I would say this more of a engineering/technical competency requirement. The fitters/ tradesmen need to suitably qualified whether mechanical or electrical etc. They also need training on the specific plant and equipment - e.g. how the plant works, how and where is is isloated and shutdown. lso in your company safe systems of work eg PtW.

Ian - not the first time. IOSH don't seem to have found a way of dealing with posts where the original poster deletes their message and any reply lacks context. 

When we had moderators, they could have simply deleted the thread.