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Pressure transmitter with diaphragm seal for very high salinity application

Pressure transmitter with diaphragm seal for very high salinity application

Pressure transmitter with diaphragm seal for very high salinity application

(OP)
I have to use a pressure transmitter with a flanged (Raised Face rating 600#) diaphragm seal on a the on the outlet of a well. The material engineer specified that the wetted parts shall be Hastelloy-C, so i chose the diaphragm material to be hastelloy-C. What should the diaphragm seal flange material be? should it be Hastelloy-C as well ? or is it ok to use a carbon steel flange, and rely on the gaskets to make the process fluid does not contact the flange ?

Also note that i can not use 316 SS flange because this will lead me to increasing the rating to 900# instead of 600#, as piping is working at the edge of rating 600# for carbon steel.

With regards to carbon steel, i am worrying about galvanic corrosion between the seal carbon steel flange and the hastelloy-C flush ring.
What do you think ?

RE: Pressure transmitter with diaphragm seal for very high salinity application

Why not use a rubber lined/coated carbon steel flange? That would be my first choice. Definitely you need to select a suitable material for the diaphragm flange. Do not rely on the gasket only! WIKA offers even coated pressure transmitters. Not sure if they are cheaper than Hastelloy-C ones but it might be worth to check.

RE: Pressure transmitter with diaphragm seal for very high salinity application

(OP)
Thank you very much micalbrch for your reply.

In general, is it a standard solution to use a rubber coated diaphragm seal flange or a hastelloy-c flange? most catalogues like emerson specify hastelloy-c for their diaphragm and 316 SS or CS for the flanges. why would some one select CS or 316 SS flanges with hastelloy-c seal if the process fluid requires the use of hastelloy-c wetted parts ?

RE: Pressure transmitter with diaphragm seal for very high salinity application

I cannot answer that question but carbon steel or stainless steel are not an option for your application as far as I understand it. So, you must either go with Hastelloy-C or find an alternative. To use carbon steel or stainless steel without any protection and just rely on the gasket sounds a bit strange for me.

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