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Pig Traps

Pipelines are routinely cleaned with the help of pigs that scrape the lines clean. This is done to remove any debris deposited thus preventing corrosion and undesirable increase in pressure drop.

These pigs are also utilized for commissioning / decommissioning of pipelines as well as to detect and measure the pipeline defects such as corrosion, wall defects and cracks.

This is achieved with the help of Pig traps which launches the pigs into the piping network from one side and receive it at the other end in a safe and controlled manner.

Role of Interlocks

The process of launching and receiving of pigs can be a hazardous operation if performed out of sequence. Hence a safety system is required that can control the process without any dependence on human judgement.

Mechanical Key Interlocks will ensure that sequence of valves and end closure operations is always performed in a predefined, single and unchanging path. Although there can be variations in the sequence to be performed, the following scenarios are always kept in mind:

  1. Avoiding unintended pressurization of pig trap.
  2. The quick opening closure can only be allowed to open only after depressurization of traps.
  3. It should not be possible to open mainline and kicker line valves when the quick opening closure is open.

Advantages of Alcatraz Interlocks for pig trap 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 Gertjan Moons is ready to answer all type of questions! For the smallest ambiguities or extra information that you need. Do not hesitate and contact us immediately!

Gertjan Moons
Technical & Commercial Engineer

Or watch our introduction video



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