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Loy Lange Box Company Pressure Vessel Explosion

Overview

On April 3, 2017, the Semi-Closed Receiver (SCR) at Loy-Lange Box Company catastrophically failed during steam system startup. The failure caused a steam explosion that killed one Loy-Lange employee and three members of the public. The vessel was launched from the building, traveled about 520 feet, and crashed through the roof of a nearby business. The CSB found that the failure resulted from oxygen pitting corrosion and generalized corrosion that thinned the bottom head, combined with an inadequate 2012 repair that left damaged material in place and deficiencies in Loy-Lange's operations, policies, and process safety practices.

Incident Snapshot

Field Value
Facility / Company Loy-Lange Box Company
Location St. Louis, MO
Incident Date 04/03/2017
Investigation Status The CSB's final report was released at a public meeting on 7.29.2022.
Accident Type Pressure Vessel Explosion
Final Report Release Date 07/29/2022

What Happened

  • On Friday, March 31, 2017, Loy-Lange stationary engineers observed a leak that appeared to be coming from underneath the SCR.
  • Loy-Lange continued operating the leaking pressure vessel throughout the remainder of the Friday production schedule and shut down the steam system as normal that evening.
  • The following Monday a Loy-Lange stationary engineer began his normal start-up routine at about 6:00 a.m.
  • At around 7:20 a.m. on April 3, 2017, the SCR bottom head catastrophically failed.
  • The SCR was launched from the Loy-Lange building and into the air.
  • The vessel remained airborne for approximately 10 seconds and traveled laterally approximately 520 feet.
  • The SCR fell through the roof of the nearby Faultless Healthcare Linen company one block away, where it came to rest.
  • As a result of the incident, one stationary engineer at Loy-Lange was fatally injured.
  • At Faultless Healthcare Linen, three employees were fatally injured when the SCR fell through the roof.

Facility and Process Context

  • Loy-Lange manufactured corrugated cardboard and used it to manufacture other products, such as cardboard boxes and retail product displays.
  • The Loy-Lange steam system was typically in operation during the day shift, Monday through Friday, matching the operating cycles of the corrugation process.
  • The steam system was started up in the morning and shut down at the end of the day each weekday, and it remained shut down over weekends.
  • Steam heat is crucial in the production of high-quality corrugated board.
  • The SCR stored hot condensate and was part of the steam generation system.
  • The SCR was physically mounted to the floor via a cylindrical skirt that was welded to the bottom edge of the cylindrical portion of the vessel.
  • The skirt acted as a stand and allowed room for a bottom drain line used periodically to flush condensate to the sewer.
  • St. Louis city water was brought in as make-up water, passed through a water softener, and then into a stainless steel make-up tank before being added to the SCR as needed.
  • Chemicals were added from the chemical tank to both the make-up tank and the SCR to control corrosion.
  • The stationary engineer analyzed water samples daily from the make-up tank and the water returned to the SCR from the steam separator.
  • Once a week, a water treatment specialist also analyzed samples from the boiler feed water, condensate from the steam header, and make-up water system.

Consequences

  • Fatalities: 4
  • Injuries: 1 stationary engineer at Loy-Lange was fatally injured; one Loy-Lange employee was left in critical condition
  • Environmental Release: None reported
  • Facility Damage: The SCR was launched from the Loy-Lange building and into the air, fell through the roof of the nearby Faultless Healthcare Linen company, and a third building in the vicinity, owned by Pioneer Industrial Group, suffered damage when a large piece of pipe punctured the roof and ruptured its water sprinkler system. A section of 1.5-inch pipe approximately seven feet in length pierced the windshield and embedded in the dashboard and through the floorboard of an unoccupied pickup truck parked in the area.
  • Operational Impact: Loy-Lange no longer operates its steam system.

Key Findings

Immediate Causes

  • oxygen pitting corrosion and generalized corrosion which thinned the pressure vessel bottom head until it could no longer contain the pressure inside the vessel
  • The vessel failed due to corrosion of the 6" ring of the original bottom head, resulting in the circumferential split of the ring and subsequent separation of the entire tank circle from the SCR.
  • The immediate cause of this incident is the mechanical integrity failure of the material of the original bottom head that remained in service following the 2012 repair.

Contributing Factors

  • deficiencies in Loy-Lange’s operations, policies, and process safety practices that failed to prevent or mitigate chronic corrosion in the pressure vessel
  • Kickham Boiler and Engineering, Inc.’s performance of an inadequate repair to the SCR in 2012 that left damaged material in place
  • Contributing to the incident was the City of St. Louis’s missed opportunities to identify and ensure the inspection of the SCR.
  • Contributing to the incident was Arise’s acceptance of and failure to detect Kickham’s inadequate repair.
  • Contributing to the incident were gaps in Arise’s and the National Board of Boiler and Pressure Vessel Inspectors’ repair inspection requirements.
  • The thinness of the corroded 6" ring of original head material provided an inherent circumferential weakness that allowed the entire 24" diameter tank circle repair piece to separate from the SCR at one moment.
  • The SCR was uniquely vulnerable to catastrophic failure because the severe corrosion of the 6" ring left it much thinner than the tank circle.
  • The bottom of the SCR below the outlet nozzle to the steam generator is a "dead leg."
  • Any sediment or solid material returning to the SCR from the corrugation process would fall down through the slowly flowing condensate in the SCR, and more likely than not, miss being drawn out with the steam generator feed.
  • Instead, it would fall to the bottom and collect there.
  • Stationary engineers reported that when conducting blowdowns, they did not see chunks or solids in the drained water, but that at times it was opaque.
  • No sampling of the bottoms for conductivity or other parameters was carried out.
  • The City of St. Louis has not provided the CSB with any evidence of inspections of the SCR.
  • The CSB has found no evidence indicating that LLBC requested a permit for the repair or that the city issued a permit.
  • The unrecognized severe corrosion of the 6-inch ring left the SCR uniquely vulnerable to catastrophic failure.
  • Additional causal factors were gaps in regulatory oversight specific to boiler inspections by the City of St. Louis.

Organizational and Systemic Factors

  • Loy-Lange did not have a robust mechanical integrity program that ensured the SCR was operating safely as intended and designed.
  • Loy-Lange never conducted an incident investigation when corrosion was found in the steam generation system.
  • Loy-Lange did not establish an inspection program that addressed the SCR’s corrosion and thinning.
  • Loy-Lange did not have a comprehensive process safety management system.
  • Loy-Lange did not take effective action to ensure that policies, procedures, and records critical to the management, operation and maintenance of its steam system were stored in such a manner that would prevent their destruction in a catastrophic incident.
  • Resource limitations contributed to the City of St. Louis’s irregular inspection of the Loy-Lange facility, which contributed to the City’s missed opportunities to identify and inspect the SCR.
  • The City of St. Louis did not inspect the SCR primarily because Loy-Lange did not register it with the City.
  • The City of St. Louis requires compliance with the Mechanical Code of the City of St. Louis, a city-specific ordinance.
  • For inspection, the Mechanical Code requires annual inspection by the code official or representative.
  • The inspection shall be as thorough as circumstances permit.
  • The Mechanical Code requires welded repairs to pressure vessels to be performed only by organizations which possess the appropriate ASME Certificate of Authority with extension to field work or an "R" Certificate of Authority issued by the National Board of Boiler and Pressure Vessel Inspectors.
  • A permit shall be required for such work.
  • The City of St. Louis does not require filing for R-1s.
  • The Mechanical Code of the City of Saint Louis has a general provision stating that all mechanical systems shall be maintained in a safe condition.
  • This responsibility falls on the owner of the building that houses the mechanical system.
  • Inspections are managed by the "Mechanical Equipment Inspection Supervisor" (code official), appointed by the building commissioner.
  • The code official is tasked with hiring enough inspectors to accomplish all inspections and enforce all ordinances.
  • The code also specifically provides the caveat that the number of inspectors can be constrained to a number less than required, subject to the city’s budget.
  • Inspections within the jurisdiction of the State of Missouri are not left to the discretion of the inspector.
  • Inspectors hold commissions from the NBBI and must conduct inspections compliant with the National Board Inspection Code.
  • FM Global stated that they do not do inspections in the City of St. Louis because they have no jurisdictional authority.
  • Broader causal factors are still under review and analysis.
  • The facility also no longer contains equipment or operations typically associated with process safety management.
  • Loy-Lange’s safety program does not address process safety elements, as required by the recommendation.
  • Loy-Lange’s overall regulatory compliance
  • records and data management
  • City of St. Louis regulatory oversight specific to boiler inspections

Failed Safeguards or Barrier Breakdowns

  • Loy-Lange and its contractors did not effectively monitor, remove, or treat the dissolved oxygen in the steam generation system’s water.
  • Loy-Lange likely introduced oxygen into the SCR during its daily startup operation.
  • Loy-Lange did not ensure that the SCR was appropriately permitted as required by the City of St. Louis.
  • An internal inspection or use of ultrasonic thickness measurement could have identified the SCR’s corrosion and thinning.
  • Kickham likely left thinned material in place when it repaired the SCR bottom head in 2012, and in so doing did not adhere to the requirements of NBIC Part 3 Repair and Alterations.
  • A repair inspector’s initial evaluation of the damaged vessel is a critical step in determining whether the method of repair is appropriate.
  • Had the repair inspector detected and refused to accept Kickham’s non-conforming repair, this incident could have been prevented.
  • The City of St. Louis had the opportunity and authority to identify, seal from operation, and ensure the inspection of the SCR despite the vessel being unregistered.
  • Had the City of St. Louis identified, sealed from operation, and ensured the inspection of the SCR, this incident could have been prevented.
  • Had any party, such as Loy-Lange via a third-party inspector, FM Global, or the City of St. Louis, inspected the SCR per the existing industry guidance contained in standards such as API 510 or NBIC Part 2, and subsequently taken appropriate follow-up action, this incident could have been prevented.
  • Had Loy-Lange had a comprehensive process safety management system requiring the control and prevention of steam system corrosion, pressure vessel inspection, investigation of leaks, and pressure vessel repair quality assurance, the incident could have been prevented.
  • The City of St. Louis has not provided the CSB with any evidence of inspections of the SCR.
  • The CSB has found no evidence indicating that LLBC requested a permit for the repair or that the city issued a permit.
  • No sampling of the bottoms for conductivity or other parameters was carried out.
  • The stationary engineers did not see chunks or solids in the drained water, but at times it was opaque.
  • The hole cut into the skirt was not an engineered modification.
  • There was no analysis of the effect of cutting this hole on the structural integrity of the skirt or on the skirt’s ability to subsequently still support the SCR.
  • The repair organization did not measure the area adjacent to the flush patch to ensure it was above the required minimum thickness.
  • The repair organization did not otherwise effectively deal with the defects discovered during the repair.
  • The repair inspector did not ensure defects discovered during the repair were effectively addressed.
  • The City of St. Louis has not provided the CSB with any evidence of inspections of the SCR.
  • A robust preventive maintenance program would have identified compromised equipment that ultimately led to an incident.

Recommendations

  1. 2017-04-I-MO-R1 | Recipient: The Loy-Lange Box Company | Status: Closed – Acceptable Alternative Action | Summary: Develop and implement a comprehensive safety management system. Include in that system process safety elements recommended in industry guidance publications, such as the Center for Chemical Process Safety (CCPS) publication Guidelines for Risk Based Process Safety.
  2. 2017-04-I-MO-R2 | Recipient: Loy-Lange Box Company | Status: Closed – Acceptable Alternative Action | Summary: Engage a qualified third-party to conduct a comprehensive review or audit of Loy Lange’s regulatory compliance practices and current compliance status.
  3. 2017-04-I-MO-R3 | Recipient: Loy-Lange Box Company | Status: Closed – Acceptable Action | Summary: Implement an electronic records and data management system that preserves all critical company records, safety policies and procedures, and operational data. Ensure that such records are stored and can be accessed remotely in the event of a catastrophic incident.
  4. 2017-04-I-MO-R4 | Recipient: Board of Aldermen, City of St. Louis, MO | Status: Closed – Acceptable Action | Summary: Revise the City of St. Louis Mechanical Code to adopt a national consensus standard such as NBIC Part 2 to govern the requirements for inservice inspection of boilers and pressure vessels.
  5. 2017-04-I-MO-R5 | Recipient: Board of Aldermen, City of St. Louis, MO | Status: Closed – Acceptable Action | Summary: Revise the City of St. Louis Mechanical Code to require pressure vessel inspections be performed by a National Board of Boiler and Pressure Vessel Inspectors (NBBI) inservice (IS) commissioned inspector.
  6. 2017-04-I-MO-R6 | Recipient: Mayor, City of St. Louis, MO | Status: Open - Unacceptable Response/No Response Received | Summary: Distribute and communicate the findings of this report to all licensed stationary engineers and all registered boiler and pressure vessel owning/operating entities in the City of St. Louis.
  7. 2017-04-I-MO-R7 | Recipient: Arise, Inc. | Status: Closed – Acceptable Action | Summary: Update company policies and/or procedures by including prescriptive elements in the boiler and pressure vessel repair and alteration inspection and acceptance process that would prevent the acceptance of a non-conforming repair or alteration.
  8. 2017-04-I-MO-R8 | Recipient: National Board of Boiler and Pressure Vessel Inspectors (NBBI) | Status: Closed – Exceeds Recommended Action | Summary: Update NB-263 Rules for Commissioned Inspectors to include prescriptive elements in the boiler and pressure vessel repair and alteration inspection and acceptance process that would prevent the acceptance of a non-conforming repair.

Key Engineering Lessons

  • Corrosion in pressure vessels can progress to catastrophic failure when thinning is not detected by internal inspection or ultrasonic thickness measurement.
  • Daily startup and operating conditions can introduce oxygen and contribute to corrosion if dissolved oxygen is not effectively monitored, removed, or treated.
  • A repair that leaves damaged material in place can preserve a hidden weak section and allow severe localized thinning to remain in service.
  • Repair inspection and acceptance must verify that defects discovered during repair are effectively addressed and that non-conforming repairs are not accepted.
  • Pressure vessel inspection and permitting gaps can allow an unregistered or uninspected vessel to remain in service until failure.
  • Critical records, policies, and operational data should be preserved in a way that survives a catastrophic incident and remains accessible remotely.

Source Notes

  • Consolidated from the CSB final report and related recommendation status change summaries; final report facts were given highest priority where conflicts existed.
  • The final report identifies the incident as a Pressure Vessel Explosion involving the Semi-Closed Receiver (SCR) at Loy-Lange Box Company in St. Louis, MO, on April 3, 2017.
  • Recommendation status updates were used only for recommendation status fields and for corroborating findings where consistent with the final report.
  • Some supporting-document details use alternate wording for the same equipment and consequences; these were merged without adding external facts.

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