Gentlemen,
I have often been confused by the acceptance std. of a weld bead with excessive width. Many discussions have been made on this topic in my daily job but it is still not clear to me, and the third party inspector always rejects the weld in following cases.
1) "excessive root pass width" and 2) "excessive cap pass with".
The former is the welder has filled the excessive root opening in an improper prepared groove during fit-up, which does not confirm to its WPS. The latter is caused by a out of tolerance groove/bevel angle, for which the weld has finished the surface to make a nice like by a single cap pass.
There is a concept "forming factor"="width of weld bead/depth of weld bead", referenced from some welding handbooks. Fortunately, there is limitation that can be referenced in AWS D1.1 Clause 3.7.2 and also Table 3.7 but I can not find the similar stipulation(maybe there is) from ISO std./ASME code. Then I am interested in how the issue-excessive weld bead width if happens, is properly solved in a satisfactory way generally.
Does anyone experience this issue and can you please share me your view?
Many thanks.
Allen.Liao
What welding process, what position, details man, we need details!
Some of your questions can be answered by referring to Figures 3.3 and 3.4. Some of the others (width of weld pass, thickness of layers) can be answered by Table 3.7. As for the depth to width ratio; it applies primarily to SAW. On occasion, one can encounter a problem with depth to width ratios with other processes if the groove angle is too tight. The bottom line is the width of the individual weld bead should be greater than the depth to avoid centerline cracking.
ASME codes do not tell the contractor "how" to do anything. The contractor is the "expert" and should know all there is to know about constructing their product. Different code, different philosophy.
Best regards - Al
I support the information stated by Al. There is no "bead Width" variable for ASME Sec IX welding other than its reference for oscillation width for machine welding and when used as a factor for controlling heat input. Other cases include UCS56 in ASME Sec VIII however I do not have a current version of that code.
Heat input would be the result you would probably be concerned with controlling in some cases. Bead Width by itself does not control heat input. It is just a factor. It is not in any case a condition which has an "Acceptance Criteria" in the context of the ASME Sec I, VIII< B31.1 and Sec IX that I am aware of.
If heat input is a concern then verifying quality by only observing bead width after the welding is completed would be a poor way to monitor/control quality since other variables that cannot be verified after the fact would be unknown.
Have a great day.
A search in the forum for "Bead Width" should result in a great deal of information.
Gerald Austin..
Is this a shop situation or some thing that is field related. Even the best welder cannot make up for bad fit.
Sometimes I sit and read, sometimes I sit, read and think.
The question I read you bringing to this group is why do they fail welds with excessive root width or seemingly wide coverpass profiles?
Good question. Got me thinking. Done.
Simply put, buddy was doing his job.
He was tasked to oversee that his employer was getting what he paid for, and that included land, gap, root penetration, fill and cover pass to it's wps.
That's not to say that everyday a skilled welder couldn't fill an excessively wide root opening. Or bridge and fill an uneven groove opening tolerance. But that wasn't what the company paid for and seemingly your guys were called on it.
While I don't fully agree with some of the concerns to centerline cracking if the cover pass is narrow compared to groove depth as I believe other factors more to that issue, I'm willing to go on record to suggest that wasn't the reason for failure of those weld in the inspectors mind.
I might suggest that while those welds looked solid, and the welder would sware to the good Lord they were, the procedure for welding them was deviated from enough to call into question tensiles, hardness, impact properties and whatever else they tested for to qualify on the material being welded
I order a steak medium rare and it come well done, it goes back.
All the reason he needs in most instances is his opinion or perception, but when you think about it, he also doesn't have to share it with you because you don't employ him if he's third party.
I would have asked him just the same.
Your guys over cooked the steaks. Thats what I think and yes, it's my final answer.
Plasma,
We have to be careful when we say things like your 5th paragraph.
There is simply no data out there that I have ever heard of, nor apparently the Section IX committee, that would suggest a wide bead effects the mechanical properties of which you speak, at least to so detrimental a condition as to render the part non compliant. This is why it is non essential variable.
Heat input certainly effects toughness but not as simply as most of us understand. I've qualified procedures where increasing heat input improved the toughness, as tested. But if toughness is not at issue in the application then it is not applicable.
Hardness is an odd property. Indirectly associated with tensile strength it is not generally a Section IX tested property (temper bead qualification being a notable exception). It is used primarily for heat treat verification as in B31.3, hard facing, or processing verifications as with Grade 91.
If the inspector has these things in mind when rejecting a weld I think he is misguided. He needs to simply think in terms of a violation of procedure, which is valid enough.
Allen,
I feel inclined to throw in my two tin pennies worth even with the excellent comments of the previous responders.
1) Though you cite examples of requirements and references from D1.1 and ask questions relating those to ASME you have not informed us as to which, if any, code you are attempting to learn how to conform to.
2) As Al asked, you have not responded and informed us as to which process, electrode class & diameter, joint configuration, tolerances of joint config, etc.
3) You state, "The former is the welder has filled the excessive root opening in an improper prepared groove during fit-up, which does not confirm to its WPS. The latter is caused by a out of tolerance groove/bevel angle, for which the weld has finished the surface to make a nice like by a single cap pass." But without know the thickness of the member that is difficult to visualize as even with the correct bevel or even leaning toward narrowing the gap by beveling to a smaller degree based upon the fit up tolerances a gap at the surface for your cover pass will be so wide on heavier sections that there is no way it can be completed with a single pass. Not even by the "Best" welder in the world (who won't even think of doing so in one pass). And also the first part of the quote being root openings, if they are to the large side based upon stated opening plus fit up tolerances then you need to use a double bead to fill in the root.
4) Weld puddles of the hot and wide variety are often allowed to just flow wide and the arc stream is not accomplishing the penetration into the root to get the correct root penetration so that if cut and macro etched you will not have ANY penetration on the two sides of your root when trying to do wide roots with a single pass.
5) There are many considerations that are normally dealt with at the engineering level that the code does not get involved in such as stresses, shrinkage, etc. They are not for us lowly inspectors. We only make sure that the job conforms to the engineer's specifications in the Contract Documents with the applicable codes used as supporting documentation for our observations and reporting back to the engineer.
6) Most all codes I am familiar with allow for the buttering of edges without tie in between the two members to accomplish getting the root opening to the correct dimensions. After allowing the part to cool it is then handled within the scope of the joint welding procedures as called out for preheat, process, filler, interpass cleaning, etc.
7) No where does D1.1 state that a root and/or cover pass must be done in a single pass. It would be impossible to comply with on materials with 3-4" of thickness. Even using a joint config to accomplish it that provided for a double Vee joint the groove opening at the surface would be so wide as to not be at all responsible if attempting to weld in a single pass.
8) Thus, rather the fit up is compliant or not it is possible to get the joint into compliance before just pouring the weld to the joint to get it done. This goes for joints that are fit too tight as well. Open them up with either air-arc, torch, grinder, or any other appropriate method, then weld. Don't just weld it then complain when the UT fails that the joint was too tight.
9) It is the TPI's job to be viewing operations to make sure the in house QC are overseeing these situations properly and making sure they are welded to the satisfaction of the customer/engineer who we are representing. But, if not being handled correctly, we are to go to lead personnel and QC first and if they won't see to the proper completion of the work we submit a non-compliant report to the engineer. Too many TPI's (but not 'MOST' in my experience) do have a god complex. We all need to know the scope of our responsibility, authority, and proper lines of communication.
Hope I made this make sense.
He Is In Control, Have a Great Day, Brent
Hi Brent,
"We all need to know the scope of our responsibility, authority, and proper lines of communication."
You do make sense my friend, alot of sense.
On behalf of those of us who learn from the greatness of others, thank you.
allenliao,
With out witnessing and measuring the fit up prior to welding, there is NO way to "guess" the root opening width (unless perhaps there is lack of fusion showing the prepared edges.). Individual welder's techniques and other factors come into play with the variables and outcome bordering on the infinite.
" the welder has filled the excessive root opening in an improper prepared groove during fit-up,"
If this were the case, then why was welding allowed to proceed??
Forget what might be suggested as "good practice" in welding Handbooks. They have no relevance to codes and specifications. Many "handbooks" as informational as they may be, are often the result of opinion and recognised techniques derived from the author's experiences.
Many inspector's prejudices and unprofessional conduct make my life difficult, but in the long run keeps me employed.
The Owner's inspector and the Contractor's inspector should be able to show the welder or the party asking the question what code or what portion requirement of the contract is being violated when work is found to be nonconforming. Both the TPI and the quality control inspector should be basing their decisions on the documents applicable to the project. If there is no requirement, there is no basis of rejecting the work.
If the welder has violated a code requirement, the clause, paragraph, or article should be easily referenced by the inspector. Likewise, if the welder has violated something contained in the WPS, it should be referenced by the inspector when the work is found to be nonconforming.
The TPI that determines work is nonconforming is out of line if he/she cannot cite a specific requirement in the code, project specification, drawing, purchase order, or WPS. The TPI that is basing a decision on personal opinion is someone that should be replaced by an individual that knows the limits of the TPI's authority.
When nonconforming work is identified by the inspector, it is only nonconforming if it doesn't meet the requirements included by the applicable contract documents. Personal opinion has no place in the inspector's decision making process. If the inspector has a concern, it should be bought to the Engineer's attention. The Engineer then must make a decision based on sound engineering judgment. If the issue was not clearly identified in the contract documents, the contractor may be entitled to additional compensation if a change in the contract document is required. For instance, if the Engineer/Owner wants to include additional criteria in the project specification once a problem is identified, the contractor can request additional compensation for making the corrections required by the Owner. This happen regularly on projects where the architect decides the visual criteria or fabrication tolerances must be "tightened" because a structural element is discovered to be exposed to sight. If the architect decides he wants all the exposed welds to be ground flush, if the tolerances for sweep are tightened, etc., the contractor can ask for a change order and is entitled to additional compensation because the "change" was not part of the original contract requirements.
Generally speaking, the TPI is not the individual that has the authority to insist on changes to the original contract requirements or the contractor's normal procedures. "How it was done on the last job", "This is how other contractors do it", "This is the way I've always seen it done" are not the basis of declaring work to be nonconforming. However, the TPI's task is made easy if the contractor doesn't pay attention to their own in-house procedures such as their QC manual, their WPSs, their written practice, or the applicable code.
Best regards - Al
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