All over the globe, underground pipelines are the preferred means of transporting liquid or gas-based products from their point of origin to the point of distribution. Obviously, such pipelines often pass through long stretches of untamed land, and monitoring and surveillance them can be quite a challenge.
Nevertheless, effective and continuous pipeline monitoring and surveillance is very essential. To a certain extent, the fact that they are underground protects pipelines from elemental damage and sabotage. However, this also has its disadvantages – the pipelines are often subject to the stresses brought on by natural shifts in the surrounding earth, sometimes causing them to rupture. In fact, any kind of geotechnical engineering event on a remote terrain can cause ruptures and disruptions in the pipeline.
Thankfully, technology has produced some very effective pipeline monitoring and surveillance options. Basically, there exist two kinds systems – one type monitors the strain placed on the actual pipeline, the other monitors the surrounding geologic medium externally. In pipeline strain monitoring, many methods are currently being employed. Some monitor the pipeline along certain points only, while others monitor it continuously. Again, such pipeline monitoring and surveillance systems may be operated and maintained either manually or automatically.
Pipeline strain monitoring measures primary deformation in cases where the strain on the pipeline is due to internal or thermodynamic stress. Geotechnical monitoring, on the other hand, measures displacements in the rock or soil that encases the pipeline. Again, these pipeline monitoring and surveillance systems can be either manual or fully automated.
TDR (Time Domain Reflectometry) is among the more advanced methods of pipeline monitoring. In TDR, coaxial cables are inserted and fixed into a drill-hole. The system then transmits a pulse of energy as a waveform and measures reflections of this transmission. This can help calculate the distance to a disturbance within the pipeline.
Optical Time Domain Reflectometry, or OTDR, is a more advanced version of this system. OTDR is very useful in monitoring ground motion along pipeline routes, and can actually identify motion in the pipeline’s geotechnical environment, thereby helping to avert failure. The network of cables also acts as an anti-intrusion measure. An OTDR reader allows operators to monitor the pipeline and to alert them to any breaks or inconsistencies in it. Operators can then locate the disruption to within a few feet, alert a maintenance crew and even shut the pipeline down before an actual rupture occurs. OTDR systems are effective over distances of up to 25 kilometres.
The damage would have been incalculable if the pipeline monitoring and surveillance equipment had not alerted the maintenance crew to a change in pressure. This allowed the crew to shut down the pipeline immediately and re-route the gas to other lines. In fact, this event did not even cause a disruption in customer services.