How do you choose the best acoustic emission testing method for your plant assets?

1 Passive vs active AET

The first distinction you need to make when choosing an AET method is whether you want to use a passive or an active approach. Passive AET relies on the natural or operational sources of acoustic emission, such as pressure changes, thermal cycles, or mechanical loads, to generate signals. Passive AET is suitable for continuous or periodic monitoring of assets that are prone to fatigue, stress, or wear. Active AET, on the other hand, involves applying an external stimulus, such as a hammer, a pulsed laser, or an ultrasonic wave, to induce acoustic emission in the asset. Active AET is useful for detecting and locating defects that are not active or visible under normal conditions, such as cracks, delaminations, or inclusions.

2 Frequency range and sensor type

The second aspect you need to consider when choosing an AET method is the frequency range and the sensor type that best match your asset and your objective. The frequency range of acoustic emission signals can vary from a few kilohertz to several megahertz, depending on the source and the propagation medium. Generally, lower frequencies are more sensitive to large-scale defects and can travel longer distances, while higher frequencies are more sensitive to small-scale defects and are more attenuated by the material. The sensor type also affects the quality and accuracy of the AET results. There are different types of sensors available, such as piezoelectric, optical, or acoustic fiber-optic sensors, each with its own characteristics and applications. You should choose the sensor type that can capture the frequency range and the directionality of the acoustic emission signals from your asset.

3 Data analysis and interpretation

The third factor you need to take into account when choosing an AET method is the data analysis and interpretation process. AET produces large amounts of data that need to be processed, filtered, and analyzed to extract meaningful information about the condition and location of the defects in your asset. There are various methods and tools available for AET data analysis, such as waveform analysis, frequency analysis, cluster analysis, source location, or pattern recognition. You should choose the data analysis method that can provide you with the level of detail and accuracy you require, as well as the ease of use and integration with your existing systems and software.

4 Cost and feasibility

The fourth element you need to evaluate when choosing an AET method is the cost and feasibility of implementing and maintaining it in your plant. AET can be a cost-effective technique compared to other non-destructive testing methods, as it can reduce downtime, inspection time, and repair costs. However, AET also involves some challenges and limitations, such as noise interference, environmental conditions, accessibility, calibration, or safety. You should assess the cost and feasibility of AET in terms of equipment, personnel, training, and regulations, and compare it with the benefits and risks of using other techniques or doing nothing.

5 Standards and guidelines

The fifth aspect you need to consider when choosing an AET method is the standards and guidelines that apply to your industry and your asset. AET is a relatively new and evolving technique that does not have a universal or standardized procedure or protocol. However, there are some standards and guidelines that have been developed by various organizations and associations, such as ASTM, ISO, ASME, or ASNT, that provide recommendations and best practices for AET applications. You should consult the relevant standards and guidelines for your sector and your asset to ensure that you follow the proper methods, criteria, and quality assurance for AET.

6 Case studies and references

The sixth and final factor you need to look at when choosing an AET method is the case studies and references that demonstrate the effectiveness and reliability of AET in similar or comparable situations. AET is a versatile and adaptable technique that can be applied to a wide range of plant assets and industries, such as oil and gas, power generation, chemical, aerospace, or civil engineering. However, each case is unique and requires a specific AET solution that fits the asset characteristics, the defect type, the operational conditions, and the inspection objectives. You should review the case studies and references that showcase the successful use of AET in your industry or your asset type, and learn from their experiences, challenges, and results.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?