Third party incidents such as anchor dropping or trawl boards can potentially threaten the integrity of the pipeline subsea. Digging with an excavator can potentially threaten the integrity of the pipeline onshore. To avoid this, it is important to be able to detect these incidents early. The leak detection project has been established with the aim of detecting third party incidents and leaks with better accuracy than today. We have been developing and tested several different sensors in this project. In the the Joint European project in Gas European Research Group(GERG) – we tested different intrusive hydrophones for onshore shock detection. We did impact testing on gas pipelines in Belgium and in France. The results show that impacts on the pipeline can be detected with this type of technology.