Fire And Explosion
Tosco Corporation Avon Refinery Fluid Coker Fire
Tosco Corporation
📍 Martinez, CA
Incident: February 23, 1999 • CSB Report: 2001
4
Fatalities
2
Injuries / Affected
Heavy Hydrocarbons / Fluid Coke (Fluid Coker Pipe Rupture and Fire — Petroplus R
Chemical Involved
3
CSB Recommendations
📋 Incident Summary

On February 23, 1999, four workers were killed and two were injured in a fire at the Tosco Corporation Avon Refinery (now the Rodeo San Francisco Refinery) near Martinez, California. The fire originated when a pipe carrying heavy hydrocarbon material ruptured inside the fluid coker unit during a maintenance activity.

Workers were performing maintenance in the fluid coker unit when the incident occurred. A pipe containing hot, pressurized hydrocarbon material failed, releasing the contents that ignited immediately. The resulting fire trapped and killed four contract maintenance workers who were working in the area.

The CSB investigation found that the maintenance procedure being followed was inadequate for the hazards of working in and around the fluid coker unit, which contained large quantities of hot hydrocarbons at elevated temperature and pressure. The investigation also identified deficiencies in the permit-to-work system and the hazard communication provided to contract maintenance workers.

🔎 Key Findings
Finding 01
Pipe Rupture Released Hot Hydrocarbons That Immediately Ignited
A pipe in the fluid coker unit ruptured during maintenance operations, releasing hot, pressurized hydrocarbon material. The released material immediately ignited, creating a fire that trapped and killed four contract maintenance workers.
Finding 02
Maintenance Procedure Inadequate for Fluid Coker Hazards
The maintenance procedure being followed at the time of the incident was not adequate for the hazards of working inside the fluid coker unit, which contained large inventories of hot, pressurized hydrocarbons at process temperatures and pressures.
Finding 03
Four Contract Maintenance Workers Killed
All four fatalities were contract maintenance workers performing work inside the fluid coker unit. The workers were trapped by the fire and were unable to escape. The incident reinforced the disproportionate fatality burden carried by contract workers in refinery process safety incidents.
Finding 04
Permit-to-Work System Deficiencies
The permit-to-work system used for the fluid coker maintenance work did not adequately identify and communicate the specific hazards of working inside the unit during the maintenance activity.
Finding 05
Hot Work and Maintenance Hazard Communication to Contractors
Contract maintenance workers working inside the fluid coker unit did not receive adequate hazard communication about the specific risks of the maintenance activities in the hot hydrocarbon environment of the unit.
🔍 Root Causes
1
Inadequate Maintenance Procedure for Fluid Coker Hot Hydrocarbon Environment
The maintenance procedure was not adequately designed for the hazards of the fluid coker unit. Maintenance in units with large inventories of hot, pressurized hydrocarbons requires procedures specifically developed and reviewed for the unique hazards of that environment.
2
Pipe Failure Released Trapped Workers to Ignited Hydrocarbon Fire
The pipe rupture and immediate ignition created a fire that trapped the four workers who were killed. The fire spread rapidly in the hot hydrocarbon environment, preventing escape.
3
Contractor Hazard Communication Insufficient for Fluid Coker Maintenance
Contract maintenance workers did not receive adequate hazard communication about the fluid coker environment — specifically, the presence of large quantities of hot, pressurized hydrocarbons and the potential consequences of pipe failure or upset during maintenance.
☑ CSB Recommendations
→ Tosco Corporation / Refinery Operators
Review and update maintenance procedures for all work conducted inside high-temperature, high-pressure hydrocarbon process units; ensure procedures specifically address the hazards of the unit environment; improve pre-job briefing and hazard communication for contract maintenance workers.
→ Petroleum Refining Industry
Develop specific maintenance procedure requirements for work conducted inside fluid cokers and other high-temperature, high-pressure hydrocarbon units; address contractor hazard communication as a specific requirement for maintenance in these environments.
→ OSHA
Conduct targeted inspections of contractor safety programs at refineries; evaluate the adequacy of pre-job hazard briefings and maintenance procedures for work conducted inside high-temperature, high-pressure process units.
💡 Lessons Learned
Contract maintenance workers in refineries and chemical plants are consistently among the most severely affected victims of process safety incidents. The Tosco Avon fire, like Partridge-Raleigh (CS-077), BP Texas City, and many other incidents, killed contract workers who were performing maintenance in hazardous process environments. The common thread is that contractor hazard communication and pre-job briefing failed to convey the specific, life-threatening hazards of the work environment to the workers most exposed to those hazards.
Maintenance procedures for work conducted inside high-temperature, high-pressure hydrocarbon process units — fluid cokers, FCC units, crude distillation units, hydrotreaters — must be specifically designed for the unique hazard profile of those units. Generic maintenance procedures adapted from less hazardous service conditions are not adequate for the consequence severity of a pipe failure or process release in a unit operating at extreme temperatures with large hydrocarbon inventories.
The permit-to-work system is the primary administrative safeguard for maintenance activities in hazardous process environments. A permit-to-work system that does not specifically identify the hazards of the unit environment — hot hydrocarbons, process pressure, ignition sources — is not performing its function. Permit issuers must have the knowledge to identify unit-specific hazards and the authority to refuse permit issuance when adequate safeguards are not in place.
SOP: Operating ProceduresPHA: Process Hazard AnalysisMI: Mechanical IntegrityTRN: TrainingMOC: Management of Change
🔨 Safety Meeting Toolbox Talk
►Do maintenance procedures for work inside your high-temperature, high-pressure process units (cokers, crackers, hydrotreaters) specifically address the hazards of those unit environments? Are these procedures reviewed and approved by process safety engineering before use?
►What hazard information do contract maintenance workers receive before entering high-temperature, high-pressure process units? Does the pre-job briefing specifically address the unit environment hazards — not just the task-specific hazards?
►Does your permit-to-work system require unit-specific hazard identification for maintenance work inside process units? Who is responsible for identifying unit-specific hazards in the permit, and do they have the knowledge to do so accurately?
Immediate Action Items
✓Review maintenance procedures for all work conducted inside high-temperature, high-pressure process units; verify that procedures specifically address the hazards of each unit environment.
✓Audit contractor pre-job briefings for maintenance work inside process units; confirm that unit-specific hazards — hot hydrocarbons, process pressure, ignition potential — are communicated to all workers before entry.
✓Review the permit-to-work system for maintenance inside process units; verify that unit-specific hazard identification is a required element of each permit and that permit issuers are qualified to identify these hazards.
✓Conduct a PHA for maintenance activities inside all high-temperature, high-pressure process units; document unit-specific hazard scenarios and the safeguards required for each.
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 5 PSM elements (SOP · PHA · MI · TRN · MOC). 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 is a direct consequence of SOP failure.
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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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Mechanical Integrity (MI)
Equipment must be designed, inspected, and maintained to operate safely in its intended service. Mechanical integrity failures contributed to loss of containment here.
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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.
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Management of Change (MOC)
Changes to equipment, chemistry, operating limits, or procedures that bypass formal review create new hazard pathways your PHA never evaluated.
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