When dealing with processes involving combustible dust, flammable liquids & gasses, and extremely toxic materials, understanding the hazards in the process is critical. This is true when designing a new process, as well as when a plant changes equipment, chemicals, and procedures. Many of the most severe industrial accidents have occurred because the facility failed to consider how changes would impact process safety. That is why a robust management of change (MOC) procedure that incorporates process hazard analysis (PHA) is so important.
In January 2015, the U.S. Chemical Safety Board released the final report(1) on a flash fire that burned seven workers at a U.S. Ink plant in East Rutherford, New Jersey. One of the key findings was that the facility failed to perform a thorough hazard analysis of a new dust collection system installed for an oil and powder mixing process. The system had been in operation for only four days when a flash fire burst from a duct and engulfed the workers standing in the room. The fire was the result of an improper design that allowed a sludge-like, combustible mixture of condensed vapors and powdery dust to rapidly accumulate inside the duct work: a design that was commissioned without a thorough hazard analysis, study, or testing of the system. Unfortunately, this is just one incident among many that could have been avoided if the time had been taken to thoroughly analyze the hazards in the system and make the necessary changes to the design before start-up.
With the U.S. Ink fire, there were several design aspects that contributed to the flash fire.
- The system was not designed to adequately relieve condensable vapors.
- The formation of cohesive dust because of the moisture was not considered, causing blockage in the duct.
- Housekeeping hose connections were added to the system without proper design and consideration of the impact to the system.
- Using long runs of combustible, rubberized, flexible hose instead of metal duct added fuel to the system and created a weak point in the ductwork.
Had the facility implemented MOC procedures, it is likely that some of the design flaws and safety gaps would have been identified. A proper MOC procedure should ensure that changes to materials, equipment, and processes are evaluated to determine their impact on employee safety and health. To determine the impact of the change, a PHA is often needed. During a PHA, a systematic review is conducted of potential hazard scenarios to determine where a fire, explosion, release of toxic material, or other catastrophic event may occur. Based on the results of the PHA, the facility will have determined where additional safety controls, procedures, and/or personal protective equipment (PPE) are needed to ensure employees, the environment, the community, and the business are protected.
Has your facility prepared Management of Change procedure or conducted a Process Hazard Analysis after installing new equipment or changing operating procedures and processes? Has your facility ever prepared MOC procedures or conducted a PHA? If you answered NO to either of these questions, now is the time to act.
References: (1)U.S. Chemical Safety Board. (2015). Case Study: Ink Dust Explosion and Flash Fires in East Rutherford, New Jersey (Seven Employee Injuries). Washington, DC. Retrieved from www.csb.gov