No. 1 BOILER INCIDENT-MARIAN MILL 2016

ON MAY 24, 2016, a furnace explosion occurred in the No. 1 boiler at Marian Mill. The incident occurred during a restart from a banked fire situation and several issues contributed to the severity of the explosion. Notably this was the accumulation of combustible gases and a large quantity of bagasse within the furnace. The explosion caused extensive damage to the water wall tubes, associated support structures, riddling hoppers and ducting. Fortunately, no people were injured. Following the explosion, the boiler was shut down and area around the boiler was made secure. The Division of Workplace Health and Safety Queensland (WHSQ) were notified as this event was classed as a notifiable incident. A full incident investigation was undertaken, which resulted in a root cause analysis (RCA) workshop and three reports being completed. This incident occurred one week before the start of the 2016 crushing season; therefore a recovery plan was developed to return the boiler to service in shortest period of time to minimise the disruption to the 2016 crushing season. In consultation with Mackay Sugar Limited (MSL) insurers, EDMS (a Townsville based contracting company) was engaged to assist in the repair process. Due to the extent of the explosion it was obvious that the repair would need to be done in two stages, as the full reinstatement of all boiler components back to ‘as built’ would have taken longer than the estimated 2016 crushing season. Initial works centred on safety and involved an independent engineer’s assessment of the boiler to determine if the main structure was secure and that there were no asbestos fibres released during the explosion. A detailed return to service plan was developed and the timeline suggested that the temporary repairs could be completed in 10 weeks. In the meantime, single milling train operations recommenced shortly after the incident and cane transfers to other mills minimised the impact to the business. Repairs to the boiler were completed within 8 weeks, under budget and with no safety incidences. Full restoration repairs are planned for the 2016–17 shutdown period.