For gaskets, “If you can’t stand the heat, stay out of the kitchen,” becomes, “If it can’t stand the heat, stay out of the joint.” Using the wrong gasket material in a high-temperature application is the fastest route to failure. It could also be expensive and even dangerous. Here’s some advice for choosing heat resistant gaskets and gasket material.
Heat Resistant Gaskets: Know the Application Conditions
When choosing gasket material always consider temperature, environment, media and pressure (remember them with the mnemonic TEMP), and temperature comes first. It relates mainly to the media that’s being sealed-in, which could be hot liquid, steam or high temperature gas, (exhaust gases for example,) but it can also refer to the temperature where the gasket is installed and used.
Heat and Gasket Materials
Elevated temperatures affect gasket materials in different ways, and the threshold at which the changes kick in varies widely too.
- Rubbers (NBR, SBR,) harden and become brittle at temperatures over 300°F (149°C). They can also oxidize, which has the same effect.
- EPDM and silicone will go to higher temperatures before losing the ability to seal. An upper limit for EPDM is around 400°F (204°C) while heat-resistant grades of silicone will go to 500°F (260°C).
- For temperatures up to 600⁰F (316⁰C) PTFE is a good choice. It also has good chemical resistance, which makes it suitable for many process plant applications.
- Compressed non-asbestos gaskets are an exception to the point about With an SBR or NBR binder that fixes a matrix of aramid fibers, these are suitable for 750⁰F (399⁰C) and some grades will go higher. (These have good resistance to steam, oil and fuels, but always check your application with us before buying!)
- For resistance to really high temperatures, graphite is the answer. Available laminated, as a foil and also in spiral-wound gaskets, this will seal at 1,000⁰F (538⁰C) and higher. Other options are ceramic fiber (which tends to be brittle,) and fiberglass.
High temperatures will lead to sealing failure faster than almost any other factor. Always consider temperature when selecting gasket material, and ask for heat-resistant gaskets whenever temperature is a concern.
Contact Hennig Gasket & Seals for a free quote.