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.