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Up Topic Welding Industry / Welding Fundamentals / Seal welds
- - By msharitt (**) Date 12-31-2015 16:00
A quick search of the form and I can't find specifically what I'm needing answered. I'll give all the information I know and maybe someone can fill in the blanks.

First off, D1.1(2010) 1/4" thick plate stiffener rings around 1/4" rolled duct work. So at the base of the stiffener and the outside of the duct we have a fillet weld around the outside of the can. Drawing calls for 1/4" 3-9 staggered fillet welds. In the tail it says seal between strength welds. For the strength welds we're using .045 FCAW.

I am obviously wanting the fastest and most economical way to seal 200'+.

A3.0 defines "seal weld. Any weld intended primarily to provide a specific
degree of tightness against leakage."

I can not find a mention of seal welding in D1.1 except for a part in clause 6 that had to do with NDT.

With it being a seal weld, not contributing to strength and I still governed by the code?

My first thought for speed and getting the job done was to take our .035 solid wire GMAW and just zip it downhill to get a nice small pass that looks nice. Although not pre-qualified and I don't want to take the time to test and re certify either.

If that was allowable how would I document how we done it considering it's not in the book?

Thanks and any input is appreciated. Maybe someone got what I was asking out of it.
Parent - - By welderbrent (*****) Date 12-31-2015 17:07
So, first, the new 2015 deals more with seal welds but not really from your standpoint I don't believe.  It deals with welds around a common plane for a seal for galvanizing.  Might be worth a check for future jobs but probably not relevant for this question.

Next, remember, the engineer can add to, delete from, or in any way they deem necessary modify the applicable code for their job and it's engineered requirements.  So, if you have approved shop drawings and contract documents then the placement of seal welds is indeed required.

How you make that happen is totally up to you with the only requirements really being on the finished weld profiles matching Table 6.1 acceptance/rejection criteria; porosity, undercut, overlap, etc.  Sizing won't really be an issue other than the process being used will dictate finished weld size a little: larger wire=larger welds, GMAW=larger welds than GTAW, etc.

I believe your welders still must be qualified for the process used.  So, some of the things I have stated would tend to indicate that 'YES' you are still governed by the code.  But, there are parts of your question that are totally outside the code and are dictated by your contract documents.

He Is In Control, Have a Great Day,  Brent
Parent - - By msharitt (**) Date 12-31-2015 17:16
Thanks for the reply Brent.

I am waiting a call back from the engineer who's probably already started his vacation.

I do agree with you as far as meeting Table 6.1 and as stated the test requirements. I'm going to(probably Monday) to resort to getting the engineer as well as the customer on the phone to discuss the contract document.

Maybe it's just the customers I deal with, but it seems like some of them use a generic contract and do not change any welding details to match the current drawings. Maybe that's just what I see across my desk.

Thanks again.
Parent - By Lawrence (*****) Date 01-01-2016 00:46
If you have to spend time, maybe it's worth a shot to appeal to the "Engineer" and get the seal weld details removed.

The American Galvanizers Association has published several times about the non-need to seal weld hot dipped galvanized weldments.  But a lot of old school detailers and engineers go forward with this time wasting and distortion producing practice none the less.

Disregard if you are not galvanizing... I just cant think of another reason to put welds in between your intermittent fillets.

Besides...  The best you will do will be to produce a 3/16" fillet in-between your 1/4" intermittent fillet welds... (no matter how you qualify and with which process)    The whole thing sounds absolutely silly.

And yes... If the project is D1.1  than the code applies for even the seal welds.

Whilst it may be possible to make a downhill 1/8" GMAW fillet... I advise against..  They will be concave and subject to cracking and smaller in size than Clause 2 would recommend.
Parent - - By Cumminsguy71 (*****) Date 01-08-2016 12:35
I had to seal weld between 3 inch "stitch welds on a tower one time. I called the engineer and asked him this, "Since it is a seal weld and not for strength of any sort can I run a 6010 downhill since it would be faster?" I didn't have my suitcase at that time.

The engineer thought about it for a second and then said, "yes, we are not concerned with penetration, strength with the "seal welds" we are just trying to keep water out". Later they started using some special caulk, thank goodness because that was a heck of a lot of welding!
Parent - - By msharitt (**) Date 01-08-2016 13:23
That is what my base problem was. It was to keep rust bleeding. I understand you can use caulk, but I guess it's per customer.

I have never personally used any form of caulk. I would like to know is there anyone that uses caulk on a regular basis? What type of caulk is it? What is the longevity of it as apposed to an engineer allowing a downhill pass for welding?
Parent - - By TimGary (****) Date 01-08-2016 16:37
We use Sika-Flex 1a to seal between intermittent welds.
It's easy to apply, paintable, durable and flexible.

As far as I know, Sixa-Flex is the world standard for this type of application, as well as waterproofing metal buildings.
It is very, very good stuff.

I think it's better to use this as seal weld because during weldment flexing, if a seal weld cracks, the crack can propagate along the entire joint, including the structural welds, and can even move into the base metal.

Tim
Parent - - By msharitt (**) Date 01-08-2016 16:48
Thanks Tim,

I am going to look into that. D1.1 states that caulking can be used.

5.28

(3) the technique and limitations on caulking are
approved by the Engineer

Have you in your place of work ever had any problems with the approval aspect of it? I am unsure if this would have to be constant change on every job we do or if it can be implemented into the QC manual that could say "unless otherwise stated sealing is done per such and such".
Parent - - By TimGary (****) Date 01-08-2016 18:32
When D1.1 talks about caulking it's referring to:

Caulking - Plastic deformation of weld and adjacent base metal surfaces by mechanical means to seal or obscure discontinuities.

This is often done by welders with access to pneumatic needlers and chisels to be used for slag removal. When they see a discontinuity like cluster porosity, wormholes or undercut, they'll often bear down on the tool to smear the weld surface to disguise the problem.

Polyurethane caulking for un-welded joint sealing is a technique issue that needs to be taken into consideration during the product design stage, so it can be considered during the approval process. Considerations need to be made for coatings, such as whether or not it will work with the type of primer / paint to be used, and that if sand blasting is involved, the caulk will have to be applied after blasting.
The substitution of seal welds with caulk, after the design approval has been completed, would have to go through an engineering approval an change order process.
What makes it attractive are cost savings and increased flexibility.

I've never experienced problems with the approval process as for the products I've been involved with, caulking use has been defined in the initial design process.

If in your situation, seal welding is an afterthought just meant to help improve corrosion prevention, you'd probly look pretty smart if you can suggest an equally yet cost effective alternative.

Tim
Parent - By msharitt (**) Date 01-08-2016 19:00
That's what I've been doing is gathering my knowledge as far as cost effectiveness. I believe most of us here can agree that cutting cost is what catches attention.

I believe we're too far past for the current situation and we're cleared the current project in question. I am going to make a push to implement it when it may be more cost effective. Throughout the day since you'd mentioned it I can think of countless ways where I could see that we would have been better off using it.

Hopefully with examples and reasons I can get the point across to the higher ups. Whether they accept it or throw me out's another story but it's worth a shot.
Parent - By welderbrent (*****) Date 01-08-2016 19:02
Tim is correct and when you check out the Commentary on the clause it details mastic and non-metallic fillers as being not prohibited but again the inspections must be complete and the component totally acceptable so they know you are not hiding discontinuities. 

Then, you can seal away to your hearts content. 

Brent
Parent - - By Cumminsguy71 (*****) Date 01-08-2016 20:27
Not sure what they used for the sealant but this stuff stays outdoors, 24/7, 365 and is subjected to snow, rain, sub zero temps, painted with ZRC galvanized paint, the tower flexes, moves, shakes so whatever it is, for it to be approved by the tower owners, it's got to be some great stuff. I do remember it was red before painted.

Sealant will not be indefinite I'm sure. I've used the best silicone caulk with the best guarantee around my house and it seems a year, two or so and I'm doing it again. I must live in a special reality of the portion of the universe that is affected differently causing premature degradation of the silicone products around my home.
Parent - - By msharitt (**) Date 01-08-2016 20:38
That was my first thought Shawn, when I think of silicone sealant I think of the stuff peeling around the house. I'm an hour or so south of you so it must be a large area that stays affected. As you stated, even the high dollar stuff doesn't seem to last.

I'm sure from an industry standpoint it has to be fairly good. I can't imagine and cost savings if they're sending someone up every other year to re-caulk. I may have to start buying a different brand for the house.

I have learned a lot from what I thought was a simple question. Turns out I have twice as much to look into as I initially thought when I asked the question.
Parent - By TimGary (****) Date 01-11-2016 13:59
Agreed, silicone caulk sucks, and is just about worthless.
One reason why it doesn't last long at all outside is that it breaks down when exposed to sunlight.

Sika-Flex, and other polyurethane caulks are not silicone.
These are the sealants used along with mastic to weatherseal metal building roofs with 20+ year warranties.
When applied right, (read-clean surface), the seal is very reliable and durable.

Where I currently work, we use it to seal between stitch welds on exposed surfaces of heavy equipment cabs, then paint over it.
It works very well, lasts damn near forever.
Next time you're close to some heavy equipment, look at the exterior cab welds and you'll see what I mean.

Tim
- By 803056 (*****) Date 01-02-2016 00:20 Edited 01-02-2016 16:21
Welded structures are monolithic, meaning all welds and members share loads even when they are not designed to do so. A large fillet weld and a small fillet weld that are attaching the same member to another member share the load. All materials deform under load, either by elastic deformation or plastic deformation. The small welds may be overloaded before the load is transferred to the larger weld.

Another consideration; AWS requires a minimum weld size based on metallurgical consideration to ensure the "small" weld doesn't cool too quickly and produce martensite in the HAZ if the base metal is carbon  or high strength low alloy steel. The concern is amplified now that D1.1 permits the contractor to weld over "residual" oil, grease, or water. Yea, I agree, "What are they thinking?"

Al
- - By msharitt (**) Date 01-04-2016 14:12
Thank you all for the responses.

After speaking with the engineer, as Lawrence pointed out, he just kinda said "well that's what we've always done". For this particular job we're out of the water and I'm going to follow up and see if we can change this "shop standard" we have of sealing weldments.

Thanks again.
Parent - By Lawrence (*****) Date 01-04-2016 15:37
Here is some good guidance to think about from Dr.  Duane Miller

http://www.jflf.org/pdfs/papers/design_file6.pdf
- - By 803056 (*****) Date 01-04-2016 22:00
A better approach might be to use a continuous fillet weld that is slightly smaller than the specified intermittent fillet weld. Assuming the smaller continuous fillet weld meets the requirements of AWS D1.1 regarding the minimum weld size, the total volume of weld will be less than the combination of intermittent fillet welds and seal welds between the intermittent increments. This will result in less filler metal, less time, less cost, and fewer locations for discontinuities such as cold starts (incomplete fusion), unfilled craters, crater cracks, etc.

Best regards - Al
Parent - - By Cumminsguy71 (*****) Date 01-08-2016 20:39
Depends on how much welding. Last tower I was on they had literally, 63 feet of weld in ONE twenty foot leg. The rest was sealed with the "special" silicone. We laughed and wondered why Einstein didn't just weld the whole stinking leg. In one twenty foot section, three 20 foot legs, 189 feet of weld total. I went thru 8, 33lb spools myself and almost got two of three legs done. I'm glad they used silicone, think I would have jumped off if they wanted the entire leg welded or become a serious drunk. I was there for four weeks. Their welder finished a job and came out and it took him about another two weeks to finish a single leg. We had to weld 100-140 feet, think it was 6-7 sections in total, each 20 feet. I think this tower was built by the first little pig, judging by the amount of material and weld we had to add.

The one we seal welded we just ran quick downhill stringers, nothing of importance. The inspector didn't even give them much notice. All engineer approved though.
Parent - - By 803056 (*****) Date 01-08-2016 23:30
Famous last words: "nothing of importance".

Al
Parent - By Cumminsguy71 (*****) Date 01-08-2016 23:33
Yep, cleared by engineers, cleared by inspector equals, not my problem, lol!!!
Parent - By michal Date 11-08-2016 08:09
Thanks
Up Topic Welding Industry / Welding Fundamentals / Seal welds

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