I need to qualify a welding procedure in accordance with Section IX, with the supplementary essential variables for Charpy impact testing as required by ASME B31.3.
The base material is 304 SS, with production material thickness ranging from 0.500" to 1.000" in thickness. This is for cryogenic service and impact testing of the weld and HAZ will be performed at -320 F. I intend to use a GTAW and SAW process combination on a 1/2" thick test coupon for procedure qualification.
I have the following problems:
1) Per QW-403.6 and QW-451 of Section IX, the qualified thickness range using a 1/2" plate will be 0.500" to 1.000". However, per Table 323.3.1 of ASME B31.3 (falling under column A for "Requiring Impact Tests Only on Welds") the qualified thickness would be 0.250" to 0.750". It seems that in order to meet both codes, 2 procedure qualifications would have to be performed. (And, it seems for someone requiring even more range qualified, the amount of PQR's would continually grow because of the way the two codes overlap in qualified thickness)
2) I recently attended a Section IX course where the instructor stated that impact tests for multiple processes should include a sample from each process. At the time I took this to mean that one set of charpies should be taken from one process, and another set of charpies should be taken from the other process, etc. Or, it now occurs to me that I suppose it could be taken that a single set of charpies should include both processes in the same specimen. The fault I see with the second interpretation is that if there were 3 processes it would not be possible to include all of the processes in one specimen. The problem I have with taking 2 sets of charpies, one set from each process, is that I am told by the lab performing the testing that even if I split the two processes evenly across the 1/2" test plate, they would have difficulty in machining a full size set from each process (given the amount of material).
Please contribute any thoughts concerning these two issues, point out any oversights, alternate ideas, or proposals on the best way to qualify the WPS. Thanks.