Reliable pig tracking and signalling in subsea environments require equipment that can withstand extreme conditions and perform consistently over time. This article explores some of the key challenges faced offshore and the technologies available to overcome them.
High Pressure Pipelines
Designing pig tracking and locating equipment that can withstand the high pressures found in offshore pipelines is a major challenge. Pressure ratings can reach up to 1000 bar, especially in deepwater fields and high-pressure transmission pipelines, and any equipment deployed must be able to survive this environment whilst still functioning.
Transmitters must be robustly engineered to endure these conditions – high-quality, high-pressure materials such titanium protect internal electronics without compromising signal detection. Titanium not only provides excellent corrosion resistance but also ensures structural integrity at high pressures.
At extreme pressures, the potential for damage significantly increases. Housings and seals are subjected to high pressure and a leak can result in water ingress, failure and loss of signal. The consequences of such failure include uncertainty about pig location and costly retrieval operations or re-runs. Ensuring reliability at these pressures requires rigorous testing, high-spec materials and attention to every detail of the design and assembly process.
Loading Pigs in Advance and Battery Life Limitations
Electromagnetic transmitters are typically activated manually before being installed inside a pig, at which point the battery begins to deplete. In many cases, pigs are loaded inside the launcher well in advance – sometimes weeks, months or even years before launch. This prolonged period can significantly reduce the transmitter’s battery life, potentially leading to power loss before the pig is launched or before its arrival is confirmed.
To address this, delayed-start endcaps have been developed. Pressure-activated endcaps keep the transmitter powered off until it reaches a specified ambient subsea pressure, making them ideal for deepwater operations. Alternatively, wet-start endcaps activate only when the pig comes into contact with liquid, providing a solution where pigs are loaded dry but not flooded until shortly before launch.
Additionally, the IK Trax EMTx Config App includes a delayed switch-on time feature. This allows operators to schedule activation in advance, but it requires accurate planning and confirmed operational dates. Once the pig is deployed subsea, any preset timing cannot be adjusted.
For certain long-term deployments, even delayed-start options may not provide sufficient battery life. In these cases, where a magnetic source is present on the pig, a magnetic surveying system offers an effective alternative. These systems detect variations in the magnetic field, allowing the pig to be detected if an electromagnetic source is not present.
Interference from ROV Operations
Subsea pig tracking and signalling operations often rely on Remotely Operated Vehicles (ROVs) to install and monitor devices. However, ROV involvement introduces a unique challenge: the risk of false readings or signal interference. This interference can arise from either electromagnetic emissions or physical movement and instability caused by the ROV itself.
To minimise these risks, the receiver should ideally be placed directly on the pipeline to ensure a stable and consistent reading. Where feasible, diver operation can offer more precise control during deployment.
For pig signallers installed by ROV, false triggers can occur due to motion during deployment. To prevent this, a stabilization delay can be programmed into the device. This delay keeps the unit inactive during installation, only beginning to “listen” once the signaller is securely mounted and stable – eliminating the risk of false events caused by movement during deployment.
Frequent Pigging Demands Permanent, Real-Time Signal Solutions
For subsea pipelines where pigging operations are performed frequently, relying on an ROV or diver to confirm pig passage for every run is often impractical. This creates the need for a more permanent, reliable solution that continuously detects pig passage and transmits signals back to the surface control room in real time.
Temporary pig signallers typically fall short in such scenarios due to limited battery life and the unavailability of ROVs or divers for monitoring. In contrast, permanent magnetic pig signallers, like the IK Trax 4004S, offer a robust and long-lasting solution. The 4004S is designed for continuous subsea installation without requiring intrusive modifications to the pipeline. It provides consistent, real-time pig detection by sensing the change in magnetic field caused by the pig’s passage.
With its durable construction, designed for long-term installation and ability to transmit pig passage data, the 4004S allows operators to integrate pig passage signals seamlessly into their control and monitoring systems. This integration supports proactive maintenance planning, minimizes downtime and enhances operational efficiency in pipelines where frequent pigging is essential.
Conclusion
As offshore pigging operations become more complex and frequent, dependable tracking and signaller solutions have become an important part of efficient pipeline management. From pressure-rated equipment to real-time signalling systems, having the right tools in place helps ensure smoother operations, fewer delays and greater confidence in pigging performance.
To find out how our systems can support your next pigging campaign, get in touch with our team to explore our full range of tracking and signalling technologies.
