As certain machines work at very high heat and have hot liquids that flow through them, a high temperature gasket is required in order to withstand the heat and to continue to supply a seal.
High temperature gaskets are commonly used in the automotive, aerospace and industrial manufacturing industries, and certain kinds, such as Teflon coated gaskets, are regularly used in the food and medical industries because Teflon is an inert substance.
In order for a gasket to seal properly, it has to have the appropriate amount of torque to compress the seal to a surface and to maintain the pressure of the load on the flange bolts and the gasket itself.
The amount of torque needed depends on factors such as the type of gasket being used and the pressures and temperatures the gasket will be subject to. Though these gaskets can also withstand below freezing temperatures, they specialize in withstanding heat; some have a maximum heat range (in Fahrenheit) in the low hundreds while others are able to reach the high thousands.
Types of high temperature gaskets include spiral wound, metal jacketed and Teflon coated gaskets. Spiral wound gaskets consist of a round metal strip, which is often made from materials such as stainless steel, nickel or titanium. The strip is wound with a sealant or filler, which is commonly made of graphite. The gasket is then put into a steel ring and fitted with the flange bolt on the machine and adjusted for bolt load.
Depending on the materials used, these gaskets can withstand temperatures from cryogenic to around 6,000° F.
Metal jacketed gaskets have a metallic casing such as soft iron, brass or copper-on the outside and a filler like graphite or a ceramic material on the inside.
The materials used depend on the pressure and temperature needs. These gaskets can withstand temperatures from about 660° to 1,115° F. While Teflon coated gaskets cannot withstand higher pressures the way metal or non-asbestos gasket materials can, Teflon can withstand many industrial chemicals that other materials cannot.
Teflon often coats a fiberglass o-shaped ring and can withstand temperatures of up to around 500° F. These types of gaskets can be used in applications for various industrial machines including ones that help build cars and aircraft.