Preventing Fatigue Cracking Via Proactive Surface Dressing

Fatigue cracking of plant and equipment presents a significant challenge to the mining industry and is often the limiting factor for the viable structural life. At a conservative estimate, the costs associated with fatigue cracking maintenance are approximately 2% of the total maintenance budget, which does not take into account lost production costs or costs for equipment/component replacement when problems with cracking become too severe.

The fundamental aim of this project was to determine whether it is possible to extend structural life by proactive surface dressing to remove accumulated fatigue damage, thereby preventing fatigue crack formation. This could be done as a preventative maintenance task, thus reducing the need for weld repairs of cracking and significantly reducing total maintenance costs and extending viable asset structural life.

The findings of this project indicate that it is possible to effectively “reset” the fatigue life of steel by removing a 100μm thick layer from the surface. For maximum benefit, fatigue damage removal should be done between 50% and 80% of the fatigue life until cracking initiates. Additional work was done to demonstrate that fatigue damage removal can be done using readily available specialised polishing products and tooling. However, specialised procedures need to be developed for practical application, along with operator training and competency.