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FireWater Design Requirements for Petrochemical and Hydrocarbon Plants

Jack Woycheese, P.E., FSFPE November 9, 2004

Assumptions

Petrochemical & Hydrocarbon Plant Units Large Volumes of Flammables Close Grouping of Process Equipment Objective: Determine Water Requirements Fire Limited to Single Unit Simultaneous Fires in Adjacent Units is Unlikely Single Largest Credible Fire Consider Cumulative Effect of Smaller Risks

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Use of Water

A gallon of water applied at 50F vaporized at 212F removes over 9000 BTUs of Heat

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Factors

Credible Fire Incidents Manpower Water availability Drainage Emergency Shut Down and Isolation Control vs Extinguish Foam Suitability and Supply Layout Congestion

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Factors, Continued

Processes Materials and State Process Pressure Process Flow Expected Release of Liquid Holdups Regulations Industry Standard of Care Corporate Requirements Fire Brigade/ Department Emergency Response Plan

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Credible Fire Scenarios

Prescriptive

Furnace Fires Compressor Fires Pump Fires Tank Seal Rim Fires Tank Loading Racks Historical Data

Performance Based

- Process Safety Analysis - Modeling

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Fire Water (FW) Supply Considerations

City Supplies On-Site FW Tankage

- Dedicated to FW Service - Prohibit Cross Connections to Process

Adjacent Waterways

- Provide for Connections to Supplement FW

Deep Wells

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Credible Fires ­ Spill Fire

Nature and Size: volume, temperature, pressure, viscosity, reactivity, material type Spill path: Type, slope & grade of area drainage Equipment exposed Fire protection systems likely to operate

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Design Rates ­ Process Areas

Generally 0.1 GPM/sq.ft. of ground area Process areas separated by 50 ft. minimum

- Roadways OK; Pipebands OK if 20ft of clear space

If process is high density with stacked equipment use 0.15 GPM/sq.ft. of ground area Generally not less than 3000 GPM; not more than 6000 GPM

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Process Pressure Vessels

0.10 gpm/sq.ft. for top half of vessel or for exposed vessel surface 0.25 gpm/sq.ft. for top half of vessel for impingement cooling. Add exposure protection for adjacent equipment and impinging fire Pool fire exposure requires 0.20 gpm/sq.ft. for exposed vessel surface

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Flow Rates and Pressures

1-1/4 inch hard rubber hose at 100 psi 40-60 GPM

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Flow Rates and Pressures

500 GPM monitor 190 ft straight stream throw at 100 psi 1000 GPM monitor 250 ft straight stream throw at 100 psi Wind may reduce by up to 40%

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Design Rates ­ Offsite Facilities

Duration & Rate 1 hr & 500-1000 GPM Facility Offices, shops, warehouses (plus sprinkler requirements)

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Design Rates ­ Offsite Facilities

Duration & Rate 2 hrs & 1-2000 GPM Sulfur plant, H2S recovery plant Utility Plants Loading Racks Small processing plants Piers (plus foam water requirements)

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FW Supply

Duration & Rate 4 hr & 2-4000 GPM Facility Midsize, 0-500 psi process plants Gas Plants Multi-berth docks Offshore Plantforms

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FW Supply

Duration & Rate 4 hr & 4-6000 GPM Facility Integrated, high value. 0-500 psi Midsize, 500-1000 psi process plants Integrated, high-value plants, large quantities of fuel at pressures above 1000 psi.

6 hr & 6-8000 psi

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Design Rates ­ Offsite Facilities

Duration & Rate 2 hrs & 1-2000 GPM Tankfield areas

- Pipeline terminals - Marketing Terminals - Refinery Tank Fields

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Design Rates ­ Tank Farms

Assume Water needs for foam applications per NFPA 11 Assume water for cooling tank on fire Assume water for cooling for any tank within the downwind quadrant and within 2Diameters of the diameter of the tank on fire.

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Design Rates ­ Tank Farms, Continued

Floating roof, 1000 gpm Internal FR or Low Flash Cone Roof Tank: Dia, ft Burning tank Adjacent tank gpm gpm 56 750 250 80 1000 500 110 1250 750 130 1500 750 140 1750 1000 150 2000 1000

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Design Rates ­ Tank Farms, Continued

Exposure cooling water supply requirements calculation:

- Four ten minute bursts for ten minutes each for four hours - Dike area (less tank area) X 0.16 gpm/sq.ft. X 30 minutes for foam cover - Burning tank cooling: 12 applications for 15 minutes each. - Clean up activities for up to 2 hours (rate?, time per application? Say ¼ foam rate, 8 times for 10 minutes each.

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Design Rates ­ Floating Roof Tanks

Small tanks

- Seal Fire Only - 1500-2000 GPM

Add 1000 GPM for cooling the shell Treat as cone roof, no seal rim protection

Internal floating roof Cone roof tanks

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Thank You

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Information

Hughes Overview

23 pages

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