hi guys/Wal, you asked about stupidity, cheers
..(1 )Have you been that stupid?  and if so (2) Do you have in place mechanisms to prove you have taken all reasonable steps?
..
 (1) Yes I have!  I have in the past used oxy/acet welding gear to successfully affect a repair to some pipe work. (2) Yes I have! I will not take welding plant anywhere near a plumbing repair or installation again). I will in future make sure that that all plumbing work is by crimp type piping or glued piping. All welding plants will be taken from plumbers vehicles and sold, any future damage claims will be because of flooding.