HAZ29 122 Failure of Above-ground Storage Tanks (AST)

HAZ29_122

Failure of Above-ground Storage Tanks (AST) :

a new methodology for assessing consequences

Authors: Chris Robinson 1, Mark Scanlon 2, Euan Stoddart 1, Kunle Fajuyitan 1, Tristan Vye 1

Organisations: 1 MMI Thornton Tomasetti2 Energy Institute

Correspondence: [email protected] | 01904 428721 | 07979 656988

mailto:[email protected]

▪ Thornton Tomasetti provides

engineering design,

investigation and analysis

services to clients worldwide on

projects of every size and level

of complexity.

Failure of Above-ground Storage Tanks (AST)

Companies Involved

Construction Engineering

Structural Engineering

Applied Science

Transportation

Buildings Renewal

Façade Engineering

Property Loss Consulting

Forensics

Protective Design & Security

Sustainability

▪ The Energy Institute (EI) is the

chartered professional membership

body bringing global energy

expertise together.

▪ We gather and share essential

knowledge about energy, provide

the skills that are helping us all use

it more wisely, and develop the good

practice needed to keep it safe and

secure

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Failure of Above-ground Storage Tanks (AST)Project Brief

EI Containment Systems Working Group

“Develop failure mode analysis

assessment tool for above ground

storage tanks”

Objective: Improve predictive

risk assessment for

catastrophic AST

failure

Clarity in

required risk

reduction

measures

Consistency in

predictive risk

assessments

COMAH

Safety

Regulations

Failure of Above-ground Storage Tanks (AST)Project Brief

EI Containment Systems Working Group



storage tanks”

Phase 1: • Focus: catastrophic primary

containment failure modes

and the factors that affect

vulnerability

• FMECA

Phase 2-4: • Phase 2: develop methodology

for assessing consequences of

AST failure

• Phase 3: calibrate the

methodology

• Phase 4: determine overtopping

fractions in methodology

Risk = frequency of event x consequence of event


How will the new methodology work

[fatalities per year] [events per year] [fatalities]

Phase 2-4: • Methodology for assessing

consequences of different

failure scenarios

Phase 1: • FMECA gives

frequencies

Consequence: • Failure of secondary containment

• Volume of spilled fluid overtopping

secondary containment

For “Risk” calculation need

additional steps: • P (ignition)

• Thermal Radiation Contours

• P (occupancy)


What are ASTs – how do they fail?

2013 - Ranger Uranium Mine,

Northern Territory, Australia• 1 ML sludge (mud/water/uranium ore/acid)

2011 - Lake Placid, Florida, USA• 300,000 gallon water tank

• “The force from the water was so great,

investigators say it tore through a concrete

block wall, forcing the building to collapse

on top of the two workers inside”



2008 - Allied Terminals

Chesapeake, Virginia, US• Spilled 2 million USgal liquid fertiliser

• Injured 4 people.

• US Chemical Safety Board determined

cause as faulty welding.

2006 - LA Gas, Salt Lake City, Utah, US• 13,000 USgal of hydrochloric acid.

• Tank topple due to strong winds



2004 - BR Petrochemicals, Vathuruthy, India• One killed, 2 injured

• 1.5 ML of water spilled during a pressure test

2004 -Chevron-Texaco, North Pass,

Mississippi, US• 423 tonnes crude oil spill,

• Collapse due to hurricane Ivan


Boston Molasses Disaster – 100 years ago.

15th January 1919

The North End neighbourhood of Boston, US

• A large molasses storage tank burst

• A wave of molasses rushed through the streets at

an estimated 35 mph (56 km/h),

• Killed 21 ; injured 150.


Existing Analysis by Computational Fluid Dynamics (CFD) Modelling



storage tanks”

Phase 2-4: • Method for assessing

consequences of AST collapse

Data & Experience

• Computational Fluid Dynamics (CFD) analysis

• Volume overtopping secondary containment (bund)

• Structural loads

• Development of wave return / retaining bund profiles

• Design of bunds and retaining structures


Existing Analysis by CFD Modelling


Existing Structural Analysis

Raw pressure-time

history manipulated

into wall/stem forces

for design

Hand calculations used

to estimate foundation

sizes & limit movement

FEA to check

displacements & extract

member/ connection

forces and moments


Methodology Logic

Developing the new

methodologyExcel based tool

Methodology

Logic


Methodology Logic

Developing the new


Define AST &

properties


Methodology Logic

Developing the new

methodologyExcel based tool Define failure

Mode 6:

Failure of

main pipe

Mode 7:

Tank Shell Scoring

Mode 1:

Rocketing ShellMode 4:

Rapid failure

/ unzipping

Mode 2:

Shell / bottom

failure

Mode 3:

Bottom failure

Mode 5:

Medium Shell

Failure


Hydrodynamic Calculations

Developing the new


Hydrodynamic

Loading Calc

Mode 1:

Rocketing

Shell

Mode 4:

Rapid failure

/ unzipping

Mode 2:

Shell /

bottom failure

Mode 3:

Bottom

failure

Mode 6:

Failure of

main pipe

Mode 7:

Tank Shell

Scoring

Mode 5:

Medium

Shell Failure

Discharge

through Orifice

Sluice

Discharge

Self-similar

Slumping

Load on

Bund wall


Structural Loading vs. Structural Resistance

Developing the new


Hydrodynamic

Calculations

Structural

Resistance

Foundation:• Overturning

• Sliding

• Bearing Pressure

Bund Wall:• Moment

• Shear

Compare with …


Structural Resistance & Overtopping

Developing the new


Structural FoS

Structural Resistance

Hydrodynamic Load


Methodology Example

Developing the new


Example: Shell /

Bottom Failure


Methodology Example

Developing the new


Data Input

Sheet


Methodology Example

Developing the new


Example: Shell /

Bottom Failure


Methodology Example

Developing the new


Example: Rapid Shell

Failure / Unzipping


Methodology Example

Developing the new


Example: Rapid Shell

Failure / Unzipping


Methodology Example

Developing the new


Example: Medium

Shell Failure


Methodology Example

Developing the new


Example: Medium

Shell Failure


Verification & Validation

Developing the new

methodology

Excel based toolVerification &

Validation

Verification:

• “do the calculations do

what I expect them to do”

• “is the maths correct”

Validation

• “does the code / method /

maths produce results that

represent the real world”

• QA (ISO 9001)

• Consistency Checks

• 3rd Party Testing

• “Cross-code” validation

with data from CFD model

• CFD model previously

validated using HSE R333


Verification & Validation

Developing the new

methodology

Excel based toolVerification &

Validation

Case No. Force [kN/m of bund]

(Source Term)

Force [kN/m of bund]

(CFD)

Ratio

Force (Source Term) /

Force (CFD)

1 0.11 0.04 2.75

2 275 130 2.11

3 828 221 3.74

Case No. Force

[kN/m of bund]

(Source Term)

Force

[kN/m of bund]

(CFD)

Ratio

Force (Source Term) /

Force (CFD)

4 6.6 5.6 1.18

5 3.2 2.4 1.33

6 4.3 4.5 0.96

Catastrophic Tank

Collapse(Mode 1 & 4)

Shell / Bottom

Failure(Mode 2 & 3)


Conclusions

▪ A new failure mode analysis assessment tool for above ground storage tanks

▪ Excel based tool incorporates a range of failure modes:

• catastrophic collapse; failure of tank shell; failure of bottom connection

▪ Provides rapid assessment of existing AST or new sites

▪ Provides data for Risk Analysis

▪ Indicative results – to inform design and indicate if more detailed analysis is

required

▪ Methodology to be published by Energy Institute later in 2019

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Documents

HAZ29 122 Failure of Above-ground Storage Tanks (AST)