Compressor Casing

[ghoshtathagata2000]

Hi,

I am working on a project involving Refrigerant compressor with a vertically split casing.

Due to the temperature of the propane gas we have been requested to use stainless steel casing.

Can anybody please clarify whether the material recommendation applies to the outer or the inner casing part?

Thanks.

 

[JJPellin]

We have three large refrigeration compressors that use propane as the refrigerant. All of these are in our Alkylation units. The oldest of these machines has been in continuous operation since 1962. All of these machines tend to experience external corrosion because the suction to the compressor operates at a temperature below freezing. The outside of the cases is ugly and deeply pitted in some areas. But, even the machine running for almost 50 years has not had enough corrosion damage to require weld repair. I would not recommend stainless steel for this service based on the very limited information provided. I would prefer to concentrate on better coatings to resist the external corrosion. If the customer insists on SS, then I believe that the outer casing is the part that would need to be changed to stainless. Corrosion of the internal parts is not a problem since there should be no oxygen present.

Johnny Pellin

 

[dcasto]

There are some people that have a belief that you are cryogenic with C3 refrigeration at or near a vacuum. That is not true, carbon steel can be used.

I too have operated 10,000HP C3 refrigeration systems that had a -50F suction temp and the whole compressor case was covered in ice. As the C3 went through the compressor, the temperature increased and the ice stopped forming. At this point on the case, yes, the external corrision was evident, but with over 50 years of operation, it was not an issue.