O Rings in Temperature from 120 Deg Centigrate to 350 Deg Manufactured Mainly from Silicon, Viton, Neoprene, Hypalon Depending upon the applications correct material is choosen to give the desired results. Choosing the right material for a high temperature seal is very important . Viton® seals resist hardening and embrittlement for more than 10,000 hours in air up to 204°C, and they withstand surges up to 315°C. Also, with the thermal capability of Viton®, some users can increase operating temperatures to improve productivity or gain other production advantages.