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Charpy on MTRs

Charpy on MTRs

Charpy on MTRs

(OP)
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?

RE: Charpy on MTRs

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.

RE: Charpy on MTRs

(OP)
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.

RE: Charpy on MTRs

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

RE: Charpy on MTRs

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

RE: Charpy on MTRs

(OP)
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.

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