Diaphragm Gasket For High Pressure Heat Exchanger

[pvskpang]

Appreciate if someone can tell me what is the diaphragm type gasket for the high pressure heat exchanger. The gasket is to be used for flange connection between the end cover plate to the channel flange. My limited knowledge for this type of gasket is that it is simply made of a thin sheet of metal to be fillet welded to the channel flange. My question is after being seal welded, how can the gasket being compressed with the bolt tightening.

Regards.

 

[gr2vessels]

The diaphragm is typically a corrosion resistant sheet metal welded on the channel end to prevent high pressure process fluid (and high temperature) to leak out, like in case of common gasket failure. It is locked in position by a bolted cover, that sandwiches the thin plate that is welded to the channel flange like a cover. The weld and the friction between the diaphragm and flanges generated by the cover bolting will seal the fluid within the channel. This diaphragm could last very long time, but could be a nuisance when welds crack and start leaking in extreme service applications.
There is no actual gasket compression involved. You simply need to tighten the bolting for pressure containment (end forces), not gasket seating forces. There is also a large volume of information about diaphragm gaskets on the internet.
Cheers,
gr2vessels