By CHGuilford 
Date 06-03-2009 16:14
Edited 06-03-2009 16:21
A572-50 is equivalent to A709-50/ M270-50 excepting minor differences.
There are more and more young engineers who refuse to do the legwork necessary to satisfy themselves that A572-50 is basically equivalent. For that reason, try contacting your steel supplier - most can arrange for the mill to reissue the CMTR with an amendment to show A709/M270 grades on those.
2nd edit - I originally mis read and answered as though you were running PQRs not WQTs. Sorry if I caused confusion.
There are a few threads around here regarding various situations where A 572 needs to be substituted for A 709 or vice versa.
The only difference between A 572 Gr. 50 and A 709 Gr. 50 is the Charpy requirements on A 709, which you don't need for your PQR plate. If anything, you want the PQR plate to be a worst case, so it really shouldn't matter if it's A 572.
That said, you'd need to convince the owner to let you do this. Show them the various A 709 requirements and how they're met. Chemicals & physicals should be identical. But it may be easier just to get the mill to issue you a dual cert. There's also a note in A 709, if I'm remembering right, about how the grades of A 709 are equivalent to various other steels out there (such as A 572).
Hg
I've only done a few to D1.5 and they were all A706. Sorry, I'm no help to ya.
