BMT WBM (BMT), a subsidiary of BMT Group Ltd, has successfully deployed its innovative DuraCluster modification and repair scheme which dramatically improves the fatigue performance of cluster joints on existing tubular dragline boom designs. Working with a major operator in the open-cut coal sector, BMT has replaced a number of fatigued boom clusters with DuraCluster to demonstrate both ease of installation and operational suitability.
Once implemented, this modification for tubular boom draglines significantly reduces maintenance and inspection workloads and dramatically reduces the problem of long-term fatigue cracking associated with the existing cluster design.
On a recent job for Westmoreland Coal Company, BMT was able to offer both reduced downtime and outage costs. Once installed, DuraCluster also reduces the risks to operators and maintenance teams in having to lower the boom and carry out complicated weld repairs with limited access. Installation for Westmoreland was successfully completed in the allocated time frame and the dragline returned to duty.
The long booms of draglines comprise a number of tubular chords with interconnecting lacings welded to the chords at cluster joints. Stresses are concentrated at the cluster joint weldments and over time, fatigue cracking becomes endemic. BMT’s innovative methodology prevents the need to cut and replace windows in lacings by removing the problematic design detail and improving load paths. Furthermore, DuraClustercan dramatically extend the fatigue life of dragline booms by reducing the stress concentrations.
Charles Constancon, Director of Canadian Services at BMT WBM explains: “A boom replacement can cost in the region of $20 million and would require a three month machine outage. With BMT’s modification and repair, the cluster design can be upgraded in around one week per cluster, depending on the extent of chord repair required, while multiple clusters can be modified simultaneously. With equivalent repair costs reduced to approximately $2 million, this is an extremely attractive incentive for mining companies. While DuraCluster provides a step change in life to cracking for tubular boom construction, it is equally applicable to tubular masts.”
Paul Charlton, Managing Director of BMT WBM’s machinery group comments: “The innovative design developed in our Vancouver office allows lacings to be cut away from the chord, providing easy access to remove damaged or previously-repaired material. The exposed chord can then be inspected and fully weld repaired before installing the plate. BMT’s innovative methodology delivers multiple benefits.”
Full patent rights for the DuraCluster design have been granted in Australia, South Africa, India and North America and discussions are taking place with potential clients in all these territories.