SPRING ENERGIZED SEAL
Spring Energized gasket are spring jacketed with other solid metal or soft material. Mostly spring jacketed with PTFE or Soft rubber used for low pressure and low temperature area. For high temperature and high pressure thin layer of solid metal is used. It holds high pressure with low torque. Spring helps to bounce back by which helps better sealing during high bolt relaxation and thermal fluctuation.
PTFE is resistant to most chemicals except chlorine trifluoride / fluorine gas at high temperatures and molten alkali metals. Excellent for light dynamic and static service. Low gas permeability. Good at cryogenic properties.
Jacketing metal like Silver, Copper, Aluminum, Soft Iron are used with SS spring as per the customer application. Metal like SS304, SS316L, Inconel 625 are used with Inconel X750 spring at nuclear application.