“What is the difference between \"expanded polytetrafluoroethylene\" and \"polytetrafluoroethylene\"?
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Recently, I read an article about gaskets for lubricant pipeline flanges, which recommended the use of \"polytetrafluoroethylene gaskets\"; for flanges in oil pipelines under high pressure, it was suggested to use \"expanded polytetrafluoroethylene gaskets\". Question: What is the difference between \"expanded polytetrafluoroethylene\" and \"polytetrafluoroethylene\"?
Gaskets made of PTFE material exhibit significant creep and cold flow properties, especially in high-temperature and high-pressure environments as well as on seals with large diameters. Expanded PTFE can to some extent overcome the creep and cold flow issues associated with pure PTFE; however, there are both differences and similarities between the two, and the choice between them depends on the specific operating conditions.
As a supplementary point, whether it is pure PTFE gaskets or expanded PTFE, 1) they are not recommended for use in applications involving pressures above 300 pounds, and 2) they are also not recommended for use in applications with pressures above 200 pounds.