Acoustic Emission leak detection and location for liquid-filled, buried pipelines was studied using various leak sources and laboratory reference standards.These standards provided significant data that have contributed to the development of test procedures for generating two-phase flow and a better understanding of the leak mechanism. Results are discussed for leak signal enhancement due to two-phase flow, leak orientation and the presence of backfill surrounding the pipe.
Field studies were performed on buried pipes to demonstrate that small leaks (less than 0.1 gallons/hour or 0.1 mL/second) can be detected under the right test conditions and that the location of these small leaks can be determined using a variety of location methods. Among the different location methods examined was a location technique referred to as “tuned” linear location. In addition, a modification to the conventional Signal Difference location technique is discussed.