An Improved System for Dragline Rope Condition Monitoring

In stage one of this project it was demonstrated that it is feasible to use magnetostrictive transducer technologies to generate ultrasonic energy in wire ropes of up to 77mm in diameter and for this energy to be transmitted through the rope and socketing assembly.  The report on stage one report is provided with the final project report.

A MsSR3030R guided wave ultrasonic inspection system was acquired and trialled on laboratory rope samples under tension. It was determined that this system was capable of "seeing" a reflection of ultrasound energy from a defect equivalent to 8% loss of overall cross section of the rope under certain specific conditions as discussed in §1.2 of this report.

The objective of stage two of the project was to trial the same system on a working 106mm diameter dragline pendant rope assembly. This trial was conducted in parallel with the existing radiographic inspection regime.

To facilitate this trial, a test subject was provided by the Rio Tinto Mount Thorley Warkworth Mine (MTW). This was a P&H 9020 Dragline (#103 at MTW). The first experiment was conducted onsite in March 2012 at the mast end of the four mast-to boom pendent ropes.  The tension in the cable was estimated at 37 tonnes when the dragline is in its isolated state.

Approximately seven to eight months later, these ropes were retired from service and later sent to the Onesteel Molycop Wire Rope Facility in Newcastle, where the experiment was repeated using two of the same rope ends trialled in March 2012, 3B & 3C at three different tension settings, 750 kN (75 tonnes), 1000 kN (100 tonnes) and 1500kN (150 tonnes). The tension was originally set at 37 tonnes; however no distinguishing features could be seen in the data above the noise. A minimum of 75 tonnes was required to produce data, where distinguishing features could be clearly seen. The region targeted was a section 330 mm from the socket on each cable as this has been shown to be the location where most of the failures occurred [3]. Selected results of these two experiments, at MTW and at Onesteel Molycop, were compared and contrasted.