Electricity and Control May 2021

PLANT MAINTENANCE, TEST + MEASUREMENT

Non-destructive testing in machine maintenance Advanced field services, transformer chemistry testing, reliability solutions – following its recent expansion these are some of the extra services offered by condition monitoring specialist,WearCheck, in addition to traditional used oil analysis.The company’s advanced field services division incorporates specialist monitoring techniques such as rope testing, technical compliance and non‑destructive testing. Adri Ludick, NDT Manager forWearCheck, outlines the process and benefits of various non-destructive testing techniques.

Adri Ludick, WearCheck’s technical specialist for mechanical and non- destructive testing, advises customers which NDT test routines will best fit their requirements.

T he NDT approach features a variety of testing tech- niques through which the properties and condition of a component or system are evaluated without caus- ing any permanent damage to it. NDT is typically used in critical component assessments, machine condition as- sessments and inspection of ancillary equipment such as main vent fans, compressors, mills, pumps and conveyors. WearCheck’s NDT team delivers quality assurance and quality control of new as well as refurbished components. The range of NDT tests includes eddy-current, magnetic- particle, liquid penetrant, radiographic and ultrasonic testing, and visual inspection. The main advantage of NDT methods is that they do not permanently alter the test object undergoing inspection. This makes NDT a valuable tool that can save money and time in a condition monitoring programme. Eddy-current testing Eddy-current testing detects surface defects, such as early-stage cracks, on metallic machine components and is used across a wide range of industries, from aerospace to beer brewing.

During the testing process, a high frequency electric current (an eddy current) is induced into the material and the response of that eddy current field is then measured. The information is processed to yield a profile of the component. Defect-free material has a very specific ‘fingerprint’; therefore, when the test results are compared to this, the presence of defects can be assessed. With regard to cracks, the earlier they can be detected, the less damage they can potentially cause to the com- ponent. Eddy-current testing can detect crack initiation at very early stages. An advanced option is the phased array eddy-current testing, which creates a 3D picture of the component, providing more visual insight into any anomalies. Magnetic-particle testing Magnetic-particle testing is similar to eddy-current testing in that both techniques detect surface cracks on magnetic materials. It is used across a range of industries. The process in this test is to magnetise the component and then saturate it with a very fine magnetised ink or powder.

24 Electricity + Control MAY 2021