caribbean petroleum vce case history · 2019. 5. 28. · caribbean petroleum vce case history...

Hazards 29 – HAZ29_049

Quentin A. Baker, P.E.Thursday, 23 May 2019

Caribbean Petroleum VCE Case History

©2019 Baker Engineering and Risk Consultants, Inc.

▪ Facility was in service as terminal (refinery shut down)

▪ Incident occurred on October 23, 2009 shortly after midnight

▪ Offloading gasoline from ship into series of tanks

▪ Filling Tank 409 at time of incident

▪ Overflowed through elevated vents

▪ Created large flammable cloud (calm conditions)

▪ Cloud occupied large, heavily vegetated areas

▪ Ignited cloud when reached unclassified area

▪ VCE damaged on and off-site structures

▪ BakerRisk performed extensive field investigation on behalf of owner

2

Incident Overview

3

Image During Fire Next Day

Tank 409

N

4

Site Aerial Photo

Tank 409

• Built in 2006 (3 yrs old)

• Internal floating roof

• 120 ft. dia.

• 63 ft. high

• 120,000 bbls.

• Six overflow vents at 60 feet

(3 feet x 9 inches)

5

Tank 409

Overflow

vents

6

Overflow of Tank 409 (1 of 2)

▪ Offloading gasoline from ship into series of tanks

o 405, 504, and 411 filled and closed; filling 409

o Tank 409 level system not communicating with control room

o Began filling tank 409 at 10:00 PM, expected to be filled at 1:00 AM

o Operators checked Tank 409 level (at tank) at 11:00 PM

o Inspectors on 411 up to about 11:23 PM (clear view of 409, no

overflow)

▪ Operators enter tank farm from west just before midnight on rounds

▪ Observe dense layer of “fog”

▪ Leave tank farm, and direct ship to stop transfer operations

▪ Tank 409 began overflowing between 11:23PM and midnight

7

Overflow of Tank 409 (2 of 2)

• Ship stops transfer operations at 12:12 am

• Other operators enter on east side, observe cloud in vicinity of Tanks

301 and 302, ignition occurs before can drive further into tank farm

• Estimate overflowed 4,600 bbls. (193x103 gal, 731x103 liters)

o Six overflow vents located at 60 ft elevation (3 ft wide, 9 in. high)

o Overflow creates “water fall” effect and generates mist/vapor

mixture

• Flammable cloud formation

o Cloud spread in all directions from Tank 409 under calm conditions

o Cloud radius and height of roughly 1,000 ft (610 m) and 10 ft (3 m)

o Cloud volume of approximately 23x106 ft3 (6.5x105 m3)

o Approximately same volume per FABIG TN-12 (HSL) methodology

8

Site Topography

N

9

Flammable Cloud Outline

Tank 409

10

Ignition and VCE

• Ignition occurs at approximately 12:22AM

o 10 minutes after gasoline transfer from ship halted

• Initial ignition (reflections from CCTV video)

• Secondary ignitions (captured on CCTV video)

• VCE modeled as deflagration and as detonation, with resulting blast

loads compared to observed blast damage both on and off-site

• Vehicles on road to east of tank farm

11

Video from FCC Tower

• Ignition occurs at approximately 12:22AM

12

Determination of Ignition Location

North

• Dashed lines denote

edges of site lines for

cameras at time of

ignition

• Used reflections from

initial flame to locate

source

• Red circle denotes area

containing likely ignition

source

13

Ignition Source

• Electrical equipment cabinet (pump switch gear, unclassified area)

14

2nd Ignition (FCC Camera)

Secondary

Ignition

15

Secondary Ignition

• Electrical equipment enclosure

• Lines up with video image sight line

• Panel throw suggests internal

pressurization

• Suggestion that secondary ignition from

sewer not borne out by field investigation

16

Congestion (Vegetation, 1 of 2)

• Aerial photo predates

Tank 409 and 107

construction

• Vegetation heavy in

wetlands north and

east of the facility

17

Congestion (Vegetation, 2 of 2)

• Examples of more and less dense congested vegetation areas

18

Blast Damage Indicators

• Developed pressure asymptote values for on and off-site indicators

• Compared observed structural damage with predicted blast loads

Vehicle Positions at Time of Ignition on Roadway on East Side

107

605

603

Damage to Vehicles on the Roadway

21

Detonation of FABIG TN-12 Cloud

0.9 psi

3 psi

5 psi

10 psi

22

VCE Blast Loads

• Assuming flammable cloud based on FABIG TN-12 cloud (1 m deep):

o Detonation of entire flammable cloud grossly over-predicts loads

o Over-predict by factor of 5 to 300, averaging 40 times

o Similar results for deeper cloud (1.8 m) at same volume

• Blast loads predicted assuming a deflagration in reasonable agreement with

observed blast damage (slightly conservative)

o Dominated by congestion in vegetated areas

• Local indicators identified by others as possible detonation indicators were

judged to be due primarily to thermal effects

23

Conclusions

• VCE resulted from Tank 409 gasoline overfill during ship unloading

o Spill volume estimated to be 4,600 barrels

o Cloud spread in all directions from Tank 409 under calm conditions

o Cloud radius and height of roughly 1,000 ft (610 m) and 10 ft (3 m)

o Cloud volume of approximately 23x106 ft3 (6.5x105 m3)

• VCE was a deflagration

o Assuming a detonation grossly over-predicts observed damage

• FABIG TN-12 (HSL) approach for cloud volume along with simplified blast load

methodology expected to yield reasonable consequence predictions for similar events

• Expected that rapid & extensive secondary fires due to gasoline mist wetting

vegetation, tanks and equipment

▪ Co-Authors

o Kelly Thomas

o Darren Malik

o Matt Edel

▪ BakerRisk had performed investigation of this incident on behalf of the owner

immediately following the incident

▪ Explosion Research Cooperative (ERC) joint industry program funded analysis

and evaluation of this incident

o Approved limited release of information as case study

24

Acknowledgements

Quentin A. Baker, P.E.Senior Principal Engineer, Blast EffectsPresident

Understanding Hazards and Risks

25

Contact Us

BakerRisk Europe Ltd.Thornton Science Park (Bldg. 49)Pool Lane, Ince, Chester CH2 4NUUnited Kingdom

+44.1244.405.960 (UK office)

+1.210.824.5960 (San Antonio office)

QBaker@Bakerrisk.com

www.BakerRisk.com

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Questions?