I expect that you may have to cook the paint out with a torch first and then try welding. Much easier to weld if the paint department leaves the paint out of the area between the lap joints.

Don't waste your time. Go to OSHA. There is a requirement that paint and coatings that can produce noxious fumes, etc. be removed far enough back from the joint such that the fumes are not produced. The fine levied by OSHA should get the contractor's attention.

Then there is the fact that the inspector should never forget. The inspector isn't working in a vacuum. Any problems should be bought to the attention of the Engineer, the Owner, and the Building Official. Don't be a goofball operating under the assumption its is you against the world.  Once the other parties have been notified, they have a responsibility to enforce the code requirements. Should anything go wrong after they have been notified, they are on the hook. Make sure your report is detailed, thorough, and uses photographs and sketches to show the reader the deficiencies.

I suspect the contractor's practice results in a good deal of porosity in the root bead. Make sure you include photographic evidence in your reports to substantiate your claim. The report should also include the specific clause from AWS and OSHA regulations. I would go as far as including a quote of the exact text of the clauses from the code and from the OSHA regulations.

Good luck. Again, don't think for a moment that you are alone in this. You can't reason with a Billy goat, you have to hit them with a 2 by to get their attention. Use your reports to the Engineer and Building Official as your 2 by to get the action needed.

Best regards - Al

Al's comments are correct of course, but please consider the following:

I ran across this problem a while back in a shipyard, where in process blasting and priming of modular construction caused a lot of this.
D1.1 is fairly clear in Section 5.15 where it requires removal of any foreign material that would prevent proper welding or produce objectionable fumes.
Paint may be considered as such as it causes weld porosity, increased potential for hydrogen embrittlement and toxic fumes.
In order to reach a compromise, we performed weld procedure qualification testing of coated materials. We found that the only way to get acceptable results was to allow the welding of joints with trapped primer only, in which the exposed joint was thouroughly wire brushed before welding. All tests with intermediate and top coat trapped in the joint failed.
If memory serves correctly, we were using a "Weldable" primer called "Dimetcoat".

Anyway, Al is correct, take it to the Engineer and be prepared to offer code and OSHA requirements.

Tim

I am going to make me look old
when I started and learned lay out and fitting
I was told some important things
#1..paint stick the part # everywhere, so they know in the field or another shop what it is and where it goes
#2..mark NP..meaning NO PAINT ...that was for where a welded joint happens in the field or another shop
times change
maybe they passed me by
sincerely,
Kent

Rocketman,

I'm a little curious so I need to ask a couple of questions:

1) Is this a field job or a shop job?

2) Especially if in the shop, why was the paint done before the work was finished and inspected (D1.1, Clause 5.30.2 last sentence)? 

3) Have you checked the Job Specifications/Contract Documents and/or General Structural Notes to see if the Engineer has any criteria called out for welding of painted joints? 

4) Do those notes mention hold back, masking, or other paint restrictions for joint surfaces to be connected in the field?

5) Are we talking about lap joints of bent plates of whatever design that are field fit to beams in the field for concrete slab edge?  Said members shop primered 'Red' iron?  Then B form decking laid in prior to pour.

Just curious.

He Is In Control, Have a Great Day,  Brent

If you are able to take Tim's comments and use them to qualify a procedure, don't forget to think about the paint mils and try to determine when too many mils becomes a problem for welding.

I understand the concern about the trapped paint, but there is also a concern about rust bleeding out from between the lap joint if intermittent fillets are used unless the joint is seal welded or is caulked with something after welding.

I run across this on tower work with the galvanizing. When they ask how I want things ground the specs call out anywhere from 1/2" from weld are to 2" from weld area. They have to grind the legs before installation of the new material so the galvanized is not under the new metal. I have heard lots of different things, stories about other welders, "the last guy just welded over it", "the last guy just burned it off with 6010/6011". I always point out that we are contractors and not the owner or the engineer and that the specifications on the job call out "removing all galvanized material within xx inches of weld joint". That's what they want, that's what we bid and that's what we need to do.