Most accidents in the process, and oil and gas, industries are related to procedures that do not happen very often but which can have catastrophic effects when performed incorrectly. Start-ups, shutdowns and handovers are all good examples of processes where a slight mistake or lack of concentration can lead to disastrous consequences. By using valve interlocks, you force operators to follow the correct valve  opening and closing procedure and so create safer working environments. Valve interlocks also reduce costs by preventing product spills or losses due to incorrect changeovers.

A valve interlock system guides the operator through a predefined sequence with unique keys for each step. Each valve interlock is supplied with two keys, one for the locked-open position and one for the locked-closed position. When the valve is open, the ‘open’ key can be released and transferred to another lock with the same code. All keys are unique and, depending on the sequence, Sofis will determine the codes to guarantee the required sequence.

Smith interlocks and Netherlocks interlocks from Sofis are used for a wide variety of applications, such as pressure relief valves (PSVs), pig launching and receiving, decoking, inert gas systems, pump start-up, flare lines, boiler blowdown, 2 out of 3, chemical dosing pots, HP fuel gas heaters, closed drain drums, vessel filling, vessel isolation, gas train alignment and pump routing.