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Up Topic Welding Industry / Inspection & Qualification / Paint on Base Metal
- - By WELDTECH (*) Date 11-12-2008 14:36
Is a special procedure required for a 1/8 inch fillet weld that connects a joist to a painted girder.  I've been told that a pre-qualified procedure for fillet welds does not cover welding to a painted surface.  This is not a critical weld.  Do I need a PQR and WPS that covers painted surfaces or do they need to grind off the paint prior to welding?
Parent - By welderbrent (*****) Date 11-12-2008 15:52
Weldtech,

I do not believe you need a new/seperate procedure.  But the main answer to your question should be answered in D1.1 section (now "clause") 8.5.1  Base-Metal Condition.  Needs to be cleaned for a distance of 2" from the root of the weld.

Have a Great Day,  Brent
Parent - - By jrw159 (*****) Date 11-12-2008 15:56
WELDTECH,
  If you are working to AWS D1.1 then Brent has nailed it.

jrw159
Parent - - By WELDTECH (*) Date 11-12-2008 16:27
I am working with D1.1.  So this means that all paint shall be removed at least 2" from the root of the weld. 
Is it ever permitted to weld a painted surface per D1.1?  I've seen it done on job sites. 
Parent - By welderbrent (*****) Date 11-12-2008 16:31
The only reason for that is welder laziness and after the weld is made, at which point the paint is burned off in the area, and haphazardly cleaned, the inspector doesn't generally know for sure rather it was cleaned prior to welding or not.  If inspected after fitup and before welding that would not be allowed.

Have a Great Day,  Brent
Parent - - By hogan (****) Date 11-12-2008 16:32
WELDTECH,
you are required to perform a pqr if you want to weld over paint, when working to AWS D1.1
Parent - - By welderbrent (*****) Date 11-12-2008 16:47
Hogan,  not trying to challenge, just clarify and broaden knowledge if I have misunderstood.

According to 5.15 and 8.5 the base metal must be clean and "free of foreign material that would prevent proper welding".  I personally do not see a provision in section 4 for including paint in the essential variables or condition of base metal that would even allow for a pqr to be developed with paint.  Besides you would have to run it with so many different paints because they do not all have the same characteristics and respond to trying to weld over them the same.

Can you clarify your position so I can see where you can develope a pqr with paint?

Have a Great Day,  Brent
Parent - By hogan (****) Date 11-12-2008 17:18
welderbrent,
I believe that paint would be considered "foreign material that would prevent proper welding" just like galv. As far as running a test for all different paint, that is what you would need to do. A separate PQR for each brand and type of paint you would like to weld over. It is by far easier to just remove the coating as allowed.
Parent - - By jrw159 (*****) Date 11-12-2008 17:29
Brent,
  I was waiting for Hogan to reply before adding my two penny's.

One could qualify a procedure for this application, but as you stated it would be only for that brand of coating. Another consideration to this is the thickness of the applied coating. A thick layer will obviously react differantly than a thin layer.

So while it could be done, to be completly compliant, it is just not feasible.

The best option is to remove the coating. :-)

jrw159
Parent - By welderbrent (*****) Date 11-12-2008 20:11
Thanks guys, and thanks Weldtech for the question, added a little to my info base.

Bottom line for myself is still to prep the material properly.  Sounds like way too much time, effort, expense, and trouble to try and find out what kind of paint was used so I could properly qualify a PQR and then still need, as js suggested, an engineer's approval anyway.

To compare with galv, I have always preferred to clean as much of that out of the way as possible to get to clean steel with as little smoke as possible.  Already had zinc poisoning once when young, what a pain. 

If you want the highest quality, with the most frequency, with the least effort and expense, clean your parts properly and don't try to cheat the code and the inspector.

Just my own conclusions from the code and your responses to Weldtech and I.

Have a Great Day,  Brent
Parent - - By jrw159 (*****) Date 11-12-2008 16:39
WELDTECH,
  Yes, the paint/primer shall be removed 2" in every direction from the weld. For it to be acceptable per D1.1 you will need to qualify a procedure, as stated by Hogan. In most cases it is easier and more cost effective to remove the coating.

jrw159
Parent - - By WELDTECH (*) Date 11-12-2008 16:45
Thanks for the help.
Parent - - By js55 (*****) Date 11-12-2008 19:20
I don't believe running a PQR with coating is enough to bring you into compliance with D1.1. You would still need Engineer approval.
Parent - - By MICHAEL B (*) Date 11-12-2008 20:25
We have a qualified  procedure for our erection company to use to weld over our standard primer. The engineer had no problem signing off on this, when the test report came back. The welding over paint typically just takes place at the bar joist to girder connection. The cleaning of all those areas, say in a million sf warehouse, is not really feasible. It has saved us a bunch of time and labor cost. Just my 2 cents.

MICHAEL B
Parent - By welderbrent (*****) Date 11-12-2008 20:54
If I understand right though, you do lots of these connections on an ongoing basis and with the same primer.  This would be an application where the one time PQR expense would be justified over the cleaning option on a smaller job.  It would also make a difference if the paint were on an existing structure and you didn't know what you were dealing with compared to new construction with known components. 

You have helped me for one though with your comments.  Thank you.

Have a Great Day,  Brent
Parent - By jrw159 (*****) Date 11-12-2008 21:00
MICHAEL B,
  This is one instance where I can see the benifit of qualifying a procedure. The coating would be fairly consistant in application and of the same brand. :-)

jrw159
Parent - - By WELDTECH (*) Date 11-13-2008 19:28
Do you have your test coupons x-rayed for paint inclusions?  Can you e-mail me a sample of your PQR and WPS so that I can see how this would be documented? fallspark2@comcast.net  Does the fabricator provide you with his specs on the standard primer paint that is used?  This would also be a bar joist to girder connection for the building I will be inspecting.
Parent - - By Joey (***) Date 11-14-2008 11:24
You might encounter welder who refuse to weld on painted / coated surfaces even though there is an approved WPS. The fumes produced from welding on painted surfaces may be harmful to their health.

Regards

Joey
Parent - By jrw159 (*****) Date 11-14-2008 14:44
Joey,
  Very good point!!!

jrw159
Parent - - By BryonLewis (****) Date 11-14-2008 14:09 Edited 11-14-2008 14:11
I've welded over paint before, its a very pleasant aroma.  I also cut aluminum shelves out of a truck body that carried Interstate batteries.  Not only did it have acid everywhere it was coated with some kind of primative Rhino lining stuff.  You want to talk about smell.  The inside of a camel's arse would've been an improvement.  I wouldn't mind seeing the WPS and PQR too.
Parent - By BryonLewis (****) Date 11-14-2008 14:14
That might be a good Forum Category to have.  A place to post WPS that could be unusual in nature.
Up Topic Welding Industry / Inspection & Qualification / Paint on Base Metal

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