Looking at the contractor involved with the refinery H2S incident last week, I came across another refinery accident involving H2S where this contractor had their employees exposed. I have no special info on this latest incident, and I will let the media release the name of the contractor, but this 1998 incident was being in the wrong place at the wrong time. Another contractor company had its team exposed to this H2S event.
Employees #1 through #10 worked at a crude oil refinery where nearby process units (crude oil and gas oil treater) were undergoing a planned turnaround. The units had staggered shutdown and startup schedules and shared some product transfer piping leading to storage. When the product flow was rerouted by operations prematurely, sour naphtha liquid was released into the crude unit from an OPEN connection installed on a NEW 6 in. piping section that served as an exchanger bypass line.
The low-pressure release lasted for several minutes and allowed clouds of toxic hydrogen sulfide (H2S) gas to accumulate in and around the nearby control room and through nearby process units.
- Emergency alarm and evacuation procedures were NOT executed according to plan.
- Operators responding in the field at first attempted rescue efforts without using emergency air packs, ultimately adding to the total of exposed employees. Numerous exposures to the evolved sour gas resulted in injury to both plant and contractor employees.
- Employees #1 through #10 were transported to the hospital, and Employees #2 through #4, #9, and #10 were admitted. None experienced permanent effects.
- Subsequent investigation revealed weaknesses and discrepancies in the plant lockout/tagout program, as well as poor implementation and upkeep of the process safety program.
- Unit isolation blinds and lockout/tagout blinds for the equipment were not clear to the operators due to poor tracking.
- Operating procedures were both outdated (e.g., the use of checklists) and/or unclear, such as to how to perform the final stages of unit startup.