A pressure relief valve that has its closing force provided by a spring.

A pressure relief valve that uses a pilot valve to indirectly activate the main valve.

A pressure relief valve that is intended to release excess pressure or admit pressure to prevent a vacuum forming when filling or emptying a pipeline or tank.

A self operating valve that is set to open at a certain pressure level to prevent the pressure in a container or system from reaching unsafe levels.

Flexible pipe, wholly or in part, resting on the seafloor or buried below the seafloor, and used in a static application.