Best Practice vis-à-vis International Standards Management of Full Surface Fires in Large Diameter Storage Tank in Petroleum Industries Best Practice vis-à-vis International Standards Prabhakar Kumar Chief Manager (Fire & Safety) IOCL , Guwahati Refinery

Introduction In the early days of the petroleum industry, tank fires were common. As the industry matured, it demanded – Safe Design & Construction Sound Fire Protection Measures Safe Operating Procedure. Improvements of International codes and standards. This resulting in fewer tank fires today than in the past. But they do happen! It is interesting to note that – The frequency of tank fires has been decreased. The size of the storage tanks have increased. This is presenting a more severe hazard & challenges in the event of a fire.

Type of Fire in Atmospheric Storage Tank Overfill ground fires (Dike fire) Rim Seal Fire Full Surface Fire

Full Surface Fire Full Surface Fire: The Fire in which all the cross –sectional area of the storage tank is burning is a “Full Surface Fire”. (Ref. EN 13565-2:2009) Open Top Floating Roof Tank. Fixed Roof Tank. Covered Floating Roof Tank.

Contributory Factors For Full Surface Fire Fire / explosion resulting in separation of roof of fixed roof tank at fragile (weak) seam leaving total surface area uncovered leading to Full Surface Fire. Fully or partially sunken roof in open floating roof tank and closed floating roof tank may lead to full surface fire. Spill on floating roof of the tank may lead to full surface fire. Lightning is most common source of ignition .

Atmospheric Storage Tank Fire Frequency Type of fire Floating roof tank (per tank / year) Fixed roof tank Fixed and internal floating roof tank Rim seal fire 1.6 × 10-3 Full surface fire on roof 1.2 × 10-4 Internal explosion & full surface fire - 9.0 × 10-5 Vent fire Small bund fire Large bund fire (full bund area) 6.0 × 10-5 Source : OGP , Risk Assessment Data Directory, Report No. 434 – 3 , March 2010

Attributes / Characteristics Attributes & Characteristics for Full surface fire : Boilover. Slopover. Explosion. Injury. Release (discharge) Dispersion in air and water. Thermal radiation Smoke and gas ingress Toxicity Overpressure Mechanical damage to tank /facility.

Management of atmospheric Storage Tank Fire Pre incident planning (Figuring out what will be need to be done) Preparing (Arranging access to needed resources & training) Implementing (Putting the plan & resource into action) Investigating (Root cause & resource effectiveness) Follow up (Use investigation for planning and corrective action)

Fire Supersession Strategy A passive strategy involve no fire fighting activities , the fire will be allow to burn out and area evacuated if necessary for personnel Safety A defensive strategy protects personnel and exposed equipment and allows the fire to burn out An offensive strategy is an aggressive attack to attempt to extinguish the tank fire.

Fire Suppression Strategy for “Full Surface Fire” Inadequate resource (Man . Material machine). Remote storage location (inadequate fire water supply). Conditions approaching Boilover. Passive Stagey for “Full Surface Fire” Resource only available for contentment of fire Defensive Stagey for “Full Surface Fire” All resource available for extinguishment of fire. Offensive Strategy for “Full Surface fire”

Fire Fighting Option Sub Surface Foam Application Top side foam application High Capacity Ground Foam Monitor Sub Surface Foam Application Permanently Installed Foam System

Sub Surface Foam Application System where foam is delivered under the surface of the liquid. The subsurface method distribute a continuous blanket of foam across the entire surface of a burning liquid. Not suitable for - Protection of Class 1A (FP <22.8 C & BP <37.8 C) hydrocarbon liquids . Water miscible fuel (alcohol , ester etc.). Sub Surface Foam injection system not suitable for fire suppression in floating roof tank . In case of fixed roof tank subsurface injection may be applied for smaller diameter tank fire . No successful experience of fire suppression in large diameter tank.

Top Side Foam Application – Foam Pourer EN 13565-2 : 2009 - Suggested, fixed system (top pouring , D>60 m) for storage tanks. “Consideration may have to be given to foam application to the tank center on large tanks. NFPA 11 , A.5.2.5.2.1- “It is recommended that , for tank greater than 60m (200 ft) in diameter , at least one additional discharge outlet should be added for each additional 465m2 (5000 ft2) of liquid surface or fractional part theroff.” Std. says the use of fixed system (top pouring) for large diameter tanks

Fire Fighting Foam limitation 30 meter Fire fighting foam can travel effectively across at-least 30m of burning liquid surface. Ref : NFPA-11 A.5.2.5.2.1 79 meter

Best Practice For Fixed Roof Tank “Full Surface Fire” Suggested Best Practice as per API RP 2021: “ A combination approach for fires in fixed roof tanks more than 200 ft in diameter could use shell- mounted foam chambers from the periphery and subsurface foam application for the center area.”

Top Side Foam Application – High Capacity Foam Monitor As per API RP 2021 , 6.7.9 - “Recent studies of successful tank fire extinguishments show that high-capacity foam monitors are effective on full surface fires either when several streams are concentrated in one area in the initial attack or when very large monitors are used.” EN 13565-2 :2009 - Suggested, monitor (Tank dia. >60 m) for full surface fire in Storage Tanks. NFPA -11 : Stipulates use of monitor as primary protection for tank up to 18 m diameters.

Top Side Foam Application – High Capacity Foam Monitor 1. Studies shows that high capacity foam monitors are effective on full surface fire. 2. Monitors can be used for Full surface fire in storage tanks even diameter greater than 60 m . 3. Fire fighting Plan to include use of large capacity foam monitor on full surface fire . 4. Largest diameter Tank fire ( 82 m) successfully extinguished by using high capacity ground monitors.

Logistic & Resource : Rim Seal fire Vs. Full Surface fire A rim seal fire is one where the seal between the tank shell and roof has lost integrity and there is ignited vapour in the seal area.. 80 m 80 m dia Full surface fire A full surface fire is one where the entire surface of liquid in the tank is exposed and involved in the fire Hockey Ground (91.4 m x 55 m) Resource requirement 50 to 200 time more in case of full surface fire

Resource Major Resources needed: Foam concentrate (quantity & right type at site). Firewater (quantity , flow & pressure at site) Foam application equipment. Expertise / People. Communication Support. For small installation , typically “Mutual Aid” help is needed for any big tank fire suppression . Very large Industrial facilities like Refineries / Petrochemical Plants have enough equipment for fighting fires in very large tanks . Moreover these Installation may also have “Mutual Aid” with other Industries / Installations.

International Std. (Foam System) NFPA 11 (Std for low , medium and high expansion foam) , 2015. BS EN 13565-2 . 2009 (Fixed firefighting system – Foam systems)

Logistic & Resources – Foam Application Rate

Logistic & Resources – Foam Concentration Once in solution the active ingredient concentration is the same for 6%, 3%, 1% . Best Practice : “Use of 1% foam concentrate may provides great logistics relief in handling to Full Surface fire .”

Foam Tender Foam availability in each Truck Number of Foam Tender 17 KL (approx) required for 10 minute Foam in each tender will be available for approx 08 minute fire fighting Number of Foam Tender Considering 4000 gallon (approx 15 KL) capacity foam truck 11 (approx.) number of Foam Tender required Foam Requirement as per EN 14565-2 : 2009 (Full Surface Fire , D:79m) 159 KL of foam required 90 minute Fire Fighting

Foam Transportation “Best Practice” API RP ,H.3.3: “When preparing for tank fire suppression large container or bulk storage is preferable as back up to onboard supply because of large quantity of foam required” Best Practice – “ Large capacity foam tender (may be more than 15 KL / 4000 gallon) capacity with suitable foam pump may be considered for foam transportation to meet large quantity of foam requirement during Full Surface Fire”

Logistic & Resources – Foam Concentration 5296 jerry can of 30 liter capacity , 3% foam. 159 foam container 1000 liter capacity , 3% foam. Great relief for logistic handling .

Case Study: Orion Refinery , Narco Orion June8, 2001 Largest Tank Fire Ever Extinguished 270 ft (82 m) Basic information Date : 8th June 2001. Location : Orion Refinery, Norco, LA., USA. Cause of ignition : Sunken roof, lightning Type of tank : Open top floating roof Volume : 51675 m3 (325 000 barrels) Amount of fuel : 47700 m3 (300 000 barrels) Type of fuel : 89,7 octane gasoline (no additives) Ref: Tank Fires ,Review of fire incidents 1951– 2003 (BRANDFORSK Project 513-021) , SP REPORT 2004:14

Case Study: Orion Refinery Narco Lesson Learned: Full surface fire can be extinguished by using High Capacity Foam monitors. Application rate for foam solution is on higher site Approximately 57% additional foam was used for after extinguishment of fire. Preburn time About 12 hours Time to knockdown 20-25 minutes Type of equipment : 2 monitors (8000, 4000 gpm) Application rate : 8.55 L/m2-min (0.21 gpm/sq ft) Total consumption of foam : 106000 litres (28 000 gallons) – extinguishment. b. 140000 L (37 000 gallons) of various brands were used for security

Effect on Environment Burchfield Oil Storage Depot (UK) fire , Dt-11.12.2005 Data source : SP REPORT 2004:14 Site before fire incident Site after fire incident Foam / water accumulation All photograph source internet ( hse.gov.uk )

Conclusion Fixed roof tank (D> 60 m) a combination approach consists of shell- mounted foam chambers and subsurface foam application . With semi-fixed system , integrity of the system , heat radiation and wind shift should be taken into account. Portable / mobile high capacity variable flow foam monitor preferable as compared with fixed foam monitors considering the Cost Benefit . Large capacity foam tender (Foam Nurser) for foam transportation to meet foam requirement . Consideration for high capacity container (1000 liter ) for foam in place of jerry can . Use of 1% foam concentrate in place of 3% may be explored for logistic relief.

Conclusion Fire fighting strategies (passive, defensive or offensive) to be included during planning stage for a specific tank fire scenario response. Risk assessments & emergency response strategies should adequately address the potential worst-case scenarios involving multiple tank/bund fire and large volumes of firewater run-off. The extinguishment of full surface fire on large diameter storage tanks require huge logistic & resources. As these are rare events but can have high consequences, a country wide strategically located capability to respond to major incidents of tank fires and other emergency may be built up.

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