Systems

Systems are defined functionally. Systems hinge on functions, so functions influence how engineers look at systems.

Imagine how a designer conceptualizes, plans, and constructs a complex facility. The concept begins with what the expected product is, how it will be produced within the physical, cultural, financial, and temporal project constraints, and what costs and income will be expected. Product output is always the overall facility purpose.

Several hundred years ago, someone wanting to mine, refine, or do practically anything just started doing so. It's not so simple today, and this is why today's facilities have many systems, functions, and requirements. People, the environment, and investors just cannot be used the way they could be in the good old days! Everyone wants assurance that manufacturing and production processes don't create risks or hazards that the public at large will either pay for indirectly, incur implicitly perhaps through ignorance or both.

Familiar system and equipment functions are easily taken for granted. Most engineers know systems intuitively and don't want to be bogged down identifying system functions for analysis sake. Engineers want substance. Folks who developed scheduled maintenance programs in use now had these mindsets. This explains why plants generally do more maintenance than they should. Plant engineers are doers, not thinkers.

Systems identify required functions, which reveal their original designers' intentions. Plan layout started with functions; equipment was added as plans developed. A design engineer integrated functional design documents into rough process P&IDs. As conceptual designs were approved, drawings froze. On...