UCS-66 curve for normalized A-105

[JLu]

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

 

[Shmulik]

Jlu,

thread292-201621

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

 

[JLu]

Shmulik,

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.

 

[doct9960]

JLu,

Does anybody know a reason/justification to use curve D? Or should I tell my client that his comment makes no sense?

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)?

 

[vesselfab]

to be curve D, the material has to be specifically listed there

it is indeed curve b
note (2)all pipe, fittings, forgings not listed in C or D below (paraphrased)

 

[SnTMan]

JLu, It is possible the SA-105 is fine grained, making this a Curve C material. You might check your MTR. I agree you won't get it to Curve D.

Regards,

Mike

 

[Shmulik]

Jlu,

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".