BASE MATERIAL FOR A P1-P1 PQR
BASE MATERIAL FOR A P1-P1 PQR
(OP)
Dear all,
We subcontracted the fabrication of a 2in thick pressure vessel (in SA 516 Gr70 N). To back-up the WPS´s the fabricator is showing us a PQR which was done using SA36 as base material, whose tensile strength is 58ksi (minimun).
Surprisingly the two tensile tests broke just above 70ksi which seems to be fine.
My questions are:
a)Is it reasonable that a SA36 base material has a much higer tensile strenght than specified (as it didn´t break @70ksi)?
b)Does the code requiere that PQR qualifications must be done in base material of same mech. properties as the one to be used in production or just to have the same P number?
Thanks in advance
We subcontracted the fabrication of a 2in thick pressure vessel (in SA 516 Gr70 N). To back-up the WPS´s the fabricator is showing us a PQR which was done using SA36 as base material, whose tensile strength is 58ksi (minimun).
Surprisingly the two tensile tests broke just above 70ksi which seems to be fine.
My questions are:
a)Is it reasonable that a SA36 base material has a much higer tensile strenght than specified (as it didn´t break @70ksi)?
b)Does the code requiere that PQR qualifications must be done in base material of same mech. properties as the one to be used in production or just to have the same P number?
Thanks in advance





RE: BASE MATERIAL FOR A P1-P1 PQR
The same P Number is usually the only requierement unless supplementary essential variables are required. In that case the group number is also an essential variable.
However that does not mean you throw out good engineering practice.
Have a nice day.
Gerald Austin
Iuka, Mississippi
http://www.weldinginspectionsvcs.com
RE: BASE MATERIAL FOR A P1-P1 PQR
I also agree with Mr. Austin, and have also heard it from a member of the ASME B&PV Section IX code committee member that as long as it is the same P#, it is permissable to qualify to weld a base metal with a weld that did not even meet the tensile strength of that metal as long as it met the tensile strength of the metal it was tested with. I do not know anyone recommending this approach though. However it is not uncommon to have lower specified strength metals meet the tensile strength of higher specified strength metals, and haven't ever heard of anyone that has an issue with that.