Connecting Flanges with Different Facings

[magreen]

Is it allowed by ASME B16.5 to connect two flanges of different facings, say, Flat Face to Raised Face or to Lap Joint? If it is allowed only under some specific conditions, what are those conditions? If not allowed what is the technical reason for that?

I appreciate any advice.

 

[moltenmetal]

Lap joint IS raised face, so no issue mating to other raised face flanges.

Flat face to raised face is a serious issue if the flat face is gray cast iron such as on a pump or large valve. It is no problem with steel or stainless steel flanges unless your fitters are complete morons, which they may be, in which case a limiter ring on the bolt circle to avoid distortion due to over-torquing is a good idea. That way they'll wreck the studs instead of the flat faced flange.

The other facings- RTJ, large male/female, o-ring grooves etc. are case by case. Some can be solved with fancy gaskets, others are a pure and simple no-no that you will regret not solving properly up front.

 

[jte]

magreen-

You'll get a more focused audience in the Pipelines, Piping, and Fluid Mechanics forum.

http://www.eng-tips.com/threadminder.cfm?pid=378.