just talked to him, he wont budge
basicly said we will just do the steel first, then the stainless, then the aluminium, and that should be fine.
i think the best we can do there is just wipe everything down before we weld it or hit it with the grinder quick. its not like we have a clean room to weld or cut in anyway. the pipes are going to be laying on teh floor rolling around in whatever is on the floor