MAINTENANCE and inspection services group CW Pope’s exhaustive longwall chain research is starting to pay dividends, with the company claiming longwall producers are optimising chain service life and performance with the help of its study results.

Three key areas have been identified by CW Pope as having the greatest scope to deliver financial benefits to longwall chain users. They are analysis of manufactured-chain quality and the chain operational environment, and assessment of chain operation maintenance practices.

“While longwall chains to have a finite life, this is governed to a large extent by the nature of the work application and the mine environment in which the chain systems operate,” the company said.

“Condition monitoring and in-service checks can not only extend the life of a chain system, but also reduce the risk of unscheduled shutdowns and the inevitable production loss incurred by chain system failure.

“Production losses vary depending on the extent of the failure and its resulting effect on other equipment, but could result in downtime from part of a shift, to 24 hours.”

A CW Pope spokesman said the company had conducted metallurgical examinations of fractured and damaged longwall chains over a period of 20 years. It was helping clients maximise the life and performance of longwall chain systems not only through the results of its extensive research, but through in-service checks and installation advice.

CW Pope said “as-manufactured” chain quality was the first link in the chain, so to speak, and the most difficult to monitor. Beyond making well-informed decisions about chain type, mining companies had little control over the quality of chain.

“The majority of chain used in Australian longwall mines is sourced either from German or UK-based manufacturers,” the company said. Adherence by the steel maker to the steel supply standard ensured that desired chain properties were achieved by the chain maker, while a standard specified test and other measurements were carried out representative samples and the “chain lot” for confirmation of adherence to specification parameters.

The uniformity and efficiency of the heat treatment process during manufacture was critical to achieving the high strength, ductility and maximum notch toughness required.

“In CW Pope’s investigations, heat treatment origin failures, although rare, have led to one AFC chain system suffering multiple chain link failure by brittle fracture,” the Newcastle company said. “Uniformity of link shape and the standard of the chain calibration process can also contribute to subtle chain performance differences.”

Investigations by CW Pope over two decades have revealed chain-link fracture failures associated with corrosion fatigue and stress-corrosion, service-induced cracks. Wear is said to be another life-limiting failure mechanism, with many different instances of wear contributing to chain system failure. These failure mechanisms have led CW Pope to develop a generic checklist of chain maintenance.

“It is chain maintenance practice that gives mine operators the greatest control over chain performance,” the company said.

“CW Pope has found that attention to these areas of chain operation can reveal problems in their early stages which enables mining companies to avoid heavy production losses as well as the confusion and pressure of the breakdown environment.”