Guidelines for process safety during the transient operating mode : managing risks during process start ups and shut downs Process industries bring vast benefits to our daily lives but we do not live in a risk free environment and mistakes are made. The timing for the highest risk period for most facilities occurs during start up and shutdowns also known as transient operations. Since transient operations in general for continuous chemical processes are performed less frequently they have increased operational risks. This increased risk is due in part to an increased likelihood for procedural errors and the special hazards associated with the start up or shutdown especially since the process is not running under normal steady state conditions. In addition it may not be possible to address the many temporary and potentially hazardous conditions which could occur during the start up or shutdown of these complex processes