Shear Stud Welding

Date 02-27-2002 23:20

Section 7 of the D1.1 pertains to SW.

7.4.3 (Base-Metal Preparation) references your question - "...areas to be welded shall be free of scale, rust, moisture, paint,..."

Although the code mandates removal, paint is not normally removed if the operator can demonstrate he/she can produce an acceptable weld. Technically, removal of the zinc from the decking material would be a consideration as well. I have never seen paint on primary/secondary structural members or the coating removed from sheet steel for SW on a structure or building. If the steel is left unpainted - then would there not be even more concern about corrosion unless the steel is welded soon after paint removal? Rust (oxide) can occur overnight when there is enough moisture present. It doesn't take much.

As far as corrosion, there are many instances where there may be corrosion problems such as the inside of tubular or built-up members. Once decking has been welded, button punched, the mud is poured, etc., how will you gain access to the weld area?

By Pio Date 02-28-2002 17:36

OK.

So basically what you are saying is that it's "easier o better" to guarantee a good, "test-compliant" stud weld even though its done through the galvanizing of the deck and the paint on the beam, than to deal with the potential corrosion problems that may arise from removing the galvanizing on the deck or the paint on the beam. Right?

Also, that even though the AWS D1.1 requieres paint to be removed, this could be unrealistic and potentially harmful when installing shear stud connectors for a steel deck composite floor system in a building. Right?

By bmaas1

Date 02-28-2002 08:41

DGXL is absolutely right. I have never seen paint or zinc removed prior to SW. As far as the underside like on floor decking for a building it would probably get fireproofing sprayed on it any way.

Hope that helps.

Brian Maas

By Niekie3 (***)

Date 03-03-2002 18:00

Just a suggestion: Qualify a SW procedure using the parameters that you intend to use on the job. (Including the paint on the beams.) If everything goes well, you can confidently approach the relevant powers to approve your approach.

My experience with this sort of thing has shown that the SW will not pass the necessary tests on a reliable basis. Maybe you will have better luck.

Regards
Niekie

By Pio Date 03-04-2002 20:37

Interesting...

So, there appears to be somewhat of a disagreement between "code requirements" and "practical applications". On one side, you must remove paint, galvanizing, and other deleterious materials for SW. But on the other side, this could increase project costs and maybe create a potential corrosion problem due to moisture caught between the formed metal deck and the unpainted I-beam flange. Even more, you could try to test SW with in-job conditions, but to confidently approve a SW method in this way could be very difficult.

So... that is the question, right?

By CHGuilford (****)

Date 03-05-2002 14:22

I think if you take another look at D1.1 Section 7.4.3 you might have your answer. It says ....free if scale, etc.etc.. TO THE EXTENT NECESSARY TO OBTAIN SATISFACTORY WELDS AND PREVENT OBJECTIONABLE FUMES. To me, that means you don't have to grind to bare metal as long as you get good welds.

Certainly that is easier with bare metal, but it is the results that count in this case. If you can consistently "fire" a stud through whatever is on the deck, and still have a weld that is acceptable per the code, nothing more needs to be done.

CHGuilford