Welding TS 5x2x3/16 To 12 or 14 guage track 1

[mjohan]

What is the appropriate size weld for a connection between a metal track (12 or 14 guage) and a TS 5x2x3/16? The application is the tube will be the bearing plate for open web steel joists. The joists will bear on the tube, which I would like welded to the top track of a 6" metal stud wall. The tube will be centered on the track.

Are their any references which discuss the maximum size weld before "burning through" the track metal? What is a recommended maximum?

Also, is a fillet weld typically specified?

Thanks so much,
Mark

 

[CWIC]

I think your looking for a minimum weld size in lieu of the maximum. Have you considered using the AWS D1.3-98 Structural Welding Code-Sheet Steel for your application?

Section 2 contains all of the design criteria. The weld for your application may be a fillet of a flare-bevel. I think the track probably has a radius at any bends were a weld is used to attach the track to the supporting structural member (tubing). That would make your weld a flare bevel groove which has a minimum length of 3/4".

Another possibility is the use of plug or seam welds in the center line of the track to the tubing. The plug weld has a minimum 3/8" effective diameter.

Regardless of the weld type you choose, try to utilize one of the prequalified weld details in Section 3 of the code.

Just a few thoughts posted here. Many possibilities.

 

[IFRs]

My fillet welds are sized equal to the thinner of the parent metals. Additional weld reinforcement may compromise the joint integrity and increase the heat affectd zone.

 

[mjohan]

I appreciate your responses.

I like CWIC's suggestion using the flare bevel groove weld to attach the tube to the track. This way, the wall panels can be delivered to the site and long, continuous, tube steels can be welded in the field. This would eliminate many field splices of the tube steel.

Just curious, do you feel a 20 gage track would be to thin for this welding application? (1/8" flare bevel groove weld, 2" @ 12" oc, each side) I don't have access to the welding codes right now, so I might be asking questions which could be answered by the code.

Thanks again

 

[CWIC]

Mark:
Please note you previously mentioned the use of 12-14 gauge material thickness(es) for the track. By using a 20 gauge track, your application is no longer a prequalified weld joint in accordance with AWS D1.3-98, Figure 3.3B (18 gauge min. thickness).

Do you need that much of an effective area (1/8" x 2&quot for your welds? I mentioned previously the minimum length for the flare-bevels is 3/4" (D1.3-98, 2.3.4.1). Excesive heat input may result in unwanted distortion to the track, supporting member or both. If you need that much area, I would split the welds up into shorter lengths and add a few more welds. Staggering the welds would help also.

Good luck with your project.

 

[mjohan]

The weld definetely does not have to be 1/8". I need to transfer approximately 600 plf, max. lateral load, into the wall. I just do not know how to spec. it. 20 gauge track is the lightest gauge allowed by IBC 2000 for a plywood shearwall analysis. Thanks for the 18 gage or less tip.

The reason I picked 1/8" as the size is as follows:
The AISC manual Table J2.2, specifies the effective throat thickness of a flare bevel groove to be (5/16)*R. R I took to be the radius of the thicker material, the tube steel, which is 2 times the thickness, or 2x.1875 = .375. (5/16)*R = .117" So my first instinct is to use the 1/8" weld. I know for fillet welds the minimum size is 1/8", table J2.4 in AISC.

Is a 1/16" flare bevel groove 1" @ 12" o.c. each side a more appropriate weld. Is this easily done in the field? And finally, is 1/16" a thick enough weld to bond to a 3/16" thick tube steel, and not burn through the 18 gauge, 14, or 12 gauge track?

Again, thanks for your help.

 

[CWIC]

M:
I know the about the PJP flare-bevel requirement in Table J2.2. This information comes from the AWS D1.1 Structural Welding Code-Steel, Table 2.1 (J2 of AISC). But, please note your track material falls below the thickness limitations of this code of 1/8" (ref. AWS D1.1:2002, 1.2(2)) which is why I originally referenced the D1.3 sheet steel code.

As far as welding goes, most arc welding processes will not deposit anything less than a 3/16" or so fillet or groove weld size. This is inherent to most commonly used arc welding processes with the exception of GTAW (TIG). The welder can deposit a relatively small weld compared to the other processes. I don't think this process is practical for field welding unless the amount of welding is minimal and there is sufficient sheltering for the welder and work as this is a gas shielded process.

Also, My guess the track is anodized, galvanized or has some type of coating. GTAW does not perform well without complete removal of these coatings unless they are brazed using the same process. But, it can be done. GMAW or SMAW can also be used , but you may have welds that are not very attractive, may burn through the track material if not performed properly, or may result in unwanted distortion to that fairly thin track.

I think the 1 on 12 PJP flare-bevel grooves should be satisfactory for the design loads.

 

[JCWilson]

This note may be overdue in terms of this particular case, but I see welds spec'd between these dissimlar metal thickness all of the time. One thing that we have come across that is not mentioned in this post is that our erector prefers to use E60xx electrodes. Because they do so much welding of galvanized light gage (often to thicker ungalvanized stock,) it would be unrealistic to grind all of the base metal before welding.

I don't necessarily know how this complies with AWS, but the "oldtimers" in the field swear by it. We attempted to research this issue through various welding bulleting boards, discussions with a metallurgist, and so forth. The only potential problem we found was when welding with E60xx to higher strength building structural steel. There we had to use E70xx. Other than that, if designed appropriately, it was deemed acceptable.