UCS-66 curve for normalized A-105
UCS-66 curve for normalized A-105
(OP)
I have a bolted cover made from normalized A-105 material at a MDMT of +4°C. (not B16.5-standard, acc. Appendix 2).
To determine impact requirements, I used UCS-66 curve B. Now I get a comment by my client that I should use curve D since the cover is normalized. Of course I like the idea of using curve D (no impact testing required anymore) but I can't find a justification in the code, not even for using curve C (since A-105 is not a fine-grain material).
Does anybody know a reason/justification to use curve D? Or should I tell my client that his comment makes no sense?
regards,
JLu
To determine impact requirements, I used UCS-66 curve B. Now I get a comment by my client that I should use curve D since the cover is normalized. Of course I like the idea of using curve D (no impact testing required anymore) but I can't find a justification in the code, not even for using curve C (since A-105 is not a fine-grain material).
Does anybody know a reason/justification to use curve D? Or should I tell my client that his comment makes no sense?
regards,
JLu





RE: UCS-66 curve for normalized A-105
thread292-201621: How Low Can You Go With SA-105 Flange?
Besides, you maybe don't have to need using of curve D.
As your cover is bolted – nonwelded (assuming it is flat) – your governing thickness for the impact test exemption curves is cover's measured thickness divided by 4 , acc. to UCS-66 (3)
In addition to the above don't forget looking for reduction in min. MDMT at FIG. UCS-66.1
Good luck
RE: UCS-66 curve for normalized A-105
Thanks for your comment.
Indeed it is a flat bolted cover (blindflange, t=150mm.) and it contains no welding except a welded set-on nozzle and weld overlay cladding.
When using curve B, exemption temp. is +10°C w/o UCS-66.1 reduction, and +8°C with reduction. Therefor impact testing is required here in my opinion since MDMT is +4°C... unless my client is right and curve C or D may be applied here for any reason. I just don't want to skip the impact testing, based on a incorrent client comment.
RE: UCS-66 curve for normalized A-105
Talk to your client and tell him it should be Curve B. He probably presumed that your bolted cover is a plate material.
Regarding MDMT reduction without impact test, did you use the correct coincident ratio as defined in UCS-66(b)(1)(b)?
RE: UCS-66 curve for normalized A-105
it is indeed curve b
note (2)all pipe, fittings, forgings not listed in C or D below (paraphrased)
RE: UCS-66 curve for normalized A-105
Regards,
Mike
RE: UCS-66 curve for normalized A-105
One "escape pathway" that I would consider is PWHT (as far as your overlay cladding may let you) acc. to UCS-68(c): "If PWHT ia preformed when it is not otherwise a requirement of this division, a 17 *C reduction in impact testing exemption temp. may be given to the min. permissible temp. from Fig. UCS-66 for P-No1 materials".