Pressure Vessel BLEVE — Inadequate Boiler Inspection and Repair
Loy Lange Box Company Pressure Vessel Explosion
Loy Lange Box Company
📍 St. Louis, MO
Incident: April 3, 2017  •  CSB Report: August 2, 2022
4
Fatalities
Steam / Pressurized Condensate (SCR Vessel)
Chemical Involved
7
CSB Recommendations
📋 Incident Summary

On April 3, 2017, a semi-closed receiver (SCR) steam condensate pressure vessel at the Loy Lange Box Company manufacturing facility in St. Louis, Missouri, exploded violently. The vessel became airborne and crashed through the roof of an adjacent business, killing four people — one Loy Lange employee and three members of the public. The failure was a BLEVE resulting from years of unmitigated corrosion.

The CSB investigation found a cascade of failures: Kickham Boiler attempted a repair in 2012 but left damaged material in place. Arise Boiler Inspection issued a certificate accepting the inadequate repair without verifying its quality. The City of St. Louis missed multiple inspection opportunities. Loy Lange had no formal mechanical integrity program.

The August 2022 CSB report issued 7 recommendations to Loy Lange, Kickham Boiler, Arise Boiler Inspection, the National Board of Boiler and Pressure Vessel Inspectors, and the City of St. Louis — focused on inspection quality, repair verification, and third-party inspector accountability.

🔎 Key Findings
Finding 01
Vessel Corroded to Failure After Inadequate 2012 Repair
The SCR vessel had been chronically corroding; a 2012 repair attempt by Kickham Boiler left damaged material in place rather than replacing it — corrosion continued progressing to failure condition.
Finding 02
Third-Party Inspector Accepted Inadequate Repair
Arise Boiler Inspection issued an inspection certificate accepting the 2012 repair without adequately verifying that all damaged material had been removed and replaced — the certificate falsely indicated the vessel was in acceptable condition.
Finding 03
City of St. Louis Missed Multiple Inspection Opportunities
City inspectors had opportunities to identify the deficient vessel condition during required periodic inspections but did not adequately perform their inspection role.
Finding 04
Vessel Became Airborne — Crossed Property Boundary
The BLEVE propelled the SCR vessel airborne, where it crossed the property boundary and crashed through the roof of an adjacent business during occupied hours, killing three members of the public who had no connection to Loy Lange.
Finding 05
No Formal MI Program at Loy Lange
Loy Lange did not maintain adequate pressure vessel records, did not employ qualified inspection personnel, and had no mechanical integrity program to identify advancing vessel deterioration.
🔍 Root Causes
1
Inadequate Pressure Vessel Repair — Damaged Material Left In Place
Kickham Boiler's 2012 repair failed to remove and replace corroded vessel material to an acceptable standard — a structurally compromised vessel was left in pressure service.
2
Third-Party Inspection Failure — Certificate Issued Without Verification
Arise Boiler Inspection's failure to verify the adequacy of the repair and issuance of an inspection certificate for a substandard repair was a critical failure of the independent safety assurance system.
3
Regulatory Oversight Failure at Multiple Levels
The failure chain involved deficiencies at the repair contractor, third-party inspector, and municipal inspection levels — no single level of the pressure vessel inspection system caught the failures at other levels.
☑ CSB Recommendations
→ Loy Lange Box Company
Implement a formal pressure vessel MI program including documented vessel records, inspection schedules based on ASME/National Board standards, and qualified inspection personnel for all pressure-retaining equipment.
→ Kickham Boiler and Equipment
Establish written repair qualification standards requiring all corroded or damaged pressure vessel material be removed and replaced to original design specifications before a repair is accepted as complete.
→ Arise Boiler Inspection and Insurance
Develop and implement inspection verification procedures requiring physical confirmation that pressure vessel repairs meet applicable standards before inspection certificates are issued.
→ National Board of Boiler and Pressure Vessel Inspectors
Develop guidance for authorized inspection agencies on required verification steps for pressure vessel repairs, including criteria for rejecting substandard repairs.
→ National Board of Boiler and Pressure Vessel Inspectors
Evaluate and strengthen the authorized inspection agency accreditation process to include audit of repair acceptance review procedures.
→ City of St. Louis
Develop and implement enhanced municipal pressure vessel inspection procedures, including verification that third-party inspection certificates are current and that underlying documentation is reviewed.
→ City of St. Louis
Establish a boiler and pressure vessel record retention and tracking system ensuring all regulated vessels have current certificates and lapsed certifications trigger follow-up inspection.
💡 Lessons Learned
Pressure vessel inspection is a multi-layer safety system — repair contractor, third-party inspector, and regulatory inspector. When one layer fails, the others must catch the deficiency. All three layers failed at Loy Lange.
Issuing an inspection certificate for a substandard repair is a safety-critical error. Third-party inspectors must independently verify repair quality — they cannot accept contractor self-certification for pressure vessel fitness.
A BLEVE does not respect property boundaries. Pressure vessel failures at industrial facilities can kill members of the public in adjacent businesses — the hazard radius extends to wherever the vessel travels.
Chronic corrosion in pressure vessels progresses to failure unless inspected, detected, and mitigated. A mechanical integrity program is the systematic process that keeps compressed energy from becoming a projectile.
Small manufacturers often lack formal MI programs — regulatory inspection systems exist precisely to compensate for this gap, but only when inspections are performed rigorously and independently.
MI: Mechanical IntegrityPSI: Process Safety Information
🔨 Safety Meeting Toolbox Talk
►Do you know where the inspection records are for all pressure-retaining equipment at your facility — and whether their inspection certificates are current?
►If a boiler or pressure vessel received a repair, how would you verify that the repair met applicable standards before returning the equipment to service?
►Who at your facility is responsible for scheduling, tracking, and following up on pressure vessel inspections? Is there a formal program, or is it handled informally?
►Have you ever had a third-party inspection identify a deficiency that your own maintenance team had missed? What did you learn?
►How far could a vessel fragment travel if a pressure vessel at your facility failed catastrophically? Have you considered the off-site consequences of a BLEVE?
Immediate Action Items
✓Compile a complete inventory of all pressure-retaining equipment (vessels, boilers, heat exchangers) and verify current inspection certificates are on file for each item.
✓Review the last inspection report for your highest-pressure vessel and confirm that any identified deficiencies have been corrected with follow-up inspection documentation.
✓Verify that your pressure vessel inspection program specifies qualified inspection personnel or a certified third-party authorized inspection agency aligned with ASME or National Board standards.
✓Identify all pressure vessels that have undergone repairs in the last five years and confirm that repair documentation and post-repair inspection records are on file.
✓Brief your maintenance team on the Loy Lange incident and ask them to identify any pressure vessels with deferred or outstanding corrosion issues that have not been formally evaluated.
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 2 PSM elements (MI · PSI). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

Mechanical Integrity (MI)
Equipment must be designed, inspected, and maintained to operate safely in its intended service. Mechanical integrity failures — degraded equipment, missed inspections, deferred repairs — contributed to loss of containment here.
Supporting documents in our library →
Process Safety Information (PSI)
Accurate, complete Process Safety Information is the foundation every other PSM element depends on. When PSI is missing or wrong — chemistry data, equipment specs, P&IDs — the entire hazard analysis is built on a flawed base.
Supporting documents in our library →
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