Overpressure Release — PSV Discharge to Unsafe Location
Kuraray America EVAL Plant Ethylene Release and Fire
Kuraray America, Inc.
📍 Pasadena, TX
Incident: May 19, 2018  •  CSB Report: December 21, 2022
0
Fatalities
Ethylene (~2,300 lbs, High Pressure via PSV)
Chemical Involved
12
CSB Recommendations
📋 Incident Summary

On May 19, 2018, a high-pressure ethylene release and fire at the Kuraray America EVAL resin plant in Pasadena, Texas, injured 21 workers. EVAL Reactor 2 was being restarted after a maintenance outage when a pressure safety valve (PSV) activated, releasing approximately 2,300 pounds of high-pressure ethylene through a discharge line terminating in an open area where contractor workers were present.

The ethylene ignited, causing a flash fire that burned contractors positioned near the PSV discharge location. The CSB found that startup procedures did not adequately control conditions to prevent PSV activation, that the PSV discharge routed ethylene to an unsafe location, and that contractors were not warned of the potential for a high-pressure ethylene release.

The December 2022 CSB report issued 12 recommendations to Kuraray America. Eleven were closed at time of report; one remained open. Recommendations focused on startup procedures, PSV discharge system design, and contractor safety.

🔎 Key Findings
Finding 01
PSV Discharged Ethylene to Occupied Area
The PSV on Reactor 2 discharged ~2,300 lbs of high-pressure ethylene through a line terminating in an open location accessible to workers — contractors were present in the discharge zone with no warning.
Finding 02
Startup Procedure Did Not Prevent Overpressure
The reactor restart procedure allowed conditions that resulted in overpressure and PSV activation — it did not include adequate controls or monitoring to prevent a PSV event during post-maintenance startup.
Finding 03
Contractors Not Warned of PSV Release Hazard
Contractor workers near the PSV discharge location were not informed of the potential for a high-pressure ethylene release during startup — they had no warning before the release began.
Finding 04
MOC Did Not Address Post-Maintenance Startup Risk
The change associated with the Reactor 2 maintenance outage and restart was not evaluated through a formal MOC process that would have identified the heightened overpressure risk.
Finding 05
Flash Fire Injured 21 Workers
The ethylene cloud ignited rapidly; the resulting flash fire caused burn injuries to 21 workers, primarily contractors closest to the PSV discharge location.
🔍 Root Causes
1
Inadequate Startup Procedure for Post-Maintenance Restart
Operating procedures for restarting Reactor 2 after maintenance did not reflect the different risk profile of a first-start-after-maintenance versus a routine restart — no additional controls were specified.
2
PSV Discharge Routed to Occupied Area
The PSV discharge system design terminated ethylene releases in an accessible work area without providing a safe dispersion path, vapor barriers, or restricted access.
3
Contractor Safety Program Did Not Address Process Hazards
The contractor safety management program did not ensure workers near the PSV discharge were briefed on specific process hazards associated with the nearby reactor restart.
☑ CSB Recommendations
→ Kuraray America
Revise Reactor 2 startup procedures to include specific controls preventing overpressure conditions, with designated hold points to verify process parameters before advancing startup steps.
→ Kuraray America
Modify or reroute PSV discharge systems to direct released flammable materials to safe locations (flare, vent stack, remote area) away from any personnel work areas.
→ Kuraray America
Implement a pre-startup safety review (PSSR) requirement for all post-maintenance restarts of PSM-covered equipment, including specific hazard assessment for first-start-after-maintenance scenarios.
→ Kuraray America
Update the facility MOC procedure to require explicit review of startup risk for any post-maintenance return to service, with sign-off verifying startup procedures address the post-maintenance risk profile.
→ Kuraray America
Establish a work area hazard communication requirement ensuring all workers (including contractors) near an ongoing PSM process startup are briefed on specific process hazards.
→ Kuraray America
Review all PSV discharge locations to confirm no relief devices discharge to areas routinely occupied by workers during any operating mode.
→ Kuraray America (open)
Complete the remaining open recommendation for PSV discharge system engineering modification to ensure ethylene discharges cannot accumulate in accessible work areas.
💡 Lessons Learned
Pressure safety valves are critical safeguards — but where they discharge matters as much as whether they open. Routing PSV discharges to worker-accessible locations turns a protection success into an exposure event.
Post-maintenance startups carry inherently higher risk than routine restarts. Procedures must be specifically designed for first-start-after-maintenance scenarios, not repurposed from normal startup sequences.
Contractors working near active process operations must be explicitly briefed on the specific hazards at their work location — generic safety orientation is not a substitute for task-specific hazard communication.
Management of Change must evaluate not just the maintenance work performed, but the startup that follows. The first restart after maintenance is itself a change that requires hazard review.
PSSRs are required by PSM before introducing highly hazardous chemicals. Treating post-maintenance restarts as equivalent to routine startups bypasses this critical safeguard.
SOP: Operating ProceduresMOC: Management of ChangeTRN: TrainingPHA: Process Hazard Analysis
🔨 Safety Meeting Toolbox Talk
►Do you know where the pressure relief valves on your unit discharge — and whether anyone could be in that area during a release?
►When we restart a unit after maintenance, do we use the same procedure as a routine startup, or a specific post-maintenance procedure with additional controls?
►Before contractors begin work near active process equipment, how do we communicate the specific hazards present at their work location that day?
►Has your facility ever experienced a PSV activation during startup? If so, was that scenario evaluated in the PHA?
►How does your MOC process address the restart phase after maintenance — is the startup itself evaluated as part of the change review?
Immediate Action Items
✓Walk down the PSV discharge locations for your highest-risk process units and verify they discharge to safe areas inaccessible to workers during operations.
✓Pull your post-maintenance startup procedures for one critical unit and compare them to routine startup procedures — identify any hazard-specific controls that are missing.
✓Review your contractor pre-job briefing process to confirm that process-specific hazards at the work location are communicated before work begins.
✓Confirm that your facility's MOC procedure requires startup hazard review as part of return-to-service planning for post-maintenance work.
✓Identify any unit where a PSV activation during startup could expose workers to flammable or high-pressure materials and develop a corrective action plan.
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 4 PSM elements (SOP · MOC · TRN · PHA). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

Operating Procedures (SOPs)
Operators cannot reliably hold safe operating limits without clear, current, enforced procedures. Deviation from acceptable operating conditions — a root cause here — is a direct consequence of SOP failure.
Supporting documents in our library →
Management of Change (MOC)
Changes to equipment, chemistry, operating limits, or procedures that bypass formal review create new hazard pathways your PHA never evaluated. MOC failures open the door to incidents like this one.
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Training & Operator Competency
Workers must understand process hazards — not just the steps on the page. Training records, refresher frequency, and verified competency are all OSHA PSM requirements that gaps here violated.
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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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