The Trevitest is an auxiliary lift assist device that allows you to check safety valve setpoint without lifting the valve or coming off-line and removing the valve. I think Trevitest is the name Furmanite uses but there are companies who do the work and they'd call their device something else. Check with Atlantic Group and DeLuca.
See thread794-133136 for some info on this.
The approach is addressed in ASME B&PV Code ection VII, PTC-25 and the OM Code for in service testing of relief valves.
