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| Pigging in the context of pipelines refers to the practice of using pipeline inspection gauges or 'pigs' to perform various maintenance operations on a pipeline. This is done without stopping the flow of the product in the pipeline.
These operations include but are not limited to cleaning and inspecting of the pipeline.
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| Pigging has been used for many years to clean larger diameter pipelines in the oil industry. Today, however, the use of smaller diameter pigging systems is now increasing in many continuous and batch process plants as plant operators search for increased efficiencies and reduced costs.
Pigging can be used for almost any section of the transfer process between, for example, blending, storage or filling systems. Pigging systems are already installed in industries handling products as diverse as lubricating oils, paints, chemicals, toiletries, cosmetics and foodstuffs..
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Pigs are used in lube oil or painting blending:
they are used to clean the pipes to avoid cross-contamination, and to empty the pipes into the product tanks (or sometimes to send a component back to its tank). Usually pigging is done at the beginning and at the end of each batch, but sometimes it is done in the midst of a batch, e.g. when producing a premix that will be used as an intermediate component.
Pigs are also used in oil and gas pipelines: they are used to clean the pipes but there are also "smart pigs" used to measure things like pipe thickness and corrosion along the pipeline. They usually do not interrupt production, though some product can be lost when the pig is extracted. They can also be used to separate different products in a multiproduct pipeline.
Our Engineers at ZERBINA ENGINEERING will consider a number of criteria when selecting the proper pig for a pipeline. First, it's important to define what task the pig will be performing. Also, size and operating conditions are important to regard. Finally, pipeline layout is integral to consider when choosing a pig.
Because every pipeline is different, there is not a set schedule for pigging a line, although the quantity of debris collected in a pipeline and the amount of wear and tear on it can increase the frequency of pigging. Today, pipeline pigging is used during all phases of the life of a pipeline. You can be rest assured that our Engineers at ZERBINA ENGINEERING will provide you with the best solution for your specific needs. |
| Types of Pipeline Pigs
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Dual Module Pig, Although first used simply to clear the line, the purpose of pipeline pigging has evolved with the development of technologies. Utility pigs are inserted into the pipeline to remove unwanted materials, such as wax, from the line. Inline inspection pigs can also be used to examine the pipeline from the inside, and specialty pigs are used to plug the line or isolate certain areas of the line. Lastly, gel pigs are a liquid chemical pigging system. |
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Utility Pig, Utility pigs are used to clean the pipeline of debris or seal the line. Debris can accumulate during construction, and the pipeline is pigged before production commences. Also, debris can build up on the pipeline, and the utility pig is used to scrape it away. Additionally, sealing pigs are used to remove liquids from the pipeline, as well as serve as an interface between two different products within a pipeline. Types of utility pigs include mandrel pigs, foam pigs, solid cast pigs and spherical pigs. |
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Inspection Pig, also referred to as in-line inspection pigs or smart pigs, gather information about the pipeline from within. . The type of information gathered by smart pigs includes the pipeline diameter, curvature, bends, temperature and pressure, as well as corrosion or metal loss. Inspection pigs utilize two methods to gather information about the interior condition of the pipeline: magnetic flux leakage (MFL) and ultrasonics (UT). MFL inspects the pipeline by sending magnetic flux into the walls of the pipe, detecting leakage, corrosion, or flaws in the pipeline. Ultrasonic inspection directly measures the thickness of the pipe wall by using ultrasonic sounds to measure the amount of time it takes an echo to return to the sensor. |
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Speciality Pig, such as plugs, are used to isolate a section of the pipeline for maintenance work to be performed. The pig plug keeps the pipeline pressure in the line by stopping up the pipeline on either side of where the remedial work is being done. |
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A combination of gelled liquids, gel pigs can be used in conjunction with conventional pigs or by themselves. Pumped through the pipeline, there are a number of uses for gel pigs, including product separation, debris removal, hydro-testing, dewatering and condensate removal, as well as removing a stuck pig. |
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