Fatal Vapor Cloud Explosion
Yenkin-Majestic Resin Plant Vapor Cloud Explosion and Fire
Yenkin-Majestic Paint / OPC Polymers Corporation
📍 Columbus, OH
Incident: April 8, 2021  •  CSB Report: November 30, 2023
1
Fatalities
8
Injuries
Flammable Resin Vapors / Solvents
Chemical Involved
📋 Incident Summary

On April 8, 2021, an explosion and fire at the Yenkin-Majestic paint and OPC Polymers Corporation resin plant in Columbus, Ohio, fatally injured one employee and sent eight others to area hospitals. A low-pressure process vessel (below 15 psig) failed due to an unauthorized alteration — the vessel had been modified without a formal engineering design review or pressure test — releasing flammable vapors that ignited as a vapor cloud explosion.

The CSB found that low-pressure process vessels (below 15 psig) containing flammable chemicals at Yenkin-Majestic were not covered by the ASME Boiler and Pressure Vessel Code, had no formal mechanical integrity program, and lacked required documentation. The facility had no flammable gas detection, no flame-resistant (FR) clothing requirements, and had resisted implementing CSB recommendations post-incident — all seven recommendations remain open.

🔎 Key Findings
Finding 01
Inadequate Mechanical Integrity for Low-Pressure Vessels
Low-pressure process vessels containing flammable chemicals were altered without engineering review, pressure testing, or documentation — creating a failure-prone vessel.
Finding 02
No Flammable Gas Detection
The plant had no lower explosive limit (LEL) detectors capable of detecting a flammable vapor release before ignition.
Finding 03
No Design Basis Documentation
The altered vessel lacked design documentation, making it impossible to determine appropriate operating limits, inspection intervals, or repair standards.
Finding 04
No Flame-Resistant (FR) Clothing Requirement
Workers handling flammable chemicals in operating areas were not required to wear FR garments, increasing burn injury severity.
Finding 05
Prevention Through Design Not Applied
The facility's new resin plant was not designed using Prevention through Design (PtD) principles; inherently safer design options were not considered.
Finding 06
Resistance to Corrective Action
Despite all seven CSB recommendations remaining open, Yenkin-Majestic/OPC has not implemented required mechanical integrity, gas detection, or PPE improvements.
🔍 Root Causes
1
Low-Pressure Vessel Outside ASME Code
Process vessels operating below 15 psig are not required to meet ASME Boiler and Pressure Vessel Code, creating a regulatory gap for vessels in flammable chemical service.
2
Inadequate MI Program
No mechanical integrity program existed for low-pressure process vessels; alterations were made without design assessment, pressure testing, or inspection documentation.
3
Absence of Flammable Gas Safeguards
Without LEL detection and alarms, workers had no warning that a flammable vapor cloud was accumulating — the first indication was the explosion itself.
4
Absence of API/Industry Standards Application
Recognized and generally accepted good engineering practices (RAGAGEP) from API and ASME for pressure vessel inspection and alteration were not applied to low-pressure vessels.
☑ CSB Recommendations
→ Yenkin-Majestic/OPC
Update MI procedures for all low-pressure process vessels in flammable chemical service to adopt API 510 or National Board Inspection Code alteration guidance.
→ Yenkin-Majestic/OPC
Document applicable design and construction standards for all pressure vessels; implement LEL detection with alarms; require FR garments in all operating areas.
→ Yenkin-Majestic/OPC
Implement Prevention through Design in future resin plant designs using a documented design safety review and PHA process.
→ American Petroleum Institute (API)
Develop specific design, construction, and alteration guidance for low-pressure process vessels in flammable chemical service (below 15 psig).
→ ASME
Assist API in developing guidance for low-pressure vessels in flammable service; reference ASME BPVC Section VIII, Division 1 for new designs.
💡 Lessons Learned
Low-pressure process vessels (below 15 psig) in flammable chemical service are NOT exempt from mechanical integrity requirements — they must be treated with the same rigor as ASME-coded vessels.
Vessel alterations — however minor they seem — require engineering design review, pressure testing, and documentation before returning to service.
Flammable gas (LEL) detection is a critical layer of protection: the absence of detection means the first warning of a release may be an explosion.
Flame-resistant (FR) clothing is a baseline PPE requirement anywhere flammable chemicals are handled — it significantly reduces burn severity.
Prevention through Design must be applied from the start of process design — retroactively adding safeguards is more costly and often less effective.
PSM Element: Process Safety Culture & Continuous Improvement
🔨 Safety Meeting Toolbox Talk
▸Do we have documented design basis, inspection records, and alteration history for ALL process vessels in flammable chemical service, including those below 15 psig?
▸Is LEL detection installed with visible and audible alarms in all areas where flammable chemicals are processed?
▸Are all process vessel alterations reviewed and approved through an engineering MOC before implementation?
▸Do all workers in flammable chemical operating areas wear FR-rated garments?
▸Has a Prevention through Design review been conducted for our current process layouts and equipment selections?
Immediate Action Items
✓Inventory all low-pressure process vessels in flammable service and establish MI records for each
✓Implement engineering MOC process that includes design review and pressure testing for all vessel alterations
✓Install LEL detectors with audible and visual alarms in all resin/solvent processing areas
✓Establish FR garment requirement for all workers in flammable chemical operating zones
✓Conduct Prevention through Design review for all new process equipment installations
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 1 PSM element (PHA). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

Process Hazard Analysis (PHA)
A structured PHA or HAZOP study exists to identify exactly these scenarios before they occur. When PHA is absent, superficial, or overdue for revalidation, hazards operate unseen until they kill someone.
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