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 ?





RE: Pressure transmitter with diaphragm seal for very high salinity application
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
The 600# CS flange, Hastelloy C diaphragm and SS wetted body is Fig C construction, where the diaphragm extends over the wetted gasket surface separating the body from process exposure. As long as the diaphragm material holds out, the process does not contact the SS 'body'.
I suspect the diaphragm failure resulting in loss of pressure measurement/indication would be a higher risk than serious corrosion at the gasket that could weaken the SS 'body'.
Flanged flush seal materials Table, Smartline remote seals
Flanged flush seals figure C
RE: Pressure transmitter with diaphragm seal for very high salinity application
In your statement "I suspect the diaphragm failure resulting in loss of pressure measurement/indication would be a higher risk than serious corrosion at the gasket that could weaken the SS 'body'." In which case and why do you suspect that ?
RE: Pressure transmitter with diaphragm seal for very high salinity application
I was thinking the extended diaphragm covered the SS area, but if SS is listed as wetted, then it is.
I think you're stuck with Hastelloy/Hastelloy unless another vendor does it slightly different.
Dan
RE: Pressure transmitter with diaphragm seal for very high salinity application
RE: Pressure transmitter with diaphragm seal for very high salinity application
RE: Pressure transmitter with diaphragm seal for very high salinity application
But the question remains. why would some body purchase a SS body if his diaphragm should be Hastelloy-C ? The body is considered wetted part as well and it's corrosion (corrosion at the contact circle between the body and the diaphragm) can result in diaphragm failure and loss of containment. Any idea ?
RE: Pressure transmitter with diaphragm seal for very high salinity application
The flange can be CS but stainless will look better 10 years down the road.
What are the pipe flanges?
RE: Pressure transmitter with diaphragm seal for very high salinity application
RE: Pressure transmitter with diaphragm seal for very high salinity application
The body is declared 'non-wetted' in figure C.
Go Figure.
RE: Pressure transmitter with diaphragm seal for very high salinity application