THERMALLY-SENSITIVE TRIGGERING MECHANISM FOR SELECTIVE MECHANICAL ENERGIZATION OF ANNULAR SEAL ELEMENT

摘要

A seal assembly for use in a valve that maintains a seal during operational excursions of high temperature, such as during a fire. The seal assembly includes a eutectic material that retains an energizing element in place during normal conditions, which in turn keeps a secondary seal spaced axially away from a sealing position. During high temperature excursions, the eutectic material (38) degrades and releases the energizing element (30). When released, the energizing element (30) energizes a secondary seal (40) that is in an annular space between a valve stem (16) and valve housing (12).