Non-routine operations such as start-up, shutdown, online exchanger switching, truck loading/unloading, etc. are some of the riskiest operations that process plants perform?
For example, the Texas City refinery explosion which killed 15 and injured over 100 workers occurred during a startup of an isomerization unit after a turnaround. More recently, at a process plant in Louisiana, a spare reboiler exchanger was being put into service while the unit was online. The operator put the heat supply to an exchanger isolated from a pressure relief valve before opening the outlet of the process side of the exchanger causing the pressure to rapidly increase above its pressure rating leading to an explosion that killed multiple workers.
Many of the hazard analysis techniques such as HAZOP and What-if analysis are focused on catching deviations in normal operations. However, non-routine tasks should be also. Techniques have been developed to evaluate procedures using guide words to spark discussion to catch potential hazards.
Whenever performing a nonroutine task, take the time to think through each step and ask yourself: What would happen if I skipped this step? What would happen if I performed this step incorrectly? This simple approach may bring forward potential deficiencies in the current setup and spark ideas for potential improvements to make the task safer and/or more efficient.