Acoustic Emission (AE) testing is a non-destructive testing method used to assess the structural integrity of materials by detecting high-frequency sound waves produced when a material is stressed. These waves originate from localised areas within the material where changes such as cracking, corrosion, or deformation are occurring.
When a material is exposed to external forces such as pressure, temperature, or load, it releases stress waves that travel to the surface and are detected by highly sensitive sensors. AE testing is especially valuable for evaluating pressure equipment, as it enables the early identification of potential failures before they become critical. This technique helps maintain safety, prevent damage, and extend the service life of essential infrastructure.
How Acoustic Emission Testing Works
Acoustic Emission (AE) testing involves attaching small, sensitive sensors to the surface of the structure being evaluated. These sensors detect stress waves generated within the material when it is exposed to external forces such as pressure, temperature, or mechanical load.
The stress waves are transformed into electrical signals and sent to a data acquisition system for further analysis. As defects such as cracks or corrosion progress, they release more energy, resulting in an increased rate and intensity of acoustic emissions. By tracking these changes, AE testing provides valuable insight into the condition and integrity of the structure.
AE can be compared to tiny seismic events occurring inside the material and it offers a way to monitor large or complex equipment in real time without interrupting its operation. Unlike destructive testing, this method enables full-system monitoring during normal use. By using multiple sensors, the precise location of the acoustic emission and the corresponding defect can be accurately identified.
There are two primary approaches to AE testing: transient and continuous.
- The transient method: The method records short bursts of acoustic activity that exceed a defined threshold and analyzes characteristics such as peak amplitude, signal energy, and burst duration. This is particularly useful for identifying structural flaws like cracks.
- The continuous method:, This method records all acoustic activity within set time intervals, such as every 0.1 seconds, and extracts features like the average signal level and root mean square (RMS) values. This technique is ideal for environments with constant background noise or subtle emissions, such as those found in gearbox testing or leak detection.
Lets analyse more detail on acoustic emission testing
Acoustic Emission Testing for Detecting Corrosion and Flaws
Ensuring the safety and reliability has become more challenging as pressure vessels evolve with more advanced and complex designs. Our use of acoustic emission techniques overcomes many of the typical challenges associated with inspecting such equipment. One major advantage is that the testing can be performed while the system is in operation, with no need for shutdowns, decommissioning, or service interruptions, making it an efficient solution.
This method is also non-intrusive and requires no entry of personnel or use of external substances like water or energy inside the vessel. It allows for the inspection of the entire pressure system, including components such as tanks and welds.
By capturing the energy naturally released from equipment during operation, we can quickly gather data that helps identify potential issues at an early stage. This allows timely action such as adjusting pressure limits. Our approach provides a complete assessment by evaluating the overall structure of the pressure equipment rather than focusing on isolated sections.
Step-by-Step Process: Non-Invasive Acoustic Emission (AE) Testing
Acoustic Emission (AE) testing is a non-intrusive technique used to identify active flaws in pressure equipment by detecting high-frequency stress waves released as materials experience stress. Commonly performed alongside hydrostatic testing, AE testing allows for the inspection of large structures without halting their operation. Below is a simplified step-by-step overview of how the process works:
Step 1: Attenuation Check and Sensor Planning
Before starting the test, an attenuation check is carried out to determine the most effective locations for placing the sensors. This step ensures that the sensors are positioned to capture the maximum signal strength across the structure.
Step 2: Sensor Installation and Signal Monitoring
A minimum of three sensors are placed on the outer surface of the equipment—often using rope access for elevated or confined areas. These sensors detect acoustic signals and help identify the source of any structural changes by triangulating the signal origin. Data is continuously collected throughout this stage.
Step 3: Data Analysis and Results Reporting
Once testing is complete, the recorded data is carefully analyzed to evaluate the structural health of the equipment. A final report is generated, detailing the areas where anomalies were detected and recommending further inspection or maintenance if necessary.
Applications OF AET
AE testing is adaptable and can be used on various types of equipment, such as:
- Industrial piping and tubes
- Storage tanks
- Spherical vessels
- Composite material structures
- Fuel and gas station containers
- Hydrogen and gas storage units
Let’s check the key benefits of acoustic emission testing
Key Benefits of Acoustic Emission (AE) Testing
AE testing method provides a comprehensive way to monitor the integrity of pressure equipment during regular operation. The method helps to detect issues early without disrupting service or compromising safety. Benefits of acoustic emission testing are
- Capable of identifying various types of damage, such as fiber fractures, frictional wear, impacts, cracks, delamination, and corrosion, at an early stage—before they evolve into serious problems.
- Testing can be performed while the equipment is in use, as well as during proof or development testing phases.
- AE technology can pinpoint the location of damage and distinguish between different types of defects based on their unique acoustic signals.
- Provides full-structure monitoring, offering a comprehensive view of structural health.
- Evaluates equipment or structures under real-world working conditions.
- A completely non-intrusive inspection method.
- Effective in extreme environments, including those with high temperatures, elevated pressure, corrosive substances, or radioactive exposure.
- Can be carried out remotely, enhancing safety and accessibility.
- Suitable for detecting damage in areas that are hard to inspect using conventional non-destructive testing methods.
Role Of Ultrasonic Testing Devices in Acoustic Emission Monitoring
Ultrasonic testing devices, such as those from the SONAPHONE series by SONOTEC, play a crucial role in acoustic emission monitoring, especially within preventive maintenance and industrial diagnostics.
- Efficient Maintenance & Early Detection
Identify bearing failures, electrical discharges, and mechanical faults before they escalate. - Accurate Leak Detection
Detects and eliminates leaks in compressed air, gas, and vacuum systems—improving energy efficiency and reducing operational costs. - Visual & Audible Feedback
Converts ultrasonic signals into audible sound with real-time digital display for quick and easy analysis. - Electrical Fault Monitoring
Detect corona, tracking, and arcing in high, medium, and low voltage systems—even inside closed cabinets. - Remote Area Inspection
Monitor hard-to-reach transmission and distribution lines using the SONOSPOT parabolic dish. - Tightness Testing
Use with the SONAPHONE T transmitter to verify the integrity of sealed enclosures and fittings. - Compact & Durable Design
Lightweight, portable device built to perform reliably in harsh industrial environments. - Versatile Applications
Compatible with a wide range of accessories to support diverse industrial inspection needs.
Maintain Structural Integrity with Oceanme’s AET Services
Acoustic Emission (AE) testing is a highly effective, non-invasive method for assessing the structural health of equipment and materials during normal operation. It can detect early signs of damage such as cracks, corrosion, or fatigue before they develop into serious issues. This allows for timely maintenance and reduces the risk of unexpected failures.
Being the leading engineering company in Oman, Oceanme offers efficient Acoustic emission testing. Our expert team provides real-time, continuous monitoring without the need to shut down systems. We also provide other condition monitoring services like vibration analysis, laser shaft alignment, CFD Analysis, and much more.
Partner with Oceanme, Improve the safety of your assets and extend the life of your equipment with AE testing.