GENERALLY YOU HAVE TO BACK GOUGE THE ROOT TO CLEAN METAL THEN PUT IN A BACKING WELD FOR THE ROOT PAS.

I sense a question behind the question here. I am not an expert on "AWS" codes, but can offer you some answers based on the ASME codes. They generally tend to be similar. Maybe you should re-phrase the question so that it is a bit clearer.

The bottom line is that if you weld "against" anything, then you have backing. As your other reply indicates, if you are going to backgrind from the second side, then it is considered that you have welded with backing for both the first and second sides. If however, you weld from the first side, without backgrinding from the second side, and just fill up the second side, then there may be some question regarding whether the first side was in fact welded without backing.

Maybe someone could reply to this. (I suspect that this was in fact your question.)

Just another issue. If you are talking procedure qualification, based on the ASME codes, there is not really an issue because this is not an essential variable. Welder qualification is another story.

Niekie

In a nut shell - yes. See AWS D1.1 para 3.12.1. (in my old 96 edition anyway). ASME Sec IX makes the statement that the weld metal is backing when welding the second side. AWS D1.1 sort of implies that it is in various paragraphs.

Regards,
Mikeomni1

[deleted]

I believe Doc stated specifically AWS in the post, why is ASME being considered?
Backing: A material or device placed against the back side of the joint, or at both sides of a weld for ESW/EGW, to support and retain molten weld metal. (ANSI/AWS A3.0-94)
My interpretation would be that a backing weld is just that, backing. I would also consider the root pass of a double groove weld as backing.

Your question asks about "qualifying a double vee butt joint weld procedure" which to me means welding a plate from both sides in order to qualify a production weld. I assume you are not talking about a pipe butt weld since they are usually welded from one side, either with a backing or with an open root.
As already mentioned, D1.1 - 3.12.1 defines the difference between partial and complete penetration. If you weld from one side, backgouge (or somehow get down to clean, sound metal), and then weld the 2nd side, you will have a complete penetration weld. So then you could say the weld on the 1st side SERVES as a backing material.
If you were welding a single vee and welded the root side first, backgouged from the vee side, and welded out the vee, you would have used a 'backing weld' in your joint.
If you welded out the vee first, backgouged the root, and welded in the backgouge, then you have a 'back weld' in the joint.
Both give the same results.
The 'backing' mentioned in D1.1 talks about extra material added to the root of a joint which could be cut away or left in place after welding is done. You wouldn't have that on a double vee weld.
Having said all that, I'll say this: my "opinion" is that filler metal is not the same thing as backing material.
CHGuilford

I say your answer is yes.

Any double welded joint (Welded from Both Sides) would be considered as a joint welded with backing. The backing is weld metal.

Any single welded joint that does not have material preplaced or in place to support the root of the weld is a weld without backing.

Any single welded joint that has material in place to support the weld metal at the root is considered a weld with backing. This material could be flux, ceramic,steel etc.


Have a nice day