Maintaining mining equipment

Mining operations and manufacturing facilities rely on the continued safe operation of vehicles and machinery to maintain safety and profitability. Any equipment failure can be expensive in terms of lost production and cost of repairs. An estimate for the cost of lost production for a single dragline is $8000 per hour in Australia, making any breakdown very costly when it might take weeks for a replacement part to be available.

One way to minimise losses is to continually monitor plant and machinery using non-destructive testing (NDT) methods to ascertain component health, and monitor mechanisms for damage. Phased array ultrasound can enhance day-to-day inspection of surface mining equipment, thereby improving safety and keeping critical equipment operational. However, it is important that inspections are performed with minimal downtime, so they need to be planned and coordinated to ensure that critical parts are available when the maintenance is carried out.

As part of the technical program at the recent Australian Institute for Non-Destructive Testing (AINDT) Conference in Brisbane, Nicholas Bublitz, a global product support specialist with Olympus Scientific Solutions America (OSSA), reported on how the use of phased array ultrasonics could improve surface mine profitability.

NDT is a group of techniques used to detect discontinuities in materials or components without causing damage or permanently altering the article being inspected. The AINDT Conference provided opportunities for NDT and maintenance professionals to meet and discuss the latest advances in NDT from around the world. Leading corporate members of the institute, such as Olympus, displayed and demonstrated some of its precision analysis instrumentation and applications supporting NDT.

NDT technicians inspecting a large-scale mining equipment part.

“NDT methods like ultrasonics, eddy current and radiography - along with condition monitoring techniques such as oil and vibration analysis - play an important part in predictive maintenance programs and help reduce unexpected expenses,” Bublitz said. Outage and emergency repair costs can be a significant percentage of the total operating cost of a mine. Finding a crack and repairing it before failure, or monitoring it until it needs replacement and ensuring that parts are ordered to arrive in time for the maintenance work, saves both time and money.

Machinery used to access, remove and haul away coal and other mineral resources at mine sites is often used during every shift and is under constant operational stress due to the sheer weight or the rotation and vibration of components and engines. Draglines and shovels are two key pieces of operating equipment where there are many beneficial applications for phased array inspection and analysis. There are many shafts, pins, bores and lugs on these machines, all of which present opportunities to benefit from phased array inspection. In addition, the benefits of phased array in weld inspection are well documented and are equally applicable in mining applications.

One example Bublitz presented at the AINDT conference was the checking of dragline swing shafts, which are often long with variable outside diameters. Cracks commonly occur at the transition or taper-down areas. Often two or more ultrasonic angles are chosen and multiple manual conventional ultrasonic inspections are performed where the probe can be applied to the shaft. He showed that the application of phased array simplifies the inspection, and provides better identification and sizing.

Phased array imaging helps identify geometric landmarks to help define the location and importance of any discontinuities. The overall probability of detection is increased using the comprehensive visual representation. Data capture allows for further offline analysis. The result is more dependable, accurate and faster assessment of potential failure sites. 

“The use of multiple angles and imaging increases coverage, reduces scanning times, and provides better detection and characterisation capabilities especially when monitoring crack growth,” Bublitz stated. “Phased array can add a huge benefit to mine predictive maintenance programs and in turn increase profitability.”

The latest generation of phased array equipment from Olympus is designed to make the technology accessible and economical to use. The products include ultrasonic flaw detectors and thickness gauges, eddy current equipment, videoscopes, borescopes, microscopes, advanced non-destructive testing systems, X-ray fluorescence and X-ray diffraction, and a large selection of industrial scanners, probes, software programs and instrument accessories.