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Up Topic American Welding Society Services / Technical Standards & Publications / staggered intermittant (stitch) welds on structural steel
- - By CHGuilford (****) Date 06-15-2007 16:54
Common sense and good workmanship tells us that staggered welds should be placed so the stitch welds on one side are centered opposite the space on the other side of a joint.  Usually, there is no problem if staggered welds are somewhat close to being centered, the weld lengths are at least the required length, and the pitch ,or the space between welds, is no greater than what is shown in the welding symbol.

(We already know that a 2 on 12 intermittant fillet weld would be 2 inch long welds spaced at 12 inches apart center to center (pitch), and that from the welder's perspective it is 2" weld, 10" no weld, 2" weld and etc.)

There does not appear to be anything in D1.1 that specifies a tolerance on centering of staggered stitch welds.  Some QA inspectors have questioned how the "centering" should be; ours are "off" by an inch.  There is nothing in the drawing notes or contract specifications to say either way- I don't believe we have a problem.     But just to be sure, does anyone know of a specification that applies to this?
Parent - - By hogan (****) Date 06-15-2007 17:52
doese aws a2.4 (98) figure 8 help
Parent - - By CHGuilford (****) Date 06-15-2007 20:46
No it doesn't but you pointed me in the right direction.  By your asking, I did look at 5.4.4 again and noticed Figure 33C which I think does answer the question.  I had looked at 5.4.4 previoulsy but failed to notice the reference to that figure for some foolish reason.  (I'll blame it on a long week with too many projects.)

No tolerances are given but I think the intent is clear.  I don't think I'll worry about this case because the welds are actually a bit longer, so it works out to be fairly close.  But some instructions to the welders should be a simple way to eliminate any future doubts.

Thank you
Parent - By monsoon12 (**) Date 06-16-2007 01:22 Edited 06-16-2007 21:50
I always just lay it out,this way you cant go wrong.If the welder has trouble seeing the lines just use a really flat soap stone so the line is visiable during welding.I was at a new job one time an i had a inspector pointing at my welds why the boss stood by an he was swearing up an down that the welds werent 2" on 12.So i whipped out my tape knowning that i had layed them out.Now i wasnt looking to prove him wrong i think that inspection is a good thing.After showing him that they were what they were suppose to be he clamed down.Sometimes you have to go to the old motto   CANT WE ALL JUST GET ALONG LOL.
Parent - - By Kix (****) Date 06-19-2007 14:46
5.4.4 is for ESW and EGW processes, but maybe i'm reading your post wrong.  Not sure where your getting the 33C from either.  Are you getting this from 06 D1.1 and Can you elaborate for me so as to help me out a bit in the future.  Thanks!!
Parent - - By thcqci (***) Date 06-19-2007 22:25
I think that comes from A2.4 not D1.1.  You are just looking in the wrong book.
Parent - - By Bill M (***) Date 06-20-2007 17:20
You have to comply with the drawing.  The weld symbol on the drawing controls the relative locations.  The weld symbol can ask for them to be staggered or not staggered.
Parent - By CHGuilford (****) Date 06-21-2007 17:29
It isn't that no one knows where to locate the stitch welds; there was a difference of opinion as to what "staggered" means.  Some felt any offset was OK, some felt the offset needs to be dead on centered.  And some felt within an inch or so of centered fulfiled the intent of the project requirements
Parent - By CHGuilford (****) Date 06-21-2007 17:24
That is correct, that is from A2.4
Parent - By jwright650 (*****) Date 06-20-2007 17:55
OK, I went to A2.4 for a look around and here is my opinion about the staggered stitch welds tolerance:

A5.4.4 says that .....the segments of staggered intermittant fillet welds SHALL BE symetrically spaced on both sides of the joint......

I think that pretty much says you have no tolerance, so have your fitters mark the effective weld lengths and be fairly accurate so the welder can come behind them and get it right.

Maybe this is a knee jerk reaction, but...get the drawing room to place a shop tolerance in the shop bill somewhere on all of your shop drawings stating what is acceptable (+/-), like a general note that you go by Unless Noted Otherwise. Then when the drawings come back from the approver "approved", the outside inspector will probably not have an issue.

(personally, I don't think the pourstop will push off the building if the drawing is right to start with and the welder gets a staggered fillet weld an inch off center)....LOL
Parent - - By jwright650 (*****) Date 06-20-2007 17:33
Chet,
How many welds (of the stitched) are off by an inch or so? If there were only a few, I would be inclined to add the extra inch or so to the weld(s) in question and give the inquiring inspector the warm and fuzzy that he is after. But that's just me, I try not to rock the boat with outside inspection unless they are causing me a lot of trouble and clearly do not know what they are doing, or have lots of personal preferences for us to add to the already approved design.

If you end up finding a tolerance or a specification listing that tolerance please be sure to post back for us.
Parent - - By CHGuilford (****) Date 06-21-2007 18:57
That was sort of the point.  The staggered stitch welds attach WT and L stiffeners to 3/16" skin plates.  The boundaries of each panel is seal welded and the panels make up square and rectangular exhaust gas ducts.  There are several hundred panels to be field welded or bolted together after the shops are done with them.  This is a fast track job being coordinated with 8 sub-contract fabricators that all leads up to an outage this Fall.

This is not an attempt to short change the owner,  they have been very happy with everything so far including staggered stitch welds that have been off center.  The owner does NOT want to split hairs over minor "stuff".   The problem we have run into is some 3rd party inspectors trying to make this into a "nuclear" job.  Most are pretty good inspectors and pay attention where they should.  But some can barely spell "D1.1" (not joking) and want everyone to know they're making the world safe for "truth, justice, and the American way" (coincidentaly, I have not met one who is actually a CWI).
When the owner overrides a trivial NCR from the inspector, the retalitation is to hit us with numerous Unsat reports (which are not an official document for this job) that range from not allowing stripe coats of paint to dry before spraying that coat, to 1/4" fillets are too small (when measured through the wet top coat of paint- again, not joking). 
I have since changed tactics; any Unsat report is met with "Show me in the specs where that is wrong".  I am pretty particular about quality; if I'm not sure I err to the stringent side until I get clarification; and I treat everyone respectfuly and professionally.  But I am through with providing these guys with an education. 

There!  That felt good!  (Maybe that's why I've been so crabby lately) 

Fact is - I did let those welds go.  If they had been small, short, or drastically off location, the welders would have had to add the right size weld in between the stitches.  The vast majority of the welds are as they should be.

I don't know if we will find a tolerance.  The diagram has no +/_  and the word "symmetrical" is in there.   I believe this is a case where some common sense (assuming common knowledge) should be used on a case by case basis.  I certainly don't think there is a need to add a tolerance to the drawings.  If the job is that critical, stitch welds would not likely be used.  But i I find a tolerance, I'll let you know.
Parent - By jwright650 (*****) Date 06-21-2007 19:34
Go on,...Get it off your chest Chet!...LOL
Hope things smooth out for you before the last weld is placed.
(the inspectors are not even CWIs...geewiz!)<--maybe they are just envious of those certs hanging on your walls<grin>
Parent - - By hogan (****) Date 06-21-2007 20:04
of all the inspectors i've met, i would have to say common sense is most frequently the one quality lacking in them
Parent - - By thcqci (***) Date 06-22-2007 13:02
Take this for how it is meant.  For what ever it is worth, as an inspector, I have often been accused of not having common sense.  I have been accused of toting my "bible" in the shop.  I have been accused of being critical on things most all on here would agree need fixing; like that little bit of undercut, or porosity (eagle eye), or fixing a discontinuity found during a UT inspection that just crosses into rejectable catagory and is difficult to find when gouging (you mean that little thing is gonna make the building fall down).  "Doug, you gotta have a little common sense and let that kinda stuff go.  Quit being so picky.  You are costing us too much money.  They are gonna fire you if you don't stop slowing us down like that."  It is not as if, when I take of my inspector hat, I can't see their arguement and think the exact same thing and even agree with their perspective.  It is not that I don't have any common sense.

Although this particular case here seems quite trivial to dispute, I don't take it as my responsibility to do too much interpretation of code or specification statements.  Someone somewhere up the foodchain is expecting me to have a black and white judgement with no grey areas.  My conscience often tells me when I haved used "common sense" and let something slide, that that was not my call to make.  I am not the engineer.  I agree my training is supposed to make me question some situations and even ask for variances of code stated situations.  My general approach is to find in the code what will allow a situation instead of always trying to find a reason why you can't.  But when I can find no legitimate reason to "allow" a situation, then it will be deemed not in conformance.

So, as for this inspector, I take it as a compliment when someone tells me I have no common sense.
Parent - By hogan (****) Date 06-22-2007 18:49
fyi having common sense is a good thing
Parent - By mountainman (***) Date 06-22-2007 19:13
i can't find in any code where they require common sense, lol. i respect your statement thcqci, it makes clear sense to me.

jj
Parent - - By pipewelder_1999 (****) Date 06-22-2007 02:18
I think we had the same situation in our shop a week or two ago. Similar thing about the spacing of intermittent welds.

Gerald
Parent - By 803056 (*****) Date 07-02-2007 04:11
Many, many years ago, AWS A2.4-76 dropped a note from the sketches used for intermittent fillet welds. Prior to 1976, the sketches included a note that the intermittent fillet weld started with a increment (or segment) at one end of the joint and terminated at the opposite end of the joint with another increment. If necessary, the increment length could be increased to accommodate the requirement. Clearly, I'm paraphrasing, so don't beat me too badly.

I wrote a letter to the committee chairman and pointed out that the new sketches in A2.4 must have omitted the note requiring that the welds start and stop at the ends of the joint.   

The reply I received (from one of my past professors) basically said: "Hey dumb ass, A2.4 is not a workmanship standard. The welding symbol is to be interpreted as follows; the length of the weld specified is to be considered the minimum length required, the size specified is to be considered as the minimum weld size required, and the maximum unwelded space between adjacent weld segments is not to exceed the pitch minus the segment length. If the engineer wants a weld at both ends of the joint, they have to be specified separately from the intermittent fillet weld, and if the spacing and length of each weld segment is a concern, then they too should be specified and dimensioned separately and the intermittent fillet weld symbol would not be approprite."

So, I have always looked to the applicable code to provide workmanship requirements and the welding symbol as the minimum requirements for weld size and length. The code specifies the workmanship requirements, such as allowing the fillet weld to run undersized, root openings within allowable limits, etc. If the workmanship portion of the code does not apply restrictions, who am I to make up my own? That is not to say the company can't impose more restrictive workmanship requirements than the code.

The bottom line is, a continuous fillet weld that has the correct size meets the reuirements of the intermittent fillet weld symbol based on the criteria provided by the A2.4 committee chairman. I don't believe I would like to see such a situation from a productivity or distortion standpoint, but as an inspector, it does meet the requirements of the intermittent fillet weld symbol as interpreted by the guidelines provided by the A2.4 chairman. Does it matter if the weld segments are exactly diagonally opposite when staggered intermittent fillet welds are specified or directly opposite each other if chain intermittent fillet welds are specified? No, if you base your answer on the interpretation I got from the committee chairman in 1976.

It will be interesting to see the latest revision of A2.4 to see if additional clarification was deemed necessary.

Best regards - Al
- - By henrry Date 03-17-2017 21:16
someone can Answer me  ??
i made a mistake ,when i Reinforce joist,doing both side  intermittant welds to staggered intermittant welds ,do i need fix  ?
Parent - - By welderbrent (*****) Date 03-18-2017 14:38
You really should have started your own thread instead of pulling up a 9 year old thread to ask a question.

Second, you will need to try to be somewhat more complete and clear in your query.  I realize language may be a problem but at least try please.

What code are you working to?  Are there shop drawings approved by the engineer?  Is this in a shop or in the field?

Did you weld some stiffener plates with Intermittent welds whereas the plans called for staggered welds, or visa versa?

If so, probably no 'fix' will be required but this needs to have an RFI sent to the engineer for his approval and just weld the rest of them as called for on the plans.  (Note I did say "probably", that does not mean absolutely and it isn't an answer we can truly give you)

He Is In Control, Have a Great Day,  Brent
Parent - By henrry Date 03-20-2017 01:32
thx i am a imigeration weld ,in my mind ,if both side  weld call  each 8 inch  2inch weld ,if we do stagger  weld each 8inch  2inch weld it will be fine ,isn't it
Up Topic American Welding Society Services / Technical Standards & Publications / staggered intermittant (stitch) welds on structural steel

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