Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
(OP)
I have a 3" pipe spool with a carbon steel WN RF CL150 flange (ASTM A105) and it needs to be bolted to a mating CL150 flange made of stainless steel (ASTM A182).
Are there any practices that I should be aware of, to prevent galvanic corrosion, when bolting the two dissimilar flanges together?
Thanks.
Are there any practices that I should be aware of, to prevent galvanic corrosion, when bolting the two dissimilar flanges together?
Thanks.





RE: Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
First of all the two flange faces do not and will not touch.
You would only need to consider the CS nut touching the back face of the SS flange and the CS bolt coming in contact with the ID of the SS Bolt Holes.
This is normally taking care of by using nonmetallic Insulating Gasket Sets (go here for example:http://www.apsonline.com/gasketkits)
Sometimes its possible to do all the right things and still get bad results
RE: Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
RE: Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
RE: Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
Key is what is the relative mass between the two different materials and where does the electrolyte come from. Massive amount of C Steel and a single Stl Stl flange - not much issue. Think of how many instrument connections you see and there are no insulating gaskets. Other way around - big issue
Be careful about internal corrosion with conductive fluids.
Isolating sleeves and washers with bolts are notorious for breaking down over time or being damaged during installation. You sometimes need thinner bolts as well which causes all sorts of grief.
But work out whether you have an electrolyte or not first.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
In general it is always recommended to have same materials installed when it comes to flanges and pipes. Furthermore, in the field I am in, stainless steel flanges are a must and the only thing that will really last.
RE: Mating Carbon Steel Pipe Flanges to Stainless Steel Pipe Flanges
You didn't post the service (the fluid flowing in the pipe), or the external corrosive environment, whether or not the pipe is insulated and/or heat traced etc., so we can't advise you at all whether your best option is a) do nothing special, other than perhaps painting the carbon steel pipe and flange, or b) use a flange isolating kit and a NONCONDUCTIVE gasket, i.e. NOT a spiral wound gasket!.