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Kuraray Pasadena Release and Fire

Overview

At 10:28 a.m. on May 19, 2018, an ethylene release at Kuraray America, Inc.'s EVAL plant in Pasadena, Texas, ignited and injured 23 workers. The incident occurred during startup of EVAL Reactor 2 following a scheduled maintenance turnaround. High-pressure conditions activated the reactor's emergency pressure-relief system, which discharged flammable ethylene vapor through horizontally aimed piping into an area where contractors were working, including welding activities. The CSB determined the cause was the long-standing emergency pressure-relief system design that did not discharge to a safe location.

Incident Snapshot

Field Value
Facility / Company Kuraray America, Inc.
Location Pasadena, TX
Incident Date 05/19/2018
Investigation Status Released December 21, 2022
Accident Type Hot Work - Explosion and Fire Investigation
Final Report Release Date 12/16/2022

What Happened

  • April 6, 2018: Kuraray started its 2018 maintenance turnaround.
  • April 22, 2018: Kuraray replaced an existing ammonia-based refrigeration system with a new system that used a hydrofluorocarbon refrigerant and prepared to start flowing chilled liquid through process equipment, including the EVAL Reactor 2 heat exchanger.
  • May 10, 2018: Kuraray cleared and restricted the entry of nonessential personnel when operations personnel introduced ethylene back into the facility.
  • May 14, 2018: personnel finished commissioning a new refrigeration compressor; chilled liquid at a temperature as low as 4°F circulated through the EVAL Reactor 2 heat exchanger.
  • May 15, 2018: Kuraray operations personnel started removing oxygen from EVAL Reactor 2 using nitrogen.
  • May 16, 2018: Kuraray operators completed the process of removing oxygen from EVAL Reactor 2.
  • May 17, 2018: Kuraray cleared out nonessential personnel as operators worked to bring ethylene back into EVAL Reactor 2 and started removing nitrogen from EVAL Reactor 2.
  • May 18, 2018: Kuraray operations personnel introduced methanol and ethylene into EVAL Reactor 2 and began increasing the system pressure by feeding more ethylene to the reactor to check for leaks.
  • At about 11:25 p.m. on May 18, 2018, the ethylene and low temperature from the chilled liquid created reactor system pressure conditions that could condense some of the ethylene gas into a liquid; the temperature inside EVAL Reactor 2 then began to decrease as liquid ethylene entered the reactor.
  • At about 5:30 a.m. on May 19, 2018, the day shift took over and two board operators divided the operational tasks inside the control room.
  • At approximately 7:00 a.m., Supervisor 1 recognized the low reactor temperature inside EVAL Reactor 2 and instructed Board Operator 1 to stop circulating chilled liquid through the heat exchanger by closing the temperature control valve.
  • At 7:08 a.m. on May 19, 2018, Kuraray began heating the reactor while simultaneously adding ethylene to raise the reactor’s pressure.
  • At 7:37 a.m. on May 19, 2018, Board Operator 1 manually activated the EVAL Reactor 2 High-High-Pressure safety interlock.
  • At 7:41 a.m. on May 19, 2018, Board Operator 1 turned the High-High-Pressure safety interlock to the off position.
  • At 8:44 a.m., the pressure inside EVAL Reactor 2 reached the target pressure of 595 psi per the nightly operating instructions.
  • At 8:46 a.m., the pressure inside EVAL Reactor 2 was 606 psi, and Board Operator 1 closed the ethylene pressure control valve to stop adding ethylene to EVAL Reactor 2.
  • At 8:51 a.m., the pressure inside EVAL Reactor 2 reached 620 psi, activating the High-Pressure alarm.
  • At 9:01 a.m., the reactor’s High-High-Pressure alarm went off at 640 psi.
  • At 10:05 a.m., Supervisor 1 asked Board Operator 2 to take over the operation of EVAL Reactor 2 to initiate the next step in the startup process—flushing a batch of methanol and vinyl acetate through the reactor.
  • At 10:10 a.m., the operators’ efforts to start the methanol and vinyl acetate flush began.
  • At 10:15 a.m., Board Operator 2 opened the pressure control valve to the flare from 30 to 35 percent open.
  • At 10:28 a.m., the emergency pressure-relief system opened and discharged high-pressure ethylene near many of the contractors working in the area.
  • At 10:28 a.m., the rupture disc burst and the emergency pressure-relief valve lifted, discharging ethylene into the air through horizontally aimed piping.
  • At 10:29 a.m., Board Operator 2 fully opened the pressure control valve to send more reactor vapor to the flare and Supervisor 1 instructed Board Operator 2 to open the emergency open valve to maximize the flow of reactor vapor directed to the flare.
  • At 10:31 a.m., enough ethylene vapor was released to reduce the pressure inside EVAL Reactor 2, allowing the spring-loaded emergency pressure-relief valve to close and extinguish the fire.

Facility and Process Context

  • The EVAL Plant produces ethylene-vinyl alcohol copolymers.
  • The plant had four production lines, and the 1200 production line was involved in the incident.
  • Each production line has a pressurized chemical reactor that uses ethylene in its polymerization process.
  • The process is highly dependent on temperature and pressure.
  • The polymerization reaction generates heat that is controlled using a reactor jacket that uses cooling water and a reactor cooler system that uses a refrigerated solution of water and methanol, commonly referred to as brine by Kuraray EVAL personnel.
  • The incident occurred during startup following a scheduled maintenance turnaround.
  • The investigation focused on the EVAL Reactor 2 emergency pressure-relief system.
  • The facility had emergency pressure-relief systems, a flare system, a chilled liquid refrigeration system, a reactor pressure control valve that sends reactor vapor to the flare, a pressure control valve that supplied ethylene to the reactor, a temperature control valve that supplied chilled liquid to the reactor heat exchanger, and a High-High-Pressure safety interlock for EVAL Reactor 2.

Consequences

  • Fatalities: 0
  • Injuries: 23 workers injured; two workers were life-flighted; one contract worker remained in critical condition for several days from life-threatening burns but survived; emergency responders transported as many as 21 injured workers to off-site medical facilities for treatment; OSHA summary stated 21 employees hospitalized and another 150 employees injured but not hospitalized.
  • Environmental release: Kuraray reported releasing 2,347 pounds of ethylene through the EVAL Reactor 2 emergency pressure-relief system to the ambient air.
  • Facility damage: The fire burned for about three minutes.
  • Operational impact: The fire burned for about three minutes until enough ethylene vapor had been released to reduce the pressure inside EVAL Reactor 2, allowing the spring-loaded emergency pressure-relief valve to close and extinguish the fire. The incident interrupted the operation.

Key Findings

Immediate Causes

  • Kuraray’s long-standing emergency pressure-relief system design that discharged flammable ethylene vapor through horizontally aimed piping into the air, near workers.
  • High-pressure conditions developed inside EVAL Reactor 2 and activated the reactor’s emergency pressure-relief system.
  • Welding likely ignited the ethylene vapor cloud, causing the fire.

Contributing Factors

  • Presence of nonessential workers during startup and upset conditions.
  • Hazardous location created by the horizontal orientation of the reactor’s emergency pressure-relief system outlet piping.
  • During startup, ethylene vapor condensed and started flowing into EVAL Reactor 2, forming an inventory of liquid ethylene and creating a low-temperature condition.
  • Kuraray operators disabled the reactor’s abnormal condition safety interlock while troubleshooting a problem that stemmed from a misaligned valve.
  • Kuraray had not completed its process alarm management efforts; the control system sent about 160 alarms per hour to the board operators on the morning of the incident.
  • Kuraray’s operating procedures did not include alarm information or operator guidance for responding to process alarms.
  • Kuraray physically and procedurally controlled when board operators could open the emergency open valve and did not provide a procedure or training directing when to open it.
  • Kuraray’s safe operating limits management system did not prevent high-pressure conditions from developing inside the reactor and set the safe operating limits for EVAL Reactor 2 too high.
  • Kuraray had an environmental permit that limited the amount of VOCs, including ethylene, that the company was allowed to send to its flare, and board operators limited flow to avoid exceeding these permit limits.
  • Kuraray’s control system did not provide workers with any special or unique warnings to help board operators recognize that EVAL Reactor 2 was different.
  • Kuraray management supplied nightly operating instructions that conflicted with the company’s written operating procedures and resulted in unmanaged changes during the reactor startup.
  • Critical gaps in Kuraray’s operator training contributed to the incident.
  • Kuraray’s safety management systems did not consider the high-pressure conditions developing inside EVAL Reactor 2 as an upset condition that should halt the maintenance work and prompt the evacuation of nonessential personnel.
  • Kuraray’s safety management systems did not control the circulation of chilled liquid through the heat exchanger during startup, leading to an abnormal operating condition—liquid ethylene accumulation inside the reactor.
  • Kuraray’s safety management systems enabled the reactor startup to continue despite the presence of an abnormal operating condition—the low temperature of the liquid inside the reactor.
  • Kuraray’s safety management systems allowed its nightly operating instructions to conflict with established written operating procedures, leading to another abnormal operating condition—high pressure within the reactor.
  • Kuraray’s control system flooded the board operators with alarms, which contributed to the incident by hindering the operators’ ability to effectively review the process information and control the high-pressure conditions that developed within the reactor.
  • The physical and procedural controls that Kuraray put in place to govern the use of the emergency open valve contributed to the incident by restricting the board operators from accessing or otherwise using the emergency open valve.
  • Kuraray set the safe operating limits for EVAL Reactor 2 too high to prevent activating the EVAL Reactor 2 emergency pressure-relief system effectively.
  • Kuraray’s desire to avoid exceeding the environmental permit limits contributed to the May 19, 2018, incident.
  • Kuraray’s project scope did not include a dispersion study of potential flammable hydrocarbon vapor releases into the air.
  • Kuraray’s project records do not show that the engineering firm was tasked with evaluating the individual emergency pressure-relief systems to ensure they were discharged to a safe location.
  • Kuraray did not implement the engineering firm’s proposal to direct ethylene from emergency pressure-relief systems to a flare.
  • Kuraray did not adopt the 2015 PHA team’s safety recommendation to perform a study to evaluate potential ethylene releases from emergency pressure-relief systems and their safety impact on personnel.
  • Kuraray’s 2015 PHA team recommended upgrading and automating the emergency open valve that directs reactor vapor to the flare, but the work was postponed to 2019.
  • Kuraray disabled its EVAL Reactor 2 low-temperature alarms.
  • Kuraray operators were not aware that liquid ethylene was flowing from the heat exchanger and accumulating inside the reactor.
  • Kuraray operators were not following the operating procedures and were instead following the conflicting nightly operating instructions.
  • The High-High-Pressure safety interlock was turned off and not turned back on.
  • The chilled liquid temperature control valve did not automatically open when the pressure inside the EVAL Reactor 2 reached the High-High-Pressure alarm condition of 640 psi.
  • Kuraray used the visual operating guideline message, “High Flare VOC Emissions Reduce, Reduce Purging,” to direct operators to reduce the flow of ethylene to the flare to prevent exceeding its environmental permit limit.

Organizational and Systemic Factors

  • Kuraray’s long chain of weakly implemented management system elements that made up its overall process safety management system contributed to the incident.
  • Kuraray’s safety management systems fostered inconsistent practices for keeping nonessential personnel from being physically present within the unit during critical events and activities.
  • Kuraray’s process safety management systems did not consider the high-pressure conditions developing inside EVAL Reactor 2 as an upset condition that should halt the maintenance work and prompt an evacuation of nonessential workers.
  • Kuraray’s internal PHA policy did not require its management to document its reasons for declining PHA recommendations.
  • Kuraray’s safety management system did not effectively prioritize keeping the reactor pressure below its alarm limits over the site’s environmental permit constraint.
  • Kuraray’s pre-startup safety review (PSSR) policy did not require a PSSR before starting an existing unit or require that nonessential personnel be removed from the area before startup after a turnaround.
  • Kuraray’s self-assessment audit developed 64 proposed recommendations in 11 of the 14 PSM elements; only 37 were accepted.
  • Kuraray’s operator training program did not cover alarm setpoints or actions that operators should take in response to specific process alarms, such as high-pressure conditions inside an EVAL Reactor.
  • Kuraray’s operating procedures did not include alarm information or operator guidance on responding to process alarms.
  • Kuraray’s management restricted its board operators from using the automated valve that could have directed even more ethylene vapor to the flare.
  • Kuraray’s safe operating limits did not consider the activation pressure of its emergency pressure-relief systems and the fact that these safety systems do not precisely activate at their design conditions.
  • Kuraray’s corporate safety guidance recognized the potential severity of discharging emergency pressure-relief systems to an unsafe location, but the company did not address this hazard for its EVAL Reactor 2 emergency pressure-relief system.
  • Kuraray’s 2015 PHA team recommended that Kuraray perform a study to evaluate potential ethylene releases from emergency pressure-relief systems and their safety impact on personnel, but Kuraray management did not accept the recommendation.
  • Kuraray’s PHA policy did not require its management to document its reasons for declining PHA recommendations.
  • Kuraray’s operating procedures nor its operator training covered the known activities or conditions that should have prompted Kuraray’s operations personnel to exclude nonessential personnel from the unit.
  • Kuraray had an unwritten safety practice to exclude nonessential personnel from a unit when reintroducing ethylene into equipment after a turnaround, but the company lacked a formal exclusion zone to protect nonessential workers for the duration of the startup.
  • Kuraray’s operator training materials did not address safe operating limits, the consequence of deviating beyond the safe operating limits, or the predetermined steps that operators must take to return the process to a safe condition.
  • Kuraray did not have a program to manage abnormal operating conditions.
  • Kuraray did not have an effective system to manage the disabling of safety interlocks and ensure that these critical systems were available before continuing startup activities.
  • Kuraray’s startup procedures lacked guidance or actions for the board operators to take in response to process alarms.
  • Kuraray did not provide its board operators with a procedure or training directing them on when to open the emergency open valve.
  • Kuraray’s self-assessment audits of these systems did not achieve the level of detail required to address the management system failures that contributed to the May 19, 2018, incident.
  • Kuraray management did not accept 27 of the 64 proposed recommendations from its November 2015 self-assessment audit.
  • Kuraray’s 2015 PHA team reviewed the March 22, 2015 incident and found that potential ethylene releases from some of the site’s emergency pressure-relief systems could result in a flash fire or a vapor cloud explosion.
  • Kuraray management supplied nightly operating instructions.
  • Kuraray had not begun any of the flush batch startup procedure steps by 10:05 a.m. on May 19, 2018.
  • Kuraray used the control system to direct operators to reduce the flow of ethylene to the flare to prevent exceeding their environmental permit limit.

Failed Safeguards or Barrier Breakdowns

  • High-pressure alarms with an operator opening the emergency open valve
  • Reactor abnormal condition (High-High-Pressure) safety interlock
  • A high-pressure switch that could trigger closing valves to isolate reactor feeds
  • The High-High-Pressure safety interlock did not automatically open the emergency open valve to send vapor from the reactor to the flare
  • The reactor’s abnormal condition safety interlock did not activate when the pressure inside EVAL Reactor 2 reached the high-pressure limit because it had been disabled
  • The pressure control response did not bring the reactor pressure back below the alarm limits
  • The emergency pressure-relief system did not discharge to a safe location
  • The control system did not provide special or unique warnings for EVAL Reactor 2
  • The alarm management program was not completed
  • The emergency open valve required manual activation and was not automatically opened by the control system
  • The safe operating limits management system did not prevent high-pressure conditions from developing inside the reactor
  • ground-level flammable gas detector alarms
  • EVAL Reactor 2 low-temperature alarms
  • emergency pressure-relief systems discharged to a safe location
  • flare diversion of reactor vapor
  • operating procedures
  • nightly operating instructions
  • manual valve alignment for liquid flow from EVAL Reactor 2 to downstream equipment
  • the emergency open valve
  • the chilled liquid temperature control valve
  • alarm management efforts at the EVAL Plant
  • safe operating limits for EVAL Reactor 2

Recommendations

  1. 2018-03-I-TX-R1 | Recipient: Kuraray America, Inc. | Status: Open – Acceptable Response or Alternate Response | Summary: Develop and implement an emergency pressure-relief system design standard to ensure that each of these safety systems will discharge to a safe location. Include a requirement to periodically evaluate the site’s emergency pressure-relief systems and make appropriate modifications to ensure that each of these systems discharge to a safe location such that material that could discharge from these safety systems will not harm people.
  2. 2018-03-I-TX-R2 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Implement a site-wide system to evacuate nonessential personnel during upset conditions and exclude nonessential workers from being near equipment during transient operating modes, such as startup.
  3. 2018-03-I-TX-R3 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Develop and implement a system requiring a periodic evaluation of the adequacy and effectiveness of any safeguard used to mitigate or otherwise lower the risk of process safety hazards. This safeguard protection analysis should be based on the requirements of Cal/OSHA’s Process Safety Management for Petroleum Refineries regulations or an appropriate equivalent methodology.
  4. 2018-03-I-TX-R4 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Develop and implement a policy detailing how to effectively address recommendations generated from company process safety management systems, including audits, incident investigations, management of change, and process hazard analysis that is consistent with existing OSHA guidance. Include a periodic training requirement for managers and other employees involved in evaluating and managing proposed recommendations to help ensure safety improvements are effectively evaluated and appropriately implemented.
  5. 2018-03-I-TX-R5 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Review the Center for Chemical Process Safety guidance on recognizing catastrophic incident warning signs and then develop and implement a program for the EVAL Plant that incorporates warning signs into its safety management system.
  6. 2018-03-I-TX-R6 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Clarify the lower equipment design pressure of the EVAL Reactor 2 within the operator training systems, written procedures, and in the control system interface.
  7. 2018-03-I-TX-R7 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Develop and implement a program to ensure that the company’s EVAL Plant nightly operating instructions do not conflict with its written operating procedures. Ensure that employees use the management of change system when changes to the written operating procedure are desired. Additionally, develop and implement a written procedure and conduct training on how to perform the EVAL Reactor methanol flush operation.
  8. 2018-03-I-TX-R8 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Strengthen the EVAL Plant’s operator training program by including the known activities, upset conditions, guidance on excluding nonessential personnel, alarm setpoints and actions, directions on when operators should use the emergency open valve, and safe operating limits, the consequence of deviating beyond the safe operating limits, and the predetermined steps operators need to take to return the process to a safe condition.
  9. 2018-03-I-TX-R9 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Complete the alarm management efforts at the EVAL Plant and implement a continual program to meet or be lower than the alarm rate performance targets established in ISA 18.2.
  10. 2018-03-I-TX-R10 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Improve the EVAL Plant’s safety management system by controlling when chilled liquid is circulated through the heat exchanger during startup; enhancing recognition of liquid ethylene accumulation and response to low-temperature conditions inside an EVAL Reactor through alarms, written procedures, and operator training; implementing a system to manage abnormal operating conditions effectively; updating to process alarms; using control system guidance to aid operator response to abnormal or upset conditions to keep the process within the safe operating limits; and removing the physical and procedural controls used at the EVAL Plant to restrict board operators from accessing or using the emergency open valve, and updating the written procedures and operator training to provide guidance on when to open the emergency open valve.
  11. 2018-03-I-TX-R11 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Action | Summary: Modify the EVAL Plant’s safe operating limits program to prevent operating under conditions that rely upon equipment design safety factors, such as the American Society of Mechanical Engineers (ASME) code material safety factors.
  12. 2018-03-I-TX-R12 | Recipient: Kuraray America, Inc. | Status: Closed – Acceptable Alternative Action | Summary: Acquire the services of an independent third party to perform a comprehensive assessment of its EVAL Plant’s process safety management systems. In addition to meeting the requirements outlined in Appendix B of this report, this comprehensive assessment should evaluate whether existing policies meet minimum federal process safety regulatory requirements and apply the Center for Chemical Process safety model to verify both the suitability of these systems and their effective, consistent implementation.

Key Engineering Lessons

  • Emergency pressure-relief systems must discharge to a safe location; horizontally aimed discharge piping near workers created the hazard in this incident.
  • Relief system design should be periodically evaluated and modified when needed so that released material will not harm people.
  • Safe operating limits must account for actual equipment behavior, including the fact that safety devices do not precisely activate at their design conditions.
  • Alarm management, operator guidance, and training must support recognition and response to high-pressure, low-temperature, and other abnormal conditions during startup.
  • Controls for emergency open valves and safety interlocks should not prevent timely operator response or leave critical safeguards unavailable during startup.
  • Startup procedures should prevent conflicting instructions and should control chilled liquid circulation so abnormal liquid ethylene accumulation does not develop.

Source Notes

  • Priority 1 final report used as the primary authority for incident cause, sequence, and findings.
  • Priority 3 recommendation status summaries used to confirm recommendation statuses and post-incident corrective actions.
  • Priority 4 supporting documents were used only where they added incident sequence or context not contradicted by higher-priority sources.
  • Where sources differed on injury counts, the final report's statement of 23 injured workers was retained as higher priority.
  • The final report states the incident was released December 21, 2022; the report itself was published December 16, 2022.

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