A reference standard for the development of acoustic emission pipeline leak detection techniques

Abstract A reference standard was constructed for setting up and evaluating AE equipment to be used in pipeline leak detection. The reference standard comprises a short length of 2-inch diameter piping with facilities for introducing several kinds of controlled leaks. The reference standard proved very valuable not only for checking out equipment, but also for characterizing source mechanisms as part of an integrated approach to quantitative AE leak detection/location technology. The effects of pressure and air injection were measured for thread leaks on the order of 0.1 gal h −1 , a leakage rate that is important in the context of environmental protection regulations. Taking this knowledge to the field, a thread leak of only 0.014 gal h −1 was successfully detected and located by injecting nitrogen into the line at 25 psi. This leak was located with 1 foot accuracy, using two different location techniques and 25-foot sensor spacing. It is envisioned that in the future, AE inspectors in the field will make systematic use of several two-phase flow processes and soil enhancement mechanisms that are being characterized by means of this new reference standard.