Airborne Leak Detector Certified In Germany For Urban Gas Grids

The first German airborne technology for detecting very small natural gas pipeline leakages in built-up or rural areas was recently tested and certified by the DVGW, the German Technical and Scientific Association for Gas and Water.

Germany is among the leaders when it comes to gas supply safety in Europe. All German gas companies belong to an association known as the DVGW, a technical organization which develops and publishes engineering standards laying down rules and procedures for work in the gas and water industries, including gas transmission.

German legislation governing the surveillance of natural gas transmission pipelines requires routine leak testing, and the relevant DVGW regulations (e.g. G465; G466) ensure that high pipeline safety levels are maintained.

In recent years, active and passive remote gas detection methods have become an increasingly important pipeline inspection tool. These methods – which utilize the fact that methane absorbs certain infrared wavelengths – promise to significantly accelerate the survey procedure.

The first European gas grids were established about a century ago and grew only by degrees. For this and other reasons (e.g. landscape) the German pipeline topology is quite complex, especially in urban areas. Visual airborne pipeline monitoring is best conducted by helicopter, making this the aircraft of choice for deploying remote monitoring systems.

The European natural gas supplier E.ON Ruhrgas initiated a project with the objective of combining visual inspection by helicopter with the detection of pipeline leaks using an airborne remote methane detector.

The gas supplier teamed up with the laser company Adlares and the German Aerospace Centre (Deutsches Zentrum für Luft- und Raumfahrt, DLR) to develop a remote natural gas detector based on infrared laser technology and which enables the pipeline operator to comply with his statutory leak testing obligations by monitoring gas pipelines from helicopters. The detector was intended primarily for use in built-up areas and for occasional leak testing in rural areas as well.

From the outset the system has been developed to meet the requirements of European gas regulators as well as the very strict German gas regulations so as to ensure the same degree of safety as is achieved by walked surveys. The fruit of this project is an innovative methane detector known as CHARM, which stands for CH4 Airborne Remote Monitoring. The detector is mounted on a BO 105 helicopter and used to check pipelines for gas leaks. A customized box contains the entire laser system, the optics and the detection system plus a powerful PC network capable of handling the demanding computational requirements.

Figure 2: A large box contains the laser system, the optics and the detection system as well as a computer network.

Figure 3: Methane detection is automatically activated on the pipeline and three cameras also take georeferenced photos of the pipeline corridor.

CHARM is based on the Differential Absorption LIDAR (DIAL) principle, an established active remote sensing method for detecting different gases in the atmosphere.