Reports issued in December contain candid admissions of error by two major operating companies, but more importantly, point out the way industry can avoid such mistakes in the future.
BP Products North America, Houston, released the final incident investigation report on the March explosion at its Texas City, Texas, refinery that killed 15 people. The incident at the 460,000-bbl/d refinery, the company’s largest and most complex, occurred when personnel overfilled a raffinate splitter and overheated its contents, causing a hydrocarbon vapor cloud to form and ignite.
The investigation team “found no evidence of anyone consciously or intentionally taking actions or decisions that put others at risk” but did identify “many areas where procedures, policies and expected behaviors were not met.” The team, which included operations and safety experts and union employees, cited several underlying causes for the accident:
• a working environment characterized by resistance to change and lack of trust and motivation;
• management’s failure to set and reinforce process safety and systematic risk-reduction priorities;
• absence of clear accountabilities and communication;
• deficiencies in hazard awareness and understanding of process safety; and
• inadequate systems for providing early warning of problems and sharing concerns at the site and company-wide.
BP is implementing the team’s recommendations. Among other moves, the company will install a more powerful maintenance-management system, improve worker training and remove blow-down stacks. It also will upgrade process control on major units. All told, BP plans to invest about $1 billion over the next five years at Texas City.
In addition, the firm has bolstered its internal audit process to better ensure that its five refineries adhere to company standards, and — on the recommendation of the U.S. Chemical Safety and Hazard Investigation Board — has appointed an independent panel to suggest improvements to its safety management and safety culture.
In mid-December, Dow, Midland, Mich., detailed the cause of a several-month-long shutdown starting in September 2003 at an ethylene oxide (EO) unit at Prentice, Alberta. The installation, owned by Alberta & Orient Glycol Co., uses Meteor EO technology licensed from Union Carbide, a subsidiary of Dow.
Problems in material selection and fabrication spurred the shutdown. Welds in the high-strength steel used in the water-cooled EO reactor had suffered from stress corrosion cracking. The cracks appeared only in sections of the reactor that handled water; it was discovered that the steel was susceptible to such cracks under typical operating conditions. The internal shell of the reactor is made of different materials — so, says Dow, there was no risk of release of reactants.
Dow notes that only a few reactors at other licensees are constructed similarly to the Prentice one, and they now have been checked.
Dow will use revamped design standards for future water-cooled EO reactors. These standards take into account its improved understanding of the susceptibility to stress corrosion cracking and commercially demonstrated ways to eliminate the problem. The company plans to release a technical paper this year to share details on the observed cracking.
The refinery explosion and the EO unit shutdown certainly are not of similar seriousness, but both offer valuable lessons for other sites — the first on the role that safety management and culture play, and the second on the realities of how fabrication affects materials’ performance.