How we monitor the safety of underground pipes
Gasunie is responsible for the safe and reliable transport of gas, which is why we inspect every pipe approximately once every 10 years. We do that with a ‘pig’. Project manager Derk Burema explains how pigging works.
‘Pig’ stands for Pipeline Inspection Gauge, an inspection device that is sent through the pipeline along with the gas flow. There are two types of pigs: one for cleaning and one for inspection, Burema explains. ‘For the inspection, we use an MFL (Magnetic Flux Leakage) tool. It is equipped with sensors and magnets that scan the pipe from the inside. This enables the pig to check for dents, scratches, and corrosion: things that affect the integrity of the pipe.’
Sounds like a train
How does this type of damage occur? Burema: ‘Dents and scratches are caused by activities like excavation work. Corrosion can develop due to the growth of bacteria or a defect in the coating. The pig shows us where these areas are.’
It works like this: the pig is carried along with the gas flow from the dispatch location to the receiving location. A temporary scraper trap is set up at both locations – a launcher at the start and a receiver at the end. This enables the pig to be safely inserted into and removed from the pipeline.
Burema is fascinated by the fact that you can hear the pig passing through the pipe: ‘It’s like a train. You can hear the gas flow and, because the pipeline consists of segments that are welded together, you can hear the pig travelling over the welds. It sounds just like a train on the rails.’
Read the full interview and watch the video about monitoring the safety of underground pipes on the Gasunie website.
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