Posted By Ian Waldram
You need to make sure that pressure can't accidentally build up in the system being blown. Also it's likely that dust and particles will be blown out of the exit, so persons should be prevented from approaching that.

You seem to be asking a series of questions about standard offshore pre-commissioning activities. The letters after your name indicate some training in accident investigation, but familiarity with these typical hazards (plus many more) and good practice controls is even more essential. Isn't there a colleague available with previous experiece of the H&S advisory role for HUC activities? If not, I suggest you should think about that approach, rather than relying on responses from this forum.