D1.1 Welders Qualification 6G/CJP /half pipe circumference

Date 04-14-2010 21:37

The clause you reference addresses the requirements for RT. It has nothing to do with the length of the weld completed by the individual welder.

The welder welds the entire pipe circumference and the laboratory randomly selects which half of the welded sample to radiograph; 0 to 180, or 180 to 360.

Best regards - Al

By Vlad Radulescu Date 04-15-2010 16:21

Dear Al,
thank you very much for your reply, I really appreciate your help ! The issue is that many times, we have to qualify the welders on the project pipes, having to weld big diameters pipes (even 48 inches). The purpose of the welders performance qualification is to make him pass all the welding position, and a half pipe circumference welded in 6G is passing him through all positions. The question is: is there any contradiction with AWS D1.1 requirements by performing the welder qual on half pipe circumference (for diameter above 4")?

Table 4.11 from D1.1 asks by the note a) for one test pipe....unless otherwise noted
(a All welds shall be visually inspected (see 4.30.1). One test pipe, plate or tubing shall be required for each position tested, unless otherwise noted.)

I suppose that if the Code allows only half of pipe to be subject to RT, allows also the Visual test on half pipe only (hence, only half pipe welded).
Many Clients have accepted this approach; this time are also open to do it, but is only the question mark if any contradiction with AWS D1.1 requirements is?
Moreover, for welders qualification performed on plates, the minimum length required is 180 mm (7 inch).
So if my welder welds half of pipe with nominal size above 4" (a 4" nominal size pipe is 4.5" OD) it means welded length above 7".
I suppose you'll say me that only pipe sizes above 24" are "equivalent" with plates...but ....
Right now I have some 16" x 15.9mm WT pipes to be used for welders qual by RT: should I ask the welders for entire circumference welds for qualification?

Thanks in advance for your advices ! Hope to help me coming out from this dilemma:)

Best regards

Vlad

By 803056

Date 04-15-2010 16:49 Edited 04-15-2010 16:57

My response is that the welder is expected to weld the entire circumference regardless of the pipe diameter. The figures referenced for qualifying welders (on pipe) indicate that the entire pipe is to be welded to completion.

Notice that the bend samples are selected from all quadrants of the pipe, not just one-half the circumference.

As I mentioned, the code allows the employer to use either guided bend tests or RT as a means of evaluating the soundness of the welded piece. Notice there is nothing stating that only 1/2 the pipe circumference is subject to VT; therefore I expect the entire circumference to be subject to VT.

The allowance to "shoot" only 1/2 the pipe circumference with RT is to reduce cost and the number of films required to be "shot" to evaluate the welded pipe specimen. That clause in no way affects any clause before it or after it. The clause, 4.30.3.1, stands alone and pertains to RT, only RT, nothing but RT, and exclusively RT. Are there any other ways to say it? I cannot think of any.

Another point to consider; if both halves of the circumference is RT'd, there is nothing in the code that allows the employer to select the "good" half for evaluation. If the entire circumference of the pipe is RT'd, then the entire circumference is evaluated. Not to do so would be akin to cutting and bending eight guided bend tests and keeping the two that passed and tossing the bad samples into the scrape barrel. "It ain't cricket to play the game that way."

ASME allows more than one welder to weld a single pipe joint, but all of the welders pass as a group within the limits of their qualification, or they fail as a group. Consider this; one welder welds the root pass and is qualified for welds without backing. A second welder deposited the remaining weld required to complete the joint. The second welder is then qualified to joints with backing. I do not know of any such provision in AWS.

Other folks here in the Forum may have a different opinion on this subject. I am not the "code authority,” so my comments are only my opinion on subject. This is an important piece of your employer's welder qualification program. There is a lot at stake here and a mistake could literarily put your employer's future at risk. I would send an inquiry to the D1.1 committee and ask for an official interpretation. Don't expect a quick answer. It may take several months for a final interpretation to be issued. The last inquiry I made to the D1.1 committee took about 18 months to resolve and resulted in a change in the code language.

Best regards - Al

By MBSims

Date 04-16-2010 01:21

I agree with the other posts. I see no provision in D1.1 to qualify welders on production welds or to only weld on half of the pipe circumference and still be able to treat it the same as a 5G or 6G qualification test. A similar question came up at ASME IX recently and the response was that the entire circumference must be welded:

Question 1: If radiographic examination per QW-302.2 is done for qualification of 2
welders on a single pipe coupon welded in the 6G position, must each welder
complete the entire circumference of the pipe coupon?
Reply 1: Yes.

Question 2: If mechanical testing per QW-302.1 is done for qualification of 2 welders
on a single pipe coupon welded in the 6G position, must each welder complete the
entire circumference of the pipe coupon in order to remove the required bend
specimens in accordance with QW-463.2(d) or QW-463.2(e)?
Reply 2: Yes.

By Shane Feder (****)

Date 04-16-2010 02:00

Hello guys,
The other thing to consider is the difference in difficulty in welding either side of a 6G coupon.
One side is forehand and one side is backhand.
The difference is not so noticeable with SMAW but the backhand side is definitely harder with GTAW.
A right handed welder could do one side and a left handed welder do the other side and neither of them would have had to weld backhand.
Regards,
Shane

By Vlad Radulescu Date 04-16-2010 12:36

Hello to everybody and thanks for your collaboration!

I appreciate your inputs and I think you are right, taking in consideration that AWS D1.1 is a structural code!
I am very familiar with the pipelines codes, where is normal practice to qualify the welders on half pipe circumference (e.g. ISO 13847 states very clear: “Except where stated otherwise in this clause, more than one welder may be employed in welding a test piece provided each welder completes at least 50 % of the circumference of a weld pass”).

Also API STD 1104 allows the welders qualification on “segments of pipe nipples” (“A welder shall qualify for welding by performing a test on
segments of pipe nipples or on full-size pipe nipples, as specified in 6.2.1).

ASME IX instead, as you has correctly mentioned already, does not allow it!
ASME IX is part of the family Boiler and Pressure Vessels Codes and has very clear statement that Welders Performance Qualification on pipes is on the entire circumference and subject to VT and RT of the entire pipe circumference.

When the qualification may be performed using small pipes diameter, it’s not any problem. Codes as ASME IX or AWS D1.1 has a very large range of qualified diameters (as essential variable). But when the qualification has to be performed using the project material, and that’s a large diameter pipe, this issue becomes rather critical !

Anyhow, you are completely right that AWS D1.1 does not give any green light regarding only half pipe circumference for welders’ qual.

But as it’s very important for my projects and could be a really important saving, I’ll send an inquiry to AWS Board, as suggested by Al!

Again, many thanks to all of you and keep in touch !

Best regards,

Vlad