im about to make a DP for a friends, and i was wondering if i can weld SS pipe to a cast iron flange?

 

its going to be tig welded.

 

you *could* do it, but my only warning is this. Cast REALLY doesn't like to be welded. It can be done successfully, but its hard. You have to preheat the cast, it has to be immacculately clean, you have to use the right filler metal, you have to hammer the weld sometimes, and you have to post heat or slow cool the cast. It is very picky as to what it will let you do to it. Considering that it is just a cast iron flange, i think you will be fine using nickel rod and tig welding it, it still has to be treated good though. Anything with a cast tube doesn't tend to go well

they crack often.