Rouseville, Pa., October 16, 1995
While this case was not investigated by the CSB because the agency was not yet funded and operational, the catastrophic nature of this hot work accident and the lessons learned from it support the case’s inclusion in this bulletin. An explosion and fire resulted during hot work activities, killing five employees; the ensuing fire forced the evacuation of the refinery and nearby residents.
The EPA investigated the incident and found that a welding operation was in progress on a service stairway located between two liquid storage tanks that contained mixtures of waste hydrocarbons and water. The explosion was attributed to the ignition of flammable vapor from one of the tanks. The EPA report found that “the tanks containing combustible or flammable vapors were not thoroughly isolated from the hot work site. … Although combustible gas testing prior to the start of hot work early in the morning indicated vapors were not present, gradual warming could make the presence of combustible vapors more likely.”16According to the report, gas monitoring was apparently not repeated during the midmorning hours when the explosion occurred. The EPA recommends that facilities evaluate the need for continuous combustible gas monitoring during hot work activities.
Applicable key lessons: Analyze the hazards; monitor the atmosphere; test the area.