In May 2017 the Chemical Safety Board (CSB) released a safety bulletin, “Key Lessons for Preventing Incidents When Preparing Process Equipment for Maintenance: Flash Fire at the Delaware City Refinery.” The bulletin discusses a November 2015 incident at the Delaware City Refinery and discusses five key lessons regarding maintenance and non-routine operations.
The Chemical Safety and Hazard Investigation Board (CSB) released a safety bulletin in May 2017 in response to an incident at a refinery. An operator suffered second- and third-degree burns when personnel were preparing equipment for maintenance work by de-inventorying and draining vessels located between two isolation points. A single block valve isolated the vessels being decontaminated from a pressurized and inventoried depropanizer column containing hydrocarbons. The valve leaked in the closed position, which resulted in backflow of flammable material from the depropanizer. The operator opened the vessel drain valve to empty what was presumed to be condensate water from the vessel to the oil water sewer. After the operator opened the valve, hydrocarbons also released to the sewer and ignited, resulting in a flash fire.
The CSB noted five key lessons that may prevent incidents during non-routine operations and maintenance.
- Develop standard operating procedures for preparing all process equipment for maintenance, including de-inventorying, decontaminating, washing, steaming, purging, and draining equipment and vessels.
- Develop a process that requires pre-planning and hazard identification prior to initiating all equipment preparation activities.
- Do not rely on single block valves when isolating equipment for de-inventorying or decontaminating activities prior to maintenance work.
- Initiate a process to evaluate hazards that may be introduced when an equipment preparation task or isolation plan needs to be modified or expanded.
- Use closed systems to control the dissipation, draining, or relieving of hazardous energy when preparing to isolate equipment for maintenance. Do not drain materials containing or potentially containing volatile hydrocarbons or flammable materials into oily water sewer systems not designed for such services.
The CSB is a federal agency that investigates chemical accidents and provides guidance to other government agencies and industrial facilities on chemical safety. The CSB does not enforce regulations, nor does it create binding regulations.
Source : Chemical Safety and Hazard Investigation Board, Safety Bulletin, “Key Lessons for Preventing Incidents When Preparing Process Equipment for Maintenance: Flash Fire at the Delaware City Refinery,” May 2017