There are some hypotheses for why the process is called ‘pipeline pigging’, though none have been confirmed. One theory is that ‘pig’ stands for Pipeline Intervention Gadget. Another states that in the past, a leather-bound tool was sent through the pipeline, making the sound of a squealing pig as it passed through.
Another theory is that after opening a pig trap, the tool lies in a pile of mud, in the same way a pig does.
Regardless of the preferred hypotheses, ‘pipeline pigging’ or ‘pigs’ refers to several tools, usually propelled through the line, to perform a specific action inside the pipeline.
While build-up of foreign materials in a pipeline can cause a reduction in flow, it can also cause a rise in energy consumption due to high pressures, or even plug the pipeline. In the worst case it can cause cracks or flaws in the line with disastrous consequences, such as spills and the many associated dangers.
We will find or build the best pig for the job.
From the construction phase until abandonment, all pipelines require pigging at certain moments. The pigging experts at Intero Integrity Pipeline Services are specialists in selecting the best pig for the job. We choose only the best quality pigs from our suppliers, however for more challenging, critical jobs, we build our own pigs to the required specifications in order to guarantee the best possible service.
For pipelines without launchers and receivers, we also provide temporary installations, which will ensure a safe pipeline pigging process. The following pigs will pass through a pipeline at some stage during its life span.
Before pipes are welded together they are gauged with pigs for dimensional control. Bends fabricated from pipes are also gauged.
During construction, several bidi (bi-directional) pigs will pass through the pipeline to empty horizontal drillings and to transport gauge plates to ensure the internal minimum dimension. When construction is complete, the line will be hydro tested. Filling for testing is also performed using bidi pigs.
During construction, the pipeline may need cleaning from mud, water, rust and welding slag etc. Depending on the anticipated contamination and eventual pipe wall coating, we select the most suitable foam pig for the most effective result. This may be partly coated, fully coated, equipped with hard, scraping steel brushes or studs or equipped with soft brushes. When hydro testing is completed and dewatered, foam pigs will also be used to dry the pipeline. Depending on the required dew point level and drying phase, we choose from several available sizes and densities to establish the most efficient foam pig for the job.
After completion of construction and prior to commissioning, a caliper pig (often referred to as an intelligent pig), may be used to identify obstructions due to damage of any pipe section. The intelligent part of the pig is its ability to register all internal dimensions in relation to the measured distance from the entrance.
Intelligent pigs (ILI)
As well as caliper pigs, we often use what are called intelligent pigs, which can register not only anomalies in dimensions, but also the pipeline’s exact location in three dimensions. In addition, it can measure the actual wall thicknesses for future comparison and determine wall thickness loss due to wear and corrosion.
Spheres, bidi pigs, brush pigs, magnet pigs, foam pigs, turbo pigs
During the production phase, debris from the product(s) may form obstructions that need to be removed. The debris can be in the form of wax, which if acted upon quickly, can be easily removed using spheres or bidi pigs equipped with or without spring loaded brushes. If wax deposit is not treated quickly, or when hard scale is formed, this can be removed using special pigs, such as studded bidi pigs, full stud pigs, or very aggressive turbo pigs. Our studded pigs were originally developed for decoking furnaces in refineries. Our experiences and calculations in this field has given us a solid foundation for solving pipeline cleaning problems.
It is a good idea to implement a cleaning process for the pipeline before the run of an intelligent pig, to ensure accurate gathering of data.
This pigging method involves the use of a gelling agent in combination with cleaning agents. Often gel pigging is a solid solution for pipelines that cannot be cleaned with normal pigs. The gelled mass can be propelled through different shapes and dimensions, with the gel able to continuously adapt to the pipeline’s shape.