For legal, economic or safety reasons, gas transmission companies must look for leaks.

The most widely used leak detection method is a planned survey of the network. It can be a simple visual inspection of the pipe’s environment. It can also be done with hand held gas detectors or aboard vehicles. New methods are being developed to improve productivity. The most promising are those based on the absorption of methane in the infrared which can be airborne. The first one is based on lidars that scan the pipe and measure the backscattered light. New lasers will permit great sensitivity for gas detection. The other is a camera measuring the absorption of the light emitted by the ground.

On-line detection exists, but it is seldom used nowadays. The rare onshore applications use the data collected by SCADA systems that are processed by more or less sophisticated statistical methods. For off-shore applications, many systems are currently used: acoustic gates, echography or hydrophones. Promising new developments by many companies are under way. The first that has shown good results is based on the vibratory waves emitted by a leak. Acoustic waves can also be used.

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