Combining stainless with carbon steel

Dear Folks,

we are frequently facing the problem of combining stainless steel with carbon steel materials in piping.

Sometimes we are using SS flange on carbon steel flange with SS bolts or in other situations mixed welds.

Does anyone have some resources what difficulties or problems may occur or what needs to be taken care of? Is there any code you are aware of where this mixing of materials is described?

Regards,
DS

Normally, I just use flange connection as a pipe spec break and put a washer under the stainless nut to avoid direct contact of stainless nut with CS flange.

I will not recommand to weld CS stuff with SS one.

Regards

Thanks for your reply!

Do you know if there is any section in ASME 31.3 or the EN standards giving requirements on combining different steel grades? What kind of washers would you recommend?

My concern is that with flanges that have not a plain surface (tongue and groove) corrosion occurs at the sealing surface and the connection starts leaking.

Best regards
DS

Google flange insulation kit

THX,

do you know any code or standard which gives some information on the topic of mixing materials or flanges in pipework?

Regards,
DS