Welding on embed steel plate, steam concerns from under plate?

[Mustangx3]

Hello all,

We have a contractor who is concerned that his welding on a steel embed plate, in technically uncured concrete (several days cure vice months), would cause steam generated from heat under the plate may damage or pop the plates. Is there a method to welding, etc. to avoid possible steam from "green" concrete slabs during welding? The plate is 12" square and will need to have a continuous 3/8 bead welded around it to join a post sitting on it. The weld is not going to be structural, just to join the post to the embed, weight bearing is in down direction only.

 

[civilperson]

Weld in small increments, say two inches and then skip 180 degrees and repeat. Fill in gaps with small increments leaving time to cool before welding adjacent space.

 

[kelowna]

Civilperson is right, and his suggestions will probably work, the issue is to weld in small portions so as not to build up enough heat on the steel plate to do any damage. It makes the welding more difficult and increases the chances of weld deffects, but the weld is so easy anyway that it should not be a problem. Welding in small steps, stagering the four sides, will also prevent too much distorsion to build up.

If your case has small loads and a very simple structure, ignore the next comment.
If the loads or the structure are significant, something that worries me is when you say that the weld is not structural. The weld does not know it is not structural or not, and if it is there, it will try to carry the load, specially if you do not have a good fit between the anchor plate and the post on top, so it is not bad idea to dimension it to carry the full load anyway. In the experience I have with structural steel design you rarely consider direct transfer of load unless you ensure a 'bearing fit' or 'fit to bear' surface.

 

[11echo]

Just out of curiosity what is the plate thickness? I'd guess that would be a big determining factor!