Dear experts, pls see PQR supplementary essential variables table 4.6 , clause 6 of AWS D1.1-2010( sorry to refer the superceded version). It tells that a 3G vertical up test qualifies for all position. What does this mean? Does it mean, for e.g, if I qualify an FCAW PQR in 3G up position with impact testing carried out, can be used in any position in production joint? If so, will that be contradictory to the qualified production welding positions in table 4.1.?
I believe the intent is the WPS must be qualified in each position used in production and if the test assembly that is welded in the vertical position using uphill progression, if it passes visual, volumetric NDE, guided bend tests, reduced section tensile tests, and CVN, passes, it exempts the contractor from having to test each assembly, welded in the flat, horizontal, and overhead positions, for CVN.
The premise is a joint welded in the vertical position, using uphill progression, will most likely have the highest heat input per weld bead, thus the slowest cooling rates, the largest grain size, thus the lowest CVN values of all the positions tested. Thus if the test assembly welded using uphill vertical progression produces acceptable CVN values, the other positions would produce even better CVN values because they most likely utilize lower heat inputs.
Note the table you reference and Part D are supplementary (in addition to) to the basic qualification requirements.
Best regards - Al
By HJLBX
Date 06-25-2016 18:00
Al's explanation makes sense...
Thank you for your explanation. Is this explanation valid for clause 2( regarding thickness) of the supplementary essential variable table also.? Normally without CVN requirements, if I qualify 25 mm thick butt weld PQR, it covers from 3 mm to unlimited thicknesses. But with CVN requirements, as per clause 2 it covers from 16 mm to unlimited only. So in order to qualify lower thicknesses, will that be enough to do only CVN testing after welding a lower thickness test piece that covers the range from 3mm to 16 mm.
CVN is not usually required for thicknesses below 5/8 inch (16 mm). I would have to review the code and the project specification to say much more.
With CVN, the Engineer must tell you what test temperature to use, the absorbed energy required, and where the CVN samples are to be removed.
But as is always the case, read the code carefully and draw your own conclusions and ask the Engineer if you have questions regarding a specific job requirement. Opinions are easy to come by, but not all opinions are worth the time it takes to read or listen to.
Al
Remember, there are a few items you must be able to keep separated in your mind:
1) CVN's have their own requirements and are not 100% overlapping with PQR's and especially not with WPS's or welder qualifications;
2) PQR's are to qualify procedures that are not pre-approved according to Clause 3 and are not overlapping with welder qualifications though both PQR's and Welder Quals are in Clause 4:
3) As both PQR's and welder quals are in Clause 4, make sure you do your due diligence to keep all the Tables and text separated accordingly.
Brent
