Before welding, it's a must that the painted surfaces be thoroughly cleaned. Preferred method is by sandblasting, If you can't afford this, a careful cleaning with a powered steelbrush is acceptable.
Giovanni S. Crisi
Sao Paulo - Brasil
By -
Date 05-31-2000 03:13
Any control document I have been involved with states either you remove the product or you qualify the procedure with the "coating as part of the prosess" and it becomes an essential variable".
The common sense approach is to remove this material.
TTFN
Burn off as much of the paint as possible with a torch. Wire brush the joint. Then weld a sealer pass with E6010, or a down-hand FCAW pass or two. Then you can use whatever process you want to finish the joint.
This seals in the paint that is trapped between the base metals and prevents porosity in the finished weld.
As you would be weakening the root, I would'nt recommend this for cyclic loading.
By -
Date 01-02-2001 00:11
You need to follow whatever Code is called out in your contract drawings. AWS D1.1 Steel Welding Code for example, allows welding over one shop coat of primer (2 mils or less). Epoxy generally is a two coat system and I can't imagine that it would be in compliance with any code or standard.
Moe www.weldingprocedures.com
