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Okay, I got a phone call from another inspector I work with asking this question:
Putting an 1 1/2" thick plate on a WF beam, top flange, plate sticks over the side. Tack welds are being done in the overhead position with SMAW by fitters with overhead 'tack' certs. But, the "tacks" are 6" long. Is there a maximum length that the fitters with 'tack' certs can 'tack' a part together with?
We have been through D1.1, 1.8, & AISC and can't find anything. We have looked in Clauses 2, 3, 4, & 5. We even went so far as to check the definition of a tack weld in the annex and A3.0. Nothing. At least that I have found.
That's why we are asking here, at what point does it become a 'weld' instead of a 'tack'? Better yet, at what point is the fitter not qualified to 'weld' this 'tack' because it is actually a 'weld'?
I would think there would be something in either Clause 3 or 4 having to do with qualifications and their limits but if it is there I keep looking over it.
Some help please.
Have a Great Day, Brent
I’ve never witnessed a tack test or seen tack "certs".
This should get interesting.
I’ve been told by old timers “youngun, if it's longer than it's wide then you're welding”.
Good luck,
Don
Just for the record Don,
Tack welder qualification/certification per D1.1 Clause 4.18.1.2, 4.18.2.2, 4.19.2, 4.31 and Figures 4.35 and 4.39 and then Table 4.12.
There have been many 'rules of thumb' through the years as to what a good tack weld consisted of, but they are not code.
With all other perameters considered as to being able to properly tie in and incorporate the tack into the finished weld and have acceptable weld appearance, the question still presents itself as to how long can it be before it becomes a weld and the tacker is not qualified?
Thanks for your input and curiosity. I too feel this to be an interesting, though not really that deep, of a subject.
Have a Great Day, Brent
There is no limit on lengths of tack welds, you can find a little more info in D1.1-2010, 5.18. although a 6 inch tack weld on a 6 inch plate would no longer be a tack weld. I use sound judgment, and expect a tack weld to hold the part in place. Tack welds must also meet visual acceptance criteria if they are not ground out or incorporated into the weld (and other requirements as stated in 5.18).
I agree with ctacker. There is no limit on the length of the tack weld other than it cannot be the only weld securing the part and transmitting the design loads. I believe I remember Duane Miller responding to a question regards a similar issue, i.e., a long tack welds. The situation was one where the contractor welded from one end of the joint to the other and called the weld a tack weld. It held the parts in proper alignment and it contained the flux when depositing the root bead with SAW. Mr. Miller concurred that it was a tack weld.
The tack weld can even be a multiple pass weld when holding large parts in alignment until the production weld is made.
Ultimately the contractor is responsible for the work their employees complete. If there is a problem, it should be bought to the attention of the one individual that has the authority to make a decision, the Engineer. Why make life more difficult than it already is? Spread the burden and the pain.
Best regards - Al
Thanks ctacker and Al. That was what I had relayed to my co-worker but wanted to make sure I wasn't missing something.
He and I had talked through the multi-pass with step backs to accomodate tie in of full welds.
I think they had one come off with smaller tacks when they rolled the member to do the weldout in the flat position and just wanted to make sure that did not happen again.
But our guy was not sure of any restrictions. And I wanted to make sure with the expert panel here that I wasn't missing something. It does seem a bit vague to leave it open like that but I understand the comments made by you guys.
Have a Great Day, Brent
AWS A3.0 Standard Welding Terms ~ "Tack Weld. A weld made to hold the parts of a weldment in proper alignment until the final welds are made." Code does not limit the length as previous posters have noted.
Just in support of Al's comment regarding the example of Mr Duane Miller - eg. a full length tack weld.
Tack welds in the root of a joint with steel backing less
than 5/16 in. [8 mm] thick shall be removed or made continuous
for the full length of the joint using SMAW with
low-hydrogen electrodes, GMAW, or FCAW-G
Only applicable to SAW but based on the above a tack weld could theoretically be 1 inch, 1 foot or 100 feet.
Cheers,
Shane
I always considered a "tack" weld length to be no more than 2" long.
I get this from the "tack test" where a 2" long weld in welded onto a 4" long piece of material.
Granted, the code doesn't state clearly the length of the weld allowed by a "tack" certified welder so technically you are probably ok. Of course that's when some third party QC person comes and disagrees, then you'll have to hash it out.
I guess this can be equated to a welder who tests on a 6" long coupon, but he certainly is qualified to make welds that are longer than 6".
It sounds like you are ok for now, good luck.
Brent I consider tack welds to only be a temporary weld like Al stated...
>The tack weld can even be a multiple pass weld when holding large parts in alignment
It can be as big as needed to prevent movement until the final pieces are welded up....sometimes it takes some giant gorilla welds to hold the big stuff in place.
I've seen base plates fall off the column during fitup....my opinion was that the fitter didn't use large enough tacks to support the #4500 base plate.
D1.1 requires an 8" fillet on a T joint to qualify a fillet welder. The same requires 2" for a tack welder. IMO, 8" is fillet welder territory.
While working as a shipfitter for 11 years, I never saw a reason for anyone to use a tack longer than 2". We put up large and heavy steel. For example: When putting up a beam against another structure, we would tack an angle up to rest the beam on. Safety is a big issue. They need to use a qualified welder if they want something welded.
Thanks guys.
It appears we are all in consensus as to how the code addresses this topic. Again, I just wanted to make sure I wasn't overlooking something. When junior inspectors come to you seeking info you hate to think you may have misled them. I don't think he was trying to be nit-picky about some welding, he had what to him was an honest question. He thought he remembered seeing something about a maximum length for tack welds. I didn't, couldn't find anything, and advised him thus. But, sometimes we all start questioning ourselves and I thought this to be a good question for our forum members.
'There is safety in a multitude of counsellors'. (Proverbs) Just another example of how resourceful this forum can be. I did not really consider it an item that required a formal/official interpretation from the committee. Just wise counsel.
Shane, thanks for that additional point. You are right, it applies directly to SAW but it sets an example of how long a 'tack' weld can be.
John, and others, yes, I agree with and was aware of the multiple pass application, but that still leaves a little wiggle room when it comes to 'length'. We all know how often we get misled by past practices, rules of thumb, etc only to find out the code addresses the item with specifics that were not previously noticed or brought to our attention. While the code does not appear to directly address this item I believe it leaves it for common sense application to the fabricator's discretion with obvious careful observation by the inspector.
Have a Great Day, Brent
Ah yes, but common sense isn't so common.
Al
So true. That's why the pay us to watch them and make sure they apply at least a little bit of it to the work.
Have a Great Day, Brent
Why you need to use a tack welder when the tack weld to be incorporated in the weld is long enough to be classified as root pass, common sense application is to use a qualified production welder
We are addressing a code issue. Common sense rarely comes into play in such cases.
Codes are legal documents when they are adopted by a legislative body such as a government body at the federal, state, or local level, or when the code is referenced by a legally binding contract between two parties. The codes are not perfect. They contain errors and omissions. The codes are not written or reviewed by lawyers or language professionals, so the language can be imprecise. Contractors may apply the provisions contained in the code very literally. If the code does not contain a prohibition, the contractor is free to apply the code provisions to their advantage.
In the case of AWS D1.1/D1.1M, the Owner, exercised through his Engineer, can modify the code provisions. The Engineer can act as the arbitrator to resolve disputes between the involved parties. The contractor can seek clarification or relief by asking for an official interpretation from the code committee. If the Engineer was wrong in his understanding of the code, the contractor can seek redress by filing suit. However, the project is not going to be place on hold while one of the involved parties awaits an official interpretation.
Under the auspices of AWS D1.1/D1.1M the certified tack welder has demonstrated the ability to deposit a sound weld that can be incorporated into the final production weld. The code does not place limits on the size or the length of the tack weld, thus the contractor is free to allow the tack welder to deposit rather large tack welds to secure the members in position until the production weld can be completed.
This case may serve as justification of why the Engineer should incorporate a minimum level of volumetric examination of all CJP groove weld even though it may not be required by the code. Maybe it would be prudent to incorporate a clause stipulating progressive NDT in the event a spot examination reveals a concern. What if the Engineer makes it a contract requirement that all welders and tack welders pass a grooved plate test? What if the tack welders are required to pass the fillet test consisting of the modified square groove with backing. The latter would be my preference.
Common sense, there are no provisions in the codes that require common sense be applied.
Best regards - Al
A follow up to this takes a slightly different turn but still very related:
Why do they even give a certification test for tack welders?
Here is the basis for the tenure of that question: You certify a tack welder per the above listed code clauses. After a year of employment they leave and go to a job with absolutely, and admittedly when returning, no welding taking place especially by the person in question. When they return two years later to the job previously held as a certified tack welder, it is not required by code to re-test/qualify/certify them. As a TPI on the job I cannot insist on a test to prove their abilities. I can only wait, monitor, and prove their abilities are not under question as to quality. See Clause 4.1.3.2 for Tack Welders and compare with 4.1.3.1 for Welders and Welding Operators. Also compare wording in Clause 4.32 with sub-clauses properly applied in their appropriate order; 4.32.1 for Welder and Welding Operator Retest Requirements with 4.32.2 Tack Welder Retest Requirements. The period of effectiveness is only applicable to the Sub-Clause for Welders and Welding Operators. There is no such clause within the Requirements for Tack Welders.
So...why bother in the first place. Just watch them and see if they can tack decently.
Better yet, change the code and require anyone who touches the components of the job with a welder to be qualified by testing with at least Al's favorite method- the Option 2 Fillet Weld Root Bend Test Plate per Figure 4.33 and Clause 4.28 or 4.25 with Table 4.11.
I find it rather inconsistent to have the code allow such a provision.
Have a Great Day, Brent
You'll get no argument from me.
ASME Section IX contains no provisions for a Tack Welder. The individual is either a qualified welder or he is not.
Expanding on what you have said about the tack welder not welding while working (or not) for a different employer, does it really make sense to accept previous qualification when putting a welder to work? While AWS D1.1/D1.1M permits the practice it seems to me to be a case of "see no evil, hear no evil, say no evil" on the part of the code committee and the employer.
I always require a fillet break test regardless of previous qualification when I have input in the project specifications. In my opinion to do less it simply hiding one's head in the sand and hoping for the best.
The codes list the minimum requirements that must be met. A prudent engineer should recognize the shortcomings of a code and address them in the project specifications. It is right back to my 10-80-10% rule. I often wonder how many engineers have actually studied the codes they are working with or is it a case where they only study the part that directly and exclusively applies to the design.
The majority of contractors make a honest attempt to do things right. There is always a minority that try to take advantage of the weaknesses in the codes. It usually bites them in the ass, but they figure they are making money until such time as it does bite them. They are the scorpions of our world. They will sting the frog even though they know they too will drown as the frog sinks to the bottom of the pond. Why does the scorpion sting the frog? Because it is their nature.
Best regards - Al
I ALWAYS re-tested a fitter if they left and we re-hired.
I agree with your opinion and the code can be exceeded in my case , just not reduced.
What blood?
Al
Thanks for being a friend.
Happy Memorial Day and thanks to all that have served this country.
Best regards - Al
Amen, here's to Henry and all the others here who have served our country and the world.... Thank you one and all. As well to remember those who are no longer amongst us...To their families, thank you for your and their sacrifice.
Have a Great Day, Brent
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Now you're getting "Meta-physical" on me Al!!! Too DEEP for my blood!!!
