By 803056
Date 02-21-2013 01:10
Edited 02-21-2013 01:13
I hate to respond to code questions without the code in front of me. There’s always a danger of shooting myself in the foot.
I do have a copy of the 2004 edition of D1.1. Generally it is recognized that text overrides a table or figure in the code. Again, remember I’m looking at the 2004 edition of D1.1, so the specific clause may be different. I am looking at clause 4.26 (4) and (5). They refer the user to figures 4.25 for qualifying the welder if the CJP T, Y, or K joint is made from one side with backing.
When the welder is qualified with backing, he is also qualified for welds make with back gouging.
There is an apparent conflict between the text and the table in the 2004 edition in that the text says the welder can be qualified for T, T, and K joints using a butt joint made with backing. However, the table listing the various positions qualified leads one to believe only the open root butt joint using different wall thicknesses is required (6GR). The text of the code states that the 6GR is permitted when the groove is not backed or back gouged.
Whether the welder qualifies with backing or whether he qualifies with the 6GR, the smallest dihedral angle for T, Y, and K joints is 30 degrees. Ithat is the case, T, Y, and Ks are covered even if a butt joint with backing is used to qualify the welder. It seems the problem is with the table listing the positions qualified.
I take the position that the table showing the limits of position qualified is in error.
I'll will look at this again when I get back to Connecticut, but that will be no sooner than early next week. I don't believe this poster wants to wait until next week for an answer. This is the type of question that should be submitted to the code committee for resolution. Especially if the most recent edition does not address the conflict that exists in the 2004 edition.
Gotta go.
Best regards - Al
Hi guys,
Sorry Brent - I am with Al on this one.
4.27 CJP Groove Welds for Tubular Connections
Welder or welding operator qualification tests shall use the following details:
There is no weld detail for double sided welding so IMHO the nearest would be item (4). This would then allow welds to be backgouged in production.
(4) CJP groove T-, Y-, and K-Connections welded from one side with backing in pipe. Use Figure 4.24(B) in pipe of the appropriate diameter.
Figure 4.24(B) is a single vee with backing strip.
If you used pipe of appropriate diameter (7' - 2.1 mtrs) it would be as Al noted - almost the same as welding plate.
There is very little (if any) difference between welding large diameter piping in the 2G position with backing and welding plate in the 2G position with backing.
Then we go to Table 4.10.
If we go to Tubular - Groove - 2G then look in the Production Pipe Welding Qualified - T,Y,K connections - CJP column there is nothing listed, even though Clause 4.27 (4) clearly nominates it ?????
Then we go to Table 4.11
There is no mention at all of Figure 4.24 (a) or (b) for qualified thicknesses or diameters ????
(2) T-, Y-, and K-Connections.
This is from the Commentary
Because of the special skills required to successfully execute a CJP groove weld in tubular T-, Y-, and K connections,
the 6GR level of welder qualification for the process being used is always required (see 4.27).
IMHO there are no special skills required to weld a 7' diameter double sided weld in the 2G position,
Regards,
Shane
Well, I'll throw some more wood on this fire looking at it from that aspect.
As the OP started to ask, it is just two PJP's if you want to excuse away the FACT that we are dealing with a TKY CJP and therefore the clauses previously posted are applicable.
Or, arguments I hear from shops that have many welders only qualified for fillets trying to tell me that a PJP is not a groove weld and is a fillet weld. Especially on skewed T joints. A slight skew is still a fillet but you reach a point where it becomes a PJP and is called out as such even on their shop drawings, but they try to get it welded out with guys only qualified for fillets.
So, my question, is it a CJP TKY falling under the above provisions or not?
Now, I do need to leave and get back up to my job and to my code book so I can check out Shane's references further and try to chase this down as to why we seem to have a discrepancy in the code. I have trouble believing this is that complicated. And, I am sure when Al gets a 2008 or 2010 book in hand the juices will start to flow. Until then, I may just be mudding the water I am attempting to throw on this fire instead of the wood that is being thrown on currently.
Have a Great Day, Brent
Now we're talking.
What is a 14 mm deep penetration weld made from one side on a 25 mm plate ? - PJP
What is a 14 mm deep penetration weld made from both sides on a 25 mm plate ? - 2 x PJPs or 1 x CJP (by default) ?
Brent,
Understand where you are coming from regarding the Skewed T joints but they are dealt with in 3.9.3 and Clause 3.9 is titled "Fillet Weld Requirements".
Obviously as the angle gets greater they can turn into PJPs but I didn't investigate further,
Cheers,
Shane