SPECIFICATION FOR PREPARATION OF PIPING AND INSTRUMENT DIAGRAMS

e) P&ID number and equipment tag number for lines going to Process Unit/Utility ... Relief valve hook-up shall refer to Isolation Philosophy, PHC 0804.02-10.01.

http://boonchoo.org/OCS4/2.1%20Project%20General/2.1.2%20General%20Project%20Engineering%20Specification,%20Procedure%20and%20Philosophy/SPC-0804.02-99.02%20Rev%20D2%20Preparation%20of%20P&I%20D.pdf