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Up Topic Welding Industry / General Welding Discussion / Full depth stiffener plates
- - By jwright650 (*****) Date 10-15-2003 14:18
I have been looking at a situation that seems to be getting worst as time goes on in our shop. I was wondering what other shops are doing when ordering full depth stiffeners. The over-run on the inside of most of the structural shapes are costing us in that we are having to oversize fillet welds to make up for the gaps where the stiffeners are short due to the wider than book D-2tf dimension. In short, it would cost less for us to order these plates a little long and cut to fit rather than oversizing fillet welds to make up. Years ago mills were rolling to closer tolerances I guess and our shop was smaller and doing less volumes of work and we cut all our stiffeners to fit. Now days we order the stiffeners right off the bill of material and it is short when the over-run comes into play. Right now I have stiffeners that require 1/2" fillets and they have 3/16" gaps that require adding 3/16" to the size of the welds (in materials less than 3" thick) to make them per D1.1. Now I end up with 11/16" welds that require 10 passes instead of the original 3 passes that was detailed.

$$ is driving my question of other shop's standard of detailing/ordering stiffener plates. Maybe other shops won't offer their help but I'm asking in case someone will share that info. I looked into our estimating dept. and found that they are not putting any time in for burning each stiffener to fit, but I know they are not figuring in extra weld either.

Any help?
John Wright
Parent - - By TimGary (****) Date 10-15-2003 14:59
Hi John,

This probably isn't any help to you, but what we do is buy 20' lengths of flat bar in the thickness and width of the stiffeners we typically use and shear them off in the length required to fit the beam, as we go.
I know what you mean about dimensional variance in the beams. It's a pain to deal with.

Tim
Parent - By jwright650 (*****) Date 10-15-2003 15:10
Hi Tim,
We used to do that too, but as of late they are ordering all the stiffener material off the drawing's BOM, rather than cutting to fit. I think the time savings are being overcome by the extra weld required. I feel we should step back and take another look at some of these bad habits we get into trying to save time.
John Wright
Parent - - By CHGuilford (****) Date 10-15-2003 16:41
Hi John,
If working on smaller beams, we try to cut our stiffeners to 1/8" less than the inside dimension as listed on the charts. Our hope is to allow 1/16" top and bottom with no increase in weld size necessary. If our gaps run larger, then the extra weld needed is still cheaper than custom fitting each stiffener plate, because we are talking 5/16" and smaller welds here.
For larger sections as you are describing, we cut our stiffeners 1/2" long and trim one end during fit-up. This works really well if you are dealing with mill-to-bear fit ups and doesn't cost as much as building a weld up to 11/16" in size.
Once in a while we end up buttering weld on the ends to close the gaps because of one reason or another, but that often costs the most to do.

I am looking out my window at a stack of beams that will not be accessible for measuring until the loader picks it up and puts it on the drill line rolls. By that time the beams detail parts are already made and it's too late to measure.
We've tried countless times to measure the beams and pre-cut stiffeners accordingly. It always happens that the beams you couldn't measure are different, or flange tilt wasn't noticed so the correction changed inside dimensions, or a new operator didn't change plasma tips and got a wide kerf, or somebody read the tape wrong. And so forth, I'm sure you could add more to that. Of course all the above seems to happen simultaneously whenever we are doing a DOT job with mill-to-bear top and bottom flanges and there is no extra material and it's supposed to be on-site yesterday. That's always fun!

(For the benefit of DOT people reading this, we DO manage to do the job right once in a while.)
But at any rate, we have grown accustomed to variations in beam dimensions so we look at the requirements and determine which method will be the most cost effective for the project.
Chet
Parent - - By jwright650 (*****) Date 10-15-2003 17:12
Hi Chet,
These are W14x120's and they are (1'-0"15/16) 5/16" larger inside the flanges than the dimn in the book (1'-0"5/8), and then the Detailers took it upon themselves to take a 1/16" off the top and bottom of these plates which leaves me with 7/16" gap to try and split up between the top and bottom. Two wrongs don't make a (w)right. Where this gets really ugly is when the stiffener gets holes in it and I have to hold the dim from the top flange to the center of the hole, which in turn puts all the slop at the bottom with no chance to split it up. In these cases I'm forced to replace this material with longer pieces. It just seems like it would be easier and less expensive to cut them all to fit like we did years ago. All this material is V50 plate which we have had to order because we only keep A36 in stock. And Yes Chet, these are always the columns or beams that have to be on the truck heading out the next morning. The fitters/welders always tell me that the buck stops at thier table and they end up having to fix everybodyelse's mistakes.
John Wright
Parent - By Michael Sherman (***) Date 10-15-2003 19:53
John, it seems the choice is to buy precut and hope it fits or to custom cut, (w)right? If it were my decision to make, and in my shop it is, this would be an easy decision. I would (and do) custom cut. I cannot see were it benefits anyone to have to overweld like you are doing. Just my opinion, have a nice day.

Respectfully,
Mike Sherman
Parent - - By CHGuilford (****) Date 10-15-2003 20:20
It looks like you might have to eat the stiffeners, but I'm wondering if the beams comply with ASTM A6 dimensional tolerances? If not, the mill might have some ownership in your problem. I've found that most mill reps do OK by us when it's their fault, even when we've bought the steel through a distributor instead of a mill order.

Chet
Parent - - By jwright650 (*****) Date 10-15-2003 21:05
Now I have another CWI here at the company that is trying to interpet the section another way. He is trying to say that it reads that we are allowed 3/16 max without building up the fillet. But if we used jacks,etc. where outside forces are compressing the gap together then you start building the weld size by the amount of gap remaining. I disagree and think I am interpeting it correctly by saying 1/16" gap is allowed without upsizing the fillet by the amount of the gap and 3/16" is the max allowable gap that you can repair this way before cutting new material.
BTW, I am referring to AWS D1.1:2002, paragraphs 5.22.1 and C5.22.1
and also the material is less than 3" thick is why I was referring to the 3/16"max gap allowed.
They are now aware of the problem and I'll wait for them to hash it out and tell me which way to go for the future.
John Wright Do you guys see it like I do?
Parent - - By - Date 10-15-2003 23:53
John, you are right on the money. Up to 1/16" gap is allowed without an increase in fillet size. From 1/16 to 3/16" an increase in fillet size equal to the gap is required. Over 3/16" some other sort of remedial action is required (new piece, correction of dimensions by weld build-up prior to fitup, changing from fillet to CJP, etc). The code seems pretty clear on this point to me.
Mankenberg
Parent - - By jwright650 (*****) Date 10-16-2003 11:07
Hello Kip,
I thought I had been reading this correctly for years and this other guy has a tendency to try and read all the specs (AWS, ASNT, Job specs, etc) to fit his needs, instead of reading it for what it says.

Anyway, I wanted to congratulate you on a great article in Inspection Trends!(page 4 for those of you who haven't read it yet, also see the question and answer section where Kip mentions this BBS as one of his favorite places online for Welding information)

I think we as a company ought to cut those stiffeners to fit rather than ordering by the D-2tf dim given in the W shapes books. I really like CHG's idea of ordering the stiffeners for the smaller beam sections already cut and adding 1/4 or 1/2 to the larger sections. I was just trying to figure out at what point do I quit calling it a small section and declare that it is a large section. I was looking at the W12's and there are some really light and heavy sections even in that size and it gets worst when you look at W14's. Normally most of our plates and accessories are A36, but in recent years the engineers are now specifying that they want that material to be V50 just like the main members. Which brings up another problem keeping the grades from getting mixed up in our misc. detail material dept. In our current method of ordering it is kept straight by the PO#'s which match the mill certs and etc. If I go to stocking V50 plate I'll need to keep it traceable back to mill certs and to keep a fitter from using the wrong grade by mistake.
More to think about,
John Wright

PS. Congrats again to Kip!
Parent - By jwright650 (*****) Date 10-16-2003 11:13
To clarify V50 is ASTM A572 Grade 50. (for those of you that weren't familiar with the old designation of V50)
John Wright
Parent - By CHGuilford (****) Date 10-16-2003 13:07
John,
I agree with you and Mankenburg re: increasing weld size up to 3/16". That's been the standard for quite a while.

Also, to expound on my definition of smaller sections....what I was really thinking is that small steel usually gets small welds. You might want to review your needs by required weld size. It isn't a huge problem increasing a 1/4" fillet by the size of a gap (up to a 3/16" increase) whereas a 1/2" fillet as you described is a huge increase in costs.

Chet
Parent - - By bmaas1 (***) Date 10-16-2003 02:34
I would check the dimensional correctness of the members to astm standards. If they are not correct backcharge the distributor or the mill a couple of times for the extra labor involved. This usually corrects the problem after a few times. But in the short term its just easier to custom fit each piece.


Brian Maas
Parent - - By jwright650 (*****) Date 10-16-2003 15:31
Hi Brian,
Maybe you can help me with this. I've been looking through A6 and I didn't see where it addresses a tolerence dim for D-2tf. Over all dims are only very tight 1/16" over (1'-2"9/16 vs the book dim of 1'-2"1/2 for "D" dim of a W14x120). "D" meaning overall depth, "2tf" meaning 2 times the flange thickness.
John Wright
Parent - - By CHGuilford (****) Date 10-16-2003 17:04
John, A6 doesn't specifically address d-2tf (depth of section minus 2 flange thicknesses). It does address section depth (A) in Table 16. Also look at 12.3.3 the part about 2.5% of sectional area. Essentially the flange and web thickness can vary but the tolerances of Table 16 and 12.3.3 apply. This is stacked in the mill's favor, since they wrote it. Normally the tolerances are "juggled" at rolling to comply with A6 but I was thinking that your section depth might be greater than the 1/8" max allowed.
Chet
Parent - - By jwright650 (*****) Date 10-16-2003 17:13
CHG,
Overall depth is just a 1/16 over. (D=1'-2"9/16 vs the book dim of D=1'-2"1/2)
John Wright
Parent - - By thcqci (***) Date 10-16-2003 19:05
John,
Just to further back you up, I agree with your and kipmank's interpretation of code concerning gaps in root openings.

We too have experienced the problem here and I have encouraged the custom fitting route, but so far production is willing to oversize welds instead of custom fitting. Tried for a while to get away without any modifications to welds or stiffeners because no one had ever called them on it before me. Makes dimensional checking, documentation of gaps, welder instructions, welding, welding inspection, etc. more difficult because of un-accounted for time all that takes. Would be much easier all around to just custom cut stiffeners in my opinion. Does not take as long to grind or flame trim/dress stiffeners.
Parent - By jwright650 (*****) Date 10-16-2003 20:59
I agree that flame cutting one end and grinding it up don't take very long at all.
John Wright
Up Topic Welding Industry / General Welding Discussion / Full depth stiffener plates

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