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Up Topic Welding Industry / Technical Discussions / backing bar
- - By CBISTEEL Date 03-07-2006 13:11
Is it acceptable to use copper/brass as back up bar for full pen welds on structural steel when it calls for removal of backing bar ? Tried ceramic but fit up was difficult.
Parent - By CHGuilford (****) Date 03-07-2006 14:20
Per AWS D1.1 5.10, yes it is acceptable. You will have to clean up the root side and fill in any defects, but it should work just fine.

Chet
Parent - By jwright650 (*****) Date 03-07-2006 14:39
I agree with Chet on the non-fusible backing, as long as you address the second side. I'm assuming you are working with prequalified procedures.
John Wright
Parent - - By 803056 (*****) Date 03-07-2006 21:32
What welding process, how thick, whats the root opening, etc.?

Don't allow the arc to impinge on the copper/brass. You can expect cracks if any copper or brass melts and enters the weld puddle.

Good luck - Al
Parent - - By vonash (**) Date 03-07-2006 23:43
Chet,
I agree back gouging to remove deletrious material is acceptable for CPJ welds. I don't allow copper/brass backing without continous inspection because the welder will not remove all of the affected material, as Al mentioned.
I know, every welder on the forum is gonna say they remove all the bad stuff.
Parent - By 803056 (*****) Date 03-08-2006 03:42
It a good move to check the back gouged root using the magnetic particle test method. Its added assurance that the root is sound and will save on repair work if the joints are subjected to UT once the joint is completed.

Al
Parent - - By CHGuilford (****) Date 03-08-2006 14:11
I wholeheartedly agree.
We visually check all background/backgouged CJPs and I MT most of them.
My comment was mainly that D1.1 does allow the use of copper or brass backing and that the second side will likely need some kind of attention.

Chet
Parent - - By ziggy (**) Date 04-16-2006 18:20
If a non-steel backing is used such as copper, brass, ceramic, etc. would the WPS need to be qualified, even if using a prequalified joint design?
I ask because of the statement in D1.1 C5.10.
Thanks,
ziggy
Parent - - By jwright650 (*****) Date 04-17-2006 10:53
Ziggy,
My take is that if you use ceramic backing because you have to remove the backing strip per FEMA, then you ARE planning on addressing the second side, so it is still prequalified. Only if you plan on using the backing and welding from one side do you need to use steel backing to remain prequalified. (See 5.9, 5.10)
Again this is just my opinion.
John Wright
Parent - By swnorris (****) Date 04-17-2006 11:15
I agree, John.
Parent - - By Bill M (***) Date 04-17-2006 15:46
from D1.1 2004

I read section 2.17 to say that a joint welded from one side with backing, "that is not steel" is not prequalified, and requires procedure qualification.
Parent - - By jwright650 (*****) Date 04-17-2006 15:57
I agree. You must address the second side or qualify your procedure.
John Wright
Parent - - By ziggy (**) Date 04-19-2006 23:13
Thank you for the comments. I concur with the comments.
Let's say that the WPS remains prequalified under these conditions.
Would you agree that the prequalified WPS shall list the type of backing as well as that backgouging is to occur?...to satisfy D1.1:2004 3.6 and Table 4.5 Essential Variable 33...
Thank you,
ziggy
Parent - By Bill M (***) Date 04-21-2006 12:34
If you use the AWS D1.1 sample WPS form-
it asks if backing is used, and if so, it then asks for the the backing material
Parent - - By CHGuilford (****) Date 04-21-2006 20:23
Not necessarily. For a joint that requires backgouging, the material used for backing is non-essential. You could use ceramic, brass, aluminum, or even steel, but you still have to backgouge to sound metal and weld the root side.

However from a production point of view, it's always a good idea to tell the welders what you expect them to do. I would list the backing material on the WPS.

Chet.
Parent - By ziggy (**) Date 04-24-2006 03:25
Thank you for the replies. Much appreciated.
ziggy
Up Topic Welding Industry / Technical Discussions / backing bar

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