Unsafe work practices caused a 2006 fire and explosion in a Mississippi oil field that killed four employees of a contractor and seriously injured a fifth employee, the US Chemical Safety Board concluded in a recently released investigation.
CSB recommended that the Occupational Safety and Health Administration increase inspections of the region’s oil and gas production facilities. CSB’s report also called on the Mississippi Oil and Gas Board (MOGB) to identify-and refer to OSHA-any potentially unsafe health and safety conditions observed during inspections of well sites and drilling operations.
The four employees worked for Stringer’s Oilfield Services and were completing piping connections between tanks in the Partridge-Raleigh oil field on June 5, 2006, when welding sparks ignited vapor that was venting from one of the tanks, CSB said.
It said two workers and a foreman had climbed on top of the tanks and placed a ladder between two of the tanks to serve as a makeshift scaffold. A welder attached his safety harness to the top of one of the tanks and positioned himself on a ladder so he could connect piping to both tanks. To do this, he had to weld a pipe-fitting onto one tank’s side before attaching a short length of pipe to the fitting and to a nearby, open-ended pipe on an adjacent tank.
Flammable hydrocarbon vapor venting through the open-ended pipe ignited almost immediately, according to the report. The fire flashed back into the tanks, creating internal pressure which caused their tops to blow off. The explosion killed the workers and foreman, while the worker’s safety harness saved his life, it indicated.
Unsafe practices
CSB cited using the ladder as a makeshift scaffolding and not capping the open pipe before welding as unsafe work practices and the causes of the accident.
It also criticized the welder’s inserting a lit oxy-acetylene torch into the tank’s hatch and then into an open nozzle on the tank’s opposite side as unsafe, although this did not cause the accident. A flammable gas detector should be used instead, the report said.
“While recognized to be dangerous, this practice is common in oil field operations and even has a name-flashing,” said lead investigator Johnnie Banks. He said neither the contractor nor the oil field operator required hot-work permits to perform welding on the tanks.
CSB found that Stringer’s lacked hot-work safety procedures and did not implement guidelines from American Petroleum Institute Standard 2009, “Safe Welding, Cutting, and Hot-Work Practices in the Petroleum and Petrochemical Industries,” in preparing and conducting welding on the day of the accident.
Stringer’s and Partridge-Raleigh also did not adhere to OSHA requirements addressing safe welding practices, CSB said. It recommended that the two companies implement such practices immediately.
CSB also urged MOGB to establish a program to identify and report unsafe oil field practices to OSHA, and called on OSHA’s office in Jackson, Miss., to implement a local emphasis program to inspect oil and gas extraction operations.
OSHA had not inspected Partridge-Raleigh or Stringer’s for 3 years before the accident or conducted planned inspections of any of Mississippi’s nearly 6,000 oil fields in the preceding 5 years, although inspections did occur following accidents or employee complaints, according to CSB. It added that following the explosion, OSHA cited Stringer’s for 13 serious safety violations.