Piping & Instrumentation Diagram Series


P&ID Layout

The layout of the P&ID should resemble as far as practicable that of the Process Flow Diagram. The process relationship of equipment should correspond exactly. Often it is useful to draw equipment in proprtion vertically, but to reduce horizontaly dimensions to save space and allow room for flow lines between equipment. Crowding information is a common drafting fault – it is desirable to space generously, as, more often than not, revisions add information. On an elevational P&ID, a base line indicating grade or first-floor level can be shown. Ccritical elevations are noted.

For revision purposes, a P&ID is best made on a drawing sheet or electronic sheet having a grid system-this is a sheet having letters along one border and numbers along the adjacent border. Thus, references such as ‘A6’, ‘B5′, etc., can be given to an area where a change has been made. (A grid system is applicable to P&IS’ s more complicated ones).

Next time: Drafting Guidelines for P&ID’ s


Total Cad System Inc.


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