Fatal HCl Release — SIMOPs Failure
Wacker Polysilicon Fatal Hydrogen Chloride Release
Wacker Polysilicon North America
📍 Charleston, TN
Incident: November 13, 2020  •  CSB Report: June 15, 2023
1
Fatalities
3
Injuries
Hydrogen Chloride (HCl)
Chemical Involved
📋 Incident Summary

On November 13, 2020, seven workers were exposed to a hydrogen chloride (HCl) release at Wacker Polysilicon North America in Charleston, Tennessee. One worker was fatally injured, and three others sustained serious injuries. Workers performing a 'hot torque' activity on a HCl desorption tower flange were trapped on an elevated platform with only a single means of egress — which became immediately inaccessible when the flange connection failed and HCl began to release.

The CSB identified two critical failures: (1) simultaneous operations (SIMOPs) were not coordinated — another work crew was performing maintenance in the same area without awareness of the torquing activity; and (2) the elevated platform from which workers could not escape had only one exit route. The investigation also found inadequate torquing procedures that failed to distinguish pressure-retaining from non-pressure-retaining connections, and insufficient PPE requirements for the task.

🔎 Key Findings
Finding 01
Single Egress Point on Elevated Platform
The T230 desorption tower platform had only one exit route; when the HCl release began, the sole egress path was immediately in the path of the release, trapping workers.
Finding 02
No SIMOPs Coordination
Two separate work crews (torquing team and maintenance crew) were performing tasks in the same area simultaneously without coordination or shared awareness of each other's activities.
Finding 03
Inadequate Hot Torque Procedures
Torquing procedures did not clearly distinguish pressure-retaining from non-pressure-retaining connections, and did not require hazardous energy risk assessment before performing 'hot torque' activities.
Finding 04
Insufficient PPE for HCl Exposure
Workers were not adequately equipped with PPE appropriate to prevent serious injury from the sudden, high-concentration HCl release during maintenance.
Finding 05
Hazardous Energy Not Controlled
The hazardous energy (pressurized HCl in the process line) was not de-inventoried or isolated before performing torquing activities on the flange connection.
Finding 06
Regulatory Gap for SIMOPs
No OSHA standard specifically requires employers to coordinate simultaneous operations — a widely recognized industry gap for multi-crew maintenance activities.
🔍 Root Causes
1
Absence of SIMOPs Management Program
Wacker had no formal program for identifying, assessing, and coordinating simultaneous operations — a recognized process safety best practice and root cause of multiple CSB incidents.
2
Single Point of Egress
Engineering design of the elevated platform did not provide a second means of escape — workers were architecturally trapped once the HCl release began.
3
Inadequate Torque Procedure Design
The maintenance procedure for hot torque did not adequately address the hazardous energy control principles required to safely work on pressurized process connections.
4
Contractor Coordination Failures
Multiple work groups (Wacker employees and contractors) working in the same area without hazard communication, coordination, or a common work authorization process.
☑ CSB Recommendations
→ Wacker Polysilicon
Develop detailed hot torque procedures distinguishing pressure-retaining components; implement SIMOPs program; install additional means of egress on elevated platforms.
→ OSHA
Promulgate a standard requiring employers to coordinate simultaneous operations (SIMOPs) involving multiple work groups, including contractors.
→ CCPS
Develop and publish detailed guidelines for evaluating and managing simultaneous operations (SIMOPs) in industrial facilities.
→ NFPA and ICC
Update NFPA 101 and the International Building Code to require multiple means of egress from elevated industrial platforms containing hazardous materials.
→ TOSHA
Promulgate a state standard requiring coordination of SIMOPs across all industries in Tennessee.
💡 Lessons Learned
Simultaneous operations (SIMOPs) must be formally identified, assessed, and coordinated — multiple work crews in the same area without coordination creates cascading hazards.
Elevated work platforms in areas with hazardous chemicals MUST have multiple means of egress — a single exit that becomes compromised by a release traps workers.
Hot torque on live process connections requires the same level of hazardous energy control analysis as LOTO — hot torque is NOT routine maintenance.
Distinguishing pressure-retaining from non-pressure-retaining fasteners on valves and process connections must be explicit in procedures and visually marked on equipment.
HCl and other corrosive toxic chemicals require immediate egress in the event of a release — PPE is a last resort, not a substitute for engineered safeguards.
PSM Element: Process Safety Culture & Continuous Improvement
🔨 Safety Meeting Toolbox Talk
▸Do we have a formal SIMOPs identification and coordination process for all multi-crew and contractor maintenance activities?
▸Have all elevated platforms in hazardous chemical areas been evaluated for adequate means of egress?
▸Do our hot torque procedures include a hazardous energy risk assessment and clearly identify pressure-retaining vs. non-pressure-retaining components?
▸Is de-inventorying hazardous process lines evaluated as a prerequisite before any work on pressurized connections?
▸Are all contractor crews integrated into our SIMOPs coordination and work permitting system?
Immediate Action Items
✓Develop and implement a formal SIMOPs identification and management program for all maintenance activities
✓Conduct a platform egress audit — identify all single-exit elevated platforms in hazardous areas and install secondary egress routes
✓Revise hot torque procedures to require risk assessment, distinguish pressure-retaining fasteners, and specify PPE
✓Implement visual identification (paint/signage) of pressure-retaining components on all flanges and valve connections
✓Integrate all contractor work crews into unified work permit, SIMOPs, and hazard communication system
🔗 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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