Hi all,

For those of you who have worked with pressure balance expansion joints that uses an elbows instead of tees. Must the Elbow be drilled through so that the balancing bellow is also subjected to the internal pressure?

I was told that it must be drilled though so it can experience the same thrust load as the in-line bellow. But EJMA does not specify that it needs to be drill through and I do think that the tie-rods are the ones that transfer the thrust loads onto the balancing bellow. So I don't believe that drilling through is necessary, but please do share your experience with these types of bellows.

And in terms of code, what do the designer usually do to ensure that these expansion joints can be used in a B31.3 system as these are unlisted components. From b31.3 para 304.7.2, it feels like the most practical option is to do a FEA / proof test as everyone has their own definitions of "extensive, successful operations", but again, please share what you have experienced?

Thank you all!