AWS D17.1 - Tube Groove Positions (CONFUSED)

By vlopez Date 05-09-2016 03:53

Hello all,

I have a question pertaining to the positions of groove weld in tube. According to the AWS D17.1 spec, under Figure 4.4, groove welding in tubes have four positions: 1G, 2G, 5G, and 6G. Only 1G allows rotation of the "pipe" during welding. I, however, deal with tubes less than 1" O.D., not piping on-site where the O.D. and length of pipes are oftentimes, too large to pick up. I perform manual GTAW welds and weld on tubes that are fastened on a fixture. I weld on a horizontal position. The tube remains fixed while welding. However, I take out the partially welded tubes from the fixture so that I can manually rotate them and weld the rest of the tubes. I repeat, I do not rotate the tubes while welding, but I do rotate them once I have to weld the portion facing opposite of me. In short, what is the difference between "rolled" and "fixed"? Am I welding in 1G, or 5G? :confused:

Thank you in advance!

By Superflux (****)

Date 05-09-2016 08:23

It is not clear if the pipe or the weld joint is horizontal.
It the pipe is vertical then you are welding in 2G position no matter how many times it is rotated.
Now if the pipe is horizontal and the joint is vertical, then are 2 possibilities.
1) If the pipe is rotated 4 times and you are welding from the 3:00 0'clock to 12:00 then it could be loosely interpreted that you are in the 3G to 1G position. I say this because if one were to roll it only 3 times, then this would include overhead welding and could be interpreted the same as a 5G.
2) If the pipe is rolled only once to weld the full circumference (6:00 o'clock to 12:00) then you would in fact be in the 5G position.

By WeldinFool (**)

Date 05-09-2016 18:20

If the tube is in the vertical position, and you are welding horizontally as you stated, that is considered 2G whether you rotate it or not. It does not matter that you only weld half of it, and then rotate it to weld the back half, you are still performing all welding in the 2G position.
The difference between 1G and 5G would be that with 1G the tube is in the horizontal position and is rotated so that all welding takes place on the top of the tube in the flat position. With 5G, the tube is fixed in the horizontal position and welding is performed overhead on the bottom, vertical as you come up the sides, and eventually flat as you get to the top. Big difference!

By vlopez Date 05-09-2016 20:04

I thought the overhead position is denoted by the number 4 and therefore only pertains to groove weld in sheet as (4G), fillet weld in sheet as (4F), and fillet weld in tube also as (4F).

By Dreizehn (*)

Date 05-09-2016 20:30

You are correct. But, since you will be welding a combination of OH, V and Flat and the pipe is in a fixed position it is given the 5G title.

By vlopez Date 05-09-2016 20:43

Ah! I finally understand what you and WeldinFool mean. Thanks!

By Superflux (****)

Date 05-11-2016 15:19

1, 2, 3 and 4G (G or F) are positions based on 90° increments. They are also defined as the groove or fillet being within a few degrees of each defined position. The 5G combines 1, 3, and 4 positions with all 180° of rotation of the welding surface included.
There is NO 5F because it would essentially be a groove.
Did that clarify it any further?
I think I'm confused now...

By kcd616

Date 05-11-2016 16:45

flux,
you nailed it
my question
how many is a few degrees?
inspectors judgement?
or a real #?
sincerely,
Kent

By Superflux (****)

Date 05-12-2016 05:35

Kent,
Of course it's a real # for AWS.
Of course it's hard to verbalise.
D1.1 fig. 4.2 explains it all in my 2004 edition.