Fillet Weld Fixtures

Date 07-20-2018 19:32

I've always used a fixture for doing our fillet weld tests to the AWS D17.1 specification.

The materials have always been less than 0.063", typically 0.040" for both the vertical and horizontal test plates.
The fixtures uses were generally a solid steel base with a thick piece of angle milled to hold the vertical plate and another piece of flat bar used to hold the horizontal plate, sometimes they have copper inserts depending on the company. I think this is a typical test fixture set up for doing fillet weld tests to AWS D17.1

Recently I tested at a company where the vertical portion was milled away directly behind where the weld is. They said that this was to allow them to be qualified without backing per table 5.6 of AWS D17.1

My question is, if you used a solid backing plate as I initially described are you only qualified to weld with a backing plate in a production setting?

Regards
Jim

By Lawrence (*****)

Date 07-21-2018 02:36

Fillet weld qualification does not include backing as an essential variable as far as I know.

Backing in the form of inert gas protection of the “other side” of a fillet is common with thin or reactive base metals.

Backing in the form of a heat sink that’s in contact with the “other side” of a fillet is also common.

But I don’t recall this type of backing for fillets to be an essential variable for either procedure or performance qualification.

This is from recollection as I don’t have my code book with me.

By jd369

Date 07-21-2018 12:06

Hi Lawrence
Thank you for the reply. Once I’m back at a computer I’ll review the specification again and respond. Are we allowed to copy a piece of the specification as a picture and post it on this site for discussion purposes?
Regards
Jim

By Lawrence (*****)

Date 07-21-2018 19:55

I do it all the time :)

By jd369

Date 07-23-2018 13:57

I was reviewing the D17.1 this morning. Section 5 is “Welding Procedure and Performance Qualification”.
5.4: Performance Qualification – Detailed Requirements
5.4.6: Other Welding Conditions – other welding conditions that require a correlation between the test weld and the production welds are given in Table 5.6
Table 5.6 depicts that if you qualify using backing, you are only qualified to weld with backing.

I interpret that if I qualify using backing then I cannot weld a fillet weld without backing in production. I hope I am wrong, any comments or different interpretation would be welcome.
Regards
Jim

Attachment: 5.4.6Referstotable5.6.JPG (36k)

Attachment: Table5.6.JPG (138k)

By TerryTerzian (*)

Date 07-23-2018 16:24

Backing as far as I understand is of a compatible material the the weld base and can become part of the weld joint. And then removed later if directed. The fixture provided should not make much difference as far as I am concerned because the instance you over penetrate the alum, the chance for suck-back is greatly increased. A weld fixture whether recessed in the back or not shouldn't make a difference. But it got you nervous. Don't forget for D17.1 you get 10% incomplete fusion to the root of the weld leg. Radiograph usually does not find this. And wire brush the living daylights out the back before radiograph so that no aberrations other than the seam show. Confusion on the part the examiner usually results in rejection. Your macro may show the incompleted fusion so don't forget to point out to the examiner the allowance. For instance if your weld leg is .12" you are allowed .012" incomplete fusion to the root. :cool:

In the early days of Mil-t-5021d we tacked the ends, and used a third hand to hold steady. All this while the cheapskate supervisor hovered over out shoulders breathing heavily of cigarettes. :twisted:

By jd369

Date 07-23-2018 17:43

Hi Terry
Thanks for the response, much appreciated. I'm not worried about individual qualifications, but more worried about how we do the qualifications. I would hate to have an audit from NADCAP and they note that we use backing for our weld qualifications, but in actual production we do not. If they interpret the specification the way that I am currently reading it I think it would be a major finding, which I do not want.

I do consulting and welding at several companies in the aerospace field and it's always interesting when you see another companies approach to the specification. It raises questions/concerns for work that I do at the other companies.

This one has me intrigued as I always wondered about the backing vs no backing for welder qualification. I've been through numerous NADCAP welding audits and it has never come up. I would like to ask the auditor directly, but if it turns out that it is an issue I would be creating a finding for myself.

Regards
Jim

By TerryTerzian (*)

Date 07-23-2018 18:38

I see where you are coming from Jim. I consider the dissimilar plate behind the weld more of an atmospheric displacement device or an alignment plate as opposed to a weld backing plate. Mine tend to be of another alloy such as carbon steel or stainless steel. When I weld stainless steel fillet test coupons I use alum atmospheric displacement plates so that I don't require the use of purging. I think wording of the devices are important.

By jd369

Date 07-23-2018 18:46

Thanks Terry, I see where you are coming from now as well, it makes sense. I hope that is correct, it would make sense as to why I have never received a finding for this.