Skip to content

Wacker Polysilicon Chemical Release

Overview

On November 13, 2020, during maintenance activities at the Wacker Polysilicon North America facility in Charleston, Tennessee, a graphite heat exchanger cracked after excessive torque was applied to flange bolts on the heat exchanger’s discharge pipe. Hydrogen chloride (HCl) was released. Seven workers from two contracted companies were in close proximity to the release. One worker was fatally injured. Two workers were seriously injured from falls while attempting to escape. One worker sustained chemical burns. The CSB final report identified ineffective written procedures, lack of hazardous energy control, lack of a formal SIMOPs program, and insufficient means of egress as key issues.

Incident Snapshot

Field Value
Facility / Company Wacker Polysilicon North America LLC
Location Charleston, Tennessee
Incident Date 2020-11-13
Investigation Status The CSB's investigation was released on June 15, 2023.
Accident Type Chemical Manufacturing - Fire and Explosion Investigation
Final Report Release Date 2023-06-15

What Happened

  • On November 2, 2020, Wacker initiated a scheduled two-week outage, called a turnaround, of the HCl regeneration unit to perform routine maintenance, equipment upgrades, and equipment repairs.
  • During the night shift on November 12, 2020, Wacker operators restarted the HCl regeneration unit, introduced acid into the system, and brought the unit to operating temperatures and pressures.
  • At approximately 7:00 a.m. on November 13, 2020, the unit reached normal operating conditions.
  • At 8:00 a.m., Wacker issued Jake Marshall a work permit to perform a “hot torque” of heat exchanger AW234.
  • At 8:10 a.m., the Wacker permit authorizer left the area and the Jake Marshall foreman led one journeyman and two apprentices to the AW234 heat exchanger to review the tasks and indicate the specific piping connections they were to torque.
  • Around 9:15 a.m., Pen Gulf workers arrived on the fifth floor and began preparing for insulation activities.
  • Some time before 10:00 a.m., the Jake Marshall journeyman and apprentice pipefitters returned to the fifth floor of the structure wearing full-body chemical-resistant suits, rubber boots and gloves, and full-face respirators with acid-gas cartridges.
  • Just after 10:00 a.m., the Jake Marshall apprentice pipefitter used the torque wrench set at 40 ft-lbs to check the torque on the blue-colored bolts.
  • At 10:04 a.m., the excess torque applied to the blue-colored bolts caused the graphite heat exchanger AW234 to crack, releasing gaseous HCl.
  • The release continued for approximately three minutes, until all gaseous HCl had escaped from the system.
  • After the release stopped at approximately 10:07 a.m., the three Jake Marshall workers and one Pen Gulf worker used the staircase to evacuate the area and reach the ground.

Facility and Process Context

  • Wacker Polysilicon North America LLC began production operations in Charleston, Tennessee, in 2016.
  • Wacker manufactures silicones and hyperpure polycrystalline silicon (polysilicon) and also began producing pyrogenic silica in 2019.
  • The incident involved the HCl regeneration unit and graphite heat exchanger AW234 used in the HCl regeneration process.
  • The fifth-floor platform was approximately 70 feet above ground level and was equipped with a single staircase for access and egress.
  • Scaffolding had been assembled on the fifth floor to support scheduled maintenance activities.
  • An emergency safety shower was also located on the fifth-floor platform.
  • Wacker is regulated by OSHA PSM and EPA RMP for processing highly hazardous chemicals and extremely hazardous substances, including HCl.

Consequences

  • Fatalities: 1
  • Injuries: 2 serious injuries; 1 chemical burn injury
  • Environmental release: Release of gaseous hydrogen chloride (HCl) from the cracked graphite heat exchanger.
  • Facility damage: $214,000 in property damage; graphite heat exchanger cracked.
  • Operational impact: The release lasted approximately three minutes and required evacuation of the fifth-floor platform.

Key Findings

Immediate Causes

  • The inadvertent over-torquing of bolts on an HCl piping flange connection to a heat exchanger, which resulted in the fracture of the heat exchanger outlet piping and a release of gaseous HCl.
  • The failure of the graphite heat exchanger nozzle was due to over-torquing the bolts connecting the graphite nozzle to PTFE-lined equipment.

Contributing Factors

  • Wacker’s and Jake Marshall’s reliance on verbal instructions, communicated sequentially by three separate people without a detailed task-specific procedure, increased the likelihood of miscommunication or misunderstanding of the task steps and precautions.
  • Poor visibility on the platform as a result of the release.
  • The location of the release and resulting lack of visibility prevented all of the workers from being able to access the single staircase to exit the platform.
  • The employee's chemical suit became entangled and tore open.
  • The tear allowed HCl to get inside the suit.
  • Wacker’s limited means of egress from the equipment access structure.
  • The absence of regulatory guidance and standards on means of egress from open-air industrial structures.
  • The absence of regulatory and published industry guidance on SIMOPs.

Organizational and Systemic Factors

  • Wacker did not have a written procedure to execute the torquing task and instead relied on the piping manufacturer’s equipment manual to communicate the torque requirements to the contractors.
  • Wacker did not treat torquing operations on equipment containing hazardous chemicals as a line break or as an activity that required isolation of hazardous energy since it did not involve the intentional opening of a line.
  • Wacker did not have a policy or procedure for evaluating SIMOPs.
  • Wacker’s maintenance management culture often allowed for the co-location of several unrelated work crews supporting maintenance tasks or turnaround efforts.
  • Wacker’s safe work permit process did not explicitly require SIMOPs considerations and relied on the knowledge and decisions of the specialists authorized to sign and issue the work permits to the work crews.
  • Wacker’s permitting practice allowed any available specialist to serve as authorized signer of a work permit, regardless of their familiarity with the work or other activities planned in the same location.
  • Wacker’s COVID-19 restrictions made it difficult to post and review active work permits for a given area.
  • Wacker considered the structure to be compliant with applicable building codes and standards and had received a certificate of occupancy by the local building code permitting authority.
  • Wacker’s lack of written procedures and lack of control of hazardous energy.
  • Wacker’s lack of a SIMOPs program and the absence of regulatory and published industry guidance on SIMOPs.
  • Wacker’s limited means of egress from the equipment access structure and the absence of regulatory guidance and standards on means of egress from open-air industrial structures.
  • The current IBC and NFPA building requirements do not provide for sufficient means of egress from elevated work platforms used for accessing equipment containing hazardous materials.

Failed Safeguards or Barrier Breakdowns

  • The piping installation and operation manual did not include the torque requirements for the bolts that were over-torqued.
  • The packet provided to Jake Marshall did not contain information indicating the 15 ft-lb torque recommendation for bolts connected to the graphite heat exchanger nozzle.
  • The Jake Marshall workers on the structure did not have the manufacturer’s drawing of the exchanger in their possession.
  • The safe work permit issued to Jake Marshall to perform the hot torque activities did not consider the hazardous energy control precautions.
  • Wacker did not perform a risk analysis to determine whether the hot torque task could be safely performed on operating equipment.
  • Wacker did not implement precautions to mitigate the risk of torquing bolts on operating equipment prior to issuing a safe work permit.
  • Wacker did not have a SIMOPs policy or procedure.
  • Wacker’s safe work permit process did not explicitly require SIMOPs considerations.
  • The permit authorizer did not realize that there was the potential for the Jake Marshall work task to hazardously impact another work crew.
  • No secondary form of egress was installed prior to the date of the incident.
  • The platform’s single means of egress.
  • Personal protective equipment (PPE) with a rip.

Recommendations

  1. 2021-01-I-TN-R1 | Recipient: Occupational Safety and Health Administration (OSHA) | Status: Open – Awaiting Response or Evaluation/Approval of Response | Summary: Promulgate a standard or modify existing standards to require employers to ensure the coordination of simultaneous operations (SIMOPs) involving multiple work groups, including contractors. Ensure that the requirements of this standard or standards apply to both general industry and construction activities and are not limited to activities occurring within confined spaces. Include in the standard requirements for Employers to ensure that the following activities occur: identification of potential SIMOPs; identification of potential hazardous interactions; evaluation and implementation of necessary safeguards to allow for safe SIMOPs; coordination, including shared communication methods, between the SIMOPs; and inclusion of emergency response personnel or services in the planning and coordination of the SIMOPs.
  2. 2021-01-I-TN-R2 | Recipient: Occupational Safety and Health Administration (OSHA) | Status: Open – Awaiting Response or Evaluation/Approval of Response | Summary: Develop a safety product providing guidance on the coordination of simultaneous operations (SIMOPs) involving multiple work groups, including contractors, that is not limited to confined space or construction. Provide guidance on the following activities: identification of potential SIMOPs; identification of potential hazardous interactions; evaluation and implementation of necessary safeguards to allow for safe SIMOPs; coordination, including shared communication methods, between the SIMOPs; and inclusion of emergency response personnel or services in the planning and coordination of the SIMOPs.
  3. 2021-01-I-TN-R3 | Recipient: Wacker Polysilicon | Status: Closed – Acceptable Action | Summary: Develop detailed maintenance procedures for torquing activities which clearly communicate differing equipment torque specifications; include procedural requirements for all torquing activities conducted on equipment containing hazardous material to perform an engineering and risk analysis and implement safeguards; ensure that terms such as “hot torque” are clearly defined and employees and contractors are trained on these terms; and ensure that procedures and training conform to the mechanical integrity requirements of the Process Safety Management (PSM) standard and the Risk Management Program (RMP) rule.
  4. 2021-01-I-TN-R4 | Recipient: Wacker Polysilicon | Status: Closed – Acceptable Action | Summary: Develop policy requirements to ensure torquing activities performed on equipment containing hazardous energy are performed safely, document these requirements in procedures, and ensure employees and contractors are trained on these procedures.
  5. 2021-01-I-TN-R5 | Recipient: Wacker Polysilicon | Status: Closed – Acceptable Action | Summary: Develop and implement a formalized Simultaneous Operations (SIMOPs) program addressing planned and/or permitted co-located work tasks and ensure relevant staff are trained on execution of the SIMOPs program.
  6. 2021-01-I-TN-R6 | Recipient: Wacker Polysilicon | Status: Closed – Acceptable Action | Summary: Install additional means of egress for the T230 desorption tower platforms and other multi-floor equipment structures on-site, and ensure workers are made aware of exit locations from the structure platforms through training, drills, or other techniques as appropriate.
  7. 2021-01-I-TN-R7 | Recipient: Tennessee Occupational Safety and Health Administration (TOSHA) | Status: Open - Unacceptable Response/No Response Received | Summary: Promulgate a standard or modify existing standards to require employers to ensure the coordination of simultaneous operations (SIMOPs) involving multiple work groups, including contractors.
  8. 2021-01-I-TN-R8 | Recipient: Center for Chemical Process Safety (CCPS) | Status: Closed – Acceptable Action | Summary: Develop and publish a safety product on Safe Work Practices, including detailed and practical guidelines for evaluating simultaneous operations (SIMOPs). The product, at a minimum, should address the content found in CCPS’s website resource for implementing Safe Work Practices and discuss guidelines for a SIMOPs life cycle, including methods to identify SIMOPs, methods to conduct a SIMOPs hazard assessment, safeguards and controls pertaining to SIMOPs, preparation for SIMOPs, and SIMOPs execution.
  9. 2021-01-I-TN-R9 | Recipient: International Code Council (ICC) | Status: Open – Awaiting Response or Evaluation/Approval of Response | Summary: Amend the International Building Code (IBC) to address conditions that may require multiple means of egress from elevated equipment platforms used for accessing equipment containing materials that pose physical and health hazards, such as the one used at Wacker in this incident. Specify the minimum number of egress points to increase the likelihood of worker escape in the event of a hazardous material release.
  10. 2021-01-I-TN-R10 | Recipient: National Fire Protection Association (NFPA) | Status: Open – Awaiting Response or Evaluation/Approval of Response | Summary: Revise NFPA 101 Life Safety Code, NFPA 55 Compressed Gases and Cryogenic Fluids Code, or NFPA 400 Hazardous Materials Code to address conditions which may require multiple means of egress from elevated industrial structures containing hazardous materials posing physical and health hazards, regardless of their combustibility, burn rate, or likelihood of explosion. The guidance should address egress situations for workers on unwalled, elevated structures in the presence of materials posing physical and health hazards. Specify the minimum number of egress points to increase the likelihood of worker escape in the event of a hazardous material release.

Key Engineering Lessons

  • Torquing activities on equipment containing hazardous material require task-specific written procedures that clearly distinguish torque specifications for different connections.
  • Hot torque work on operating equipment should be subject to engineering and risk analysis with safeguards implemented before work is authorized.
  • Safe work permit processes should explicitly consider hazardous energy control and simultaneous operations involving co-located work crews.
  • Elevated equipment access structures used for hazardous materials should have more than one means of egress when a single exit could be blocked by a release.
  • Procedures and training should define terms such as “hot torque” so contractors and employees understand the work scope and precautions.

Source Notes

  • Priority 1 final report facts were used to resolve conflicts over incident sequence, causes, consequences, and recommendations.
  • The Spanish translation and English final report were consistent on the core incident facts; English wording was preferred where available for official terminology.
  • Recommendation status change summaries at priority 3 were used to confirm later recommendation statuses and closure actions.
  • The supporting investigation update at priority 4 was used only where it provided incident details not conflicting with the final report.
  • The incident involved seven workers from two contracted companies; one fatality, two serious injuries from falls, and one chemical burn injury are reflected in the consolidated consequences.

Similar Incidents

Incidents sharing the same equipment, root causes, or hazard types.

Same Equipment

Same Root Cause

Same Hazard

← View in Knowledge Graph