Acoustic Emission Testing (AE)
Acoustic Emission (AE) is a passive NDT method that detects transient elastic stress waves emitted by active discontinuities such as growing cracks, plastic deformation, or leaks, using sensors mounted on the component during loading.
Definition
Acoustic Emission Testing (AE) is a passive NDT technique in which sensors are bonded to a structure and listen for high-frequency stress waves released when defects grow, materials deform plastically, or fluids leak. Unlike most NDT methods, AE detects only active damage — flaws must be evolving for the sensors to hear them.
Technical Context
Multiple sensors permit source location by triangulating wave arrival times. AE is typically applied during a controlled pressure or load test of an entire vessel or structure, giving a global view of integrity.
When It Is Used
- Periodic in-service testing of pressure vessels and storage tanks
- Composite pressure vessel and pipeline qualification
- Real-time monitoring of bridges, cranes, and rotating equipment
Related Standards
ASME Section V Article 11–13, ASTM E1067, ASTM E1419, ISO 12716.
Synonyms
Also called AE or AET. Related to leak testing when used for leak detection.
How it works
Materials under stress release transient elastic waves as damage grows — crack extension, fibre breakage, plastic deformation, leakage-driven turbulence. Sensors on the surface pick up those bursts, and arrival-time differences between sensors locate the source.
What it finds
Active, growing damage across a whole structure at once, while it is loaded. That global-and-live quality is its distinguishing feature: it listens to the entire vessel rather than examining one square metre at a time.
What it will not find
Damage that is not growing. A large, stable, benign flaw is silent, and acoustic emission will not find it. The method identifies where something is happening, and follow-up examination by another method is then required to characterise what was heard.
How it is actually done
Sensor coupling and layout determine location accuracy; background noise from flow, rain, machinery and fretting must be characterised and rejected or the data is uninterpretable. Loading must be controlled, since emission is a response to stress change rather than to stress.
Governing codes and standards
ASME Section V Article 11 covers acoustic emission examination of fibre-reinforced vessels and Article 12 covers metallic vessels; ASTM E569 and ASTM E1139 address the practice more broadly.
Where it goes wrong
Interpreting hit counts as damage severity without source location and waveform discrimination. Noise generates hits abundantly; a clean, well-located cluster of high-energy events means something entirely different from a scatter of low-amplitude ones.
Where Acoustic Emission Testing fits in an inspection programme
A term is only useful when it connects to a decision. Acoustic Emission Testing appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.
Related terms
- Leak Testing (LT) — Leak Testing (LT) verifies the pressure boundary integrity of vessels, piping, and tanks by detecting and quantifying fluid leakage using methods such as pressure decay, bubble emission, mass spectrometer helium tracing, or ultrasonic leak detection.
- Thermography / Infrared Testing (IRT) — Thermography uses an infrared camera to map surface temperature patterns; subsurface defects, moisture, missing insulation, electrical hot spots, and CUI alter heat flow and create detectable thermal signatures.
- Attenuation (Ultrasonic) — Attenuation is the loss of ultrasonic energy as it propagates through a material due to absorption, scattering, and beam spread, expressed in decibels per unit path length and material-dependent.
Further reading
acoustic emission testing principles industrial applications
More method terms
Ultrasonic Testing · Radiographic Testing · Magnetic Particle Testing · Penetrant Testing · Eddy Current Testing · Visual Testing · Microwave Testing · Phased Array Ultrasonic Testing · Time-of-Flight Diffraction · Total Focusing Method
Where this comes up in practice
Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.
Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.