As usual, Superman, (like most Hollywood Blockbusters) defies all known laws of Science), as well as Health laws & Safety Requirements, ISM code etc.
The Captain will probably get the sack for not getting Superman to fill in a risk assessment and Hot Work permit and having a Toolbox talk before starting work, as for the PPE, I don't think Superman's clothing has been approved by any Safety Body
I suspect there are also violations of the laws on disposing of oil spills. Was the repair Class approved?? Is Superman a coded welder?
Why let reality spoil entertainment?? Most Politicians ignore reality all the time, why should Film Directors be any different?
It is always better to ask a stupid question than to do a stupid thing.