This seems tricky to me too. I hope others chime in as I would like hear my interpretion seconded, or refuted if I'm in error.
Assuming "the code" is AWS D1.1
A welder qualified with a backing strip can weld an open root joint if that root pass is back gouged and welded from the back side, but cannot weld an open root filled only from one side.
D1.1 2004 4.23 CJP Groove Welds for NonTubular Connections.
"...Note that qualification on joints with backing qualifies for welding produtions joints that are backgouged and welded from the second side."
Welder Performance Qualification for Tubular connections has it spelled (and drawn) out even more clearly.
See 4.26
"(1)CJP groove butt joints with backing or backgouging in pipe Use Figure 4.25"
"(2) CJP groove butt joints without backing or backgouging. Use Figure 4.24"
Again
Performance qualification with a backing strip qualifies the welder to do production work without backing strip if there is back gouge and weld from the back side, but not to weld from one side only without backing strip.
Lawrence,
I would have to agree with your interpretation based on the definitions in AWS 3.0 and your quoted paragraphs.
Regards,
Gerald
Refer to you sentence:"(1)CJP groove butt joints with backing or backgouging in pipe Use Figure 4.25", even though 4.12.1 has put "CJP with backgouging" together with "CJP with backing" in the same paragraph, but if follow the detail shown in Fig. 4.25 (A), it is under CJP "without backing."
I have consulted many ppl including AI and AIS, they're all saying that even though the welder may initially weld without backing on one side then backgouge and back weld, it's still considered a welding with backing. It's because the welder doesn't have to care or worry about how good is the root of the welding. The root will be backgouged and then back weld. Therefore, it's considered welding with backing. Please correct me if i'm wrong. Thank you.
regards,
-Alex-
This is something you have to be careful with, the actual process depending on the code has values for with or without backing.
From the ASME standpoint it is as follows:
The 2004 edition ASME section IX defines backing as;
QW/QB-492
" a material placed at the root of a weld joint for the purpose of supporting molten weld metal so as to facilitate complete joint penetration. The material may or may not fuse into the joint."
Going to to Article III of section IX QW 310.2 last paragraph states that a a double welded groove weld test is considered welding with backing.
Therein is what can get you in trouble code wise. Some of the processes state that the addition or deletion of backing is either an essential variable or a supplementary variable. (in reference to Article III welder qualification).
For example, QW 352 OFW states that addition of backing is essential, QW-353 SMAW deletion of backing is essential, FCAW, GTAW, and PAW being the same as SMAW.
It's confusing to a lot of people because in Article II non of those processes list backing either way as an essential variable or a supplementary variable.
If your application is ASME, the person you are having a discussion with is correct, but only insofar as welder qualification is concerned.
Regards,
Gerald
Forum
