Hello everyone,
I was wondering how HOLDS on a P&ID are usually used:
I regard the HOLDS as a To-Do List that gets smaller until the P&IDs can be issued for construction, so basically all pieces of information conveyed by the P&ID which still need to be confirmed (e.g. by vendor documentation, or a hydraulic calculation, input by another engineering discipline, decision by the client etc.) are marked with a cloud and a short explanation is given (stating what information is required and who is expected to provide it)
I’m always suspicious when I start a Detail Engineering Phase with a set of P&IDs that do not have HOLDS on them, as I know that the Process Engineer who prepared them in the Basic Engineering could not have been certain that all of the information conveyed in the P&ID are final (otherwise there would be no point in working on the P&IDs in the Detail Engineering Phase anymore at all) but chose not to write down what pieces of information are still missing, or to quote Donald Rumsfeld: “We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don't know we don't know.”
In my opinion by not using HOLDs, we create those “unknown unknowns”, which is a real problem, as the P&ID then suggests a stage of completion of the project that does not reflect reality, with the respective effects on the schedule and the necessary man hours.
Does this philosophy make sense in your opinion/experience?
Kind regards
Philipp