What Is Pig Tracking?

In order to understand what pig tracking is, it’s important to know what a ‘pig’ is first. The word ‘pig’ isn’t referring to the farm animal that squeaks and wallows about in the mud. The ‘pig’ we’re talking about is a tool for pipeline inspections. Pigs travel through pipelines to clean or evaluate the inside of a pipe. This helps keep our pipelines running safely. The United States has the largest network of oil and gas pipelines in the world, amounting more than 2.4 million miles. As required by the US Department of Transportation (DOT) and the Pipeline and Hazardous Materials Safety Administration (PHMSA), this network of pipelines must be inspected and checked for damage, corrosion or leaks to maintain safe, efficient and operational. Operators do this by running ‘pigs’ through the pipeline.

‘Pig tracking’ is the monitoring of these pigs as they move through the pipeline. Because pipelines are typically buried and don’t usually have built in monitoring systems, an above ground team or technology is usually needed to keep track of where the pig is inside the pipeline. Pigs are not usually self-propelled, usually they are driven pressure behind them, which means their location must monitored throughout the run to determine the speed and effectively control the pig. A lost pig could spell disaster for an operator if it becomes stuck somewhere in the line, or moves too fast, potentially damaging valves or other parts of the pipeline. The tracking team is there to ensure the pig isn’t going too fast, or if it does get stuck – knowing where it is and how to get to it.

An X-ray of a stuck pig inside of a pipeline




How does it work?

Pig tracking is generally done by a team of technicians above ground who will intercept the pig at predetermined Above Ground Markers (AGM) and report its passage. Usually a pig cannot be tracked continuously from start to finish because of obstacles on the pipeline right of way (ROW), property issues, buildings or roads, so it’s important for the team to have an organized plan of AGMs where they will wait for the pig to pass.

Technicians monitor the passage of the tool with special equipment. Before most runs, a signal emitting transmitter is placed inside the pig, which can be picked up above ground as it passes. On ILI tools, special marker boxes pick up a magnetic signal from the pig as it passes and note the passage time, location and other information depending on the box. As another measure of ensuring passage, technicians will listen to the pipeline with a geophone (basically a microphone that goes into the earth) and physically listen to the acoustic passage of the pig.

Types of Pigs

Cleaning Pigs: The least expensive yet most common type of pig that is run is a cleaning pig. This may be a foam or rubber pig that is meant to clean the inside of the pipeline.

Caliper tools: Caliper tools are used in conjunction with cleaning tools, to prepare for an ILI tool run. Caliper tools will generally alert the operator to any inward deformation in the pipe wall – such as a large dent or diameter change; generally caliper tools do not report the location of this dent.

ILI tools: ILI stands for inline inspection. ILI tools make up the meat of the inspection process. ILI tools inspect the walls of the pipeline for corrosion, dents, thickness or any type of damage using a variety of data collection processes including magnetic flux leakage (MFL), ultrasonic (UT) and inertial mapping (IM). As time goes on, ILI technology improves and the quality as well as the amount of data improves with it. These ILI tools can cost in excess of $1-2M USD, which is why it is crucial to have safe and efficient controls and understanding of the pipeline on every single run. An out of control pig can end up costing a lot of money!


ILI Tool before a run in Crane, TX


What do we offer?

Diamond Edge has been tracking since it’s formation in 1994, providing tracking services around the United States to a variety pipeline operators across varieties of terrain. Diamond Edge’s technicians are known for their quality and strive for perfection on the pipeline on every run, no matter the job, no matter the location. If you’d like to know more about our tracking process or are interested in other integrity services that we provide, check out our services or fill out the form below.

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