On June 5, 2006, a fatal explosion and fire at the Partridge-Raleigh oilfield killed three contractors from Stringer's Oilfield Services and caused another to suffer serious injuries as they were welding on top of three 15- to 20-feet-tall tanks that contained flammable hydrocarbons, ethyl benzene, xylene, toluene and naphthalene fumes.
According to CSB, the contractors were completing piping connections between the tanks when welding sparks ignited the flammable vapor venting from one of the tanks. The fire flashed back into the three tanks and the pressure from the burning vapor inside the two tanks caused the tops to blow off.
Three workers were thrown by the force of the explosion, which resulted in blunt force trauma and fatal injuries. The fourth contractor, a welder, suffered a broken ankle and hip but survived, because, CSB points out, he was wearing a safety harness that prevented him from falling to the ground.
Three Years Without an OSHA Inspection
CSB discovered that OSHA had not inspected Partridge-Raleigh or Stringer's Oilfield Services in the 3 years prior to the explosion and had not conducted a planned inspection at any of the nearly 6,000 oilfields in Mississippi in the preceding 5 years. This was an important observation in the investigation, according to CSB Chairwoman Carolyn Merritt, as unsafe work practices directly contributed to the accident.
“While it is the responsibility of the company to comply with OSHA standards, without effective enforcement, too many companies may simply ignore these lifesaving protective standards,” Merritt said.
Following the explosion, OSHA cited Stringer's for 13 serious safety violations, CSB said.
According to the CSB report, the workers had placed a ladder in between two tanks to serve as a makeshift scaffold – an unsafe act. In addition, an open pipe on the adjacent tank was not capped or otherwise isolated with a closed valve to prevent flammable vapor from accumulating near the area where the welding was to be done.
Unsafe Work Practices
While not a cause of the accident, CSB pointed out that the welder inserted a lit oxy-acetylene welding torch into the tank's hatch and then into an open nozzle on the opposite side of the tank to verify that all flammable vapor was removed from the tank, instead of using a flammable gas detector. CSB's lead investigator, Johnnie Banks, said that the practice is common in oilfield operations despite the fact that it is recognized to be dangerous.
“ ... [It] even has a name – flashing,” Banks said.
Banks added that the two contracting companies required hot work permits to perform welding on the tanks.
CSB found that Stringer's lacked hot work safety procedures and did not implement available guidelines from the American Petroleum Institute (API) 2009 standard, Safe Welding, Cutting and Hot Work Practices in the Petroleum and Petrochemical Industries, in preparing and conducting the welding operation on the day of the incident.
In addition, CSB determined, Stringer's and Partridge-Raleigh did not adhere to OSHA requirements addressing safe welding practices.
CSB: OSHA Should Be More Involved
The report recommends that management from both Stringer's and Partridge-Raleigh develop and establish procedures that would ensure safe work practices during hot work, tank cleaning and work from elevated locations as well as establish written safety performance standards such as those found in API Recommended Practice for Occupational Safety for Onshore Oil and Gas Production Operations – API RP-74.
In addition, the report recommends that the Mississippi State Oil & Gas Board develop a procedure to refer unsafe practices discovered during well inspections to OSHA. The report also recommends that the OSHA area office in Jackson, Miss., implement a local emphasis program to inspect companies in the oil and gas production and extraction sector.