Acoustic Emission (AE) is defined as "the transient elastic wave generated by the rapid release of strain energy within a material".
In the case of pressure vessel testing, the test item is stimulated by pressurising the vessel contents or by hydrotest. Under this stimulation, any 'active' defects which are growing will emit acoustic energy and are located and graded for examination by conventional NDT.
In the case of corrosion in Above Ground Storage Tanks, the stimulation is applied by ensuring that the head of liquid is above 50% level. This causes fracture and spalling of the oxide layer on the tank floor causing acoustic energy to be emitted, the corroded areas to be located and mapped and the data graded to determine the severity of the corrosion.
Both of the above applications can be carried out without opening the vessel and removing the contents. The acoustic energy is picked up by external sensors gives a "global" test of the plant item.
MTI offers an AE testing service mainly for:
- Integrity testing of pressure vessels
- Monitoring floor corrosion in large above ground storage tanks
More information on this technique is available in our Acoustic Emission AE website at http://www.mti.eu.com