Back gouging and backing welds

Date 03-12-2014 16:31

I use a software package that checks your inputs against the D1.1 code and when writing a procedure it has separate check boxes for backing used and back gouging. I have a customer that tests to D1.1 using a BU-2 joint design that shows backgouging and putting a backing weld on the back side of the plates. My question is that if you put on a backing weld then is that then considered welding with backing? So then should the qualification be " with backing only"?

By 357max

Date 03-13-2014 00:46

There are two operations; back weld and backing weld. Backgouging to sound weld metal in a groove weld and then rewelding is a back weld and welding a backing weld acts as a backing bar. Yes backing weld is considered welding with backing.

By Mwccwi

Date 03-13-2014 08:43

I have a related question.
When you qualify a double sided groove weld per section 4 and do not back-gouge prior to making the second weld side, I understand that this cannot be a prequalified per section 3 weld as CJP but since it was qualified per section 4 it is a qualified CJP. How would the second side weld relate to the backing question?

By SCOTTN

Date 03-13-2014 13:22

hittman375,

With regard to the referenced B-U2, that is not considered welding with backing. There’s a backing pass, which is defined as a weld pass made for a backing weld. There’s a backing weld, which is defined as backing in the form of a weld, and there’s a back weld, which is defined as a weld made at the back of a groove weld. The latter is applicable to B-U2.
The weld symbol at the B-U2 joint shows the bevel weld on the arrow side and a back weld at the other side (not a backing weld). The back weld is deposited after the V groove weld is made and the back side of the joint is backgouged, as referenced in ANSI/AWS A2.4, “Applications of Back or Backing Weld Symbol”. So with regard to B-U2, this “other side” weld is not being used for backing. The backing weld application is also shown in A2.4, where the V groove weld is made after the backing weld is made on the “other side”. In your initial post, you referred to it as a “backing weld”, but it’s actually a "back weld".