This particular device is an EBV, or an Electromatic Ball Valve, that was manufactured by GE. Part of the Consolidated Series 3500, it was created to provide overpressure protection.
These can be operated manually or automatically. Little maintenance is required due to the power-actuated relief valve, which comes with a ball assembly that is replaceable, and graphite seals on the expandable body joints. The body is made from alloy steel and is Colmonoy coated, while the ball and seat assembly is coated with an Inconel alloy.