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Interlock solution for pressure safety systems

Whether onshore or offshore, maintenance procedures to Safety Relief Systems on live plants is a cause for concern, particularly as an open path to relief must be maintained during all times of the work exercise. Alcatraz Interlock PSV system ensures maintenance procedures on safety relief systems operate in a safe sequence. Most modern piping arrangements include spare relief capacity, which enables continuous production while routine maintenance procedures are conducted. This eliminates the need to isolate and shut down the process on a live plant, which has major time and cost saving advantages.

Twin or multiple safety relief valve systems are usually fitted with isolation block valves upstream and downstream of each safety relief valve. It is imperative to open the block valves isolating the spare relief valve before the block valves of the work-piece relief valve are closed. This is a more acute problem if the respective relief valves and isolating block valves are distant or out of sight of each other.

Role of Interlocks

Various API and ASME codes recognise this hazard and recommend the use of interlocks to safeguard the process. By fitting an Alcatraz valve interlock to the upstream and downstream isolating valves, it ensures the process occurs only in the safe, designated sequence and recommendations are fully implemented.

Advantages of Alcatraz Interlocks for PSV system applications:

1) With the piping networks becoming more and more extensive, pig traps may need to be located in remote locations and hence can be subject to extreme weather conditions. Alcatraz Interlocks can operate successfully in a wide variety of extreme weather conditions from a desert environment laden with moisture and very fine dust to extreme cold conditions with temperatures as low as -50°C.

2) As pig traps are used intermittently for maintenance purposes, so there can be quite a long time in which interlocks are not operated at all. Our interlocks are designed to avoid ingress of dirt or contamination by environmental factors irrespective if the key is inserted or not with the help of an automatic closing dust cap and keys which encapsulate the lock portion when entered. This helps in avoiding any surprises when the Interlocks need to be operated.

3) Easy to operate also with gloves.

4) Sometimes the space available for Interlocks on pig traps system is limited (e.g., In FPSO’s). Our Interlocks can be installed in the most convenient way possible (even upside down) without any effect on the key operation. This is with the help of the partial linear and rotational action of the key.

5) The hand wheels / drive tubes all have a parallel splined connection. This spreads operating forces, prevents any loosening of hand wheels (even in scenarios with excessive vibrations) and higher HSE standards.

Want to know more?

Our own specialist Anshul Garg is ready to answer all your type of questions! For the smallest ambiguities or extra information that you need. Do not hesitate and contact us immediately!

Anshul Garg
Technical & Commercial Engineer

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