On Sunday, November 29, 2015, an operator at the Delaware City Refining Company’s (DCRC) sulfuric acid alkylation unit suffered second-degree burns to the face and neck and third-degree burns to
On Sunday, November 29, 2015, an operator at the Delaware City Refining Company’s (DCRC) sulfuric acid alkylation unit suffered second-degree burns to the face and neck and third-degree burns to the wrist from a flash fire. The incident occurred when operations 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; unknown to operations personnel, the valve leaked in the closed position, resulting in backflow of flammable material from the depropanizer. When an operator opened the vessel drain valve to empty what he assumed was condensate water from the vessel to the oil water sewer, the hydrocarbons from the depropanizer also released to the sewer and ignited, resulting in a flash fire.
Prior to maintenance work, operations personnel commonly prepare equipment by depressurizing, de-inventorying, washing, and draining. These activities often involve opening process equipment and piping and can result in a release of hazardous energy. Though equipment preparation activities can occur rather frequently in process plants, the tasks involved may vary among pieces of equipment and piping and combinations of equipment and, thus, may be non-routine and not be included in an existing procedure. Because of the non-routine nature of equipment preparation activities, process plants should develop a system to ensure that equipment preparation activities are carefully planned, which includes selecting proper isolation methods and identifying hazards through a risk assessment.