Risk Engineering Energy Forum Oil Tank Fires - The...2018/01/26  · Tank Design / Types Types of tanks commonly used to store liquids include: 1. Fixed-roof tanks 2. External floating

Risk Engineering Energy Forum

Crude Oil Tank Fires:

The Fundamentals

January 12, 2018

Ken Donaghey

Introduction to Tank Fire Protection

Objective:

Provide basic knowledge of:

• Fire Protection Concepts

• Passive & Active

• Risk Reduction Through Design

• Types of Tank Fires

• Tank Fire Protection Systems

• Response Options to Major Incident

NFPA 550 Fire Safety Concept Tree

Managing Fire Risks

Risk Reduction Measures

• Eliminate or Reduce Known Hazards (Design & Practice)

• Choose Inherently Safer Design (Floater vs Cone Roof)

• Process Safety & Control Systems (Detection & Isolation)

• Solid Operations & Maintenance Programs

• Pre-Emergency Planning

• Fire Protection Features

Introduction to Tank Fire Protection

• Tank Design – Cone, Floater, Weather Dome, etc

• Tank Monitoring – Level Gauging to avoid overfills

• Tank Spacing and Concentration

• Intermediate Tank Diking

• Equipment Location, Pumps and Manifolds located outside

primary dike area.

• Isolation and Emergency Shutdown

• Grounding & Bonding (Lightening Protection)

• Pre Fire/Emergency Plans

• Allowance for Fire Fighting Access

Passive Protection for Tank Farms

Active Fire Protection includes the following concepts or

systems:

Fire Detection

• Thermal – Primarily Property Protection intent

• Linear Detection – Thermistor or Optical (Rim Seal)

• Spectrum – UV IR or combination detection (IR CCTV)

• Fusible Plugs or Sprinklers

• Early Detection – Life Safety/High Value Electrical

• Smoke Detection Ionization/Photoelectric

• High Sensitivity Smoke Detection

• Open Path/Liner Optical (Laser/IR)

Active Tank Fire Protection

Gas Detection

• Provides early warning

• Not Common in tank farms with the exception around

pumps

Suppression Systems – Water based

• Deluge systems ( Pumps & Exposure Protection)

• Foam system

• Fix Monitors

• Hydrants

Active Tank Fire Protection

The group or class of water based suppression systems rely on

several key fundamentals, these are:

• Water Hydraulics – Head & Friction Loss Calculations

• Agents – Additives (Foam Concentrates) – Dry Chem

• Density – Delivery of water in gpm (lpm) per sq ft (m2)

• Design area

• Rim Seal

• Full Surface (Not Common for large tanks)

• Dike Area/Equipment

The factors above influence system capacity or volume delivery

Suppression Options

Tank Fires – Causes & Sources

(A study of storage tank accidents, Journal of Loss Prevention in the Process Industries 19 (2006) 51–59)

Tank Design / Types

Types of tanks commonly used to store liquids include:

1. Fixed-roof tanks

2. External floating rood tanks

3. Internal floating roof tanks

4. Domed external floating roof tanks

5. Horizontal tanks

6. Pressure tanks

7. Variable vapor space tanks

8. LNG (Liquefied Natural Gas) tanks

External Floater

Floating Roof Tanks

Internal Floater

Floating Roof Tanks

Geodesic Domes

Floating Roof Tanks

Typical Floating Roof Fire Scenarios

Floating Roof Fires

Tank Fires Escalation Paths

Fire Initiator

Rim Seal

Fire

Roof Spill

Fire

Sunken

Roof

Dike

Fire

Full Surface Fire (single tank)

Boilover Full Surface Fire (multi tank)

Escalation

Escalation

Crude tank potential fire event types:

Risks of Full Surface Fires

Escalation of a Full Surface Fire

Escalation of a Full Surface Fire

Escalation of a Full Surface Fire

Tank Boilover

Nicaragua, 2016

Boilover Fire Escalation

California, 1924

Nonintervention:

• High Risk – Low Value – Ensure Safety of Public and

Personnel and let fire burn out

Defensive:

• May except loss of a tank or product, but take actions to

prevent or limit escalation or addition loss, i.e. Pump out

product, Protect Exposures, etc.

Offensive:

• Aggressive intervention to control and extinguish fire

Fire Protection / Fire Fighting Strategies

Depending on tank type, there are typically several options

for providing tank fire protection. This presentation will focus

on Floating Roof Tanks as they are the most common and

recommended tank type for Crude Storage.

Options:

• No Protection (rely solely on passive – not generally recommended)

• Type II Systems

• Semi-Fixed (requires support of Foam Apparatus)

• Fixed – Manual or Automatic (automatic is not common)

• Combination Rim Seal – Full Surface System (not common)

Tank Fire Protection - Options

Introduction to Tank Fire Protection

Foam Engine Supported Pump Solution via Hose Connection

Semi-Fixed

Rim Seal Systems - Fixed

Foam Tests of Rim Seal Systems

Rim Seal Systems - Fixed

System design must:

• Have Sufficient Volume & Pressure

• Be capable of Rim and Full Surface

Application

• Must Consider Foam “spread” limits

Rim Seal & Full Surface (External Floaters)

Monitors Fix Spray Systems

Exposure Protection

Over the Top – Full Surface Fires

Big Guns

Large Capacity – Foam Pumpers

Water Supply

• 300 ft tank = 11,300 GPM (0.16 GPM/ft2)

• Often Requires 1,000’s of feet of Large

Diameter Hose 5” or Larger (12” is

becoming common)

• Supplemental Fire Pumps

Full Surface Fires - Logistics

Foam Supply

• Over the Foam Application Rate 0.16 x 65 minutes

• 113 GPM of 1% = ~8,000 gallons of concentrate

• 340 gpm of 3% = ~22,000 gallons of concentrate

Proportioning

• Foam Pumpers

• Jet Ratio Controllers

• Self Educting Nozzles

Full Surface Fires - Logistics

Drainage / Runoff

• Can prevent access to fire

• Can carry hydrocarbon liquids into

undesirable locations

Full Surface Fires - Logistics

Buncefield UK - 12/11/2005 - Product Terminal

Large Tank Losses

Nicaragua 2016

• Fire Started in a Crude Oil

Tank

• Escalated from Rim Seal to

Full Surface Fire

• Tank Suffered Multiple

Boilovers

• Exposed Naptha Tank

failed on day two

Recent Large Tank Losses

1. Design Options

• Greenfield vs Brownfield Options

• Water Supply Options

• Select Safer Technologies /Design

2. Protection Options

• Passive Only

• Fixed – Semi Fixed

• Rim Seal, Full Surface – Combination

3. Emergency Planning

• Strategies & Tactics

• Available Equipment

• Mutual Aid or Specialist Contractor - Services

Summary – Crude Oil Tank Fires

NFPA 11,20,600

API 650, 653, 2030, 2350, 2510

Lastfire

Journal of Loss Prevention in the Process Industries

Energy Institute – Code Of Safe Practice 19

Williams Hazard Control

References & Sources

Historical Note – Early Tank Protection

BONUS QUESTION

What piece of motorized Fire Apparatus cannot

proceed down a one way street the wrong way???

Fire Protection 101