Barrier Qualification & Quantification

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v1.2 © Process Safety Integrity 2018 | www.ProcessSafetyIntegrity.com

Barrier Qualification & Quantification

Using LOPA plug-in to evaluate risks and exploiting BowTieXL to perform numerical analysis

David HATCH

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[email protected]

mailto:[email protected]

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Introduction◇BSc(Hons) Chemical & Process Engineering

◇30+ Years in High Hazard & Highly Regulated Industries

•Oil & Gas, Chemical, Power, Life Sciences …

◇Value Added Consultancy Partner

•Process Safety (Loss Prevention)

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Scientia = “Knowledge”

Ingenium = “Ingenuity”

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Topics◇LOPA basics

◇LOPA Plug-In

◇BowTieXL basics

◇Applications

•Cost Benefit Analysis

•Qualitative LOPA

•Cumulative Risk

•Escalation Factors

•Consequence Effects

•Chained Bowties

◇Demand Data

•Sensitivity Analysis

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Layers of Protection

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COMMUNITY EMERGENCY RESPONSEEmergency Broadcasting

PLANT EMERGENCY RESPONSEEvacuation Procedures

MITIGATIONMechanical Mitigation Systems

Safety Instrumented Systems

Operator supervision

PREVENTIONMechanical Protection System

Process Alarms with Operator Action


CONTROL and

MONITORINGBasic Process Control

System

Monitoring Systems

Operator Supervision

PROCESS

PRV

Chemical = A

Material = B

Pressure = X

Temp. = Y

Volume = Z

LSHLAH

FIC

LSHH

In a typical chemical process, various protection layers are in place to lower the frequency of undesired consequences:

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Barrier Analysis

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ACTIVE HUMANEvacuation procedures

Emergency broadcasting

PASSIVE HARDWAREMechanical Mitigation Systems

Containment Systems

ACTIVE HARDWARE + HUMANProcess alarms with operator corrective action

Operator supervision

ACTIVE HARDWAREMechanical Protection Systems

Control Systems


CONTINUOUS

HARDWAREVentilation

PROCESS

PRV

Chemical = A

Material = B

Pressure = X

Temp. = Y

Volume = Z

LSHLAH

FIC

LSHH

Layer of protection analysis (LOPA) is a semi-quantitative tool for analysing and assessing risk.

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Hazard Line of Sight

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FHE = Σ(FIE × PFDIPL01 × … × PFDIPLn) for all IE

FME = FHE × (PMCM01 × … × PMCMn)

RRF = FME ÷ FTE

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Risk Targets (Events/Time)

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Top Event, e.g.

◇Releases/year

Consequences e.g.

◇Deaths/year

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Frequencies & Probabilities

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◇Frequency = Events/Time ◇Probability of Failure on Demand (PFD)

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Scenarios

◇One to One

◇One to Many

◇Many to One

◇Many to Many

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LOPA Example

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LOPA Features

◇Current & Future Evaluation (“What-If” analysis)

◇LOPA diagrams can also include Actions

◇Safeguards can be included as barriers but excluded from calculation (PFD = 1)

◇Specific Threats can be excluded from analysis

◇Enabling Conditions can be included

◇Conditional Modifiers on Consequence or as individual Mitigation Barriers

◇Change values for Individual or Group

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LOPA Import & Export

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Scrapbook

Reports

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So Far So Good ?

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Presence & Probability is not everything…

Are your barriers:

◇BIG enough?

◇FAST enough?

◇STRONG enough?

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BowTieXL – User Data & Keys

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BowTieXL – Spreadsheet

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Diagram Sheets (Keys & Values)

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Excel Formulae

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Use conventional Excel formula to manipulate & read values, e.g.

◇SUM & PRODUCT

◇INDIRECT

◇OFFSET

◇VLOOKUP

◇IF(condition,then,else)

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BowTieXL – Display User Data

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Conditional Formatting using HEX colours e.g. Red #FF0000Green #00FF00

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Cost Benefit Analysis

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◇Barriers cost money to;• Install/Implement Capital Expenditure CAPEX•Maintain/Sustain Operating Expenditure OPEX

◇How much return (risk reduction) do they provide?

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Qualitative LOPA - Product

◇In the absence of (or to avoid debate about) numbers, select:• Threat Frequency = High (1) Medium (0.1) or Low (0.01)

• Barrier Effectiveness = High (0.01) Medium (0.1) Low (0.5)

• Consequence Severity = Major (10) Medium (1) or Min (0.1)

◇Risk Prediction based on aggregate of contributions

• Acceptable/Unacceptable compared to (Consequence) target

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Qualitative LOPA - Sum

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More Threats, More often = increase Likelihood.

More Prevention/Recovery Barriers with Better performance = decrease Likelihood.

Higher Hazard impact = increaseSeverity

More Mitigation Barriers with Better performance = decreaseSeverity

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Cumulative (Group) Risk

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Chained Risk

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Escalation Factors

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Degradation (Escalation) Factors: “A situation, condition, defect, or error that compromises the function of a main pathway barrier, through either defeating it or reducing its effectiveness.”

Degradation Control: “…measures which help prevent the degradation factor impairing the barrier.”

Overall effectiveness of main pathway barrier determined by:◇ Contribution each Factor makes.

◇ Number & Effectiveness of Controls.

• More & Better Controls reduces Degradation Factor contribution

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Consequence Effects

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A well defined Hazard includes:

◇Situational context

◇An indication of scale

Each Hazard component has impact score (e.g. 1 = Low to 4 = High):

◇Sum the contributions to give Consequence Severity (Concern)

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“Lies, Damned Lies & Statistics”◇There are two kinds of statistics, the

kind you look up and the kind you make up.

◇Interrogate numbers and they’ll confess to anything.

◇One swallow does not make a summer.

• SIGNIFICANT

◇Compare Apples & Apples.

• RELEVANT

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Demand Data & LOPA validation◇Planned Demands (Audits)

•Inspection & Testing of Barriers

•Barrier failure probability prediction

◇Unplanned Demands (Incidents)

•Threat frequency

•Barrier failure probability confirmation

◇Enterprise-wide Database

•Statistically significant & relevant data

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Visualising Audits and Incidents

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Sense & SensitivityHSE RR716 “The conclusions drawn from a LOPA study will be sensitive to all the input assumptions. Therefore, some form of sensitivity study is required to demonstrate the robustness of any conclusions.”

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◇What if the Frequencies and/or Probabilities are Increased by a Factor of 3

◇ Conditional formatting on result:

• Red = Fail on Max Freq & Probability, Green = Pass on Max Freq & Probability

• Orange = Fail on Max Probability, Yellow = Fail on Max Frequency

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◇Visualising hazards in BowTieXP makes risk Understandable

• Qualify your Scenario(s)

◇Evaluating risks using LOPA plug-in makes risk Measurable

• Quantify your Scenario(s)

◇Data from AuditXP & IncidentXP makes risk Verifiable

• Threat Frequency

• Barrier Failure Probability

◇Make informed decisions based on:

• Qualified Evidence (Barrier Presence)

• Quantified Data (Barrier Performance)

◇BowTieXL customisation offers Consistency

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Reflections

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Want to Know More ?

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Workshops Webinars

We are already planning more LOPA & BowTieXL events in your region and online briefings in your time zone.

For more information, please contact:

Niels van den Bosch (CGE Global Account Manager) [email protected] Hatch (Process Safety Integrity) [email protected]

mailto:[email protected]?subject=LOPA & BowTieXL workshops & webinars

mailto:[email protected]?subject=LOPA & BowTieXL workshops & webinars

Barrier Qualification & Quantification

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Transcript of Barrier Qualification & Quantification