The following information is usually not shown on P&IDs:
• Pipefitting details are not shown, except for reducers. These details include hydrotest high- and low-point vents and drains, elbows, tee’s, other joints, and (sometimes) unions
• Pipe supports are not shown. These supports include hangers, anchors, guides and pipe expansion loops
• Structural information is usually not shown. This information includes most support structures, platforming, ladders, etc.
• Electrical information is not shown, except for special controls such as threeway switches
• Instrument piping/tubing is not shown, except for level instrumentation piping. In major processing facilities, level piping valves and details are placed on auxiliary P&IDs or piping drawings, leaving only a skeletal piping outline on the main process P&IDs. By contrast, producing organizations usually retain valving and level piping details on the main P&IDs
