(120b) Flag on the Play; Delay of Game

Author: John W. Herber, CCPSC

Process Hazard Management Services, LLC.

11 Moonlight Bay

Stillwater, Mn 55082

Many process safety systems are aimed at attaining and maintaining normal operation. How to maintain a safe process during abnormal operation is more difficult to assess. Initiating events that could cause abnormal operation are varied and they are easily overlooked or discarded as highly improbable.

Many incidents have occurred when operations are in start-up or shutdown mode. However, there is a nether-world between that is neither of these; when operations are suspended or the process is on hold. Hold can be a distillation unit that is placed on total reflux or a reactive process where the process is not at reaction conditions; perhaps reactant additions have also been suspended. The assumption is that the process remains at a static condition until we want it to resume. The proverb. “Time and tide waits for no man” should have also included chemical reactions. A number of incidents have occurred due to placing the process on hold either due to required maintenance, recovery from an upset, or utility interruptions. While some of these causes are not preventable, they can be anticipated and plans developed to safely manage the process until normal operation can resume. Maintenance activities are also prone to increased risk due to delayed or suspended operations. All of these situations have warning signs that can be recognized, but only if an effort is made to assess the situation and develop plans to safely manage the process through the delay.

This paper will explore risks that are presented by suspended or delayed operation and recommend several management system improvements that can be considered to recognize and address new or different hazards when operations are encountered.