Expansion Joints

[Cluain]

Can one use a welded expansion joint per ASME VIII-I UG 11 (c), or does one have to use APPX 26.
Also, can one use Fig, 26-13(C) for the attachment of a billow to collar for lethal service.
Opinions are great, but please reference code paragraphs when responding.
Thanks!!!

 

[gr2vessels]

cluain,
I assume you are considering the pressure vessel and heat exchanger's expansion joints, not the duct or piping ones.
UG 11(c) does not exclude Appendix 26 and viceversa, hence "or" doesn't make sense. You can use the Expansion Joints that were designed and fabricated per Appx 26, in conjuction with UG11(c). Please also note that UHX 16 refers you to the Appendix 26 with particular attention to Clause 26-4.1(f), U2(g) and in conformance with UW2(a), you can use bellows fitted with butt welding "billows" at the ends. Hope this helps,
cheers,
gr2vessels

 

[SnTMan]

Cluain, I agree with gr2vessels regarding UG-11 vs Apx 26.

As for the weld detail, UW-2(a)(1)(b) states pretty clearly all category B joints are to be butt-welds for lethal service. I don't think I would care to build one this way though. I would much prefer the joint be lapped over a weld end, and fitted with a collar, like Fig 26-13(c).

I am having a hard time imagining a suitable butt-weld detail which could be reinforced and still leave the weld exposed for future inspection.

Regards,

Mike

 

[Cluain]

Lads,
I agree with your summation. I do believe that the expansion joint billows needs to be attached with either a type 1 or type 2 joint as per UW 2 requirements for lethal service and category (B) joints.
I have not read Appx 26 in its entirety, but I think it’s a safer way to proceed rather than using UW 11. One does have the advantage of having a U2pdr in hand when utilizing App 26.
Thanks for being specific fellas!!!!

 

[LSThill]

Cluain (Mechanical)

Please review Fluid Service comments by John Breen 6 Oct 07 15:42 thread292-198830. CAT M "lethal service"


L S THILL