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Major Hazard Facilities Major Accident Identification and Risk Assessment The approaches outlined in this seminar are required for new facilities (as.

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Presentation on theme: "Major Hazard Facilities Major Accident Identification and Risk Assessment The approaches outlined in this seminar are required for new facilities (as."— Presentation transcript:

1 Major Hazard Facilities Major Accident Identification and Risk Assessment
The approaches outlined in this seminar are required for new facilities (as well as existing)

2 Overview This seminar has been developed in the context of the MHF regulations to provide: An overview of MA identification and risk assessment The steps required for MA recording Examples of major accidents identified The steps required for a risk assessment Examples of risk assessment formats

3 Some Abbreviations and Terms
AFAP - As far as (reasonably) practicable BLEVE – Boiling liquid expanding vapour explosion BPCS – Basic process control system DG - Dangerous goods Employer - Employer who has management control of the facility Facility - any building or structure which is classified as an MHF under the regulations HAZID - Hazard identification HSR - Health and safety representative LOC - Loss of containment LOPA – Layers of protection analysis MHF - Major hazard facility MA - Major accident SIS – Safety instrumented system

4 Topics Covered In This Presentation
Regulations Definition - Major accident (MA) MA identification issues Approaches to MA identification MA recording Pitfalls

5 Topics Covered In This Presentation
Definition of a risk assessment Approaches Risk assessment Likelihood assessment Consequences Risk evaluation and assessment Summary Sources of additional information Review and revision

6 Regulations Hazard identification (R9.43) Risk assessment (R9.44)
Occupational Health and Safety (Safety Standards) Regulations 1994 Hazard identification (R9.43) Risk assessment (R9.44) Risk control (i.e. control measures) (R9.45, S9A 210) Safety Management System (R9.46) Safety report (R9.47, S9A 212, 213) Emergency plan (R9.53) Consultation The approaches outlined in this seminar are appropriate and relevant for new facilities

7 Regulations Regulation 9.43 (Hazard identification) states:
Occupational Health and Safety (Safety Standards) Regulations 1994 Regulation 9.43 (Hazard identification) states: The employer must identify, in consultation with employees, contractors (as far as is practicable) and HSRs: All reasonably foreseeable hazards at the MHF that may cause a major accident; and The kinds of major accidents that may occur at the MHF, the likelihood of a major accident occurring and the likely consequences of a major accident.

8 Regulations Regulation 9.44 (Risk assessment) states:
Occupational Health and Safety (Safety Standards) Regulations 1994 Regulation 9.44 (Risk assessment) states: If a hazard or kind of major accident at the MHF is identified under regulation 9.43, the employer must ensure that any risks associated with the hazard or major accident are assessed, in consultation with employees, contractors (as far as is practicable) and HSRs. The employer must ensure that the risk assessment is reviewed: Within 5 years after the assessment is carried out, and afterwards at intervals of not more than 5 years; and Before a modification is made to the MHF that may significantly change a risk identified under regulation 9.43; and When developments in technical knowledge or the assessment of hazards and risks may affect the method at the MHF for assessing hazards and risks; and If a major accident occurs at the MHF. Historically there has been a focus on risk from hazardous facilities to neighboring land users. Under the OH&S Act an Employer is required to provide a safe place of work. The MHF regulations focus on both on-site and off-site risk exposures

9 Regulations Regulation 9.45 (Risk control) states:
Occupational Health and Safety (Safety Standards) Regulations 1994 Regulation 9.45 (Risk control) states: The employer must, in consultation with employees, contractors (as far as is practicable) and HSRs, ensure that any risk associated with a hazard at the MHF is: eliminated; or If it is not practicable to eliminate the risk – reduced as far as practicable. The employer must: Implement measures at the MHF to minimise the likelihood of a major accident occurring; and Implement measures to limit the consequences of a major accident if it occurs; and Protect relevant persons, an at-risk community, and the built and natural environment surrounding the MHF, by establishing an emergency plan and procedures in accordance with regulation 9.53.

10 A sudden occurrence at the facility causing serious danger or harm to:
Definition Major Accident A major accident is defined in the Regulations as: A sudden occurrence at the facility causing serious danger or harm to: A relevant person or An at-risk community or Property or The environment whether the danger or harm occurs immediately or at a later time It is important that the focus of MHF is on Schedule 9 materials, DGs etc and large consequences not on identifying natural disasters. “Sudden Occurrence” – infers release of “energy”. In many cases this will mean material although an explosion is a direct release of stored energy. We are not considering OH&S type incidents – slips, trips, falls, traffic accidents etc. Although these can have serious consequences, they are not the focus of the MHF regulations.

11 MA Identification Issues
Unless ALL possible MAs are identified then causal and contributory hazards may be overlooked and risks will not be accurately assessed Likewise, controls cannot be identified and assessed Identification of MAs must assume control measures are absent/unavailable/not functional That is: WHAT COULD HAPPEN IF CONTROL MEASURES WERE NOT APPLIED AND MAINTAINED ? Hazards are there all the time. The controls are what prevent the hazards from becoming major accidents.

12 MA Identification Issues
MAs can be identified in three different areas These are: Process MAs MAs arising from concurrent activities Non-process MAs

13 MA Identification Issues
Process MAs These are MAs caused by hazards which are associated with upsets in the process, or failure of equipment in the process, etc MAs arising from concurrent activities Typical concurrent operations which must be considered are: Major shutdowns/start ups Other activity on site Activities adjacent to the facility Process MAs: Overpressure of the vessel, overfill of the storage tank Concurrent activities MAs: Construction activities, new projects

14 MA Identification Issues
Non-Process MAs MAs created by non-process hazards that could cause release of Schedule 9 materials Non-process hazards may typically include the following: aircraft crashing; dropped objects; extreme environmental conditions (earthquake, cyclone, high winds, lightning); non-process fires (e.g. bush fire); vehicles and road transport; heat stress Non-Process MAs: External events

15 MA Identification Issues
Collate appropriate Facility information Incident data/histories To ensure a thorough understanding of : The nature of the facility Its environment Its materials Its processes All aspects need to be considered

16 MA Identification Issues
Develop/select a structured method for determining what types of MA can occur: Loss of containment Fire Explosion Release of stored energy Where they can occur Under what circumstances Define and document any restrictions applied to the above

17 MA Identification – Tools Usage
Examples of tools which might be used include: Analysis of Schedule 9 materials and DG properties Use of HAZID techniques Review of existing hazard identification or risk assessment studies Analysis of incident history – local, industry, company and applicable global experience A good HAZID would form the basis for selection of potential MAs for further analysis. This screening would be done based on consequence only and not consider any prior screening of the hazard register based on likelihood or risk.

18 Approach to MA Identification
It may be efficient to treat similar equipment items handling the same Schedule 9 materials together - as often they have similar hazards and controls Further, to ensure correct mitigation analysis, the equipment grouped together should contain similar materials at similar process conditions, resulting in similar consequences on release As an example, LPG storage vessels will be different to ammonia storage vessels and should not be grouped together as the same MA, but a group of storage tanks all used for the same material could be grouped together.

19 Approach to MA Identification
For consistency of analysis, all MAs should be defined in terms of an initial energy release event This can be characterised as a loss of control of the Schedule 9 material As an example, in the case of a hydrocarbon release from one vessel leading to a jet fire that subsequently causes a BLEVE in a second vessel, the MA should be defined in terms of the initial hydrocarbon release from the first vessel Define for an explosion. – Loss of controls preventing the initial detonation of explosives and mitigating controls preventing escalation.

20 Approach to MA Identification
Review HAZID studies to identify initiating events for each MA Review to ensure all hazards have been identified Special checklists should be developed to assist with this process Further hazards may be identified from: Discussions with appropriate subject experts Review of incident data Review of the records from a similar system Subject matter experts can provide valuable experience and input into specific situations and provide direction for the group to be investigating for the later controls and adequacy demonstration

21 MA Recording A structured approach is important
It can then link equipment management strategies and systems Record the key outputs in a register For each MA, the register should record the following information: Equipment that comprises the MA Group similar items into one MA Description Consequences A structured approach is important as it enables the identification of common issues and system problems and the development of strategies. The central hazard register may be used if well structured and managed.

22 MA Recording Consider all Schedule 9 materials - regardless of quantity Screen out incidents that do not pose a serious danger or harm to personnel, the community, the environment or property Screening should only be on the basis of consequence not likelihood i.e. Events should not be screened out on the basis of likelihood or control measures being active Consequence modelling should be used as justification for screening decisions External influences need to be considered, for example, potential for a power failure to cause a plant upset leading to an MA A degree of practical evaluation is also required and this should be backed up with consequence modelling/analysis. For example, a release rate of 0.1 kg/sec of crude oil will be unlikely to cause an exposure to personnel if it caught fire. Unless MA recording is managed (documented and communicated) then this will lead to a significant additional workload during the safety report preparation and will not add value to the safety report process and will increase costs unnecessarily

23 Example – MA Recording The following are examples of MA recording details MA Reference No. MA Description Equipment Included LPG-PU LOC - pumps LPG transfer pumps (P254/A) TKF-SA10 LOC – finished flammable product release from tank farm Flammable storage tanks A202, A205,A206, B21, C55 A26 Ignition of material Extruders E21/E22/D54 Helps to use a standardised reference numbering system for each MA. This will make it easy to link HAZID, MA and risk assessments and controls.

24 Major Hazard Facilities Risk Assessment
The approaches outlined in this seminar are required for new facilities (as well as existing)

25 What is Risk? Regulatory definition (per Part 20 of the Occupational Health and Safety (Safety Standards) Regulations 1994) : “Risk means the probability and consequences of occurrence of injury or illness” AS/NZS 4360 (Risk Management Standard) “the chance of something happening that will have an impact on objectives” Risk combines the consequence and the likelihood RISK = CONSEQUENCE x LIKELIHOOD For MHF, the application is a wider than that defined in Part 20 – also includes ‘risk’ to environment and property. It can be easy to confuse ‘hazard’ and ‘risk’. ‘Hazard’ is the source of potential harm. ‘Risk’ includes the likelihood of that hazard occurring and the consequences that may result if it did occur. Hazards are present in almost everything we do. E.g. Cars driving on the road. There are very high consequences of that hazard (e.g. our death) yet we accept that risk every day in walking across the road because we perceive the likelihood to be low due to good controls in place (traffic rules, crossing signs). We also have a higher tolerance for risk that we choose to take versus those risks imposed on us (e.g. from a neighbouring MHF) Review if needed.

26 Hazard versus Risk Is that a hazardous task? Is it high risk?
What is the damaging energy? Gravity (electricity too) What is the hazard? Falling What are some controls that could be used? Cherry picker, extended pole, fold light pole to ground How would these effect the hazard? The risk?

27 Risk Assessment Definition
Any analysis or investigation that contributes to understanding of any or all aspects of the risk of major accidents, including their: Causes Likelihood Consequences Means of control Risk evaluation These are the main factors included in a risk assessment.

28 The Risk Assessment Should…
Ensure a comprehensive and detailed understanding of all aspects for all major accidents and their causes Be a component of the demonstration of adequacy required in the safety report - e.g. by evaluating the effects of a range of control measures and provide a basis for selection/rejection of measures Demonstration of adequacy will be covered later.

29 Approach The MHF Regulations respond to this by requiring comprehensive and systematic identification and assessment of hazards HAZID and Risk Assessment must have participation by employees, as they have important knowledge to contribute together with important learnings These employees MAY BE the HSRs, but DO NOT HAVE TO BE However, the HSRs should be consulted in selection of appropriate participants in the process Involvement of employees in both hazard identification and risk assessment is essential.

30 Qualitative Assessment
Approach Types of Risk Assessment Qualitative Assessment Hazard Identification Quantitative Risk Assessment Asset Integrity Studies Plant Condition Analysis Human Factors Studies Consequence Analysis Likelihood Analysis Technology Studies Detailed Studies The information from the more detailed analysis can be presented in a qualitative manner, enabling a method to be used that provides clear understanding of the risk for every MA.

31 Causes From the HAZID and MA evaluation process, pick an MA for evaluation From the hazard register, retrieve all the hazards that can lead to the MA being realised In a structured approach, list all of the controls currently in place to prevent each of the hazards that lead to the MA being realised Examine critically all of the controls currently in place designed to prevent the hazard being realised

32 Ignition of materials (MA - A26)
Causes As an example, from hazard register, MA - A26 Ignition of materials (MA - A26) This might be an example of a major accident identified in the hazard register.

33 Ignition of materials (MA - A26)
Causes List all possible causes of the accident (identified during HAZID study) Ignition of materials (MA - A26) Hazard Scenario 1 Hazard Scenario 2 Hazard Scenario 3, etc

34 Ignition of materials (MA - A26)
Causes List all prevention controls for the accident (identified during HAZID study) Ignition of materials (MA - A26) Hazard Scenario 1 Hazard Scenario 2 Hazard Scenario 3, etc Prevention control C1-1 C1-2 C2-1 C3-1

35 Likelihood Assessment
Likelihood analysis can involve a range of approaches, depending on the organisation’s knowledge, data recording systems and culture This knowledge can range from: In-house data - existing data recording systems and operational experience Reviewing external information from failure rate data sources Both are valid, however, the use of in-house data can provide added value as it is reflective of the management approaches and systems in place In-house information is a very good source as it represents the company’s actual management strategies

36 Likelihood Assessment
A “Likelihood” is an expression of the chance of something happening in the future - e.g. Catastrophic vessel failure, one chance in a million per year (1 x 10-6/year) “Frequency” is similar to likelihood, but refers to historical data on actual occurrences Note that probability is something different – it does not have a time scale so does not tell you how often something may occur!

37 Likelihood Assessment
Likelihood Analysis can use: Historical Site historical data Generic failure rate data Assessment Workshops (operators and maintenance personnel) Fault trees Event trees Assessment of human error Operators and maintenance personnel are very valuable sources of information to verify or validate based on their specific experience for issues of interest. Need to ensure the Facilitator provides suitable examples to expand participants’ horizons beyond “not in my experience” Site historical data covers site incident information, external incident and frequency information, maintenance records, corporate history Near miss information from the site should also be used. For example, if a compressor has activated a vibration sensor, how many times has this gone off, is it indicative of an underlying fault and how have management dealt with the issue? External information – can be very useful, incident information, generic failure rates/data, sometimes qualitative, also may avoid finger pointing on known issues Maintenance records – if well kept excellent source of information, can be used for both causes of failure and how often, can support decision making and identify system problems As an example, testing of PSVs. If a PSV is within test period and conforms to a known suitable testing standard and it is appropriately documented then very good information will be collected on the service of that PSV with the known duty. Should there be an argument raised to vary the testing period, then the data can be used for this purpose. If the PSV is not tested in accordance with the stated requirements, and it is found to be severely deficient, then it could be questionable as to its suitability for an independent layer of protection within an assessment. Corporate history – useful if information is available and transparent, relates to corporate culture, testing and inspection regimes, management systems need to be consistent with management requirements so that they are useful Workshops – good for analysis of hazards and likelihoods, usefulness depends on getting right mix of attendants, recommendations/further work need to be recorded. Subject experts within a company (if they have them) can be very valuable sources of information and should be used when possible for checking and validating issues. Ensure any assumptions are documented and validated, where possible, with hard site data on operational experience.

38 Likelihood Assessment – Qualitative Approach
A qualitative approach can be used for assessment of likelihood This is based upon agreed scales for interpretation purposes and for ease of consistency For example, reducing orders of magnitude of occurrence It also avoids the sometimes more complicated issue of using frequency numbers, which can be difficult on occasions for people to interpret The approach is shown in the following slide.

39 Likelihood Assessment – Qualitative Approach
Category Likelihood A Possibility of repeated events (once in 10 years) B Possibility of isolated incidents (once in 100 years) C Possibility of occurring sometimes (once in 1,000 years) D Not likely to occur, (once in 10,000 years) E Rare occurrence (once in 100,000 years) Qualitative terms for likelihood helps people to assign for the risk assessment. Frequencies are not a requirement.

40 Likelihood Assessment – Fault Trees
A fault tree is a graphical representation of the logical relationship between a particular system, accident or other undesired event, typically called the top event, and the primary cause events In a fault tree analysis the state of the system is to find and evaluate the mechanisms influencing a particular failure scenario

41 Likelihood Assessment – Fault Trees
A fault tree is constructed by defining a top event and then defining the cause events and the logical relations between these cause events This is based on: Equipment failure rates Design and operational error rates Human errors Analysis of design safety systems and their intended function Fault tree is used to calculate frequencies for a ‘top event’ based on the underlying failure rates of components. Used for complex or multiple causes. Requires quantitative failure rate data.

42 Likelihood Assessment – Fault Trees Example
AND OR PSV does not relieve Process pressure rises Control fails high PSV too small Set point too high PSV stuck closed Fouling inlet or outlet Pressure rises Process vessel over pressured Estimates of failure rates would be needed for each of the basic failures. Generic or specific ‘random’ failure rate data is available for equipment and instrumentation (engineering controls) but would be harder to develop for human factor or systematic causes.

43 Likelihood Assessment – Generic Failure Rate Data
This information can be obtained from: American Institute of Chemical Engineers Process Equipment Reliability Data Loss Prevention in the Process Industries E&P Forum UK Health and Safety Executive data and other published reports (Refer to Sources of Additional Information slides for references) Note that these relate to ‘random’ failures only. Systematic failures (e.g. environmental conditions, operator errors etc) would need to be determined for the specific facility/process/procedure under study.

44 Likelihood Assessment – Human Error
Human error needs to be considered in any analysis of likelihood of failure scenarios The interaction between pending failure scenarios, actions to be taken by people and the success of those actions needs to be carefully evaluated in any safety assessment evaluation Some key issues of note include: Identifying particular issue Procedures developed for handling the issue Complexity of thought processing information required Humans can be unreliable, especially in emergency situations. With modern day controls it is very easy to add on alarms to ease the operational interaction of the plant and to aid diagnosing of faults. This is alright if the plant is not in an emergency operational situation. A control room operator can be faced with having lots of alarms coming up in an emergency and it is required to sift through all of the alarms and determine which is the important ones to act upon and take the correct action to minimize the consequences of the plant upset, including mitigation of potential MAs. Abnormal situation management approaches have been developed to handle this. Human factors evaluations have an important contribution to provide, especially when there are many controls in place that are procedural and their effectiveness needs to be critically evaluated.

45 Likelihood Assessment – Human Error
Type of Behaviour Error Probability Extraordinary errors: of the type difficult to conceive how they could occur: stress free, powerful cues initiating for success. 10-5 (1 in 100,000) Error in regularly performed, commonplace, simple tasks with minimum stress (e.g. Selection of a key-operated switch rather than a non key-operated switch). 10-4 (1 in 10,000) Errors of omission where dependence is placed on situation cues and memory. Complex, unfamiliar task with little feedback and some distractions (e.g. failure to return manually operated test valve to proper configuration after maintenance). 10-2 (1 in 100) Highly complex task, considerable stress, little time to perform it e.g. during abnormal operating conditions, operator reaching for a switch to shut off an operating pump fails to realise from the indicator display that the switch is already in the desired state and merely changes the status of the switch. 10-1 (1 in 10) Table 5: Example Human Error Potential Values (based on Hunns and Daniels 1980 and Kletz 1991

46 Likelihood Assessment – Event Trees
Used to determine the likelihood of potential consequences after the hazard has been realised It starts with a particular event and then defines the possible consequences which could occur Each branching point on the tree represents a controlling point, incorporating the likelihood of success or failure, leading to specific scenarios Such scenarios could be: Fire Explosion Toxic gas cloud Information can then used to estimate the frequency of the outcome for each scenario

47 Likelihood Assessment – Event Trees
Event tree example – LPG Pipeline Release

48 Consequences Most scenarios will involve at least one of the following outcomes: Loss of containment Reactive chemistry Injury/illness Facility reliability Community impacts Moving vehicle incidents Ineffective corrective action Failure to share learnings

49 Consequences Consequence evaluation estimates the potential effects of hazard scenarios The consequences can be evaluated with specific consequence modelling approaches These approaches include: Physical events modelling (explosion, fire, toxic gas consequence modelling programs) Occupied building impact assessment Occupied buildings assessment are undertaken to determine whether any impacts form explosions or fires will exceed the building design criteria. For instance administration buildings located within the plant, or temporary huts located for projects – BP Texas city incident.

50 Consequences - Qualitative Evaluation
A qualitative evaluation is based upon a descriptive representation of the likely outcome for each event This requires selecting a specific category rating system that is consistent with corporate culture

51 Consequences - Qualitative Descriptors Example
Consequence descriptors Insignificant Minor Moderate Major Catastrophic Health and Safety Values A near miss, first aid injury One or more lost time injuries One or more significant lost time injuries One or more fatalities Significant number of fatalities Environmental Values No impact No or low impact Medium impact Release within facility boundary Medium impact outside the facility boundary Major impact event Financial Loss Exposures Loss below $5,000 Loss $5,000 to $50,000 Loss from $50,000 to $1M Loss from $1M to $10M Loss above $10M Purely an example and each company will have their own approach to these

52 Consequences – Quantitative Evaluation
Consequence analysis estimates the potential effects of scenarios Tools include: Potential consequences (event tree) Physical events modelling (explosion, fire and/or gas dispersion consequence modelling programs) Load resistance factor design (building design)

53 Consequences - Qualitative Evaluation Example
Example: Impact of Explosions Explosion Overpressure (kPa) Effects 7 (1 psi) Results in damage to internal partitions and joinery but can be repaired. 21 (3 psi) Reinforced structures distort, storage tanks fail. 35 (5 psi) Wagons and plant items overturned, threshold of eardrum damage. 70 (10 psi) Complete demolition of houses, threshold of lung damage. This is an example of criteria that would be used for building overpressure design. Ref: NSW Department of Urban Affairs and Planning, ”Risk Criteria for Land Use Planning”, Hazardous Industry Planning Advisory paper No. 4, 2nd Edition, Sydney 1992, p Note: Calculations can be undertaken to determine probability of serious injury and fatality

54 Consequences - Qualitative Evaluation Example
Example - Overpressure Contour - impact on facility buildings Release scenario location 35 kPa 21 kPa 14 kPa 7 kPa The overpressure contours are developed from explosion modelling software and can be plotted onto the site plan to determine buildings that would be impacted.

55 Risk Evaluation Risk evaluation can be undertaken using qualitative and/or quantitative approaches Risk comprises two categories - frequency and consequence Qualitative methodologies that can be used are Risk matrix Risk nomograms Semi – quantitative techniques Layers of protection analysis Quantitative - quantitative techniques Risk evaluation considers both the likelihood and the consequence to determine the risk.

56 Risk Assessment - What Type?
Simple, subjective, low resolution, high uncertainty, low cost Qualitative Assessment Semi-Quantitative Assessment Detailed, objective, high resolution, low uncertainty, increasing cost Choose the appropriate method to suit the facility and the type of analysis needed. Quantitative Assessment

57 Risk Assessment – Issues For Consideration
Greater assessment detail provides more quantitative information and supports decision-making Strike a balance between increasing cost of assessment and reducing uncertainty in understanding Pick methods that reflect the nature of the risk, and the decision options Simper methods are easier to understand for employees but may not provide the information required – e.g. difficult to assess off-site risk using a risk matrix.

58 Risk Assessment – Issues For Consideration
Stop once all decision options are differentiated and the required information compiled Significant differences of opinion regarding the nature of the risk or the control regime indicate that further assessment is needed

59 Risk Assessment - Qualitative
Qualitative risk assessment can be undertaken using the following Risk nomogram Risk matrix Both approaches are valid and the selection will depend upon the company and its culture The frequencies used for these methods can be purely qualitative or semi-quantitative (I.e. assign numbers to the frequency categories).

60 Risk Assessment - Risk Nomogram
A nomogram is a graphical device designed to allow approximate calculation Its accuracy is limited by the precision with which physical markings can be drawn, reproduced, viewed and aligned Nomograms are usually designed to perform a specific calculation, with tables of values effectively built into the construction of the scales NOTE: HAVE NEVER SEEN THIS USED BY MHFS FOR SAFETY REPORT WORK, actually never seen it used by industry for any risk assessment work – although academics and risk assessment teachers do like it!!

61 Risk Assessment - Risk Nomogram
Practically Impossible Conceivable but Very Unlikely Remotely Possible Unusual but Quite Possible Could Happen Might well be Expected at Sometime LIKELIHOOD Continuous Frequent Daily Occasional Once per Week Unusual Once per Month Rare Few per year Very Rare, Yearly or Less EXPOSURE TIE LINE Noticeable Minor Injury / First Aid >$1k Damage Important Disability >$10k Damage Serious Serious Injury >$100k Damage Very Serious Fatality >$1M Damage Disaster Multiple Fatalities >$10M Damage Catastrophe Many Fatalities >$100M Damage POSSIBLE CONSEQUENCES 500 400 300 200 100 80 60 40 20 10 Very High Risk Consider Discontinuing Operation High Risk Immediate Correction Required Substantial Risk Risk must be Reduced SFARP Acceptable if Reduced SFARP Most nomograms are used in situations where an approximate answer is appropriate and useful

62 Risk Assessment - Risk Nomogram
Advantages and Disadvantages Accuracy is limited Designed to perform a specific calculation Cannot easily denote different hazards leading to an MA Typically not used by MHFs

63 Risk Assessment - Risk Matrix
Hazards can be allocated a qualitative risk ranking in terms of estimated likelihood and consequence and then displayed on a risk matrix Consequence information has already been discussed, hence, information from this part of the assessment can be used effectively in a risk matrix Risk matrices can be constructed in a number of formats, such as 5x5, 7x7, 4x5, etc Often facilities may have a risk matrix for other risk assessments (eg Task analysis, JSA) Very commonly used – both purely qualitative and semi-quantitatively

64 Risk Assessment - Risk Matrix
Results can be easily presented In tabular format for all MAs Within a risk matrix Such processes can illustrate major risk contributors, aid the risk assessment and demonstration of adequacy Care needs to be taken to ensure categories are consistently used and there are no anomalies Australian/New Zealand Standard, AS4360, Risk Management 1999, provides additional information on risk matrices

65 Risk Assessment - Risk Matrix
E Rare occurrence, (1 x 10-5 per year) D Not likely to occur, (1 x 10-4 per year) C Possibility of occurring sometimes, (1 x 10-3 per year) B Possibility of isolated incidents, (1 x 10-2 per year) A Possibility of repeated events, (1 x 10-1 per year) Likelihood Financial Loss Exposures Environmental Values Health and Safety Values Significant Risk Moderate Risk Low Risk High Risk Loss of above $10,000,000 Loss from $1,000,000 to $10,000,000 Loss from $50,000 to $1,000,000 Loss $5,000 to $50,000 Loss below $5,000 Major impact event Medium impact outside the facility boundary Medium impact. Release within facility boundary No or low impact No impact Significant number of fatalities One or more fatalities One or more significant Lost Time Injuries (LTI) One or more Lost Time Injuries (LTI) A near miss, First Aid Injury (FAI) or one or more Medical Treatment Injuries (MTI) 5 4 3 2 1 Catastrophic Major Moderate Minor Insignificant Consequences Risk matrix example (AS4360) NOTE: risk matrix cannot be used additively to present cumulative risk

66 Risk Assessment - Risk Matrix
Advantages If used well, a risk matrix will: Identify event outcomes that should be prioritised or grouped for further investigation Provides a good graphical portrayal of risks across a facility Help to identify areas for risk reduction Provide a quick and relatively inexpensive risk analysis Enable more detailed analysis to be focused on high risk areas (proportionate analysis)

67 Risk Assessment - Risk Matrix
Disadvantages Scale is always a limitation regarding frequency reduction - it does not provide an accurate reduction ranking Cumulative issues and evaluations are difficult to show in a transparent manner There can be a strong tendency to try and provide a greater level of accuracy than what is capable Unless the consequence changes (unlikely for an existing MHF unless the Schedule 9 material is eliminated), the only aspect to change on the risk matrix will be a reduction in frequency of the MA result – this is also true for other methods

68 Risk Assessment - Semi-Quantitative Approach
One tool is a layer of protection analysis approach (LOPA) It is a simplified form of risk evaluation The primary purpose of LOPA is to determine if there are sufficient layers of protection against a hazard scenario It needs to focus on: Causes of hazards occurring Controls needed to minimise the potential for hazards occurring If the hazards do occur, what mitigation is needed to minimise the consequences

69 Diagrammatic Representation - LOPA
Risk Assessment - Semi-Quantitative Approach (LOPA) Diagrammatic Representation - LOPA Analysing the safety measures and controls that are between an uncontrolled release and the worst potential consequence Explain briefly each layer.

70 Risk Assessment - Semi-Quantitative Approach (LOPA)
The information for assessment can be presented as a bow-tie diagram Preventative Controls Mitigative Controls MA Causes Outcomes Control measures can be quickly identified The approach identifies convergence of different hazards into a single 'causal path', and control measures that prevent multiple hazards Early warning signs of an MA are explained, by showing both basic hazards and resultant hazards, in a 'cause' and 'effect' representation - “preventative” and “mitigative” The importance of mitigating controls to minimise the severity of an MA is highlighted and explained Linking consequences on the right hand side of one diagram to basic hazards on the left hand side of another diagram allows analysis of escalation events such as BLEVEs Hazards Controls Controls Consequences

71 Risk Assessment - Semi-Quantitative Approach (LOPA)
Advantages and Disadvantages Risk evaluation can be undertaken using a bow-tie approach A procedural format needs to be developed by the company to ensure consistency of use across all evaluations External review (to the safety report team) should be considered for consistency and feedback Correct personnel are needed to ensure the most applicable information is applied to the evaluation approach Consistent procedures are required.

72 Risk Assessment - Quantitative
Quantitative assessments can be undertaken for specific types of facilities This is a tool that requires expert knowledge on the technique and has the following aspects: It is very detailed High focus on objective Detailed process evaluations Requires a high level of information input Provides a high output resolution Reduces uncertainty Frequency component can be questionable as generic failure rate data is generally used Provides understanding on the high risk contributors from a facility being evaluated

73 Risk Assessment - Quantitative
Typical result output from such an assessment is individual risk contours Example shown is for land use planning Use only to determine off-site risks. Commonly used for land use planning issues. Published criteria are available.

74 Risk Assessment - Quantitative
Time consuming Expensive Expert knowledge is required Not suitable for every MHF site Process upsets (such as a runaway reaction) cannot be easily modelled as an initiating event using standard equipment part counts - incorporation of fault tree analysis required Use of generic failure rate data has limitations and does not take into consideration a specific company’s equipment and management system strategies Ensure analysis is transparent and well documented and that all controls, as far as practicable, are appropriately reflected in the analysis For instance, it is not suitable for a storage warehouse MHF but would be suitable for a refinery

75 Summary A risk assessment provides an understanding of the major hazards and a basis for determining controls in place Risk assessments can involve significant time and effort Operations personnel and managers could cause, contribute to, control or be impacted by MAs Hence they should be involved in the risk assessment HSRs may or may not take part, but must be consulted in relation to the process of HAZID & Risk Assessment They should also be involved in resolution of any issues that arise during the studies, including improvements to methods and processes

76 Review and Revision Employer must review (and revise) Hazard Identifications, Risk Assessments and Control Measures to ensure risks remain reduced to AFAP: At the direction of the Commission Prior to modification After a major accident When a control measure is found to be deficient At least every 5 years Upon licence renewal conditions

77 Sources of Additional Information
The following are a few sources of information covering risk assessment Hazard and Operability Studies (HAZOP Studies), IEC 61882, Edition 1.0, Functional Safety – Safety Instrumented Systems for the Process Industry Sector, IEC 61511, Fault Tree Analysis, IEC 61025, Hydrocarbon Leak and Ignition Data Base, E&P Forum, February 1992 N658 Guidelines for Process Equipment Reliability Data, Center for Chemical Process Safety of the American Institute of Chemical Engineers, 1989

78 Sources of Additional Information
Offshore Hydrocarbon Release Statistics, Offshore Technology Report – OTO , UK Health and Safety Executive, December 1997 Loss Prevention in the Process Industries , Lees F. P., 2nd Edition, Butterworth Heinemann Layer of Protection Analysis, Simplified Process Risk Assessment, Center for Chemical Process Safety of the American Institute of Chemical Engineers, 2001 Nomogram, Wikipedia, the free encyclopaedia

79 Questions?

80 Example LOPA Assessment – Spreadsheet Format
Cause Hazard Independent Preventative Protection Layers Mitigative Protection Layers Loss of cooling tower water to condenser once every 10 years Catastrophic rupture of distillation column with shrapnel, toxic release Columns condenser, reboiler and piping maximum allowable working pressures are greater than maximum possible pressure from steam reboiler Logic in BPCS trips steam flow valve and steam RCV on high pressure or high temperature. No credit since not independent of SIS. High column pressure and temperature alarms can alert operator to shut off the steam to the reboiler (manual valve) Logic in BPCS trips stream flow valve and steam RCV on high pressure or high temperature (dual sensors separate from DCS). Pressure safety valve opens on high pressure

81 Example Example Bowtie Assessment – System Format

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