As part of their continuous maintenance plan, Dampier Salt Ltd had planned to replace the existing mild steel spatial trusses supporting the CV002 Conveyor Belt in Dampier with similar spatial trusses made of a more durable material. CV002 conveyor is approximately 68m long and connects the Wet Salt Dump Bridge with the Salt Washplant at an angle varying between 10 and 16 degrees. McDowall Affleck were appointed to undertake a preliminary study to compare alternative materials including FRP and various grades of stainless steel (AISI304, AISI316L and Duplex), and to provide the detailed design of the Conveyor Belt supporting structure using the preferred material of AISI316L.
Our project challenges were; minimal tolerance at the interface of existing substructure, electrical cable tray could not be removed during structure replacement, minimisation of site work and potential risk of stress corrosion cracking for AISI316L.
We overcome these issues by having an accurate survey requested from DSL, catenary support for cable tray was designed to be connected to both existing and new supporting structure and spatial trusses fabricated off site requiring minimal installation time. In accordance with Australian Standards a risk assessment report was provided to DSL. This included administrative control measures to reduce the risk of stress corrosion cracking.
McDowall Affleck provided value engineering by having extensive offsite prefabrication done to reduce installation time, smart catenary support structure was designed to replace trusses without the need to remove the electrical cable tray. As we were using laminated sections in AISI316L a risk assessment on stress corrosion cracking was conducted, as required by Australian Standards.