Traditional Method
Valves are padlocked using traditional chain and lock method to prevent any unauthorised operation. Tagging is then hanged on the valve to indicated valve opened or closed position.
In switching over procedure, the authorised personnel will take the key from designated cabinet and proceed to the valves and finish the procedure of switching supply of cryogenic gases from different tank before the gases supply is fully depleted from the tank.
In this operation, the switching over procedure required both cryogenic gases supply valves to be opened before the closing the other valve so that continuous supply of cryogenic gases can be provided to the plant.
Mishaps
In one of the incidents, the valve suppling the cryogenic gases was closed before the standby tank valve is opened. This human error causes disruption of cryogenic gases supply to the plant and cause the plant to be shutdown for a few hours. This shutdown causes the lost both in manhour and production which is very costly for wafer plant.
Alcatraz Interlock Solution
Alcatraz interlock system are mechanisms used to eliminate errors by effectively making it impossible to make mistakes in each process. It eliminates human error by simply forced the operator to follow a predetermined sequence by means of a mechanical code key transfer.
Even without the open or close tag, the interlock itself will clearly show the valve actual open or close position and this is especially important for globe and gate valve.
According to HSE, human failure can be active or latent in general terminology. Alcatraz Interlock System task is to eliminate human failure regardless of whether it is active or latent. With the installation of Alcatraz Interlock System, we do not just minimise the risk, we ELIMINATE them.