Gas injection leak detection will be used once the in-line leak detection has been completed. There is a possibility that the smaller branch lines would need to be gassed as the in-line leak detection work with dynamic flow and pressure and can not take bends of a smaller diameter. However, the bullet will still pick up the sound while passing the branch line, tee-piece or saddle etc…

The gas leak detection will be effective with the smaller branch lines and smaller diameter pipes. It will be needed to locate leaks of a smaller diameter pipe and of a shorter distance, therefore minimising the gas usage and labour.



Another method used on a smaller section that is still effective is correlation. Correlation can be used in conjunction with the gas leak detection.
Correlation is a way of finding and pinpointing leaks in water pipes. A leak in a pipe under pressure creates noise that travels through the pipe walls, the surrounding ground and along the contents of the pipe. If two highly sensitive microphones are attached to two different locations on a pipe with a leak, the sound from the leak will take longer to travel to the microphone furthest from the leak.

This is referred to as the ‘time delay’ or trianglet . Uitilising this and other information(pipe diameter, material and length of the section under test), the exact leak position can be calculated by the correlator SeCorrPhon AC 06.