tack welds

By kfluca1 Date 08-28-2015 14:34

I have a question about a welding method in D1.1 or D1.6, I am an active CWI and, the company that I am presently overseeing is trying to convince me that using a tack weld procedure using GMAW .035 wire which overlaps the previous tack weld by 50% is acceptable. The base metals are .5" A588 plate to .125" 301 1/4 hard. this is a 1 1/4" ring weld situation. The weld is applied in a tack to tack to tack bead, not using a stringer or weave bead as described in the codes. If this makes sense. I am concerned with the lack of fusion in the A588 .5" base metal for a structural weld requirement. Your help/opinion would be greatly appreciated. I cannot find info. in the codes to support their position, Their position is the code doesn't say they can't do it this way.
Thank you in advance

By Superflux (****)

Date 08-28-2015 15:39

1) Has the GMAW tack procedure been qualified?
a) GMAW is not prequalified in D1.1. and should not be used with out passing muster.
2) Raise your concerns with the EOR.

By welderbrent (*****)

Date 08-28-2015 18:42

Easy, GMAW is prequalified in D1.1 UNLESS it is in short arc mode: low voltage, gas below 80% Ar such as 75/25 Ar/CO2.

So, IF we are talking about a spray arc transfer mode then it may be okay.

The next factor is using D1.6. I believe GMAW is qualified in both spray and short modes for D1.6. Not positive. Hopefully one of our stainless code guru's will chime in asap.

So, I would begin by asking, what are your welding procedures?
What length are the tacks that are overlapped by 50%?

But next, I think with a procedure like that they would need to prove in some fashion that they can get a sound weld. Sounds like PQR time even if the process in prequalified. Why would they do it in such a manner?

He Is In Control, Have a Great Day, Brent

By Lawrence (*****)

Date 08-28-2015 18:54

There are some issues as mentioned above.

I'm more interested in why a series of tacks would be desired.

Half inch steel to eighth inch stainless fillets (or visa versa) should be easily obtained with spray mode GMAW.

I'm not clear on what a "ring weld" is but it sounds like something that wants to be on a rotator to get a continuous pass made quickly and consistantly.

Say more.. give pics :)

By kfluca1 Date 08-28-2015 19:05

This is a plug weld, slot weld. faying surface in the base of a plug weld. The company says that this type of weld is sufficient for the application . The company also says it is very difficult to acheive an effective weld by stringer or weave progression as D1.1 describes. The plug weld is in vertical 6 to 12 progression as required on each side of ring. My question is, whether or not anybody has encountered this situation and if AWS recognizes this type of weld method. My main objective is to ensure that the weld has the correct fusion to the .5" A588 carbon steel.

By Lawrence (*****)

Date 08-28-2015 19:50 Edited 08-28-2015 19:54

Ok,

Still pretty skeptical about a series of tacks producing consistent fusion.

Another consideration would be a gas shielded FCAW electrode that could be employed vertically. There have been some pretty impressive improvements in FCAW both stainless and carbon steels that would hold the weld pool together and keep a good solid spray type penetration profile and keep prequalified status. Slag removal in a plug/slot configuration might be problematic however.

You could just do a t-joint, thin to thick vertically with that series of tacks and do a fillet break... This will show in minutes the wisdom of the "triggering" method vertically with GMAW.

By kcd616

Date 08-28-2015 19:55

let us break this down in simple steps
1. we need to butter the mild steel with stainless filler metal where the welds go
if not all places that come in contact
( I would run 3 passes and after each one mill it flush)
2. now weld the 2 parts together as the print indicates
3. go ask the EOR why they want this and if their whole family is genetically stupid or just them
or how many brain injuries they have had? :eek:

just my thoughts and how I would do this
sincerely,
Kent