gaskets, or you believe you have an application that could utilize a high temperature gasket please contact firstname.lastname@example.org.