Although the terms pig tracking and pig locating have distinct meanings, they are often used interchangeably. In many cases, pig tracking is used as a catch‑all term to describe both monitoring a pig’s movement and identifying the position of a stationary pig. For the purposes of this article, we will use pig tracking to refer to both activities.
Why Pig Tracking Matters
Pig tracking (sometimes referred to pig locating) is a key operational requirement during any pigging job. It involves monitoring the movement of a pig along the pipeline or confirming the location of a stationary pig. In many cases, tracking is simply used to verify that a pig has reached the expected location, such as the receiver. In other situations, it may be needed to help locate a pig that has stalled on its way through the line . Knowing exactly where the pig is at each stage is vital. Confirming arrival in the receiver removes uncertainty and avoids unnecessary delays, while identifying the location of a stalled pig becomes critical to prevent further disruption to the operation.
This urgency is even greater during subsea pigging campaigns, where vessel costs are high and delays can quickly affect project budgets. Stalled pigs in subsea environments can lead to extended vessel time and operational downtime, making rapid and reliable tracking essential.
Pig tracking systems typically consist of two key elements:
- A device attached to the pig such as an electromagnetic transmitter
- A device outside the pipeline – often a handheld receiver – used to detect the signal
Pig tracking as a concept is straightforward – detect a signal generated by a device mounted on the pig such as a transmitter – but industry expectations have changed significantly. Operators now expect a higher level of reliability, accuracy and real-time visibility and there is increasing focus on using technology to improve assurance and reduce the time spent searching for a pig’s location. As a result, modern tracking systems are designed not only to detect pig passage but to provide better data, improved flexibility and clearer insight throughout the operation.
Overview of Pig Tracking Methods
There are several types of pig tracking systems used across the industry. Each relies on a different method of detecting a signal from the pig, and each comes with its own set of benefits and limitations.
Acoustic Tracking
Acoustic pig tracking has been used for many years and was traditionally the go-to option for subsea pigging projects. An acoustic pinger is mounted on the pig, and the signal is detected using a diver-held or ROV-mounted hydrophone and receiver. Acoustic technology is effective for detecting a signal over long distances, but it is not designed for pinpoint accuracy. It is also limited to subsea, liquid-filled pipelines that are not buried, which makes it far less flexible for wider pipeline operations.
Radioactive Isotope (RAI) Tracking
RAI tracking involves attaching a small radioactive source to the pig and using an external gamma receiver to monitor its progress. RAI is highly accurate and removes any concern over battery life. However, it is heavily regulated, requires specialist handling and trained operators and can be difficult and expensive to ship. These logistical challenges often limit its practical use despite its technical effectiveness.
Electromagnetic (EM) Tracking
Electromagnetic pig tracking is the most versatile of the available options. It can be used onshore, offshore and subsea, with any pipeline medium, and even when the pipeline is buried or trenched. An EM transmitter inside the pig generates a signal that can be detected externally using a handheld receiver or an above-ground device. With IK Trax’s EMRx Receiver, the signal is typically represented by LED bar graphs which display received signals at any three frequencies between 10Hz and 30Hz. EM tracking can locate a pig to within centimetres, making it a highly accurate option for both routine passage confirmation and the rapid location of a stalled pig. Many EM receivers can also detect magnetic signatures, adding further flexibility when pigs are fitted with magnets.
Electromagnetic Pig Tracking and Real-World Considerations
Electromagnetic (EM) pig tracking has become the industry’s preferred solution for good reason. It is the most versatile tracking method available, suitable for onshore, offshore and subsea pipelines, regardless of whether the line carries gas or liquid. EM systems are straightforward to operate, highly accurate and supported by a wide range of transmitter and receiver models. The technology allows operators to locate a pig to within centimetres and provides the confidence that if required, the pig can be found quickly and efficiently. For most operators, EM tracking acts a practical form of insurance; if something unexpected happens, the tools are in place to respond.
Another advantage is the safety profile. EM transmitters typically use alkaline cells and many models are available with hazardous-area certification, making them suitable for a broad range of operating environments. Combined with modern configuration apps and clear, digital receiver displays, EM tracking offers a level of reliability and ease of use that other tracking methods cannot match. It also supports a wide range of operational scenarios, from simple passage confirmation to the swift locating of stalled pigs.
Although EM tracking is straightforward to deploy, there are still operational factors to consider to ensure optimal performance. These challenges usually relate to the pipeline itself and the environment in which the equipment is used. With buried pipelines, the distance between the transmitter and the receiver naturally increases, which can reduce the signal detected at the surface. It’s not just the depth that matters – the make-up of the ground (e.g local substrate and how well it transmits or attenuates the signal) can further affect detection performance. Pipeline wall thickness can have a similar effect. This thicker the wall, the more material the EM field must pass through. In all of these cases, you can adjust receiver sensitivity and/or transmitter output or frequency but there are trade-offs; higher gain can introduce more background noise and higher transmit power reduces battery life. Finding the correct balance between these settings is therefore essential.
Pig design is another important consideration. EM transmitters may experience reduced signal strength or decreased battery life when surrounded by certain materials. For example, a 315 stainless steel pig body generally provides good performance, whereas carbon steel can cause significant attenuation. Correct placement of the transmitter within the pig also contributes to reliable detection.
To address these factors, the recommended approach is to carry out representative testing ahead of the pigging operation whenever possible but especially when there are known factors which could affect the equipment performance. Testing confirms the capabilities of the selected equipment in real-world conditions and helps identify the most suitable configuration. IK Trax can support this process by working with clients to assess transmitter performance, review settings and ensure that the tracking setup is optimised before operations begin.
Electromagnetic System Capabilities
Modern EM pig tracking systems offer a range of capabilities that make them flexible and easy to use across different pipeline environments. Much of this flexibility comes from the use of configuration and visualisation Apps, which allow operators to adjust settings in the field and understand the signal behaviour in real time.
EM transmitters can be programmed using an app – such as the IK Trax EMTx Config App – to suit the requirements of this operation. Parameters including transmit frequency, pulse rate, power level and switch-on delay can all be adjusted quickly on site without returning the unit to the manufacturer. This provides operators with a high degree of flexibility and makes it easy to tailor the transmitter to achieve the right balance between detection range and battery life for the specific project.
On the receiver side, multi-frequency detection is now a common feature. This allows a receiver to detect more than one transmitter at the same time, provided they are configured at different frequencies. This is especially useful when dealing with a pig train or when multiple pigs are being tracked in close succession.
Apps such as the IK Trax EMRx App provide an additional layer of insight into how the signal is behaving. Operators can view live signal strength across up to six colour-coded electromagnetic signals, helping them understand the quality of the received signal at a glance. The app also shows the frequency and pulse rate of one or more signals simultaneously and provides a spectrum view, which is helpful when troubleshooting or identifying noise sources outside the 10-30Hz range of interest.
In addition to visualization, the Receiver App allows operators to scroll through logged data, add markers to points of interest and export this information for reporting or review. It also makes receiver configuration more efficient. Settings such as tracked frequency or gain can be changed directly via the app, rather than using the receiver’s physical push-button interface, which is more time-consuming.
The combined effect of configurable transmitters, multi-frequency receivers and app-based visualisation is a system that is easy to optimise, provides clear insight during the operation and gives operators greater confidence throughout the pigging campaign.
Remote Pig Tracking with Above-Ground Markers
For certain operations, particularly those involving long distance, remote block valve stations or unmanned facilities, it is not always practical for an operator to track the pig with a handheld receiver. In these scenarios, an above-ground marker (AGM) provides an effective alternative. AGMs are positioned at key points above the pipeline and are designed to detect the pig as it passes, without requiring continuous operator presence.
The Patriot AGM is an example of this type of system. It combines magnetic, electromagnetic and acoustic detection, allowing it to identify a wide range of pigs fitted with different tracking devices. This multi-technology approach improves confidence during pigging campaigns, particularly when the pig may be travelling through challenging environments.
One of the main advantages of an autonomous system is the ability to communicate pig location information remotely. The Patriot AGM supports Bluetooth, cellular and satellite communication, making it suitable for pipelines that span remote terrain or areas where physical access is limited. Operators can view live pig passages, receive notifications and review historical events through the Pat Track software, which displays data such as maps, signal graphs and run history. This provides a clear and accessible view of the pig’s progress throughout the operation.
AGMs are particularly beneficial during multi-day pigging campaigns or when working on cross-country pipelines where sending personnel to monitor each location would be inefficient or impractical. They reduce the need for continuous field presence, improve situational awareness and provide reliable confirmation of pig passage at predefined points.
Choosing the Right Tracking Method
Choosing the most suitable tracking method depends on a few key factors: pipeline medium, pig type, access to the line and the level of visibility required throughout the operation. In most cases, electromagnetic tracking provides the most balanced and reliable option, combining accuracy, versatility and ease of use across almost any pipeline environment.
For longer-distance operations for pipelines located in remote or unmanned areas, remote systems such as the Patriot AGM offer an additional layer of visibility by confirming pig passage at fixed points without the need for continuous operator presence. When used alongside EM tracking, they provide a clear and consistent view of the pig’s progress throughout the run.
Other tracking technologies such as acoustic or radioactive isotope systems have their places in specific scenarios, but they are far less versatile and typically for more niche applications.
Reviewing the operational environment, pig design and monitoring requirements early in the planning stage will help ensure the most suitable tracking method is chosen. IK Trax can support this process and provide guidance on selecting the right solution for each project.
