Charpy on MTRs

[Hurmanetar]

I have SA-516-70N plate that says on the MTR it was charpy impact tested at -30F.
MDMT is -40 F.
Based on my design calculations, charpy impact testing is not required for my MDMT of -40F.

In my opinion, there should be no problem using this plate for -40 F but I'm being told that since the MTR says it was tested at -30 F, the plate is not good for -40 F. This doesn't make sense since the plate would be good for -40 F if it had no charpy test shown on the MTR.

Am I wrong?

 

[Afox88]

Assuming Section VIII-1, per UCS-66 SA-516-70 would fall under Curve B which can only be impact test exempt up to a temperature of -20F. If you need the plate to handle anything less than -20F, you will need to impact test to at least that temperature.

Therefore, you would have to impact test to -40F.

 

[Hurmanetar]

The plate is normalized so it is curve D. Governing thickness are 1/2" and 5/8" so the MDMT per UCS-66 is -48 F and that can be reduced further due to excess thickness.

So as I said, no charpy test is required, so I don't know why the -30 F impact test on the MTR would preclude it from being used at -40.

 

[SnTMan]

Hurmanetar, should be no problem exempting your plate. You are "being told" nonsense.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[metengr]

I agree with SnTMan except use of nonsense should be substituted with hogwash.

 

[Hurmanetar]

This is for some box headers on an ACHE and the thinner plate is 1/2" and 5/8" while the thicker plate is 1", 1.25" and 1.375". At those thicknesses the curve D gives -30F, -21F, and -18F so maybe that is where the confusion is coming from. But the governing thickness is the thinner plate, so again, I think that it shouldn't matter that the thicker plate was charpy tested at higher temperatures than my MDMT.