ST. LOUIS • A steam tank explosion at a box company that killed four people last month was caused by a failure where the tank had been patched in an emergency repair in 2012, according to a report issued Thursday by a federal investigative agency.
The company never obtained a permit for the repair nor acted on a recommendation for a more permanent solution, according to a report issued Thursday by the U.S. Chemical Safety and Hazard Investigation Board. And the city didn’t inspect the unit.
An engineer at Loy-Lange Box Co. noticed the tank was leaking on March 31, and shut it down for a repair scheduled for three days later, the report said.
But before the repair, the box company inexplicably started up the tank the morning of April 3, and it exploded near the end of the startup process, the report found.
The 1-ton tank ripped away from where it had been repaired and launched like a rocket through the roof at 120 mph. It sailed more than 10 seconds, rising 425 feet above street level — about two-thirds as high as the Gateway Arch — and crashed through the roof of Faultless Healthcare Linen Co. 520 feet away.
Kenneth Trentham was killed at Loy-Lange; Christopher Watkins, Tonya Gonzalez-Suarez and Clifford Lee were fatally injured at Faultless Healthcare Linen.
While not assigning blame for the incident, the board issued an update on its investigation that pointed to several problems:
• Loy-Lange needed a permit from the city for the 2012 repair, but the board found no evidence the company asked for a permit, or the city issued one.
• The repair contractor suggested a more extensive replacement after making that emergency repair, but Loy-Lange did not follow through.
• Investigators could find no record that the steam tank had ever been inspected by the city of St. Louis, despite a city ordinance that requires annual inspections.
• While insurance companies also commonly inspect pressure vessels, Loy-Lange’s insurance company said it has no jurisdictional authority in St. Louis, so it does not do inspections there.
Loy-Lange officials could not be reached for comment Thursday.
The report pointed to the city’s hands-off approach to inspections. The state of Missouri — and pretty much every other jurisdiction in the United States — requires annual inspections of high-pressure units, under standards set by a national safety board.
The city opts out of those, the report found. Although the city code requires annual inspections, the city puts the responsibility on the companies.
Even if the city did inspections, city code does not require them to meet national standards set by the National Board of Boiler and Pressure Vessel Inspectors. Instead, it requires annual inspections that are “as thorough as circumstances permit.” And the code also says the city can employ fewer inspectors than required “subject to the city’s budget.”
The city has said it stopped doing any inspections about six years ago. Instead, it has required all companies to have a stationary engineer licensed by the city on the premises when a high-pressure boiler or steam tank is in operation.
On Thursday, acting St. Louis building commissioner Frank Oswald defended the city’s practice as more stringent than state or national standards. And he said delegating the inspection to the company’s engineer worked — kind of.
“The station engineer actually did say that the system was not proper,” he said. “I really can’t speculate why they would have done this when they had a professional saying not to. I don’t know who made the decision. I guess that’s the real question.”
He said the city has a “pretty aggressive system.” He said there was no way a municipal government could inspect thousands of boilers and steam tanks. He said the only other option would be to hire a third party to conduct inspections.
“We’re going to review whether we go to a third party, but I don’t know at this time,” he said.
Outside of St. Louis, the state Department of Public Safety does accept inspections by third parties who have a strong interest in steam tanks safety: insurance companies.
But the box company’s insurer, FM Global of Rhode Island, told the federal investigators it does not inspect steam vessels in St. Louis because the city does not give insurance inspectors jurisdictional authority.
Oswald said “that’s not true at all.” At many other companies in St. Louis, he said, inspectors from insurance companies do thorough inspections without interference from the city.
A representative for FM Global could not be reached on Thursday.
Oswald said the city’s “point all along has always been that an annual inspection as far as a visual inspection does very little in this situation. What you want is a professional there at any given time to ensure the thing is operating in accordance to the manufacturer’s standards.”
The federal report differed on that point.
“After 2012, if any city inspections … had been carried out, the large, irregular, torch-cut hole in the side of the (tank) skirt would have been a visible alteration to the vessel,” it said.
City code requires operators of high-pressure vessels to obtain permits before making repairs. As for Loy-Lange’s 2012 repair, Oswald said, “I think you’d have to talk with the company there.”
The 17.5-foot-long, 30-inch diameter carbon steel tank was part of the steam heat system used to manufacture corrugated cardboard. It was inspected and registered with the National Board of Boiler and Pressure Vessel Inspectors in February 1997, the report says.
In 2012, Loy-Lange hired Kickham Boiler and Engineering of St. Louis to repair a leak at the bottom of the boiler.
The bottom of the head was sliced off. From the detached section, a 24-inch disc was cut out of the middle. It was said to be badly corroded, pockmarked, like the surface of the moon. Engineers kept it around as a memento, the report says.
That left a 6-inch ring of the original head behind. A new disc fabricated by Kickham was patched onto it, and the combined piece was welded back to the tank, according to the report.
Kickham submitted a proposal about a month later to replace the entire bottom 4 feet of the tank. The new steel would have been 50 percent thicker than the original as a “corrosion allowance.”
But the box company never made that repair, the report says.
Representatives from Kickham and Loy-Lange could not be reached for comment on Thursday.
On Thursday, Cheryl MacKenzie, the team leader on the chemical safety investigation, said investigators were asking more questions about the inspection process and Kickham’s proposal for the more permanent repair.
The thickness of the tank should have been about a quarter-inch, but when Loy-Lange fired up the tank for the final time, the ring on the repaired head had been diminished to half that.
It finally blew, detaching from the repaired section, allowing the tank to launch.
The water inside the tank instantly converted to steam, increasing its volume by a factor of 75, Mackenzie said. The result was an explosion with the force of 350 pounds of TNT.
That failure was the immediate cause of the incident, MacKenzie said. “Broader causal factors are still under review and analysis” and a final report is expected later this year, she said.