Spotlight On Safety: Bypassing a Safety System Can Have Serious Consequences


Safety systems are designed to prevent unsafe operations from occurring, as well as to safely shut down an operation if an unsafe condition does occur. The goal of a safety system is to prevent loss of containment and protect people, property, and the environment.

Safety interlocks and emergency shutdown (ESD) systems are critical and should be connected and operable whenever a process is in operation. In a very small number of scenarios, however, it may be necessary to bypass or inactivate a safety interlock or ESD system for a short period of time using fully reviewed and approved procedures that implement alternative safeguards.

For example, during a process unit startup, it may be necessary to bypass safeguards until certain operating conditions are reached. This action is incorporated into an approved startup procedure and alternative safeguards are implemented. The procedures typically specify the limiting conditions required for operation without critical safeguards and indicate stringent limits on duration and operating conditions.

Examples of situations where it is appropriate to bypass a safety system are few and in each scenario...

Author Bios: 

Louisa Nara

Louisa Nara is the Technical Director of the Center for Chemical Process Safety (CCPS) for the American Institute of Chemical Engineers (AIChE). Louisa comes to AIChE/CCPS after 15 years with Bayer where she held positions of increasing responsibility including: Manager Process Safety and Crisis Management; Director of HSE, Security and Emergency Response at Bayer’s largest US Manufacturing site; and, Director, Risk Management and Compliance, NAFTA. Prior to joining Bayer, Louisa also gained significant experience in process safety, engineering, and HSE with Diamond Shamrock, PQ...Read more

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