In this article, the importance of valve safety measures and procedures are discussed after a fatal incident at an acetic acid plant.
By Lyndsey Denton-Fray, Valve World
In Valve World magazine, we publish many articles that highlight the importance of valve safety. Whether it is about the types of valves being used, selection, installation or general knowledge on how valves work, understanding and following protocol to ensure safety is paramount. That being said, sometimes things do not always go to plan.
The incident
During an attempt to isolate a pipe section between a leaking pipe and an acetic acid reactor, three contractors decided to lock a plug valve in the closed position by removing the valve’s actuator. However, there was not only no procedure in detailing how to remove the actuator, but the contractors were also not trained in how to remove the actuator. Instead, the contractors inadvertently removed the pressure-retaining fasteners that were holding the valve cover in place, causing the compromised valve to fail and spray all three contractors with acetic acid mixture. Two of the contractors died from their injuries.
Response and suggestions
In response to this fatal incident, the US Chemical Safety and Hazard Investigation Board (CSB) released a new safety video, addressing two key safety issues in their final report that contributed to the incident.
The first issue addressed the design of valves to prevent human error. The CSB’s investigation showed that similar incidents have occurred where workers have inadvertently removed pressure-retaining components from a plug valve while attempting to remove an actuator.
The second issue addressed the need to provide workers with conditions, procedures and training to safely conduct work. It was concluded that without appropriate risk assessments, maintenance tasks can be perceived as simpler than they actually are. The investigation further indicated that proper training and written procedures could have helped to prevent this incident.
To address the issue of safety, suggestions were made to redesign plug valves that would make it very difficult to accidentally remove any pressure-retaining components. However, the CSB acknowledged that this is not something that can change overnight, and instead suggest that in the meantime, facilities should clearly label pressure-retaining components on existing plug valves through warning signs or colour-coordination. On the issue of conditions, procedures and training, the CSB state that at some facilities a risk assessment may determine that depressurising and de-inventorying equipment is required before removing plug valve actuating equipment. Written procedures also need to be provided for workers, which will ensure that they know what to do, and if not, inform whether they are unqualified to carry out the task. Proper training and oversight of such tasks also need to be provided, lowering the risk for any misunderstandings of how the task should be carried out.
With new suggestions to improve measures, there is hope that companies will follow suit and update their procedures for removing actuating equipment from plug valves. CSB board member Johnson stated that: “As this tragic incident has shown us, even a simple task can turn deadly if it is not properly performed,” a quote that can resonate with industries in how policy change and safety measures can help save lives.
About the CSB
The CSB is an independent, non-regulatory federal agency whose mission is to drive chemical safety through independent investigations to protect people and the environment. CSB investigations look into all aspects of chemical incidents, including physical causes such as equipment failure, as well as inadequacies in regulations, industry standards and safety management systems.
CSB Safety Video
The CSB’s safety video on its investigation into the fatal release of acetic acid was released in July 2024. This video and further information can be found at: https://www.csb.gov/csb-releases-new-safety-video-on-fatal-acetic-acid-release-/
About this Technical Story
This Technical Story is an article from our Valve World Magazine, December 2024 issue. To read other featured stories and many more articles, subscribe to our print magazine. Available in both print and digital formats. DIGITAL MAGAZINE SUBSCRIPTIONS ARE NOW FREE.
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