Hot Work Flash Fire — Inadequate Atmosphere Testing at Crude Oil Terminal
Sunoco Logistics Partners Hot Work Flash Fire
Sunoco Logistics Partners, L.P.
📍 Nederland, TX
Incident: August 12, 2016  •  CSB Report: September 28, 2022
0
Fatalities
Crude Oil Vapors — Hydrocarbon Vapors
Chemical Involved
0
CSB Recommendations
📋 Incident Summary

On August 12, 2016, a flash fire and explosion at the Sunoco Logistics Partners crude oil terminal in Nederland, Texas, injured seven workers, three of them critically burned. Workers were performing hot work — grinding and cutting — at a crude oil storage tank when flammable hydrocarbon vapors ignited, causing a flash fire that engulfed workers in the immediate area.

The CSB found that atmospheric testing prior to hot work did not adequately account for residual crude oil vapors from tank bottoms and sediment, which continued to generate flammable vapor even after the tank appeared empty. Testing was conducted at the tank opening but did not sample conditions throughout the work area or account for evolving vapor generation.

The September 2022 CSB report focused on findings and analysis of the incident — hot work permit deficiencies, inadequate atmosphere testing methodology, and contractor hazard communication failures were central to the conclusions.

🔎 Key Findings
Finding 01
Atmosphere Testing Did Not Account for Tank Residue Vapors
Pre-work atmospheric testing was conducted at the tank opening but did not adequately sample conditions throughout the work area or account for ongoing vapor generation from crude oil residue, sediment, and tank bottoms.
Finding 02
Hot Work Permit Did Not Control Flammable Atmosphere Risk
The hot work permit did not establish adequate controls to ensure a continuous, flammable-vapor-free atmosphere at the work location throughout the duration of the grinding and cutting operations.
Finding 03
Contractors Not Briefed on Vapor Generation Hazard
Contract workers performing the hot work were not adequately informed of the ongoing flammable vapor generation potential from crude oil tank residue — they believed the tank had been adequately prepared.
Finding 04
Flash Fire Critically Burned Three Workers
Ignition of accumulated hydrocarbon vapors produced a flash fire of sufficient intensity to critically burn three workers — a consequence entirely preventable with adequate hot work atmosphere controls.
🔍 Root Causes
1
Inadequate Atmosphere Testing Methodology for Tank Residue
The facility's hot work permit process did not require a testing methodology accounting for the specific hazards of residual crude oil vapors — including vapor pockets, ongoing sediment evaporation, and the need for continuous monitoring.
2
Hot Work Permit Controls Insufficient for Tank Vapor Hazards
The permit system relied on a single pre-work atmospheric test that could not reflect changing conditions during the work — controls were not designed for the unique vapor generation characteristics of crude oil tanks.
3
Contractor Hazard Communication Gap
The contractor management program did not ensure workers received task-specific information about vapor generation hazards from crude oil tank residue, leaving them without awareness of the specific flammable atmosphere risk.
☑ CSB Recommendations
→ Sunoco Logistics (Findings-Based)
Revise hot work permit procedures to require continuous atmospheric monitoring during all hot work within or adjacent to crude oil tanks, with immediate work stoppage if flammable vapor exceeds defined thresholds.
→ Sunoco Logistics
Update atmosphere testing methodology to require multi-point sampling accounting for tank geometry, vapor stratification, and ongoing vapor generation from tank residue.
→ Sunoco Logistics
Enhance contractor pre-job briefings for hot work near crude oil tanks to specifically address the vapor generation hazard from tank residue, sediment, and bottoms.
→ Sunoco Logistics
Review and update the hot work permit system to include specific controls for the crude oil terminal environment, including tank preparation verification steps and defined vapor-free criteria before authorization.
💡 Lessons Learned
Crude oil tank residue, sediment, and bottoms continue to generate flammable vapors long after a tank appears empty — pre-work atmospheric testing that ignores ongoing vapor generation can provide false assurance of a safe hot work atmosphere.
Hot work permits must include continuous atmospheric monitoring requirements, not just pre-work spot testing. Vapor conditions near crude oil tanks can change rapidly during work due to temperature changes or disturbance of sediment.
A single atmospheric sample at the tank opening does not characterize the vapor hazard throughout the work zone. Multi-point sampling covering the actual work area — including low points where heavy hydrocarbons accumulate — is essential.
Workers performing hot work near crude oil tanks must understand the specific vapor generation hazard from tank residue. Generic hot work training is not a substitute for task-specific hazard communication.
Critical burn injuries from hot work flash fire are entirely preventable. The hierarchy of controls for hot work starts with elimination — can the work be performed without creating an ignition source near a flammable atmosphere?
HWP: Hot Work PermitSOP: Operating ProceduresCON: Contractors
🔨 Safety Meeting Toolbox Talk
►When hot work is performed near tanks that have contained crude oil or other hydrocarbons, how do we account for vapor generation from residue and sediment that persists after emptying?
►Does your hot work permit require continuous atmospheric monitoring during the job, or only pre-work testing? What happens if vapor levels rise during the work?
►How does your hot work permit control zone account for the geometry of the work area, including low points where heavy vapors can accumulate?
►Before contractors start hot work near your tanks, what specific hazard information do they receive about the chemicals that have been in that equipment?
►Have you ever issued a hot work permit where the atmosphere testing methodology later proved inadequate for the specific hazards at that location?
Immediate Action Items
✓Review your hot work permit procedure to confirm it requires continuous atmospheric monitoring — not just pre-work testing — for all hot work in or adjacent to tanks that have contained hydrocarbons.
✓Identify the highest-risk hot work locations at your facility and verify that your atmosphere testing methodology is specific to those hazards.
✓Brief your hot work permit issuers on the Sunoco Nederland incident and ask them to evaluate whether your current permit adequately controls for ongoing vapor generation from tank residue.
✓Confirm that your contractor pre-job safety briefing for hot work near tanks includes specific information about residue vapor generation hazards and continuous monitoring requirements.
✓Audit the last 10 hot work permits at your facility to verify that atmosphere testing documentation reflects multi-point sampling and continuous monitoring requirements were specified.
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 3 PSM elements (HOW · SOP · CON). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

Hot Work Permits
Unauthorized or poorly controlled ignition sources near flammable atmospheres are entirely preventable. A rigorous hot work permit system with pre-job atmospheric testing closes this pathway.
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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.
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Contractor Safety Management
Contractor workers must be held to the same PSM standard as employees. When contractor safety oversight fails, knowledge and compliance gaps follow contract workers onto your site.
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