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Up Topic Welding Industry / Welding Fundamentals / Welding Galvanized A36 Steel
- - By SH21 Date 04-18-2008 16:14
Hello all...  Every now and then we get a job where we have to weld through a galvanized coating (the time spent grinding it all off would be enormous).  We currently use Lincolns Innershield NR-202 and gap the joint 1/8".  We have been successful with this procedure.  Lincoln is going to discontinue this product and I need to find a replacement.  Does anyone have any experience with welding through galv?  NR-202 was the only electrode that didn't show latent cracking.  Any suggestions will help.
Parent - - By hogan (****) Date 04-18-2008 17:03
run a pqr
Parent - - By SH21 Date 04-18-2008 20:43
Yeah, That's the plan.  I am trying to find an electrode that has been used successfully on zinc coatings.  I was hoping to get input from people who weld galvanize regularly.
Parent - By hogan (****) Date 04-18-2008 21:06
typicaly it is not welded through. It is removed.
Parent - By jrw159 (*****) Date 04-18-2008 21:22
SH21,
  Before I go into suitable filler metal, I must bring up the safety concerns for welding galvanized material. Hot dipped or not, OSHA regulations require removal of coatings a full 4" from the weld area in all directions. I know this is something you do not want to hear, but it is a fact. You have not stated whether you are working to any code, so I will go out on a limb and say AWS D1.1, 5.15, addresses this and imo it would fall under "other foriegn material that would prevent proper welding or produce objectionable fumes."
That being said, there are probably several filler metals that would meet your needs. We use Lincoln E70C-6M to join A36 to Galvanized carbon steel tube on a daily basis and have no problems, but we also follow proper safety guidlines per OSHA for the long term health, safety and well being of our employees.

I would suggest going to OSHA's website and doing a search on welding galvanized coated material as there is an abundance of information. I guess the big questions are:
1-Are you working to a code?
2-Are you regulated by OSHA?
3-Do you really care about code or OSHA and the health of the employees?

Again, I am sure this is not what you were wanting to hear, and I am not trying to "burst your bubble" so to speak, but zinc coatings are nasty. I hope this helps in some way.

John 
Parent - - By dschlotz (***) Date 04-24-2008 12:26
Try ESAB Coreshield 15

Dennis
Parent - - By swnorris (****) Date 04-24-2008 13:30
John,

You said "OSHA regulations require removal of coatings a full 4" from the weld area in all directions".  Can you give the section or reference to this?

Thanks 
Parent - By jrw159 (*****) Date 04-24-2008 14:57
1926.354,  I am in the process of finding the determining factors for enclosed spaces. If memory serves me correctly it is somewhat missleading in the fact that a small shop with low ventalation, could fall under the enclosed space catagory, and the ventilation requirements would put you in a predicament as exhaust fans create to much wind flow for welding applications.

I think this is also covered in another regulation, but I need to get to my office to find that information.
I will post again as soon as I get there.

John
Parent - - By jrw159 (*****) Date 04-24-2008 16:16
OK, I am back at the office. See 1926.353, Ventilation and protection in welding, cutting, and heating, in its entirety. Then see 1910.252(c)(6)(ii)  which will send you to paragraph (c)(3) and notice the minimum air flow requirements.

Sorry, it might be benificial for proper interpretation to read the entire document, or at very least start at 1910.252 (c)(2), ventilation for general welding and cuting.

Now I could very well be misinterpreting thes regulations, but what I see is that the coating must be removed prior to welding or adequate ventilation must be provided, which is a heck of a hoop to jump through while keeping weld quality.

Now to the question of code: Since none has been referanced I will use D1.1 first. D1.1 5.15  while the entire paragraph applies, I beleive that the pertinant part would be "other foriegn material that would prevent proper welding or produce objectionable fumes." I do not think anyone can classify zinc oxide as anything but objectionable fumes. It is a health hazzard.
D1.1 8.5.1 while this is in the repair section it does address new base metal and in my opinion would be applicable to new material that has coating on it.
I by no means have a closed mind to this subject, and I am very well aware of the fact that I have much to learn so anyone who has a different outlook on this please chime in, I am more than willing to listen. We weld galvanized product on a daily basis and if we can tone down the steps we feel we must go through and still keep our employee's healthy and safe, I am all for it.

John
Parent - - By jwright650 (*****) Date 04-24-2008 16:56
John,
You referenced a paragraph pertaining to welding/cutting on galavanized steel within a confined space(therefore the special need for ventailation requirements). A shop with adequate cross ventilation and ceiling heights of 16ft or more and in spaces that are 10,000 cubic feet or more per welder is a whole different ball game.
Parent - - By jrw159 (*****) Date 04-24-2008 17:06 Edited 04-24-2008 17:11
John,
  Please note "enclosed space" as opposed to "confined space" in 1926.354. You are correct about adequate cross ventilation, however, meeting the requirements for adequate cross ventilation without local exhaust hoods and booths causes a conflict with the gas shielding required for certain processes, as the air flow will blow the shielding gas away with the fumes. This was one of the first obstacles I ran into in our shop. The first and most obvious answer was to install fans at each welding station. But for them to be effective at fume removal they were at the same time blowing the shielding gas away from our GMAW & FCAW gas shielded operations, obviously resulting in porosity and fusion problems.


John
Parent - - By jwright650 (*****) Date 04-24-2008 19:14 Edited 04-24-2008 19:17
Save yourself some headache and have an air quality study done. You will be amazed that if you place the collection filter under your welder's shield (where he/she is actually breathing) you most likey won't need a fan blowing to stay well within the OSHA PELs. I have air quality studies and audio surveys done at the same time, this gives me an 8 hour weighted survey and we have yet to even come close to any of the PELs in our shop. Our ceilings are fairly tall and the bays are wide open probably a little over 400 feet long and 60 feet wide, with truck traffic entering and leaving the building at each end so the doors stay open most of the time for natural air flow yet hardly ever so much that it effects the gas coverage at any of our welding/fitting tables. We use FCAW with 100% CO2 and SMAW on a few tables....but we only weld mild steel.

Moral of the story is to perform the testing to see if there is even a problem before getting too excited about trying to meet all of those other requirements. You may find that you are OK as is or you may need to find ways of reducing the exposure...but you won't know if you don't test.

Edit: About the confined space...I was just looking at the section and paragraph that you posted from OSHA 29CFR 1910 (for "general industry" which is shop work not construction like OSHA 29 CFR 1926).....
Parent - - By jrw159 (*****) Date 04-24-2008 19:35
John,
  This is something that I have been contimplating. I feel that with the very low ceilings in our shop and the way it is configured, that we are probably not within the PELs. Is there a way to test this myself, without getting OSHA involved? The other thing that worries me is as you have stated, the test samples would be taken from under the welders hood. I think in our situation this will be where the levels will be the highest, refering again to our shop configuration. Again, very low ceilings and areas of poor air flow.

John
Parent - - By jwright650 (*****) Date 04-24-2008 19:58 Edited 04-24-2008 20:02
Oh yeah...I never had OSHA even ask for the test results until I explained to the auditor that we had historical data that we have been collecting.(BTW, that thrills them to see that you take this on your own)....Yeah, I set it up with our annual testing firm that does our facilities audio and respirator testing...they have all of the equipment and come in and pin a few filters and data recorders on a couple of guys in the morning and come back that evening at quitting time and pick them up and it isn't all that expensive. They guys wear this stuff all day and it collects the data and they will draw up the reports and give them to you. You can do this all on your own without OSHA getting involved. Keep in mind that if you find that you need to do something about the PELs, you probably should go ahead and engineer or come up with a way to get the PELs in check. I have three bays of fitting/welding tables with two guys(welder and fitter) paired up on each table, so I just pick two guys from each bay and have them tested for air quality and audio levels.
Parent - - By jrw159 (*****) Date 04-24-2008 23:01
John,
  This is great info for me, thank you. I am aware of how the tests are conducted, but I have only had experiance with OSHA administering them. I will look into other options for this, and any suggestions for someone in my location, TX, would be great, but I should not have a problem finding someone.

Now, as for code requirements, we are working to AWS D1.1 so with all due respect, what is your code take on welding through the coating as opposed to removing it?

John



Parent - - By jwright650 (*****) Date 04-25-2008 00:02
Look for a industrial hygenist in your area, these people do this everyday and can help you get this done.

D1.1 is sorta vague and skips around this issue in my opinion, but arguements can be made by using the objectionable fumes paragraph...I don't have my D1.1 here at home with me so I won't try to quote it from memory.
Technique and rod manipulation has been proven to help boil the galvanizing out ahead of depositing filler material due to the temperature of the arc vs the temperature that zinc, tin, and bismouth vaporize.
Parent - - By jrw159 (*****) Date 04-25-2008 00:36
I would definatly agree that AWS, and in my opinion, OSHA and ASME all kind of dance back and forth through that little mine field.

My big issue right now is, I want to protect the employee's health and well being, for sure! But I also do not want to jump through unnecessary hoops while acomplishing this.

Another issue that follows me is that the many different environments that I have been exposed to, all seem to have variations of interpretation on what is base line for welding over galvanized coating.

Thanks for the info, as I said I have been involved in this at lower levels in the past, but in this instance it is all in the "developmental stages" and we have a long way to go. Without going to deep into it I will say it is quite interesting to say the least.

John
Parent - - By jwright650 (*****) Date 04-25-2008 09:42
Several many years ago, I had a few guys say that we were killing them everyday...well, that kind of attitude is contageous and needs to be put to rest before the whole shop feels this way. That was when I took that bull by the horns and started having the air quality tests done. I drafted a memo and posted the results and that rumor and chatter completely disappeared. It was driven home to these guys that we do care when we were audited by OSHA and the auditor was talking with the guys and telling them how far ahead of other companies we were in terms of safety and care for the employee's health. If you play this up right, I'm sure it will have a similar effect in your shop as well.
Parent - - By jrw159 (*****) Date 04-25-2008 12:22
John,
  I am pleased to hear that you have the concern to make sure that it is done in a safe manner. However it is becoming apparent to me that safety is not a concern for some.

As for myself and my employee's, it has always been and always will be:
Safety first
Quality second
Production rate third.

Thank you for your valuable input,

jrw159
Parent - By jwright650 (*****) Date 04-25-2008 16:55
John,
I completely agree....Good employees are very valuable to any company and we need to take care of them if we want to continue to run a successful shop. Injured employees won't make ya any money if they are at home and you have parts to fabricate and no one to do the work. Shops that don't push safety are wasting lots of money that could be going to fatten the bottom line, but many of them have this get-r-done-at-all-costs attitude and it will come back to bite them in a big way.
Parent - By jwright650 (*****) Date 04-25-2008 11:47
Another thought....we also supply disposable 3M #8514 respirators to the welders when they have galvanized material to weld on. These disposable respirators are available for the asking, this keeps us from having to run these guys who use one on occasion from having to go through the respirator program. The respirator is good for filtering out 95% of the metal particulates, ozone, and nuisance organic vapors that are airborne in the plume of welding smoke. These are very slim and fit under the shield.
Parent - By jwright650 (*****) Date 04-24-2008 20:01
About the placement of the filters...trust me on this one...you definitely want those filters under the hoods, most of the welding smoke will rise and go around the welding shields just by their design. If you let them pin those filters out on the guy's shirt it will be tremendously higher than if placed under the shield (pinned to the shirt collar).
Parent - - By RBeldyk (**) Date 04-24-2008 15:45
Here is a link on "Inspecting Welds in Galvanized Steel." http://www.aws.org/itrends/2005/10/023/
and a link from the AGA on Welding hot Dipped Galvanized Steel http://www.galvanizeit.org/resources/files/AGA%20PDFs/T_WHDG_02.pdf

When welding over galvanizing ( the zinc alloy will melt and boil. givien enough time most vaporize.  However the heat input at any one point is transient and the time at temperature may not be enough to erradicate all the zinc alloy, resulting in porosity, zinc inclusions and cracking.  Some of the techniques that could be employed is to weld hot-dipped galvanized steel are:
- to use a rutile based flux.
- wider openings to allow for outgassing.
- weaving 3x.
- use a shorter than normal arc.
Parent - - By jrw159 (*****) Date 04-24-2008 16:35 Edited 04-24-2008 19:54
Richard,
  Both of these documents reference the removal of the coating before welding. I have also learned something again thanks to you. AWS D 19.0 Welding Zinc Coated Steel calls for the welds to be made on steel that is free of zinc in the area to be welded. Thus for galvanized structural components of a fabrication, the zinc coating should be removed at least one to four inches from either side of the intended weld zone, and on both sides of the workpiece.

This would lead me to beleive that in short the zinc coating shall be removed prior to welding.

Again, see my previous post concerning any other takes on this, as I am always openminded to other opinions.

John
Parent - - By preston davis (**) Date 04-25-2008 00:05
was on a hurry up fire sprinkler job one time, all 1 1/2 10 gauge gal. pipe, every thread-o-let on the job was welded with 5p plus. no leaks and no prep was done to the pipe. just weld it on and cut the hole. I know it isnt code, or even good practice, but it got the customer out of a pinch.
Parent - - By jrw159 (*****) Date 04-25-2008 00:48
I was the welding supervisor on the largest outdoor hog farm in southeastern CO  and we welded galvanized hog panels to carbon steel frames fabricated out of 3/4 X 3/4 X 1/8 angle. as well as some other hut fabrication involving plastic and fiberglass lined oilfield pipe. It was for sure something for FC2002 recommendable practices. And as in your case, it got the job done, and quick. We finished that job four months ahead of schedule for steel fabrication.

I am sure that we can all agree that it can in fact be done. But to what degree of safety and documentable quality? I can tell you this, I still own a few of those hog gates mentioned above that I use in CO for blocking the dogs to one side of the yard or the other. Not a weld failure one. FWIW.  COUGH< COUGH :-):-)

John
Parent - - By Stringer (***) Date 04-25-2008 03:39
I'm thinking the original question was 'how to do it' not 'how do we talk ourselves out of doing it'. Yeah, it's noxious. Now on to business. I like the 1/8 gap idea and I'd try fluxcore wires made by Lincoln. Since they are discontinuing your present solution I would contact them for a replacement. When I'm forced to weld heavy galvanized I put a fan behind me. Cracking and antioxidants are a cost issue to management but I see that as a cost of not using 304l.
Parent - By jrw159 (*****) Date 04-25-2008 12:09
I would agree that the question is "How do we do it". I think you are missing a key point to that. How do we do it safely. One thing that has not been answered is to what code. If there is no code involved, that just leaves a safety concern, I would hope. But all to often the people that make these calls are not the ones that will be exposed to the health hazzards, making it very easy to say, just get-er-done. I personally am very gratefull that when I was under a hood there was someone there that was concerned about my health and well being and would take the time and effort to make sure the job was done first and formost in a safe manner, secondly in a quality manner that met code and specification, and last but not least in a timely fashion. But ALWAYS safety first.

But again sometimes there are people in places who just do not gave a white rats pink litle a** about the health of there employee's. They will not post it that way and in the company of certain people will NEVER say it, but by thier actions, which always speak louder than words, show they really could care less about the long term effects, as long as they are not exposed and they get thier pay check.

So I guess if safety is not a concern, and code is not mentioned, then it really just does not matter, just weld it. E70C-6M

John
Up Topic Welding Industry / Welding Fundamentals / Welding Galvanized A36 Steel

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