Understanding Acoustic Emission Testing- Reading 1 Part B-A

■ Object and target
The method of testing requires the use of sensing devices placed on existing
pipelines fittings as well as conditioning, acquisition and signal analysis
instrumentation in order to detect and locate the leaks.
The method described applies to the control of underground supply and
distribution water pipelines of steel, ductile iron, cast iron, asbestos cement,
polyethylene and PVC. Cast iron, steel or asbestos cement pipe sections of a
maximum length of 250 meters can be controlled by using non-intrusive
sensing devices (accelerometers) and up to 600 meters by intrusive sensing
devices (hydrophones).
The maximum controllable length of plastic pipes such as PVC or (high and
low density) polyethylene is 50 metres only, when accelerometers are used,
and 120 meters when hydrophones are used.
Charlie Chong/ Fion Zhang
http://www.ndt.net/article/wcndt00/papers/idn183/idn183.htm