Piping Layout : Vent and Drain Systems


Piping and instrument diagrams (P&ID’s) shall show connections, valves and piping for equipment filling, draining, venting and pressuring. The P&ID’s should show connections, valves and piping needed for plant start up operation and shutdown.

All other services shall have vents and drains provided at the piping high and low points, so the system can be completely filled, vented, hydrostatically tested and drained.

Hydrotest vents and drains shall be normally unvalved. Valved vents or drains will only be installed if shown on the P&ID’s.

Piping low point drains shall be 3/4″ minimum size plugged or blinded. Piping high point vents shall be 3/4″ minimum size, plugged or blinded.

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