Acoustic Emission

Acoustic emission is a monitoring technique where elastic waves are generated by the release of energy built up in stressed materials revealing the formation of a defect. The elastic waves must be continuously recorded for interpretation. This method is complicated by the normal emission of waves produced by thermal or mechanical stresses exhibited on the system. The interpreter must therefore be experienced to dismiss such “background noise” and diagnose abnormal events. This technique can be used to detect the formation of defects such as crack growth, material corrosion, surface rubbing, and leaking fluids. A summary of the corrosion monitoring methods is provided in Table 61.