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02 Detection without envelope

We continue our Electromagnetic Pig Tracking for Newbies series with a post by our Regional BD Manager for Asia Pacific, Jeremy Andrew Lopez which explores the impact pipeline specification has on EM pig tracking.

One of the first things our sales team ask a customer when we receive an enquiry is “what is your pipeline specification?” This isn’t just the pipeline diameter – there are many other factors that need to be taken into consideration when selecting a suitable EM pig tracking system.

As a rule, EM transmitters operate effectively in every type of pipeline either topside, buried, gas or liquid and in pipeline bundles where acoustic is either less effective or ineffective.

As previously mentioned pipeline diameter is an important factor and will affect the suitable EM Transmitter selection. As an example, the OEL 3015 transmitter is an electromagnpigetic transmitter that can be used for pig tracking and locating in pipeline diameters above 12”. Larger transmitters are preferred in larger diameter lines to enhance detection capability. The bigger the pipe size, the bigger the transmitter should be to achieve optimum signal.

Wall thickness can have an effect on an EM signal and very heavy walled pipelines or launchers and receivers can pose some challenges, as can pipe-in-pipe and buried pipelines. Whether an EM signal can be comfortably detected through a certain wall thickness depends on several factors including the type of transmitter used, the distance between the EM receiver and the transmitter, pig design, pig speed, pipeline diameter, pipeline material and background EM noise level. It is always recommended to carry out testing prior to operations, replicating the project conditions as closely as possible.

Temperature and pressure play a part in EM transmitter selection. Each transmitter will have a maximum operating pressure with high pressure options often available. With subsea projects now being carried out in deeper waters, being able to supply a high-pressure option is essential. Transmitters will also have an operating temperature range usually dictated by whether the unit is powered by alkaline or lithium cells with lithium cells able to withstand higher temperatures.

For a pig tracking manufacturer to recommend the most suitable EM pig tracking system, they need as many pipeline details as possible - information (and testing) is key.

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