Can a shut-off valve be installed upstream of a relief valve to allow for the removal of the relief valve for servicing without emptying the contents of a tank?

The installation of a shut-off valve upstream of a relief valve is not permitted due to safety regulations governing the operation of pressure relief systems. Relief valves are designed to protect tanks and piping from overpressure conditions. If a shut-off valve is installed upstream, it could potentially isolate the relief valve from the system. This could lead to a situation where, during servicing or maintenance of the relief valve, the system remains pressurized without the necessary relief mechanism in place, thus creating a hazardous condition.

Regulatory standards dictate that relief valves must always be operational and able to relieve pressure without obstruction. It is essential to maintain clear and unimpeded access to these safety devices to ensure the safety of the equipment and the environment, reinforcing the no shut-off valve upstream rule.