The API Plan 72 + Plan 75 seal support system is designed for API 682 Arrangement 2 (2CW-CS) applications. It supports non-pressurized double mechanical seals with a dry-running isolation or containment seal.
Plan 72 supplies external buffer gas, commonly nitrogen, to the containment chamber. It provides stable purging and dilution while carrying leakage away from the inner seal. The buffer gas module provides pressure reduction, regulation, filtration, flow indication, and flow control. Check valves and orifices or needle valves help maintain stable and controlled gas flow.
The buffer gas pressure is controlled below the seal chamber pressure. This pressure relationship helps prevent buffer gas from flowing back into the process side.
Plan 75 provides condensate and leakage collection for the containment chamber. A collection tank provides centralized liquid collection and monitoring. Liquid level indication is available, with optional level switches or transmitters. The gas phase can be routed to a recovery or flare system.
A dedicated liquid drainage outlet supports controlled discharge. A normally closed discharge valve or centralized drainage connection can be provided according to application requirements.
Optional features include pressure, flow, and level alarms with interlock functions. Explosion-proof electrical components are available for hazardous-area applications. Trace heating and insulation can support low-temperature operating conditions.
A backplate assembly, quick-connect fittings, and an isolation valve panel are also available. The modular design simplifies on-site installation and maintenance. Standardized interfaces support convenient piping connections and system integration.
The Plan 72 + Plan 75 configuration follows the API 682 piping plan concept. It provides controlled buffer gas supply and condensate management for Arrangement 2 seal applications.
