Interlock for Cryogenic Globe Valves

Humans make mistakes; these can initially be small but can quickly turn catastrophic in the correct circumstances. “As the known proverb states, the butterfly effect in flapping its small wings can lead to natural disasters in far-off lands.” Meaning a simple small error at work, can have far-reaching consequences.

We are REALTEC, the Alcatraz Interlocks partner based in Singapore. We support a wide selection of end-users within the SEA region with process safety and support services. One of our clients, a supplier of cryogenic gases to a Semiconductor Plant in Singapore. The gases are used in manufacturing and testing of processes or removing excess heat from them. Any breakdown in the supply of these Cryogenic gases to the operational plant may cause a serious disruption, or even a possible shutdown.

To prevent this, standby tanks of Cryogenic gases are located onsite, and will be used if or when any disruption occurs to the supply chain, the host valves used to control the switch over from these different tanks are critical pieces of equipment, and their operational status needs to be clear.

The correct process method of switching over the supply of cryogenic gases from the various tanks is critical, any oversight made during this process, will cause further disruption of the supplied cryogenic gases into the Plant.


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.


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.



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