PTFE - A Sealing Option with Many Advantages!
The most common O-ring materials are rubber or elastomeric compounds, but certain operating conditions and hardware configurations merit the use of PTFE.
PTFE offers many distinct advantages over elastomers, including corrosion resistance, chemical compatibility, massive temperature range (-325° to +500°F), excellent electrical properties, and virgin PTFE is FDA, USDA and 3-A dairy compliant and has an almost unlimited shelf life.
There are several considerations before making the switch to an O-ring made of PTFE. Virgin PTFE hardness is 55 Shore D, which is much harder than a typical Nitrile O-ring at 70 Shore A. The higher hardness of the PTFE material won't conform to mating hardware surfaces as easily as a lower hardness material.
Also, unlike rubber, compression set occurs after only one use, so PTFE would not be recommended for a seal that needs to be opened and closed frequently.
Overall, PTFE seals are high performing, versatile and they are commonly used in many industries, including medical, oil and gas, food and beverage, and pharmaceutical.
PTFE joint sealant is a cost-effective and handy replacement for custom-made gaskets in most flat flange applications. Some people call it "gasket on a roll", and almost everyone is familiar with PTFE thread sealant tape.
Consider all the factors before switching to a PTFE seal. It may be a viable alternative to highly expensive special elastomer compounds, or it may be the wrong choice when all factors are taken into account.