Acoustic Emission (AE) is high frequency sound generated by cracks and similar flaws in materials when stressed. Surface mounted, high frequency acoustic sensors detect AE signals generated by the test. The test procedure and AE data evaluation are designed to detect damage and provide a measure of a vessel’s response to the applied load. Structurally significant defects produce relatively intense acoustic emission activity when subjected to additional stress from filling or pressure.
AE inspections are used to highlight structural weaknesses and cracks in pressure vessels, piping and tanks. Testing generally requires loading of a vessel or piping by filling with liquids or increasing the pressure. For most in-service equipment, the pressure or level is increased from 5% to 10% over the operating level while the AE is monitored and recorded. In some special applications, such as on-line monitoring and storage tank floor assessments, the AE signals are generated by the environmental conditions and no additional loading is required.
