Impact testing of expansion joint root rings (Appendix 26 EJ)

[flexy]

I am presently designing a high pressure expansion joint per Appendix 26 of the 2004 Edition of the ASME Section VIII, Div.1 Pressure Vessel code.

I would like to use 1" diameter A36 bar for the root rings with 1/2" x 1" high thick SA 516 70 gussets welded to the root ring to provide the necessary addditonal area.

Appendix 26 definitely addresses the issue of stresses in the root rings. My questions are as follows:

1) Are the the root rings considered pressure retaining or load retaining? Is there a distinction in this case?
2) Are the root rings subject to the impact testing requirements of UCS-66?
3) We are using clamp-on (fastener) type rings. Does the fact that we are not welding through the full thickness of the 1" diameter bar make any difference?
4) I would like to meet an MDMT of -20F.

If anyone has any experience in this area, I would greatly appreciate your input.

 

[codeeng]

I would consider the root rings essential to the integrity of the expansion joint in which case UCS-66 would apply. Governing thickness would be per UCS-66(a)(1)(a) or (b) for butt or fillet welds respectively.

 

[flexy]

I tend to agree. I will change the root rings to 3/4" double XX pipe SA 53 pipe. This pipe falls under Curve B and allows me to avoid the impact testing issue altogether. I don't see a reason to impact test root rings. It's just a major waste of time and money.