Plan 65 is a leakage detection plan for single seals.  Plan 65 has been used for many years in pipelines but can be used in many applications where the seal leakage would normally be in a liquid state.

Because of the many variations of Plan 65, the 4th Edition Taskforce of API 682 decided to emphasize the two most popular variations as Plan 65A and 65B.  Plans 65A and 65B are considered to be leakage management systems.  That is, the leakage has already occurred and the piping plans serve to alert the operators as well as to route the leakage to a disposal area.

In Plan 65B, leakage is directed from the gland drain connection into a reservoir containing a level transmitter with a local indicator.   As the level increases over time the level transmitter will activate an alarm at a preset level. The system has an overflow line running from the upper section of the reservoir to piping below the closed valve to allow excessive leakage to be drained to either a sump or liquid collection system.