task-line gasket

[keller529]

i posted in M.E section but not any replies there. does anyone have experience using the task line gasket? it's a ptfe gasket with a metal ring inside and the teflon is molded around it. it gives the ptfe better creep and relaxation characteristics but makes the gasket nearly blow out proof as i understand. im trying to see how it compares to something like a durlon 9000, but mostly just looking for anecdotal experience

 

[A8yssUK]

Generally, they are frankly a bit of an oversell, a decent sheet PTFE is 99 times out of 100 more than adequate for blow out resistance. However if creep resistance and blow out resistance are your bugbear then perhaps check out expanded PTFE sheets like Gore GR, Teadits 24SH or even Durlons own 9600. They have higher tensile stresses, better relaxation properties and better installation resilience than other PTFE sheet materials. (Full disclosure, I work for Gore Sealants).

 

[shvet]

I have the extensive experience in the past with very similar design with asbestos instead of metal core ring. The most critical parts were:
- PTFE is the material having no memory (in contrast to metal or rubber), that means a minor decompression or compression/decompression cycling (e.g. process temp fluctuations) leads to lost of tightness and leak
- PTFE shell is made by a sort of welding of inner diameter of 2 PTFE rings, this "weld" (I do not know the correct name of this detail) is prone to destruction by a process fluid and leaking through voids between the gasket and the shell
- PTFE is a soft material and is easy to be flattened and exposes an inner material to a process fluid (pipe metal or gasket metal in your case)
Bearing in mind that a lined spool max length is limited to 6' (if recall ASME correctly) the amount of these leaks was tremendous. The personnel spent most of their working time on endless fixing those instead of major issues.

This is not clear to others but the gasket in the picture above is not PTFE gasket. This is a metal gasket with a PTFE shell.