A product called Lab Metal for moulding before powdercoat. Welding can introduce tension into the structure and so can fit up, tubing has already been welded along it's length. cycle frames have been known to relax from the pc baking process and walk(though typically smaller dia tube). Like stated above the longer the unsupported run the higher the chances.

It all depends how much tension is already there, but I have definitely seen where the baking process is enough heat to tweak stuff if the structure hasn't been "normalized" after welding.

Hydrogen embrittlement pretty serious , I cringe when I see plated suspension components.