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 65A, leakage is directed from the gland drain connection past or through a reservoir containing a level transmitter with a local indicator, through an orifice and finally into either a sump or liquid collection system. If the leakage from the seal is excessive the orifice downstream from the reservoir restricts the flow allowing the level in the reservoir to increase setting off an alarm. The downstream orifice should be located in a vertical pipe run to avoid accumulation of leakage in the pipe. This system has a line running from the upper section of the reservoir connected to the piping downstream of the orifice so excessive leakage can drain properly.