ST. LOUIS – More than five years after an industrial storage tank exploded in Soulard, killing four people and hurting three others, federal safety investigators released a video that shows the series of mistakes that led to the tragedy.

The explosion occurred on the morning of April 3, 2017, at the Loy-Lange Box Company, located at 222 Russell Boulevard. The 2,000-pound steel pressure vessel went airborne and crashed through the roof of Faultless Healthcare Linen, located at 2030 S. Broadway, approximately 520 feet away. A third building, Pioneer Industrial, located at 400 Russel Boulevard, sustained water damage.

Google Map illustration showing the trajectory of the exploded storage tank, which crashed through the roof of Faultless Healthcare Linen. (Courtesy: FOX 2)

Kenneth Trentham, an employee at Loy-Lange, was killed in the explosion. He was 59.

Three Faultless Healthcare Linen employees were killed: 46-year-old Christopher Watkins, his wife, 43-year-old Tonya Gonzalez-Suarez, and their friend, 53-year-old Clifford Lee. It was trio’s first day on the job at FHL.

Their families and the three people who were injured sued Loy-Lange and other companies for negligence. In July 2019, the lawsuits were settled for a combined $47 million.

The U.S. Chemical Safety and Hazard Investigation Board (USCSB) investigated the explosion and found four key safety issues that led to the pressure vessel’s failure:

  • Uncontrolled pressure vessel corrosion
  • Ineffective pressure vessel repair
  • Gaps in pressure vessel inspection and regulation
  • Deficient process safety management systems

“Had Loy-Lang instituted elements of an effective safety management system, including mechanical integrity, incident investigation, and effective corrosion-prevention programs, the hazard of corrosion could have been mitigated, and this incident could have been prevented,” said Drew Sahli, USCSB lead investigator.

The USCSB learned that in 2012, a leak was discovered at the bottom of the pressure vessel due to corrosion caused by the presence of oxygenated water. The oxygen was supposed to be removed from the water in a makeup tank prior to flowing into the pressure vessel, which consisted of the makeup tank being heated to 200 degrees Fahrenheit and treating the water with oxygen-scavenging chemicals. But the USCSB discovered the water had not properly been treated. Meaning that, over time, oxygenated water would gather at the bottom of the vessel and corrode the steel.

But instead of replacing the entire bottom head of the tank, as required by federal regulatory code, only a portion was replaced, leaving a corroded outer ring behind. That outer ring corroded further over the next five years.

City of St. Louis municipal code requires annual inspections of all boilers and pressure vessels. But during the lifespan of the pressure vessel, Loy-Lang never applied for an installation or inspection permit, nor did they register the tank, meaning the city was not aware of the device.

Fast-forward to Friday, March 31, 2017. The storage tank was leaking again, along the corroded outer ring of the bottom head. A local welding company was contacted to assess the leak and make repairs. However, the company could not dispatch anyone to Loy-Lang until the following Monday – April 3.

Loy-Lang employees continued to operate the pressure vessel throughout the day on Friday. On the morning of April 3, the tank was turned on at 6 a.m. as normal. By 7:20 a.m., the pressure vessel failed. The water in the pressure vessel turned into steam and resulted in what the USCSB called a boiling liquid expanded vapor explosion.

The energy released in the explosion was equivalent to about 350 pounds of TNT, the USCSB said at the time.

Watch the USCSB’s video on the Soulard explosion.