Fatal Acetic Acid Release — Valve Maintenance Error
LyondellBasell La Porte Fatal Acetic Acid Release
LyondellBasell Industries / Turn2 Specialty Companies (contractor)
📍 La Porte, TX
Incident: July 27, 2021  •  CSB Report: May 25, 2023
2
Fatalities
30
Injuries
Acetic Acid (Hot, ~225°F)
Chemical Involved
📋 Incident Summary

On July 27, 2021, two contract employees were fatally injured and 30 others were transported to medical facilities following a massive release of approximately 100,000 pounds of hot acetic acid at the LyondellBasell facility in La Porte, Texas. Contract workers from Turn2 Specialty Companies were removing what they believed to be a non-pressure-retaining gearbox from a plug valve — but instead removed the pressure-retaining bonnet bolts, causing a catastrophic release of hot acetic acid (approximately 225°F) under full process pressure.

The CSB found that plug valve design is inherently ambiguous: pressure-retaining and non-pressure-retaining fasteners look nearly identical on many designs. No equipment-specific written procedure was provided to the contractors for this work, contractor oversight by LyondellBasell was inadequate, and the contractors had not been trained on the specific plug valve design. This incident exposed systemic weaknesses in contractor management and plug valve safety across the industry.

🔎 Key Findings
Finding 01
Ambiguous Plug Valve Design
Pressure-retaining bonnet bolts and non-pressure-retaining actuator mounting bolts appeared nearly identical on the plug valve, making it easy for workers to mistake one for the other.
Finding 02
No Equipment-Specific Maintenance Procedure
No written procedure specifically describing how to safely remove the gearbox from this plug valve design was provided to Turn2 contractors.
Finding 03
Inadequate Contractor Oversight
LyondellBasell did not verify that Turn2 employees were trained and qualified on this specific task or supervise the work on the high-hazard process connection.
Finding 04
Hazardous Energy Not Controlled
The acetic acid line was not de-inventoried or depressurized before the gearbox removal work began — full process pressure and temperature were maintained.
Finding 05
100,000 Pounds of Hot Acetic Acid Released
The resulting release was catastrophic: approximately 100,000 lbs of acetic acid at ~225°F created an immediately dangerous environment for workers in the area.
Finding 06
Inadequate Process Safety Information for Contractors
Contractors were not provided with equipment design information — such as plug valve type, design pressure, or content — necessary to safely perform the work.
🔍 Root Causes
1
Plug Valve Design Creates Confusion Risk
The lack of physical distinction between pressure-retaining and non-pressure-retaining fasteners on plug valves creates an inherent design hazard that has caused multiple incidents across the industry.
2
Absence of Equipment-Specific Procedures for Contractors
The failure to provide contractors with written, equipment-specific maintenance procedures is a persistent industry weakness that enables maintenance errors on complex process equipment.
3
Inadequate Contractor Safety Management
LyondellBasell's contractor management system did not ensure that Turn2 personnel were competent and qualified for work on this specific valve type under these process conditions.
4
Hazardous Energy Control Not Applied
The requirement to control hazardous energy (de-inventory and depressurize) before working on process connections was not enforced for this maintenance task.
☑ CSB Recommendations
→ LyondellBasell
Require equipment-specific procedures for all plug valve gearbox/actuator removals; verify contractor competency; require risk assessments before authorizing work.
→ Turn2 Specialty Companies
Develop and implement written, detailed procedures for process equipment work; train workers before authorizing task execution.
→ API
Revise API Standard 599 (Metal Plug Valves) to require clear marking of pressure-retaining components and Prevention through Design to prevent inadvertent removal.
→ ASME
Revise ASME B16.34 to require visual differentiation of pressure-retaining fasteners and Prevention through Design for new plug valve designs.
→ Valve Manufacturers Association
Develop industry guidance addressing plug valve design to prevent inadvertent removal of pressure-retaining components; work with API and ASME.
💡 Lessons Learned
Plug valve actuator/gearbox removal is a high-hazard task — equipment-specific written procedures identifying pressure-retaining vs. non-pressure-retaining fasteners are essential.
Contractor competency verification must go beyond general qualifications — contractors must demonstrate specific knowledge of the equipment they will work on.
Hot process lines must be de-inventoried and depressurized before any maintenance work on valves or connections — hazardous energy control is non-negotiable.
Prevention through Design in valve manufacturing (visually distinguishing pressure-retaining components) can prevent fatal maintenance errors across the industry.
A 100,000-lb release of a hot corrosive acid is catastrophic — robust written procedures and contractor oversight can prevent it.
PSM Element: Process Safety Culture & Continuous Improvement
🔨 Safety Meeting Toolbox Talk
▸Do we have equipment-specific written procedures for removing actuators and gearboxes from all plug valve types at our facility?
▸Are pressure-retaining components on our plug valves visually marked (paint, tags, or signage) to distinguish them from non-pressure-retaining hardware?
▸Does our contractor management system require verification that specific workers are competent and trained on the specific equipment they will work on?
▸Is de-inventorying and depressurizing process lines a required prerequisite in our work permit process for any valve or connection work?
▸Are all contractors provided with relevant process safety information (chemical properties, design pressure, temperature) before beginning work?
Immediate Action Items
✓Audit all plug valves in hot or hazardous service — mark pressure-retaining components with paint or permanent labels
✓Develop equipment-specific maintenance procedures for all plug valve gearbox/actuator removal tasks
✓Revise contractor management system to require task-specific competency verification for all high-hazard maintenance
✓Update work permit system to require mandatory de-inventory/depressurization of process lines before valve maintenance
✓Provide all contractors with process safety information (PSI) packages specific to the equipment and chemicals they will work on
🔗 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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