September 4, 2002—The U.S. Chemical Safety and Hazard Investigation Board (CSB) voted to recommend that the U.S. Occupational Safety and Health Administration (OSHA) work to ensure that aboveground chemical storage tanks be regulated under OSHA’s Process Safety Management (PSM) standard.
The Board convened outside Wilmington, DE, to deliberate and vote on a series of findings, root causes, and recommendations arising from a yearlong investigation into the July 17, 2001, explosion at Motiva Enterprise LLC’s Delaware City refinery.
One employee was killed and eight other workers were injured when a spark from carbon-arc welding equipment ignited flammable vapors in a 415,000-gallon sulfuric acid storage tank at the refinery. The surrounding sulfuric acid tank farm was heavily damaged in the blast, and an estimated 1.1 million gallons of the powerful corrosive were ultimately released to the environment, including nearly 100,000 gallons that flowed into the nearby Delaware River. A significant fish kill occurred there.
The CSB investigation found significant deficiencies in Motiva’s mechanical integrity program. If effective, this program should have prevented the extensive corrosion damage that was evident in several tanks at the farm. Some of the tanks contained thousands of pounds of flammable hydrocarbons in addition to the corrosive sulfuric acid.
According to CSB lead investigator David Heller, “Motiva did not act to prevent hot work, high-temperature cutting that could generate molten metal and sparks, from being performed directly above a corroded hazardous storage tank that had holes in its roof and shell and was known to contain flammable vapors.”
The Board found that the incident likely would have been prevented if good safety management processes had been adequately implemented at the refinery. Investigators found Motiva did not consider the tank farm to be covered by the requirements of the OSHA Process Safety Management Standard, which sets safety standards for various chemical operations. The Board recommended that OSHA take steps to include such tanks farms under its regulatory system. Under federal law, OSHA will have 180 days to consider the recommendation.
The Board approved a full suite of preventive measures, including recommendations that:
- The U.S. Occupational Safety and Health Administration expand its Process Safety Management regulatory standard to ensure coverage of similar hazardous storage tanks.
- The State of Delaware ensure that new regulations under the recent Jeffrey Davis Aboveground Storage Tank Act require prompt action when tank corrosion results in a safety hazard.
- The Motiva Delaware City Refinery take numerous specific steps to improve chemical process safety, including better mechanical integrity planning, reporting systems, communication with workers, an upgraded hot work program, and improved designs for existing tanks.
The Board’s final report will be available from the CSB Web site.
