Stainless Steel to Carbon Steel Flanges
Stainless Steel to Carbon Steel Flanges
(OP)
We have an application where we have a stainless steel tank with a flanged outlet (also stainless steel). We are looking to connect a carbon steel valve (flange) to the outlet.
I'm wondering if there are any (code/standards) rules prohibiting or advising against connecting stainless steel flanges to carbon steel flanges. I have looked in our Piping Handbook and ASME B31.3 and even a few catalogues but can't find anything prohibiting us from doing this. Can anyone confirm what the "rules" are for connecting stainless steel to carbon steel flanges? Do we need special gaskets or "extra thick gaskets", etc.? Can anyone point me in the right direction (maybe I missed something in the literature or the Code)?
I do not yet know the grade of stainless. The tank will be stainless because it will be installed in such a manner that there will not be much opportunity for removal in the future, and even "patching" or repairs would difficult.
Fluid is solids-laden water (i.e. essentially light to medium weight mud) with no particular corrosive elements (although the pH could range from mildly acidic to mildly basic). Temperature is ambient (+/- 20 degrees Celsius).
Much obliged for any assistance.
Cheers,
CanuckMiner
I'm wondering if there are any (code/standards) rules prohibiting or advising against connecting stainless steel flanges to carbon steel flanges. I have looked in our Piping Handbook and ASME B31.3 and even a few catalogues but can't find anything prohibiting us from doing this. Can anyone confirm what the "rules" are for connecting stainless steel to carbon steel flanges? Do we need special gaskets or "extra thick gaskets", etc.? Can anyone point me in the right direction (maybe I missed something in the literature or the Code)?
I do not yet know the grade of stainless. The tank will be stainless because it will be installed in such a manner that there will not be much opportunity for removal in the future, and even "patching" or repairs would difficult.
Fluid is solids-laden water (i.e. essentially light to medium weight mud) with no particular corrosive elements (although the pH could range from mildly acidic to mildly basic). Temperature is ambient (+/- 20 degrees Celsius).
Much obliged for any assistance.
Cheers,
CanuckMiner





RE: Stainless Steel to Carbon Steel Flanges
RE: Stainless Steel to Carbon Steel Flanges
Use insulation gaskets and bolts sleeves instead.
RE: Stainless Steel to Carbon Steel Flanges
RE: Stainless Steel to Carbon Steel Flanges
I think if you get corrosion, it'll likely be dissolved oxygen in the water going after the carbon steel. If you're concerned at all, though, go with the dielectric gasket kit. You get a gasket, sleeves for the bolts, and washers to go under the bolt heads and nuts.
RE: Stainless Steel to Carbon Steel Flanges
As a project/maintenance engineer for a major refinery, the question that needs to be discussed is if the product will corrode the CS valve body in such a way to generate a flaw or failure to this valve. Design pressure, temperature, flowrate (potential erosion?), pH level, other contaminants such as H2S, chlorides, ammonia, etc. need to be determined to prevent such an event.
Agree with the dielectric kit at the joint. Especially if the tank needs to be isolated and is cathodically protected.
In summary, it is not uncommon to bolt a SS flange to a CS flange to create a 'spec-break'. Keep in mind, the process conditions need to be determined and verifed so not to generate another problem.
RE: Stainless Steel to Carbon Steel Flanges
Cheers,
CanuckMiner