In 2009 McDowall Affleck were engaged by Jord International to complete finite element analysis for numerous assemblies of Flash Vessels, Ducts and Barometric Vessels for the Worsley Alumina site in Collie.
The main objectives of the analysis were to allow determination of the stresses and deflections induced at key areas of the vessel assembly during very high temperature caustic wash and seismic conditions. The stress levels found were compared against AS1210 – 1997 to determine compliance. Key concerns were flexibility and thermal growth of the vessels and the potential for flange leakage under seismic loads due to caustic contents.
The vessels ranged in size up to 7500mm diameter, with the ducts connecting the flash vessel and barometric vessel being 1500mm diameter. Various load cases were applied to the assemblies, including pressure, temperature, mechanical loads, wind and seismic loads. The bolted flange connections were analysed in the FEA model to assess leakage of the joint. The bolt preload in some of the flanged connections was found to be insufficient, and a higher preload was recommended to maintain a sealed joint.