[TheForge] warped 1" plate table

[Ray Miller]

Pete,
There is science and mostly art to reshaping steel beams and plates with 
heat. I have watched an expert at this repair a bent buckstay. (A 
buckstay is an extra heavy weight I beam used in power plants to 
surround the boiler and keep its shape, forcing expansion and 
contraction vertically, as designed. In one power plant there was a 
boiler controls excursion and BOOM the boiler was "puffed" bending back 
24" buck stays.

The expert used huge rose buds and buckets of water to reshape the 
beams. When he was done you could not tell they were ever bent. IF I 
recall correctly most of the time he heated the steel on the side 
opposite of the bend, and let it cool naturally. He quenched at the end 
of the process to fine tune the dips and cupping in the flanges. He also 
wasn't very shy about how hot he got the steel. Those of watching, 
questioned the structural integrity after the fact, but we were assured 
there was no problem.

I wish I could be more help. But the process basically, as I understood 
it, was to heat the convex side and as it cooled it would cool back past 
where he started. The other key element I recalled was using other steel 
to restrict movement. I think you may need to "nail down" edges of the 
plate by welding strong back across the plate.

Ray
Cincinnati

Peter Fels and Phoebe Palmer wrote:

> I'm in over my head again and wish to beg some of you-all's expertese.
> This 1"x8'x9' plate is warped and while I've been able to herd  the  
> warpage around, I've been unable to get it flat.
> It is up on house jacks in the work yard and presently has a gentle 
> diagonal crease about 3' long  so the thing is high on 2 corners.
> The theory I had was that by spot heating and quenching, it would 
> shrink a little at that spot and that if a line was heated and 
> quenched,it would shrink along  the length of that line.
> What seems to be happening instead is that the spot heated area bulges 
> and only partially returns to flat when quenched and that the heated 
> line seems to  cause a folding  along the line that draws the sides up 
> perpendicular to the heated line.
> So the theory is wrong.
> Would someone be so kind as to explain this  and how to control it and 
> fix the problem..or where to find the info?....thanks...Pete F
>
>
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