Carbon steel & 316L Flange pressure rating

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We make products with 316L ANSI flanges. Rating is 100 bar at 38C, but they're applied in CS pipelines w/ 102 bar (1480 psi) rating. Anybody w/ experience of welding CS flanges onto CF3M castings? Any other ideas about how to get 1480 psi rating on the flanges?

Thanks,

Tim

 

[hacksaw]

what is the flange rating for the cs line?

 

[Scipio]

At 1480 psi and 100°F that'll be an ANSI 600# line...but I don't see the benefit in welding 316L stainless flanges onto a carbon steel pipeline. In addition to the flanges costing more than CS and requiring more specialized welding procedures & rods to weld stainless to carbon steel, wouldn't that just set up a galvanic corrosion cell across the butt weld?

 

[TBP]

With most piping systems, the flanges are the limiting factor for the maximum allowable pressure rating. You can install higher pressure flanges, but what are you flanging to? If it's a 150# cast steel valve, then you'll use Class 150 flanges. The fact that the piping can take far more pressure is not really relavant, at that point. You can always install something like Class 600, 900 or 1500 flanges, but the flanges themselves, and the components that will fit between them may be FAR more expensive than necessary for the service.