Pipeline pigging is a process whereby devices called pigs are used in the maintenance of pipelines. The pigs clean and check the conditions of the pipes. In the meantime, the flow of the fluids in the pipe remains uninterrupted. The pig concept is used in industries such as lube oil, fracking oil, pharmaceuticals, chemical plants, oil, and gas. Understanding which type of pig to use for a particular application calls for experience and vast understanding. Here are the types of pipeline pigs:
Foam pipeline pigs
This is the most common type of pipeline pigs. Its aim is to get debris and liquid out of the pipeline. Foam pigs are available in various sizes and shapes and used for different purposes. For instance, the foam disc pig is suitable for the removal of liquids like hydro test water. They can be found in a large size range and help in proving and in the safe cleaning of pipelines. Bare foam and coated pipeline pigs are utilized after construction due to their flexibility. They are often used in proving, batching and general cleaning of pipelines. The power brush pig comes with brushes that get rid of stubborn matter such as corrosion deposits.
These are produced as one-piece constructions. Their bodies are more flexible and are used for liquid displacement, cleaning and wax removal. They can be manufactured using a formulation of polyurethane which is long lasting and is wear resistant.
Mandrel bodied pigs
These pigs have a metal body that can be tailor-made with replaceable scraper brushes or gauging plates, cups and discs. Disc pigs are used in the removal of wax and liquids. Where more sealing or wear resistance is needed, cups are added. They are specifically useful for housing pipes that are out of round. Mandrel bodied pigs are used in cleaning, liquids removal, and removal of black powder. Corrosion pitting and black powder are removed using uniquely designed pencil brushes.
Pipeline pigging process
A pipeline pig is placed inside the pipe with the help of a pig trap. A pig trap is normally huge enough to house the tight fitting pig. Another pig trap is located at the end of the pipe to receive the pig after it has gone through the whole pipeline. As the pig travels along the the pipeline, it produces a sound. If it fails to do so a TX Transmitter is then installed in the pig so that it can be tracked from above the ground with the help of receiver or geophone.
Precautionary measures to take when using pigs
There are numerous risks in the pipeline pigging process. Some of the risks include exposure to high-pressure hydrocarbon gas and possible loss of containment via leaking flanges and open valves. The following are some of the safety measures that should be observed during pigging operations:
Follow manual handling requirements
Pressure build-up over time—never assume the launcher is depressurized
Wear personal protective gear
Use a trolley to help with insertion and removal of a pig if possible
Reduce exposure to the open launcher
Do not open the barrel unless it is at atmospheric pressure
Learn more about pipeline pigging and pipeline supports from Rain for Rent.