RISK ASSESSMENT CONCEPTS AND PRACTICE

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RISK ASSESSMENT CONCEPTS AND PRACTICE

• Presentation to University of South Australia
• Environmental Engineering
• 23 March 2004
• Richard McDonough
• Manager Pipeline Operations
• Petroleum Group

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The Author

• Chemical Engineering graduate
• Mines Energy / PIRSA - 19 years!!!
• Reservoir engineering
• Economic analysis for gas pricing, royalty
  review, gas production
• Gas reserves advice / computer modelling
  simulation
• Environmental approvals monitoring
• Petroleum Act 2000
• Pipelines
• AS 2885 (pipelines standards) committees
• Responsible for review of risk assessment for
  pipelines in AS 2885

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Overview

• Risk concepts
• what is risk?
• risk perception
• acceptable risk
• ALARP
• Risk assessment methodology
• AS 3931, AS 2885, AS 4360
• Example high pressure gas pipelines

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What would you do?

• THE BOX OF DEATH

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What would you do?

• THE BOX OF DEATH

5 Caramello Koalas
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What would you do?

• THE BOX OF DEATH

5 Caramello Koalas, 5 Snakes
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What would you do?

• THE BOX OF DEATH

9 Caramello Koalas, 1 Snake
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What would you do?

• THE BOX OF DEATH

9 Caramello Koalas, 1 Taipan
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What would you do?

• THE BOX OF DEATH

What would STEVE IRWIN do??
9 Caramello Koalas, 1 Taipan 99 Caramello Koalas,
1 Taipan etc
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What would you do?

• THE BOX OF DEATH

9 Caramello Koalas, 1 Python
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What would you do?

• THE BOX OF DEATH

9 Caramello Koalas, 1 Jelly Snake
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What is risk?
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Risk Concepts

• Frequency
• Consequences
• Perception
• Risk Acceptance

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Risk Definitions

• AS 3931
• combination of the frequency, or probability, of
  occurrence and the consequence of a specified
  hazardous event
• Note the concept of risk always has two
  elements, the frequency or probability with which
  a hazardous event occurs and the consequences of
  the hazardous event

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What is risk?

• Risk combines FREQUENCY and CONSEQUENCE
• Risk estimation requires us to be SPECIFIC about
  the consequence

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Risk Definitions

• AS 4360
• the chance of something happening that will have
  an impact upon objectives. It is measured in
  terms of consequences and likelihood.
• I would suggest that this is a poor definition,
  because
• it uses imprecise language and
• it is misleading (risk can only be expressed for
  a single consequence, NOT consequences - eg.
  death risk is different to injury risk).

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Frequency Consequence

• Consequences
• positive
• negative
• hierarchy of consequences
• Frequency
• frequency of CONSEQUENCE
• NOT frequency of initiating event

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PIPELINE THREAT OCCURS
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Risk Perception

• A problem for engineers
• (rational, numerate beings!!!)
• Perception is reality
• Behaviour is driven by perception and not cold
  hard facts.
• Risk communication is an issue

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Acceptable Risk

• Individual Risk
• eg 1 in a million per year
• Societal Risk
• It is more acceptable to have 1000 incidents each
  resulting in single fatalities than 1 incident
  resulting in 1000 fatalities
• Accepted risk will reflect either or both of
  these
• Refer to HIPAP4

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ALARP

• As Low As Reasonably Practical
• In the range 10-4 to 10-6
• No single definitive definition
• Ultimately determined by courts
• A working definition
• where the cost of mitigating the risk exceeds the
  costs of the risk consequences

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Comparison of AS4360, AS3931, AS2885

• Different objectives, audiences and emphases
• AS 4360
• generic
• AS 3931
• technological systems
• AS 2885
• pipelines

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Risk Assessment Process
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AS 2885 RISK ASSESSMENT PROCESS (proposed
revision)
PROBLEM DEFINITION
Describe Design and Operation Parameters
Determine Safety Review Methodologies
Location Analysis
THREAT ANALYSIS / MITIGATION BY DESIGN
Identify and Specify Threats
Classify Threats
Non-credible threats
External Interference Threats
Design Threats
Eliminate or Minimise Threats by Design
Identify Residual Threats
Identify Loss of Integrity Events
RISK EVALUATION LOSS OF INTEGRITY EVENTS
Risk consequence frequency
RISK MANAGEMENT
Risk Management Actions as Required
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Key Aspects of AS 2885

• Concentrates effort at Initial Evaluation and
  Control stage
• highlights importance of consequence analysis
• not obvious in AS3931 and AS4360
• If risk can be eliminated it MUST be eliminated
• not a feature of AS3931 and AS4360

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Key Aspects of AS 2885 (2)

• Minimizes risk-based decision-making
• minimizes decisions based on uncertainty
• Maximizes pipeline safety
• ALL threats must be addressed

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Pipeline Example

• High pressure gas pipeline traversing a number of
  different land use areas
• Concentrate on external interference protection
  (the most common cause of pipeline incidents in
  Australia).
• Pipeline Risk Assessment focuses on specific
  incidents on a specific pipeline at a specific
  location (NOT generic)

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Step 1 - Scope Definition(1)

• Pipeline Properties
• mechanical properties, operating parameters
• under what circumstances can a hole be put in the
  pipe?
• if a hole is put in the pipe, what can occur?
• All this is known, or can be calculated
• Pipeline-specific information (not generic
  information)
• Real information for decision-making

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Step 1 - Scope Definition(2)

• Location analysis
• land use, environment, crossings, population
  density determined on a metre by metre basis
• Threats and consequences are dependent on the
  location
• Generic guesses are not good enough
• Can only design against real threats which are
  properly defined

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Step 2a - Threat ID

• The elimination of threats by external
  interference protection and engineering design
  must be based on quantifiable data.
  Consequently, the threats analysis must generate
  sufficient information about each threat to allow
  such design to take place. (HB105)

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Step 2a - Threat ID

• For each location, identify all activities which
  occur on the pipeline easement
• Develop specific information for each threat
• what happens?
• what equipment?
• who is responsible?
• how deep?

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Step 2b - Eliminate threats where possible

• AS 2885 mandates physical and procedural measures
• Physical measures
• eg. wall thickness, depth of burial, slabs,
  barriers
• Procedural measures
• eg. signs, liaison, patrols, dial-before-you-dig

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Bobcat Bob

• 2 physical protection
• Digs 50 cm holes (pipe buried at 1m)
• Bobcat is not powerful enough to penetrate pipe
• 2 effective procedural protection
• signs on Bobs fences
• liaison with Bob once a year
• Threat eliminated
• No risk evaluation required (it is not meaningful)

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Water Company

• Water main below gas pipe
• Excavator powerful enough to penetrate pipe
• No physical protection
• Risk evaluation must be carried out

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Step 3 - Water Company Risk Evaluation

• Consequence analysis shows that an ignited gas
  release may result in multiple fatalities
• Frequency analysis suggests this is an unlikely
  occurrence (ie. might occur once every hundred
  years)

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Water Company Risk Evaluation
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Step 4 - Risk Management - Water Company

• High risk category demands risk management
  action
• Examples include
• increase pipe wall thickness at this location
• bury gas pipe below water pipe
• raise water pipe above gas pipe
• concrete slabs around pipe at this location

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Conclusions

• Risk analysis is not rocket science
• However, brain needs to be switched on
• Be specific
• Be highly critical of any numbers, assumptions
  and conclusions (always ask hard questions)
• Minimise risk-based decisions by eliminating
  threats where possible
• In general, the process is more important than
  any numbers generated because it has forced
  people to think about the problem

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