Pig Launcher, Pig Receiver & Intelligent Pig

PIG LAUNCHERS AND RECEIVERS

In simplest terms the PIG launchers and PIG receivers are the sections of the pipeline which allow the PIG to enter and exit the pipeline. They are generally funnel, Y-shaped sections of the pipe which can be pressurized or depressurized and then safely opened to insert or remove PIGs. Most pigging systems use bidirectional launchers and receivers that can work in either direction. This is important to allow the PIG to be retrieved by the launcher if there is a blockage in the pipeline which prevents it from reaching the receiver.

PIG launchers and receivers come with safety valves and locking system to prevent accidents. They are also optimized to be suitable to the pressure and temperature requirements of the pipeline. Launchers and receivers may be horizontal or vertical depending on the needs of the pipeline.

Some launchers are designed to hold multiple PIGs at once and configured to launch them according to preset conditions. This is very useful because it allows much of the work to be done remotely. Additionally it prevents the launcher from having to be depressurized and repressurized again each time a single PIG is needed. It is the pressure from the flow of product that moves the PIGs through the pipeline. Thus one of the main roles of launchers and receivers is to safely interface between the low-pressure outside world and the high-pressure pipeline.


The exact procedure for operating a PIG launcher or PIG receiver will vary somewhat depending on the particular pigging system being used. However, for the most part it will include the following steps:

Launcher:

• Pipeline operator should make sure that the isolation valve and kicker valve are closed.
• If the system is a liquid system then the drain valve and vent valve should then be opened to allow air to displace the liquid; if the system is a gas system then the vent should be opened so that the launcher reaches atmospheric pressure.
• After the PIG launcher is completely drained to 0 psi, with the vent and drain valves still open, the trap door should then be opened.
• The PIG should then be loaded with its nose in contact with the reducer.
• Closure seals and other sealing surfaces should be cleaned and lubricated as needed and then the trap door should be closed and secured.
• The drain valve is then closed and the trap is slowly filled by gradually opening the kicker valve.
• Once filling is complete the vent valve is closed so that the pressure will equalize across the isolation valve.
• The isolation valve is then opened and the PIG is ready for launching.
• Next the main valve is gradually closed, increasing the flow through the kicker and behind the PIG until finally the PIG leaves trap altogether and enters the pipeline itself.
• After the PIG leaves the launcher the mainline valve is fully opened and the isolation valve and kicker valve are closed.

Pig launcher

Receiver:

• The receiver should be pressurized.
• The bypass valve should be fully opened.
• The isolation valve should be fully opened and the mainline valve partially closed.
• Once the PIG arrives the isolation and bypass valves should be closed.
• The drain valve and vent valve are then opened.
• Once the trap is fully depressurized to 0 psi the trap can be opened and the PIG removed.
• The closure seal and other sealing surfaces should be cleaned and lubricated as needed and the trap door should then be re-shut and secured.
• The receiver should then be repressurized and returned to its original condition.
• These processes may differ somewhat on different systems and of course if the launcher will be launching multiple PIGs then they should all be loaded at the loading stage.

Pig receiver

INTELLIGENT PIGS

Intelligent pig

The accuracy of location and measurement of anomalies by the intelligent pigs has continued to improve. Initially, the electronics and power systems were so large that intelligent pigs could be used only in lines 30 in. and greater in size. The continued sophistication and miniaturization of the electronic systems used in the intelligent pigs has allowed the development of smaller pigs that can be used in small-diameter pipelines. Newly enacted DOT pipeline-integrity regulations and rules acknowledge the effectiveness of the intelligent pigs and incorporate their use in the pipeline-integrity testing process.

Reference :

http://en.wikipedia.org/wiki/Pigging
http://setxind.com/midstream/what-are-pig-launchers-and-receivers/