Welding of Cor-ten Steel in below freezing temperatures

[csd72]

We have an existing building with exposed cor-ten steel members that needs to be welded this winter while subject to below freezing temperatures(possibly even below 0 Fahrenheit).

Can anyone point me towards a good reference regarding
1. is preheating required for this temperature
2. how can preheat be applied to an existing building members.

 

[bridgebuster]

1. Yes, you need to preheat.

Check AWS D1.1. The preheat is a function of the steel grade, thickness, and the welding process.

2. I do bridge work mostly and when field welding needs to be done in the conditions you describe the contractor erects a heated enclosure. As far as how to preheat, it comes down to using a torch. You'll need a surface thermometer to check things. Most important - a skilled welder.

 

[csd72]

Thanks bridgebuster,

I actually just found it in the welding code. It gives no specific requirements for A588, but as a general rule if below 32 it needs to be preheated to 70 degrees.

Preheating is going to be very interesting as it is 800' off the ground and the column is filled with liquid (to disperse heat in case of fire). As I said, very interesting.

 

[bridgebuster]

800' up, that is going to be interesting. I hope it works out.


A588 weathering would be similar to M270 W

 

[HgTX]

And preheat requirements should be similar to A 572 Gr. 50.

Hg



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[hokie66]

I would have thought that the liquid would act as a heat sink and prevent effective preheating. You may have to draw down the liquid to below the level of your welding.

 

[HgTX]

Or maybe treat the thickness as if it's the entire water-filled section, not just the wall thickness?

Hg

Eng-Tips policies: faq731-376

 

[csd72]

hokie66,

Exactly - that is the crux of the problem. Unfortunately I think they are sealed so the liquid cannot be drained.

HgTx,

Im not sure that I understand your point, but it is an 800' long column, so the heat sink will be in the length more than the thickness.

 

[metengr]

Treat the base material as being welded with water backing. If necessary, qualify a weld procedure with water backing.

 

[HgTX]

I'm saying pretend it's a solid column (the preheat charts top out around 2.5" anyway).

But I like metengr's idea better.

Hg

Eng-Tips policies: faq731-376

 

[gtaw]

If this is a building and D1.1 applies, you can't meet the welding requirements of a prequalified WPS, so you have to qualify a welding procedure that replicates what you propose to do.

As metengr suggests, you can qualify the procedure using the same thickness material, same material specification and grade, same electrode, and make a "box" that allows you to cool the plate as you weld. The cooling rates would have to replicate field conditions, likewise, the temperatures would have to be replicated if you propose to weld in temperatures below 0 degrees F. That means you will have to chill the "anti-freeze" solution you use to cool the test pieces. You may want to read API 1104 to get a few ideas of how a "wet weld" like this is qualified.

In my opinion I would wait until warmer weather if at all possible.

Good luck.

Best regards - Al

 

[weldtek]

You may want to consider using electrical resistance heaters along with a torch.