API Plan 54 is a pressurized external barrier fluid system designed for dual pressurized mechanical seals, ensuring zero process leakage by continuously supplying clean, cooled barrier fluid from an external source. Unlike Plan 53A and 53B, which rely on self-contained barrier fluid reservoirs, Plan 54 uses an independent pump or external system to maintain pressure and flow, providing superior cooling, lubrication, and contaminant removal.

This plan is ideal for applications demanding continuous high-pressure sealing performance, particularly in processes involving hazardous, toxic, or high-temperature media. It extends seal life, prevents coking and vaporization, and ensures optimum lubrication for mechanical seals.