KMCO LLC Fatal Equipment Rupture, Explosion, and Fire

📋 Incident Summary

On April 2, 2019, a cast iron y-strainer fractured in the isobutylene piping system at KMCO LLC's chemical facility in Crosby, Texas, releasing a large cloud of highly flammable isobutylene vapor that ignited and exploded. One worker was killed, two were seriously injured, and at least 28 others sustained injuries. The explosion and fire caused significant damage to the facility.

The CSB found that KMCO's hazard evaluation process had consistently failed to recognize that the y-strainer in service was made of cast iron — a brittle material that industry standards and guidance documents either prohibit or warn against using in flammable hydrocarbon service. The fracture of the cast iron fitting triggered the release.

Compounding the material selection failure, KMCO's emergency response procedures directed unit operators to attempt to stop the isobutylene release rather than evacuating to safety. Workers who were in safe locations moved toward the expanding vapor cloud — placing them in the path of the ignition event. KMCO subsequently filed for bankruptcy and the facility was purchased and the process dismantled.

🔎 Key Findings

Finding 01

Cast Iron Y-Strainer Fractured in Isobutylene Service

A cast iron y-strainer fractured in KMCO's isobutylene piping system, releasing a large flammable vapor cloud. Cast iron is a brittle material that is known to be unsuitable for use in hazardous flammable hydrocarbon service under recognized industry standards and guidance.

Finding 02

Hazard Evaluations Failed to Identify Prohibited Material in Isobutylene System

KMCO's process hazard analysis and hazard evaluation process consistently failed to recognize that a cast iron fitting was in flammable hydrocarbon service. Existing PHAs had not flagged the material incompatibility despite industry standards clearly warning against cast iron in such applications.

Finding 03

Emergency Response Procedures Directed Operators Toward the Vapor Cloud

KMCO's emergency response program directed unit operators — rather than trained emergency response personnel — to take action to stop chemical releases. Workers in safe locations moved toward the expanding isobutylene vapor cloud, placing themselves in the blast zone when it ignited.

Finding 04

No Adequate Safeguard to Detect or Mitigate Vapor Cloud Before Ignition

After the release began, there was no effective combination of detection, isolation, or ventilation measures that could prevent the formation of an ignitable vapor cloud of the size that developed. The absence of rapid isolation capability magnified the consequence of the initial equipment failure.

Finding 05

KMCO's Plant Culture Normalized Operator Response to Releases

The CSB found that KMCO's plant culture had normalized the practice of operators taking action to stop chemical releases during emergencies — behavior that placed workers in unnecessary danger when the release involved a large flammable vapor cloud rather than a minor, controllable event.

🔍 Root Causes

Cast Iron Material Used in Flammable Hydrocarbon Service — Prohibited by Industry Standards

KMCO installed and maintained a cast iron y-strainer in isobutylene piping service despite industry standards and guidance documents either prohibiting or explicitly warning against cast iron in flammable hydrocarbon applications. The brittle material fractured under operating conditions, triggering the vapor release.

Process Hazard Analysis Failed to Identify Material Incompatibility

KMCO's PHA process did not identify the cast iron y-strainer as a hazard, allowing the incompatible material to remain in service without corrective action or engineering controls. The PHA gap prevented the facility from recognizing and correcting a known material incompatibility.

Emergency Response Program Placed Operators in Harm's Way During Releases

KMCO's emergency response procedures and plant culture directed operators to respond to active chemical releases rather than evacuate. This procedural deficiency caused workers to move toward the isobutylene vapor cloud, placing them in the path of the subsequent explosion and fire.

☑ CSB Recommendations

→ Industry (API, AIChE/CCPS)

Develop or strengthen guidance prohibiting the use of cast iron and other brittle materials in flammable or toxic hydrocarbon service, including y-strainers, flanges, and other fittings; ensure guidance is integrated into PHA screening and Process Safety Information requirements.

→ Chemical Facility Operators

Review all process equipment in flammable or toxic service for the presence of cast iron or other brittle materials; replace non-conforming materials; document the review and correction in the facility's mechanical integrity program and PSI.

→ KMCO LLC (now Altivia) / Industry

Revise emergency response procedures to ensure that unit operators are not directed to approach or attempt to control large-scale flammable chemical releases; establish clear roles that keep operations personnel out of the hazard zone during emergency response.

→ Industry

Integrate emergency response role limitations into PSM training programs — ensuring that operators understand that their role during a large release is to evacuate and notify, not to attempt to stop the release.

💡 Lessons Learned

Cast iron is a brittle material that is well-known to be unsuitable for flammable or toxic hydrocarbon service. Its prohibition in such applications is documented in industry standards. When a PHA repeatedly fails to identify a prohibited material in a hazardous service, it reflects a fundamental gap in how PHA teams are trained to evaluate material specifications — a gap that can persist for years without an independent audit.

The KMCO incident illustrates how emergency response procedures can place workers in greater danger than the original release. Directing unit operators to stop a large flammable vapor cloud release does not increase safety — it places unprotected workers directly in the hazard zone. Emergency response programs must clearly define the line between operator control actions and evacuation triggers.

Plant culture shapes how workers respond during emergencies — and when that culture normalizes approaching releases, it overrides even well-intentioned training. PSM programs must include explicit behavioral expectations: large-scale flammable releases require evacuation, not intervention by unprotected operators.

Process Hazard Analysis is only effective if it includes a systematic review of materials of construction against applicable industry standards. When PHA teams evaluate existing equipment, they must have access to material specifications — and a framework to compare those specifications against known prohibitions in the applicable service.

The KMCO incident resulted in bankruptcy and facility shutdown — consequences that extended well beyond the immediate casualties to impact workers, the community, and the local economy. The cost of replacing a cast iron fitting with an appropriate material is trivially small compared to the cost of a single catastrophic failure. Material selection in hazardous service is a PSI issue with life-safety consequences.

PSI: Process Safety InformationPHA: Process Hazard AnalysisSOP: Operating ProceduresEP: Emergency PlanningTRN: Training

🔨 Safety Meeting Toolbox Talk

►Does your facility have any cast iron fittings, y-strainers, valves, or flanges in flammable or toxic hydrocarbon service? When was the last time your PHA team systematically reviewed materials of construction against applicable industry standards?

►Do your emergency response procedures specify what unit operators should do — and not do — when a large-scale flammable vapor release occurs? Is the expectation for evacuation versus intervention clearly defined and trained?

►When your facility performs a PHA on existing equipment, does the PHA team have access to current material specifications for process equipment, including piping components like strainers, flanges, and valves?

►Has your facility's plant culture ever normalized operator response to chemical releases that should require emergency evacuation? How would a new operator know where the line is between taking control action and evacuating?

Immediate Action Items

✓Conduct an immediate walk-down audit of all process equipment in flammable, toxic, or reactive service to identify any cast iron or other brittle material components; document findings and initiate replacement for any non-conforming materials.

✓Review your emergency response procedures to confirm that unit operators are not directed to approach or attempt to control large-scale flammable vapor releases; revise procedures and retrain operators on evacuation triggers vs. control actions.

✓Add materials of construction to your PHA screening criteria — ensure that PHA teams systematically compare materials in hazardous service against applicable industry standards (API, ASME, CCPS) as part of every PHA and revalidation.

✓Verify that your Process Safety Information documentation includes current materials of construction for all process equipment in hazardous service, including piping components; update PSI where documentation is incomplete.

🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 5 PSM elements (PSI · PHA · SOP · EP · TRN). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

Process Safety Information (PSI)

Accurate, complete Process Safety Information is the foundation every other PSM element depends on. When PSI is missing or wrong — chemistry data, equipment specs, P&IDs — the entire hazard analysis is built on a flawed base.

Supporting documents in our library →

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.

Supporting documents in our library →

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 →

Employee Participation

OSHA PSM requires workers to be meaningfully involved in hazard analyses and procedure development — not just trained on the finished product. Active participation catches gaps that management alone misses.

Supporting documents in our library →

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.

Supporting documents in our library →

SafeGuard PSM

Process Safety Management Consulting & Document Library

📂

PSM Document Library

32 ready-to-deploy PSM documents covering all 14 OSHA elements — procedures, checklists, and audit templates built for facilities operating under 29 CFR 1910.119.

Browse the Library →

📊

Free PSM Health Score

Find out where your PSM program stands across all 14 OSHA elements. Our free health score surfaces your biggest gaps in under 10 minutes — no account required.

Check Your Score →

📞

Consulting Services

PHA facilitation, PSM program builds, compliance audits, and OSHA inspection support. Transparent flat-fee pricing — no retainer required to get started.

View Pricing →

📋 Explore the full incident library: All 132 CSB Case Studies →