Washington D.C. January 23, 2026 – Today the U.S. Chemical Safety and Hazard Investigation Board (CSB) commended the city of St. Louis, Missouri, Board of Aldermen for implementing two important recommendations from the CSB’s investigation of the tragic explosion at the Loy-Lange Box Company in April 2017 that resulted in the deaths of four people.
On April 3, 2017, an explosion occurred at Loy-Lange when a pressure vessel catastrophically failed. The explosion fatally injured a Loy-Lange employee working nearby. The explosion also launched the pressure vessel out of the Loy-Lange building into the air, after which the vessel crashed through the roof of a nearby business, killing three other people.
When the CSB issued the agency’s final report for the investigation in July 2022, the CSB recommended that the Board of Aldermen revise the city’s Mechanical Code to adopt a national consensus standard to govern the requirements for the in-service inspection of boilers and pressure vessels in the city. The CSB also recommended that the Board of Aldermen revise the Mechanical Code to require that pressure vessel inspections be performed by an inspector meeting the National Board of Boiler and Pressure Vessel Inspectors’ (NBBI) standards for in-service (IS) inspections.
In response to the CSB recommendations, the Board of Aldermen recently approved revisions to the city’s Mechanical Code that standardize in-service inspections for pressure vessels and establish minimum qualifications for personnel conducting in-service inspections of boilers and pressure vessels. The updated ordinance, which took effect November 15, 2025, strengthens in-service inspections by requiring that they be conducted in accordance with the National Board Inspection Code. The updated ordinance also requires that such inspections be performed by a NBBI IS commissioned inspector.
CSB Chairperson Steve Owens said, “The Board of Aldermen have taken an extremely important step toward helping prevent another tragic incident like the one at Loy-Lange from happening again.”
The only remaining open recommendation from the CSB’s Loy Lange investigation was issued to the Mayor of St. Louis. The CSB recommended that the Mayor distribute and communicate the findings of the CSB’s investigation report to all licensed stationary engineers and all entities in St. Louis registered as owning/operating boilers and pressure vessels in the city. The CSB and the Mayor’s office have been actively communicating about the recommendation. The CSB is looking forward to the implementation of this final Loy Lange recommendation in the near future.
The CSB is an independent, nonregulatory federal agency charged with investigating incidents and hazards that result, or may result, in the catastrophic release of extremely hazardous substances. The agency’s core mission activities include conducting incident investigations; formulating preventive or mitigative recommendations based on investigation findings and advocating for their implementation; issuing reports containing the findings, conclusions, and recommendations arising from incident investigations; and conducting studies on chemical hazards.
The agency's board members are appointed by the President subject to Senate confirmation. The Board does not issue citations or fines but makes safety recommendations to companies, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA.
Please visit our website, www.csb.gov. For more information, contact Director of External Affairs Hillary Cohen at [email protected].