794 efficient work practices, and vastly increased capacity for mathematical computation. Of note, the increased simulation capacity can allow extremely detailed fatigue analysis practices. Which, if used correctly, can guide design changes that dramatically improve fatigue resistance. With modern access to Finite Element Analysis (FEA) hardware and software, conducting arudimentary fatigue analysis for a grinding mill is now relatively straightforward. However, the accuracy of such analyses is highly dependent on the underlying assumptions. The analysis geometry should be suitability detailed, the setup must be carefully defined, and results must be thoroughly scrutinized. To mitigate the risk associated with assumptions and model simplifications, the best fatigue analysis methods are supported by, and developed with reference to, field-stress measurements of operating mills (Bordi & Green, 2023). Recent validation campaigns have shown that accurately reproducing in-service stresses requires adding significantly more detail within the simulation environment. Two-dimensional (2-D) simulation methods, which were considered state-of-the-art in the 1990s, have been superseded by far more detailed three-dimensional (3-D) analyses. At the SAG conference in 2015 Green et al. (2015) reported that the inclusion of non-axisymmetric geometry and loading details, together with explicitly modelling fasteners and frictional contact between flanges, reveals high stress regions which would have otherwise been underreported by as much as 50% in an equivalent 2-D analysis. Although there are practical limits to the level of detail that can be incorporated into a finite element model, modern computing capability continues to extend these limits, and there is now little justification for omitting stress inducing geometric features. By developing a model that accurately captures the true performance of a mill in operation, critical stress regions can be readily identified and optimised. These regions, which include radial and longitudinal split flanges, can be refined by blending geometric transitions, tuning the stiffness of surrounding geometry, and a range of related optimisation techniques (Green et al., 2015). To translate a highly fatigue resistant design into equipment with maximum availability and reliability, manufacturing and installation quality must be prioritised. The following aspects are particularly important when defining and conducting quality related activities: • All dimensions in stress-critical regions must align with the design intent, including material thicknesses, weld sizes, radii, bolt circle diameters, and other specified features. • All welding should comply with an appropriate standard (AWS D1.1 or equivalent). • Welds must be treated as required by the design, including processes such as grinding or peening. • Comprehensive non-destructive testing (100% coverage) should be carried out on all welds and castings to ensure material integrity and freedom from defects. • All surfaces must be smooth and free from sharp transitions, gouges, impressions, or other unnecessary stress-raising features. • All flanged connections must meet tolerance requirements. The above is achieved by utilizing trusted mill vendors, with proven sub-suppliers, who have developed and adhere to stringent manufacturing specifications, procedures, and Inspection and Test Plans (ITPs). These ITPs must be supported by suitably qualified and experienced inspectors and Non-Destructive Testing (NDT) technicians. This ensures the structural stress is as calculated, and that the material strength is equal to or greater than the required limits. A final consideration for fatigue performance is the equipment condition. From a fatigue standpoint, the two most common contributors of reduced fatigue resilience are inadequate bolt preload and material washout. Consistency and accuracy in fastener tensioning during installation, followed by appropriate
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