Piping & Instrumentation Diagram Series


Notes for lines, showing equipment and Special Items

Notes for lines

Special points for design and operating procedures are noted-such as lines which need to be sloped for gravity flow, lines which need careful cleaning before start up, etc.


The P&ID should show all major equipment and information that is relevant to the process, such as equipment names, equipment numbers, the sizes, ratings, capacitites, and or duties of equipment, and instrumentation.

Standby and paralleled equipment is shown, including all connected lines. Equipment numbers and service functions (‘STANDBY’ or ‘PARALLEL CP’) are to be noted.

Future equipment, together with the equipment that will service it, is shown in broken outline, and labeled Blind-flange terminations to accomodate future piping should be indicated on headers and branches. ‘Future’ additions are usually not anticipated beyond a 5-year period.

Pressure ratings for equipment are noted if the ratings is different from the piping system. A ‘Typical’ note may be used to describe multiple pieces of identical equipment in the same service, but all equipment numbers are written.

Next time:

Closures, Separators, screens, Strainers, and Steam Traps on the P&ID


Total Cad System Inc.


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