A legal appeal has been filed by owners of a 120,000 barrels per day refinery in Anacortes, WA, challenging a record $2.38 million fine by the Washington state Department of Labor & Industries leveled following an April 2010 explosion that killed seven workers.
"The company continues to work closely with investigators regarding this incident and continues to drive safety improvements throughout the company," a press release issued Nov. 4 by the Tesoro Corporation states.
Efforts to restart the refinery, closed since mid-April, have been ongoing since Oct. 17, the release states.
"Today, most of the refinery is operating and we expect to be back to normal operations soon," said Greg Goff, president and CEO of Tesoro. "In addition to completing repairs to the damaged units, extensive future inspections and maintenance work was accelerated to take advantage of the down time."
Michael Silverstein, assistant director of DLI’s Division of Occupational Safety and Health, said the company’s decision to appeal came as no surprise.
"We look forward to hearing how the company intends to address the violations we found," he said.
In October, DLI cited the owners for 39 "willful" violations and five "serious" violations of state workplace safety and health regulations in connection with the April 2 explosion. The $2.38 million fine is the largest ever issued by DLI.
Results from an investigation being conducted by the U.S. Chemical Safety Board are pending.
The six-month DLI investigation determined that the explosion was preventable, a DLI press release states. A heat exchanger at the refinery blew apart along cracks in welded areas, the investigation found.
"This equipment had been weakened by nearly 40 years of exposure to chemical and physical stresses resulting in cracks," Silverstein said during an October press conference. "Cracks in the metal could have been discovered with proper testing that had not been done in more than 10 years."
Investigators found a long history of significant leaks, Silverstein said. Workers were assigned to work in the danger zone surrounding the heat exchanger with inadequate training.
Built in 1955, the refinery was taken over by its current owners in 1998. Part of the refinery process, leading to high octane fuels, requires that naphtha be treated using hydrogen to remove sulfur and other contaminates by means of a naphtha hydrotreator.
"The hydrogen treating process heats the naphtha to very high temperatures, then reduces it back down," Silverstein said. Six heat exchangers, divided into two equal stacks, are used to control the temperature.
Each exchanger is a steel cylinder about 30 feet long with a bundle of tubes inside. Once the naphtha is treated, it passes through the tubes on its way to a reactor where the temperature is raised even higher. It then returns through the exchanger’s outer shell to cool down.
"In overly simplified terms, the heat exchangers function very much like a radiator on your car," Silverstein said.
In March, the exchangers had been shut down for maintenance. On April 1, workers began bringing the exchangers back on line.
"As that happened the temperature and pressure in these vessels were rising," Silverstein said. "They were rising faster and with more force that Tesoro policies allowed."
A spike in the temperature and pressure in the exchanger labeled "E" blew it apart at its welded seems with incredible force, he said.
The exchanger was sent to an independent laboratory where it was dismantled for specialized metal testing, he said. Testing was also done on site in Anacortes.
"These tests showed cracks along several of the welds in the "E" exchanger," Silverstein said. "It showed that the rupture occurred along those weakened areas."
Testing shows that the exchanger’s heavy gauge steel first split apart in a longitudinal direction, then turned in the direction of its circumference, he said.
"The heat exchanger that blew apart had been subjected to nearly 40 years of stress from extreme heat, pressure and chemical exposures," Silverstein said. "It is well known in the refinery industry that this can cause steel to become brittle and can cause cracks and other forms of damage."
State safety regulations, based on engineering industry practices, would have revealed these cracks. The exchanger had last been subjected to specific testing for these types of cracks in 1998.
"Even that testing was not done on the most vulnerable part of the heat exchanger," Silverstein said.
The company planned to inspect for cracks again in 2008, but that was never done, he said.
"If they had, we believe they would have found the cracks that caused this explosion," Silverstein said.
Investigators also determined that the heat exchangers had a long history of leaking flammable liquids and vapors from the various flanges, valves, gaskets and other components, he said.
"That leaking was particularly true during the start up periods," Silverstein said.
In anticipation of leaks, the company had adopted the practice of positioning workers around the heat exchangers equipped with steam lances, apparatus that directs steam to disperse leaks as they occur, he said.
Although company policy called for a slow increase in temperature and pressure during the start up process, Silverstein said it had become standard practice to accelerate this in an effort to reduce the leaks.
"This not only subjected the heat exchangers to added thermal stress during the start up process but it also required some workers to go into the danger zone to turn some of the valves necessary to raise the temperature and pressure," he said.
"At the time of the blast there were eight people involved in the start up process," Silverstein said. "One of them was a manager operating a control board in a protected room. The other seven, all who died, were stationed in and around these heat exchangers."
Only the manager survived.