Torch cut and then weld

[marinaman]

I've got a situation where a steel beam flange needs to be welded to an angle.

The flange is too long right now, and needs to be trimmed back before it is welded to the angle.

That said, the erector wants to flame torch the beam flange, back to the proper length, before welding the flange to the angle. In other words, he wants to weld the flame cut edge of flange steel.

I've recommended that he cut or grind the flange back, and then weld.....but do not torch.

I've stated that he should not torch for several reasons. Torching changes the material property right where you want to weld. Torching also creates a jagged edge that you'd then be trying to weld.

What do you guys think? Could torching be allowed...right on the edge you want to weld? Seems like a no-go to me.

 

[EdStainless]

Speaking as a materials guy and not a fabricator...
I don't know that heat input is a big deal with most structural steels, but the rough edge and the contamination (usually excess oxidation) are the bigger issues. If the cut-back is more than they want to grind then torch cut within 1/4" and then grind the edge clean. That way they can also get the weld prep angles correct.

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P.E. Metallurgy

 

[azcats]

Link below has some info and references on thermal cutting and surface prep/finish including where weld is to be deposited.

[URL unfurl="true"]https://www.aisc.org/globalassets/modern-steel/steelwise/2014/steelwise.pdf[/url]

 

[Ron]

As long as the flame cut edge is ground down a bit to clean up any latent slag or other impurities, it should not present an issue to subsequent welding...either in capability or quality. The material properties of mild steel are not significantly altered by flame cutting.

 

[gtaw]

It shouldn't be a problem as long as the surfaces to be welded are free of dross and oxides. Without a detail of the joint, we don't know if the angle is jointed to the flange by fillet welds or groove welds or how the cut surface makes up the surface to be welded or not.



Best regards - Al