Flexible graphite and PTFE are commonly used in cryogenic sealing.
by Chett Norton, Triangle Fluid Controls Ltd. and Ron Frisard, A.W. Chesterton
July 13, 2018
  • Bundesanstalt für Materialforschung und –prüfung (BAM): Gaseous & Liquid O2 Drop Test
  • American Society for Testing and Materials (ASTM): G86 LOX mechanical impact testing
  • Det Norske Veritas and Germanischer Lloyd (DNV-GL)

Another issue—the loss of bolt load in the joint when it has a thermal cycle—can compromise the joint and cause a leak. Making sure the joint has enough stored energy from bolt load analysis is essential and, in some cases, the use of flange disc spring technology to supplement joint travel is necessary.

Lastly, although gasket material selection in both LNG and cryogenic sealing applications is important, it cannot be stressed enough that proper installation remains a critical part in the bolted joint flange assembly (BJFA). Using the recommended torque value from the manufacturer while using a proven installation method such as ones listed in ASME PCC-1, Appendix F, should always be the first step.

Please make sure that the installation is completed at ambient temperature and, just like hot-torquing, retorquing at low temperatures is never recommended.

It is good to know that sealing technology advances to resolve new challenges as the world moves toward energy efficiency and continues to convert its energy sources.

Next Month: Bolt Lubricant

We invite your suggestions for article topics as well as questions on sealing issues so we can better respond to the needs of the industry. Please direct your suggestions and questions to sealingsensequestions@fluidsealing.com.

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