John,
Unfortunately, unlike the ligh-commercial building projects, no one set of "engineering standards" exists for the process chemical industry.
Unlike the "design-build-inspect-maintain" standards used for ummmm.....say a new warehouse construction, nothing like this exists for a petrochemical refinery or a pulverized coal power plant.
This is why large companies like Foster-Wheeler, Shaw Bechtel and Fluor exist. They have the people, the experience and the knowledge necessary to build a large project involving large expensive, custom made equipment.
The PIP standards are useful, but are somewhat limited in application (i.e. good for specification of a small flat bottomed tank, bad for specification of a steam surface condenser...)
Again.....my opinion only
-MJC