The Nord Stream natural gas pipeline has its integrity checked regularly by pipeline inspection gauges (PIGs). PIGs are like intelligent drain cleaners, being inserted into the pipes before proceeding to automatically detect the smallest changes in the pipeline’s structure – due to corrosion, for example – and recording that for later analysis at a control station.
PIGs are also able to register any possible movements that the pipeline may have made since installation, such as those generated by small impacts.
Each PIG is inserted into the Nord Stream pipeline via a launcher based in Russia, before being fired through the system and extracted in Germany. If any issues are detected, a maintenance and repair team is dispatched to investigate.