Heat Shrinking

[IAL2002]

We are welding 5/16" mild steel plate on the top of a helideck to the top of W12x 16 beams with the spacing in between the beams are approximately 32". The fillet weld used is a 3/16" ("according to spec.&quot and we are using GMAW-S to minimise heat input. We are experiencing the sheeting sagging up to 3/8" in between the beams.
What can be done to minimise this as well as fix these sagging areas?
Heat shrinkage is allowed but how is it done?

 

[unclesyd]

Sounds like you need a little engineering help. Was this deck engineered for loading by a helicopter. They can make some hard landings. Since your are already welding I would get engineering help, as 3/8" sag in this distance is lot.
Bracing can be used but its needs to be engineered.

Is the 32" flange to flange or web to web?

 

[IAL2002]

The dimension is web to web.Yes it was engineered for loading by a helicopter.
Any pointers on Heat Shrinking?

 

[CWIC]

"Heat Shrinking" or distortion control is relatively easy.

My first recommendation (to save me a lot of typing) is to get your hands on a copy of the Lincoln Procedure Handbook of Arc Welding. This publication is inexpensive (<$30) and will give you many guidelines on how to avoid the distortion for future welds. I think this book can be ordered directly from Lincoln, but most welding suppliers keep them in stock. Section 3 has many procedures on how to avoid the distortion before it becomes a problem.

Heat the area that is sagging (from the side that is concave) to about 1100 degrees F, weed burners work better than acetylene w/rosebuds by the way. Apply cool water at this location gradually, not all at once. We used this procedure a few weeks ago for a similar problem where plate was warping between channels at a location where we needed a relatively flat surface. Worked like a charm.

 

[unclesyd]

&quot;CWIC&quot; beat me to the punch. Check with the structural crew there is probably some one experienced at this. It maybe difficult to achieve flatness you started with. So start at the edges. &quot;CWIC&quot; is correct that weed burners work very well. You may be able to rent them. An inexperienced person with a rosebud can ruin you.

Here is Lincoln website to order from.

https://ssl.lincolnelectric.com/foundation/