B31.1 Bellows XJts - Complete Disengagement

B31.1 2006, para. 101.7.2, states "...corrugated bellows...may be used if...their design prevents the complete disengagement of working parts while in service."

I have interpreted that to permit the use of an externally pressurized bellows joint in which there are plates at the end of the bellows which would prevent the joint from completely disengaging.

Do tied universal bellows joints comply with this B31.1 requirement? Some recent code interpretations have not addressed this...are there older code interpretations that have?

I have an outdoor (-20 to +110 Deg. F ambient range) application for saturated 250 psig steam. I have rarely installed bellows type joints, and in this application, a tie-rod universal joint would be an option to reduce anchor loads and "column" buckling. I want to be open minded to the use of this type joint (with Inconel 625 bellows) if it meets code. The client has already said bellow joints would be an acceptable option.

Ken A. Nisly-Nagele, P.E.
Mechanical Engineer
Applied Engineering Services, Inc.
Indianapolis, Indiana

[Non-text portions of this message have been removed] Received on Sun Sep 09 10:02:00 2007