Welding on galvanized metal .... allowed without cleaning ??

Date 03-23-2009 19:48

FSmalley,
That would be the section that covers your concerns. Surfaces shall be free of foreign material that would prevent proper welding.

By FSmalley (**)

Date 03-24-2009 11:31

Ok, so that is the only section of the code that addresses the welding on galvanize issue? Has anyone ever run into this issue? any constructive comments?

By jrw159

Date 03-24-2009 12:43

FSmalley,
It also can be addressed from a safety standpoint. In D1.1 5.15 there are also the words "or produce objectionable fumes" and OSHA also requires that all coatings be removed 4" in all directions from the weld area. These two aspects usually take care of the situation. Safety and quality first.

jrw159 :-)

By eekpod

Date 03-24-2009 17:55

I run into this occasionally and I have to tell my fitters to grind off the galv before fitting/ welding the parts. This is because of the section you referanced. It would be nice if they made it easy and said "all galv and paint shall be removed before welding/ tacking" but they don't do that, they leave a little intrepetation in there. then it gets sticky becasue an inspector will read it one way, and they welder will read it another. Of course the inspector usually has to win. chris

By FSmalley (**)

Date 03-24-2009 18:39

I was the fabricator at one point and i remember if i tried to weld (GMAW) on or near the galvanize coating the weld puddle would pop leaving behind a trail of porosity. Having said that as a CWI i would need to reject a weld that was on or near galvanize coating, not only for the sections outlined above but for the fact that i know the weld can contain discontinuities.

By FSmalley (**)

Date 03-24-2009 18:50

Just came across this in my search ...

AWS B2.1-1-003 Standard Welding Procedure Specification (SWPS) for Gas Metal Arc Welding of Galvanized Steel, (M-1), 18 Through 10 Gauage, in the As-Welded Condition, with or without Backing Site License

http://engineers.ihs.com/document/abstract/HQVEABAAAAAAAAAA

pretty much negates AWS Section 5.15 of D1.1 .... but this might fall under d1.3

By jrw159

Date 03-24-2009 19:47

I have not seen the actual procedure, only the link to the scope that you provided. The PQR and subsequent SWPS have perameters that need to be adhered to as noted in this section cut from the scope. " The American Welding Society considers that this SWPS presents information for producing an acceptable weld using the conditions and variables listed." It is not as if because this procedure exists that any weld on random galvanized items will also be good.

Now we need to see the PQR to find out what if any variables are listed concerning what "as is condition" is. IE thickness of coating, brand, application, and such. If these perameters are met then indeed the code part of this would be met.

Now to satisfy OSHA one would need to look at what should be done to protect the welder from the resulting fumes. But that is a whole other thread there. LOL

jrw159

By FSmalley (**)

Date 03-24-2009 18:57

also came across this ...

http://www.galvanizeit.org/aga/designing-fabricating/fabrication-considerations/welding/welding-after-galvanizing

most important part here is ...

"For galvanized structural fabrications, 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 piece. Grinding back the zinc coating is the preferred and most common method; burning the zinc away or pushing back the molten zinc from the weld area also are effective."

"

By FSmalley (**)

Date 03-24-2009 19:00

Down below they tell you the whole procedure for welding galvanized steel but does that exclude structural steel?

Adding more to the murky waters of this problem.

By hogan

Date 03-24-2009 22:07

FSmalley,
I see no murky waters. The code is very clear on this. Is a galv coating a foreign material that would prevent proper welding?

By swnorris (****)

Date 03-26-2009 14:26

The difference between welding galvanized steel and welding uncoated steel comes down to the low vaporization temperature of the zinc coating. Zinc melts at about 900 degrees F and vaporizes at about 1650 degrees F. Since steel melts at approximately 2,750 degrees F and the welding arc temperature is 15,000 to 20,000 degrees F, the zinc that's near the weld is vaporized. So, by the time the weld pool freezes, the zinc is gone. If galvanized steel is going to be welded without removing the coating, it's important to point out that the welding electrode composition should be checked to assure that the silicon content is very low because a high silicon content can cause zinc to penetrate the weld metal, leading to cracking. I think that the actual recommended level is a subject of debate. All this being said, I believe that not removing the coating prior to welding would simply be too risky. In our shop, we remove it.

By FSmalley (**)

Date 03-30-2009 15:44

This is very consistent with what i have read from various internet pages so far. We also remove it and will continue to do so.

By 803056

Date 03-26-2009 14:28

Several years ago a contractor hired me to run some tests on hot dipped galvanized materials. The contractor supplied me with 1/2 inch plate that were HDG and I was directed to run single pass fillet welds using 1/8 and 5/32 inch diameter E7024 and E7018.

I ran a number of tests using some weave beads or stringers using both electrodes. The fillets were sectioned for macroetching and break testing. All the samples had some degree of galvanize inclusions, primarily at the toe of the fillet welds. The welds all failed through the throat, but the welds required fewer hammer blows to break than would be expected when compared to plates welded without the galvanize. The best results were obtained with the E7018 in the vertical position using upward progression.

I know of no one that has attempted to qualify a welding procedure using a grooved butt joint on HDG plate. I would be interested to hear of the results if anyone reading this has performed a standard procedure test using HDG plates without removing the HDG first. It would be interesting to see how the tensile tests and bend tests performed.

Based on my experience, I don't accept welds deposited on HDG materials. I've had engineers override my calls, but then I make them put their "John Hancock" on the dotted line stating that they accept the welds hat I have rejected. A few of them have balked and then agree the welds are not acceptable. The one's that issue the signed memo accepting the welds are few and far between.

Best regards - Al

By CSmalley (*)

Date 03-28-2009 03:21

I have had this problem with a few Parking Decks near the coast here in North Carolina. The first one I inspected after initial inspection by another firm, I started to find centerline cracks on the connection plates to the embed plates which were both galvanized. I asked if the previous inspector had required the removal of the coating and the answer was no. I told the erector they had to remove the coating which started a firestorm. Eventually the structural Engineer required a PQR which failed the macroetch due to cracks at the root. I have forced the issue of removing the galvanized coating since and have not had any resistance since. Hope this helps.

By FSmalley (**)

Date 03-30-2009 15:49

Al:
That is just what i'm getting to here, if faced with a weld on galvanize metal do you reject or allow by AWS D1.1 and what i'm getting is you reject per 5.15

I called the AWS office and spoke to John Gayler and asked him that exact question "if faced with a weld on galvanize mental do you reject or allow" and he told me I could reject per section 5.15 but there is nothing concrete that states galvanize metal.

I would have thought over the years they would have had some commentary on this subject ??!!

By 803056

Date 03-30-2009 18:53 Edited 03-30-2009 19:00

You have to remember the fabricators have a huge presence on the D1.1 committee (as they should have) and they like to leave themselves some wiggle room. The letters "ASME" are just as appropriate for the codes published by the American Welding Society as it is for the codes developed by the American Society of Mechanical Engineers. :)

The galvanizers are going to promote welding over the galvanized coating to make their products appear to be competitive with other coatings. For the most part, if the galvanize is thin (electrogalvanized), you can most likely "get away" with welding over it if the application isn't critical. With that in mind, many jobs that don't require code compliance, i.e., Farm Code work, and those applications where a failure isn't going to endanger life or limb, welding over galvanized coatings may be tolerated. In those cases where code compliance is required or where failures have a high associated cost, it is best to remove the coating first and reapply a zinc rich paint or other appropriate coating after the welding is completed.

Best regards - Al

By 803056

Date 03-30-2009 19:22

Here's a link to an article written by a person that I hold in high regard, Walter Sperko. I believe it has been posted before, but I don't remember who posted it and I found this by doing a web search. http://www.sperkoengineering.com/html/articles/WeldingGalvanized.pdf

This isn't the only article I've read on welding galvanized steel. Having been a welder for over 40 years and considering my experiences welding galvanized steel decking, parking structures, etc., I will take exception to the notion that all the galvanize coating will be vaporized by the welding arc. I will agree that thin galvanize coatings will be vaporized, but I am not so sure the heavier coatings observed with HDG will be as easily vaporized. Mr. Sperko's comment regarding removing some of the heavier HDG is more than reasonable, as is the comment on leaving an exit route for the fumes generated by welding over HDG. As for the affects of metal fume fever diminishing over a short period of time, I disagree. I have a very low tolerance for fumes generated by welding or cutting galvanized materials after having experienced "metal fume fever" a few of times over the years (the result of welding decking in enclosed areas).

Still, the article by Mr. Sperko is well written and contains useful information that welders should be made aware of as part of their training. The point that is made with regards to the silicon content is interesting and worth remembering if it is imperative to weld over the HDG.

Best regards - Al

By FSmalley (**)

Date 03-31-2009 11:59

AL
Thank you very much for all your input here you have been a great help.

If you or anyone else has additional input on this subject it would be greatly appreciated. I'm putting together a report against welding galvanize (in structural applications) without stripping back the zinc coating.

By FSmalley (**)

Date 03-31-2009 11:53

"With that in mind, many jobs that don't require code compliance, i.e., Farm Code work, and those applications where a failure isn't going to endanger life or limb, welding over galvanized coatings may be tolerated."

And that is just what i'm trying to get to the bottom of here. In a structural application is welding over galvanize allowed? I would gather form all the commentary here and section 5.15 i would need to reject.