Tack Welders Length of Time Qualified

Date 05-29-2007 13:55

Under 4.1.3 "Period of Effectiveness" there are two subclauses, one for welders/operators and one for tack welders. Each have separate and distinct limitations on qualification so, yeah, I'd agree with your conclusion.

By Kix

Date 06-05-2007 17:40

Do you guys happen to know what the length of the weld has to be to throw you out of the tacking category?

By HgTX

Date 06-05-2007 17:57

I Have Been Told By People In The Know that there is no max length on what is considered a tack. Which puts a very fine line between a continuous tack and a root pass...

Hg

By pax23

Date 06-05-2007 20:59

I see no maximum limitation on the length of tack welds in D1.1, but the definition in the glossary makes it clear that tack welds have a specific purpose or role which is simply to hold the pieces in place until the final welds are made. I would use that definition to counter any claim that a root pass or any weld that obviously is intended to be a final weld could be categorized as a tack weld.

By HgTX

Date 06-05-2007 21:23

Any tack made inside the joint itself (which is where they're encouraged to go in bridge welding) is going to be part of the final weld. So how does one distinguish?

Hg

By pax23

Date 06-05-2007 21:36

That's covered by 5.18.2.1 in D1.1 and is most certainly covered by some section in D1.5 (both FCM and non-FCM) which I am not going to look up at 5:30pm (end of the working day).

There's a difference between a tack weld that is incorporated into a final weld and a weld pass layer that someone is trying to pawn off as a tack weld. "What is that weld's purpose", is the question that must be asked. If it is solely to hold the pieces in alignment then it is a tack weld. If it has a greater purpose such as to provide the root bead in a multi-pass weld then no its not a tack weld.

A weld is a weld, its purpose and location allows us to label it as a tack weld, fillet weld, groove weld, hot pass, backing weld, back weld, filler pass, root pass, cap pass, or whatever other names we can come up with.

By HgTX

Date 06-05-2007 22:57

Any tack weld made in the weld root will be, in effect, a root pass, if one of limited (but not code-limited) length. Does a potential root pass become a continuous tack when it's ground down like tacks are? When it's made by a different process and is of smaller bead size than the rest? If the fabricator decides that it's less labor-intensive to use more wire and not start and stop between the various tack welds in fitting up a joint (and the tacks, when they do stop and start, are often 30-50% of the total joint length, sometimes more, and are a good 18" long), does that automatically turn the tack into a root pass?

Hg

By Joseph P. Kane (****)

Date 06-06-2007 02:03

I am the inspector on the new World Trade Center "Freedom Tower" column fabrication. The column has a W14X730 ASTM A913 Gg. 65 QST column core with two 3 inch thick ASTM A 572Gr. 65 "Mod" 42 inch wide plates welded across the flange legs with a TC-P4 SAW weld. The contractor is using 2-G FCAW tack welds to assemble the plates to the W14 shape and 1-G FCAW and SAW tack welds deposited between the 2G tack welds, making a continuous "Tack Weld". This continuous "Tack Weld" is necessary to prevent cracking of the tack welds duting the first three SAW weld passes.

The required preheat for the SAW Welding is 300 Degrees F. Per the D 1.1, the contractor elects to deposit the "Tack Welds" without preheat. The fabricator contends that they are re-melting the so called "Tack Weld", and that they do not need to preheat. I cannot force them to perform a fillet weld soundness test. I could not find anything in D 1.1 that would allow me to classify this technique as a "root pass", and compel them to preheat.

It would be nice if the D 1 Committee would look at some of the comments on the forum and clarify parts of their Codes.

By Lawrence (*****)

Date 06-06-2007 05:54

Joe,

Off topic but....

It sure would be cool to see some pictures of the tower fabrication if that kind of thing is allowable...

By ssbn727 (*****)

Date 06-06-2007 07:01

Hey Joe!

When you say "inspector" - are you referring to the chief inspector, source/ vendor surveillance or do you mean the only inspector?

Btw, Do you remember Alex Odonnell, James Madison Sr. & Jr. from Prest-O-Sales which is now run by James Madison Jr.?

Respectfully,
Henry

By Kix

Date 06-06-2007 13:14

What about guys that put 1/2" to 1" welds every foot or so all over a production truck cab. Could they still be considered tack welders even though the weld they are putting on the truck is the final weld? Sometimes they might lay a 3" fillet every so often to tie in a square tube.

By js55

Date 06-06-2007 14:12

I think pax 23 is on the right track. In my opinion to try and define tacks by a dimensional limitation demonstrates an ignorance of manufacturing realities. Especially in piping. And I believe this is why the code bodies, in their wisdom, in general have been reluctant to do so.
Defining them by purpose may be messy but I would have to ask, where are the failures to argue that this situation DEMANDS change?

By welderwv (*)

Date 06-06-2007 15:08

It seems that if one would use the Fillet Weld test in Figure 4.37 of D1.1 for the tackers test than any question of how long the tacks are would be resolved. The tack welder would be qualified to tack or even to weld fillet welds in the position tested in.

This applies to fillet welds only. D1.1 - 4.19.2.1 does not allow a tack welder to make tacks on CJP w/o backing. This must be done by a person qualified in CJP w/o backing in that position.

By Joseph P. Kane (****)

Date 06-06-2007 15:09

Since there is no definition, or direction, nor restriction or any other limitation in the D 1.1 Code, how would a third party inspector disallow a full length tack weld.

By js55

Date 06-06-2007 15:19

Joe,
Two points. First of all I am sympathetic to your problem. There are manufacturers who take advantage of gray areas, to be sure. Seen it often, as I know you have. But I would argue that first of all why would a third party inspector be thinking in terms of disallowing something that he first of all has no data that supports it as being a problem, and is also fully aware of the fact that it is not a code violation?
Too often third party inspectors get in the habit of trying to disallow something they don't like and then seek for justification. My argument is, that is not what their responsibilities are.
On the other hand, being sympathetic to your argument, I would say that if the manufacturer is taking this situation to the extrme there is always an appeal to the Engineer who has ultimate say so on matters of manufacture. I would have no problem with any inspector taking an issue to the Engineer. I do however have problems with inspectors looking for way to reject something that they wish weren't done that way.

By Kix

Date 06-06-2007 16:37

So i could classify my body welders as tackers and quit haveing to keep track of their qualification paperwork during the 6 month intervals. This could come in handy here in my future.

By js55

Date 06-06-2007 16:43

Kix,
Explain body welders.

By Joseph P. Kane (****)

Date 06-06-2007 18:49

js55

Fighting words! What I have not said in the previous reply was that I know through experience that the fabricators are not re-melting the "Tack Weld / continuous tack weld", but do not have the explicit authority under the Code to require them to demonstrate.

As for looking for reasons to disallow the "full length tack weld" without preheat, I feel quite justified in saying that "Full length" tack welds are not what the average person envisions when they think of tack welds. When I heard they were doing it, the alarms went off in my head, and I researched the Code provisions for justification. proper research revealed that the code was neutral on the subject.

I then tried to get the EOR to require them to demonstrate that they could fully remelt the Tack Welds made per D 1.1 Para. 5.18.2.2 without preheat. Again there is no specific authority in D1.1 to allow the EOR to "Require" it.to be performed. So, I have good reason to doubt they can conform to Para 5.18.2.2, and fully re-melt the tack weld with the first SAW pas, but I cannot prove it without their willing cooperation. (Destructively tested mock up weld would be required.)

As a third party inspector, I often try to disallow something that I don't like. Of course, I don't do it without "Chapter and Verse" justification. for instance, on this project one of the subcontractors routinely preheated to 800 degrees so he could make multiple passes without re-heating for the next pass. This is proscribed in D 1.5, and in ASME, but after research, I found out it was not addressed in D 1.1. Also, in my investigation I found out that the D 1.1 Committee had rejected this limitation before! The EOR did not want to allow this, to be done, but he had already approved the WPSs where the maximum preheat temperature was not addressed. So, now when the contractor would not cooperate voluntarily the EOR was out of luck. However, when the contractor submitted a new higher deposition WPS, the EOR would not approve it unless they agreed to a 450 degree maximum preheat limitation. Now the contractor was out of luck!

You see, the contractor is a low bidder, and if the EOR imposes something new on them, they get to back charge and feel justified in recovering not only the difference in price due to the change, but the diffference from profit they are actually making and how much profit they wanted to make on the job.

I think of my actions as being "Responsible". I am in fact a replacement to the previous inspector who was removed by the owner for other weld conditions that came out in the first set of columns. It is always the inspector who gets asked "Why did YOU let this happen?". (Of course you didn't make weld one on the whole project, and their QC let it go, or didn't even inspect at all!) To me, it is not just CYA, but responsibility to the public safety. So, as long as I don't impose something on the contractor that is not required by code or contract specifications, I feel completely justified doing due dilligence research. If I don't, I will be that "Last F___ing Inspector"!

Furthermore, as a third party inspector, I find that the contractors are always trying to get one over. I am always dealing with EORs who will allow something improper to be done without supporting the NCR written by his inspector. In this case above, the EOR doesnt know anything about welding, so he has deferred the welding issues approvals / disapprovals to the Port Authority Engineers.
I am the Eyes orf the EOR, and It is my responsibility to make him fully aware of all conditions and the reasons for my comments.

By js55

Date 06-06-2007 19:16

Joe,
You are absoutely right in stating that contractors sometimes try to get one over. And inspectors are there to see that they don't, within their authority, within the contract, and within the code. But as soon as you step beyond contract and code requirements and attempt to impose your own will you are no longer an inspector. You are a self appointed engineer.
As for full length tacks I'm wondering how it is the Engineer could find no justification within the bounds of the posted definition to halt a process wherein it was clearly way way beyond 'holding parts in proper alignment'.
The engineer certainly has the authority to impose such a clear and intended interpretation. It seems as though he was just reluctant to do so. IMO your answer wasn't to be found in 5.18.2.2 but in AWS 3.0.
And far from fighting words, in the case of full length tacks we would be in total agreement. And it seems to me under AWS 3.0 the full length tacks would be justifiably disallowable. I'd put the hammer down on that myself.
I've seen some absolutely atrocious pipe ends due to thickness variations, out of roundness, etc., used Deerman's, dogs, port-a-powers, spiders, etc., and never seen a situation where a tack needed to be the full circumference to hold alignment.

By Joseph P. Kane (****)

Date 06-07-2007 13:33

js55

The reality is that the fabricator really does need full length tack welds to hold this assembly together during the preheat cycles until they can get two or three SAW Filler passes welded. I have often seen very substantial tack welds crack simply from the preheating operation. Many times the tack welds cracked as often as three times! These are really massive steel columns made of GR. 65 material and the welds are highly restrained. Preheating of just two of these columns and maintaining it for five days of 24/7 welding used 750 gallons of propylene and cost the contractor $4000.00.

One of the contractors also needs a full length tack weld to provide a backing so that the root gap does not allow the SAW Flux to drip away. Yes there is a 1/16 inch gap limitation by Figure 3.3 (TC-P4s joint), but in some areas it may be a little larger due to the thickness of the metal and the ASTM dimensional allowance limitations. The fabricator made this pitch to the EOR, and the EOR bought off on it. The EOR did not know, (or did not connect the dots,) that there was no preheat, but now, legally, cannot go back on his approvals without incurring back charges.

At one of the fabricators, tack weld cracking was a problem even when the assembly was preheated for tack welding. They also tried lower preheats, to no avail.

As for the legal ramifications of imposing changes, The owner's legal branch has a lot of case law experience with back charges and knows how the courts will rule. I have consulted for clients that have back charged this owner for things you and I would think are "Understood", such as visual inspection, and win! Thus, when they direct me not to enforce some aspect of the Code, or let something go, I comply. I do note it at least once in my report, for CYA purposes, and alert my employer. In this case, I am not sure that even that would cover me in a court of law, but there is nothing else I can do. Many times the EOR lets things go, because he really doesn't need full compliance with some code requirement. Under the law, the EOR can allow conditions contrary to the code requirements based on engineering judgement.

By js55

Date 06-07-2007 14:17

Joe,
I can understand how frustrating it can be if the EOR will not back you up. Glad to hear you have your CYA records in good order.
But it seems to me you have a different type of problem than the one I was targeting. If, as you say, it is necessary to run full length tacks, then per AWS 3.0 there is no code circumvention and nothing to enforce, and therefore as an inspector, at least on this issue, your responsibility is fulfilled.
The problem of viability is up to the EOR. Having said that, I have never had any problem with an inspector, certainly not one as obviously experienced as yourself (though I've known many that were better off keepin their pie hole shut) opening a dialogue with the EOR to keep them abreast of any possible issues. I think keeping the EOR and your employer abreast IS an inspector responsibility.

By QCCWI

Date 06-06-2007 18:27

Per AWS A3.0 a tack weld is a weld made to hold the parts of a weldment in proper alignment until the final welds are made.

I work in a structural steel fabrication plant. Fitters tack weld parts on, the material is check by a back checker then welded. If the parts are on wrong ,hit part with hammer tack breaks. Hammer will not break full lenght tack. So a full length "tack" is not a weld is not a cost effective arguement.

(Hey Bubba, I will hold this part in place and you run a tack the entire length on both side. Then we will check it to make sure it is right.
If you say so, Bobby Joe.)

I bet Bubba and Bobby Joe would never make a profit.

By js55

Date 06-06-2007 18:40

Yes, and I think that definition is adequate. As you state, there is a built in efficiency to tacking as little as possible (which isin position) and then welding roots in a more productive application like rolling pipe or with more accomplished welders as in the caseof structural. Why someone would really want to have their inexperienced tackers run full roots escapes me.
The only time we even came close to something such as that was with Grade 91 where purges and preheats need to be maintained. Preheats essentially for the full duration of the weldment. So instead of tacking and then losing purge and preheat while transporting to a position on the floor or a welders bay we just had the fit station make a full root hot pass and filler to get to the 3/8" volume. In this case we had full cert welders in the fit stations.

By HgTX

Date 06-06-2007 19:30

And yet, they do it. I've seen 100-ft girders with continuous GMAW tacks to be gone back over with single- or multiple-pass SAW. For a continuous tack, they just babysit the buggo. For stopping and starting, they have to do some actual work. Same man-hours, though, so I still don't really get it.

So are we calling remelting the determiner as to whether something's a tack or not?

Hg

By js55

Date 06-06-2007 19:41

I thought QCCWI's post of the AWS definition made it clear. I have to admit, I suppose, I don't understand how this definition fails to give an inspector the authority to stop this practice. I would have to argue that the definition as it exists in the code is intended to do that very thing.
It seems that much of what is being argued is similar to arguing for Congress to make a new law to solve a problem when there is already one on the books that just isn't being enforced.

By HgTX

Date 06-06-2007 22:09

You can't prove "intent" by looking at a weld. I say it's a root pass, they say it's a continuous tack and the *next* pass is the root pass. I can't prove or disprove the welder or welding supervisor's state of mind.

Hg

By Kix

Date 06-07-2007 12:22

The guys that do the body welding basically tack thin stainless sheet metal to the cab. I couldn't classify the cab welders as tackers because they make full welds around the tubing and it's structural. Body guys just tack the sheet metal all over because if they were to make a continuos weld it would warp all to crap.

By js55

Date 06-07-2007 13:37

Kix,
Keep in mind, as long as "the 'tack' is used to hold the part in alignment until the final weld". If this is not the case then the 'tack' is a weld, no matter how short. Thats why they call spot welding spot welding, not spot tacking.

By HgTX

Date 06-07-2007 21:33

Both a tack and a tackless root pass are holding the parts in alignment until final weld. How do you prove that first pass/tack has no other purpose? Once the rest of the weld is deposited, the atoms in the tack pass don't "know" that they're not supposed to contribute strength to the connection.

Nothing anyone has said so far indicates to me how one can prove that a continuous tack necessarily is something more, if it's followed by other passes. Sure, if it's the only weld you're putting down, then it has to be the final weld because there's no other weld someone can point to as the final weld instead. But if you're putting something else down on top of it, how do you conclusively show what the purpose of that first pass is? How is it "obvious" that pass is for more than holding things together? I can't prove it.

If the WPS is for a specific number of passes and they put that number of passes down on top of the tack, the claim might be made that the tack is truly just a tack. But for a WPS that doesn't specify number of passes?

Back to another subtopic, can't a macroetch sample show whether a typical tack is typically remelted?

Hg

By js55

Date 06-08-2007 13:22

HgTx,
You've created your own counter argument by stating "tackless root". Clearly, by being forced to use the terminology of 'root', because there is no alternative, you have explicitly determined it to be, by definition, an integral part of the final weld, and therefore NOT a tack, simply a root pass that happens to function as an alignment condition. You clearly know what it is,and its not a tack. Also, roots always function to a certain extent as final alignment passes. It doesn;t chang etheir definition. Root gaps close, square alignments vary, etc. And these conditions are less likeley to vary after the root is applied. So roots always function as alignment passes.
And bottom line is there is no reason to get hung up on proof. The EOR doesn't need proof. He doesn't need to read the manufacturers mind. All he needs to do is read the definition in AWS 3.0 and make a judgment, then assert his legal authority to impose his will.

By HgTX

Date 06-08-2007 15:47

No, I brought up the contrast BETWEEN continuous tack and tackless root..

I call something tackless root, they say no, it's a continuous tack, the next pass is the root.

For the case I'm thinking of, the tack or root pass (depending on one's perspective) is a very small GMAW pass under an otherwise SAW weld. Single SAW pass is called for, and a single pass is deposited atop the GMAW "tack", which is done with the same procedure they'd use for discontinuous tacks. Two feet on, three feet off, that's a tack. Three feet on, two feet off, still a tack, since it doesn't go all the way and thus can't qualify as a root pass. Four feet on, one foot off--still gotta be a tack. 4'11" on, one inch off, has that tack now become a root pass with some repairs needed? This same fabricator also has some procedues on file for SAW groove welds with SMAW root passes (presumably tacked together by some means or other). They apparently don't consider the GMAW to be a root pass, or they'd write a similar procedure. I don't see how this is black and white at all.

And the EOR sure as hell does need proof, unless the EOR wants backcharges or change orders. The EOR does not get to just randomly dictate, with no financial consequences.

Hg

By js55

Date 06-08-2007 16:29

HgTx,
"Two feet on, three feet off, that's a tack {Only if it is required to maintain the fit}. Three feet on, two feet off, still a tack {only if it is required to maintain the fit}, since it doesn't go all the way and thus can't qualify as a root pass. Four feet on, one foot off--still gotta be a tack{only if it is required to maintain the fit}. 4'11" on, one inch off, has that tack now become a root pass with some repairs needed?
It does no good to run tack length ad infinitum when tack length isn't the code criteria. The problem here isn't proof, its a lack of understanding of the definition as made explicit in AWS 3.0. And there is just something inherently unconvincing about a manufacturer arguing he requires a 40' tack to maintina his fit. The odd EOR may buy it, the odd QC Manager may buy it, but I doubt you would find consent amongst knowledgeable EOR's, QC Managers, or even ANI's.

By HgTX

Date 06-08-2007 17:53

I don't think they require 40' to maintain fit. I think it was an economic decision that it was simpler to run an automatic process on a track for the full length of the joint than to start and stop by hand.

In this case, I believe them. The next case, I might not, but I'd be hard pressed to find a concrete and code-written basis by which to separated one case from the other. When I mention continuous tacks, people generally seem to know what I'm talking about--so the concept of continuous pass vs. root pass is certainly in existence.

Hg

By Joseph P. Kane (****)

Date 06-08-2007 13:27 Edited 06-08-2007 13:33

hgTX

I agree, that a macro-etch would show that the root pass was not re-melted. I even have proof that their new WPS, that was fully qualified Per Section 4, D 1.1, did not re-melt the tack welds. However in a miscommunication error to the EOR, he approved the WPQR for use, not knowing that I had told him that the contractor did not re-melt the tack welds. The contractor can now back charge the owner, if the EOR subsequently revokes the OK to use the WPQR. In the case of the D1.1, the macroetch examination performed in the WPQR test Paragraph 4.8.4.1 does not list "Assuring that the Tack Welds have been re-melted" as one of the "Acceptance Criteria". The owner's legal department holds a tight rein over what the EOR can say and can do.

I had actually sent the EOR pictures of the macro-etch where the tack weld was still visible prior to his approval action, but his E-Mail server could not take the file size and I did not realize that the E-Mail rejection by the server involved him before I deleted the rejection notice. When I was asked by the EOR to comment on a subsequent WPS approval request, I asid that the WPS had proved not to re-melt the Tack Weld. This upset him, and he wanted to know why I didn't mention this when I witnessed the actual WPQR coupon test results. So, even though I did attempt to E-Mail him photos of the lack of re-melt, he never did get them.

There is one thing that saves the situation. When the contractor was doing the WPQR welding, the company QC inspector left the area, and I as third party QA wound up recording the parameters and the heat data. The highest interpass temperature on that test was 480 degrees F.   So, now when they want to use this WPQR for a welding WPS, they get stuck with the 480 degree limit, which they cannot follow. However thay can still use the pre-qualified WPSs that have been previously approved.

Another interesting thing for the macro-etch testing per D 1.1, Paragraph 4.8.4. is that the only acceptance requirement is for a "clear definition of the weld" So, no microstructure need be shown, only weld size, leg size, fusion to the root, no cracks, weld profile and no undercut. It is only luck that allowed me to see the microstructure enough to count all the passes.

Joe Kane

By ssbn727 (*****)

Date 06-09-2007 02:56

Not to intentionally go off topic again but Joe! That's why you should use 'Winzip' and compress those huge files so you do'nt run into those problems like when you tried to send me the NYSSCM... Capish? ;)

Respectfully,
Henry

By js55

Date 06-07-2007 13:34

HgTx,
I do beieve that what you are saying IS exactly how it is. I understand that it really couldn't be any other way for this process to continue as it is. And I have no disagreement with the explanation.
But the Engineer (cap intended) does not need to prove intent. He has, by code the authority to disalloy a practice that is clearly not code compliant. The very idea of a full length tack demonstrates such absurdity that I find it hard to believe that in a confrontation of QC and Mfg that the Mfg supervisor could even argue it with a straight face. Its simply a matter of the manufacturing supervisor having more resolve to circumvent the code than the Engineer or QC Mgr has in enforcing the code.
It is a requirement of virtually every regulatory auditing system (AISC, ASME, ISO) that the QC Manager or inspector has the "Manual" explicit power to stop work. Question is, does he have the 'sand' to actually do it. A process in my opinion that actually puts the onus of proof on Mfg.
And a third party inspector theoretically has even more power. Since he does not even have to answer to the President of the manufacturing firm. That is if the Engineer is willing to stand behind him. This is the problem though, as I understand it.
Also, I would ask, what are the comments by AISC (or ASME) auditors when they do their shop inspections and observe this practice. Or does Mfg stop doing it for one day, which of course would indicate they are very well aware of the fact that what they are doing is unnacceptable.

By eekpod

Date 06-07-2007 15:53

Joseph P Kane.
You mentioned that the contractor elected to not pre-heat for the tack weld per D1.1. Maybe my intrepretation is wrong but I read D1.1 that says any welding must be pre-heated depending on material type/grade/ and thickness, I don't see where it differentiates between a "tack" weld and a final "structural" weld.
In other words, I train all our fitters that they must pre-heat to tack parts just like the welders must pre-heat to weld as well. Chris

By pax23

Date 06-07-2007 16:56

Section 5.18.2 (1) allows the contractor to perform tack welds without preheat if the tack welds will be remelted into a SAW weld. Joe is not so certain that the tack weld is being completely remelted into the SAW weld.

Seems to me that the best thing to do is simply inform the EOR in writing of the concerns and let the EOR crack skulls. If the EOR decides not to investigate or to require the contractor to change the procedure then it seems to me that the verification inspector has perform his job with due diligence.

By eekpod

Date 06-07-2007 18:09

I didn't pick up on the SAW part in the posts, I skipped ahead to save time.

By Kix

Date 06-07-2007 19:26

I know what your saying and i will do the right thing. I don't have to keep track of the paperwork anyway, but it would be nice for the company to be able to call them tackers.;-)