IA5 The Assessment and Evaluation of Risk

Question 1

Identify internal information sources used in identifying hazards and assessing risk

Answer 1

• Injury rate
• Ill-health data
• Property damage
• Near-miss information
• Maintenance records
• Absence records
• Fines records
• Enforcement agency’s notices record

Question 2

Identify external information sources used in identifying hazards and assessing risk

Answer 2

• National governmental enforcement agencies such ad the HSE (UK based) and the OSHA (USA based)
• International bodies such as the ILO, WHO and the ESA (European Safety Agency)
• Professional bodies such as the IOSH
• Trade unions
• Trade associations
• Insurance companies

Question 3

Identify the benefits and limitations of internal information sources

Answer 3

Benefits:

• Relevant to risk assessments as it will relate to the organisation’s risks and work activities
• Easy to access and easy to ask questions should clarification be required

Limitations:

• Data may be limited in quantity e.g. due to under-reporting
• Data may be limited in quality e.g. due to a poor H&S culture
• Collecting data is time consuming (effect in costs)

Question 4

Identify the benefits and limitations of external information sources

Answer 4

Benefits:

• More data based on a larger sample
• Type of data covered is much wider than own situation, difficult for an organisation alone to have that quantity of data
• Experience of others are used

Limitations:

• It may be difficult to decide what is relevant to particular situation, some information may not be relevant to the organisation.
• Time consuming, it may be difficult to find the particular information within a lot of data.
• Some of the information may be out of date
• Some international standards may not apply to national legislation

Question 5

Regarding individual risks and societal concerns, risks may be classified into three categories, they are:

Answer 5

1. Unacceptable
2. Tolerable
3. Acceptable

Question 6

Define acceptable risk

Answer 6

• Risk regarded as insignificant or trivial and adequately controlled
• No further action required

Question 7

Define tolerable risk

Answer 7

• People and society are prepared to accept risk in order to secure benefits
• Tolerable does not mean acceptable
• Tolerable risks need effective controls and constant review to reduce them as low as reasonable possible
  *

Question 8

Define hazard

Answer 8

A hazard is any source of potential damage, harm or adverse health effects on something or someone.

Question 9

Define the methodology for Task Hazard Analysis (THA)

Answer 9

1. Select the task to be analysed.
2. Break the task down into a sequence of steps
3. Identify potential hazards at each step
4. Determine control measures to overcome the hazards
5. Implement the control measures
6. Monitor and review

Question 10

What is a possible disadvantage of using a checklist to identify hazards?

Answer 10

The risk assessor might focus too much on the hazards on the checklist, and not pay attention to other obvious hazards.

Question 11

How does a hazard analysis needs to be approach?

Answer 11

On a structured and systematic way in order to identify potential hazards

Question 12

Give the purpose of a HAZOP study

Answer 12

• The purpose of the HAZOP is to investigate how the system or plant deviates from the design intent and create risk for personnel and equipment and operability problems, or
• The purpose of a HAZOP is to identify deviations from design intent, determine the causes and consequences of deviations and recommend solutions.
• A HAZOP uses systematic examinations to identify and evaluate hazards from processes/operations that present risks to people, plant and/or successful operation.

Question 13

Identify HAZOP’s terminologies and features

Answer 13

• Adopts the holistic approach (examines the system as a whole) to analyses probability of failure
• Performed by a multidisciplinary team, led by a “trained” team leader
• A scope of work has to be defined, what part of the process is included and excluded in the study
• NODES, part of the processes to be investigated
• GUIDE-WORDS, e.g. no/not/none, more, less, part of, reverse, other than, as well as
• PARAMETERS, e.g flow, pressure, temperature, reaction, level, composition
• Guide-words and parameters are used to evaluate every step of the process
• Identify causes and consequences for the deviations
• Identify control measures and recommend
• HAZOP study to be recorded, documented and communicated.

Question 14

Give the steps to perform a HAZOP study

Answer 14

• Appointment of a multidisciplinary team
• Appointment of a “trained” team leader
• Decide on the scope of the study (which parts of the process or components are included and excluded)
• Ensure all technical information (data) is available
• Break down the process into smaller parts (called NODES)
• To identify DEVIATIONS, the Team Leader applies (systematically) a set of GUIDE WORDS (No, More, Less, As Well As, Part Of, Reverse,etc ) to each PARAMETER (temperature, pressure, flow,etc.) for each section of the process.
• Once the HAZOP team have determined the possible significant deviations from each intention, they must then identify the possible CAUSES (human, hardware, software) and likely CONSEQUENCES.
• Evaluate current control measures and advise on new or extra measures if necessary
• The HAZOP study is recorded and documented.

Question 15

Give the advantages of a HAZOP study

Answer 15

• Systematic and comprehensive hazard identification technique
• Examines the causes and consequences of the failure
• Recommends for methods to minimise or mitigate the hazard.

Question 16

Give the limitations of a HAZOP study.

Answer 16

• Time consuming and expensive.
• Requires detailed design drawing to perform the full study.
• Additional guide words are required for unusual hazards, e.g. radiation for the nuclear industry
• Requires experienced practitioners for identifying deviations and recommending on mitigation.
• Focuses on one-event causes of deviation only. Hazards that are caused by two or more separate deviations cannot be identified by the technique

Question 17

Identify the 5 steps to follow to perform a risk assessment

Answer 17

1. Identify the hazards.
2. Decide who might be harmed, and how.
3. Evaluate the risks, and decide on precautions.
4. Record your significant findings.
5. Review your assessment and update if necessary.

Question 18

Organisations need to reduce risk to a ‘reasonable’ level, what does this mean?

Answer 18

• This means that the cost of a control measure, the time to implement it, the trouble and disruption it will cause, must be weighed against the benefits in risk reduction.
• If a control is very costly and disruptive, but has limited benefits, then it may not be ‘reasonable’ to implement it.

Question 19

Identify the types of Risk Assessments

Answer 19

1. Generic Risk Assessments
2. Specific Risk Assessments
3. Dynamic Risk Assessments

Question 20

Give the Limitations of Risk Assessment Processes

Answer 20

• Risk assessment has been completed afterwards as a means of justification
• Using a generic assessment when a site-specific assessment is needed.
• When existing or relevant good practice is not considered as part of the risk assessment process.
• Carrying out a risk assessment using inappropriate good practice.
• Completing the risk assessment without consulting or including those involved in the process/activity
• Ineffective use of consultants, who may give poor advice, or recommend additional controls because it gets them more work rather than because they are needed.
• Failure to identify all hazards associated with an activity.
• Failure to fully consider all the possible consequences of a risk.
• No consideration of what measures would be reasonable in the circumstances (i.e. no consideration of risk versus cost).
• Attempting to use cost benefit analysis to argue that it is reasonable to reduce safety standards to save costs.
• Not doing anything with the results of the assessment. Failure to action the recommendations.

Question 21

Identify long-term health hazards

Answer 21

• Radiation
• Dusts
• Gases
• Poor ergonomics
• Noise
• Vibration
• Biological hazards
• Asbestos
• Stress

Question 22

When should a risk assessment be reviewed?

Answer 22

• A certain time has lapsed, and there is a suspicion the risk assessment may be out of date.
• An incident or accident has occurred. This would indicate that either the controls have not been used, or the risk assessment failed to correctly identify the risk and what controls were needed.
• Changes have been made to the layout of the workplace. Or the location of the workplace changes.
• New processes and/or activities have been introduced, or existing ones have been changed.
• New technologies have been introduced.
• A major change has occurred in the workforce. For example, a growing number of apprentices, or an influx of migrant workers speaking a different language.
• A third party requests it. For example, an enforcement agency may require risk assessments to be reviewed. Or an insurance company auditor may recommend this.
• There have been complaints from the workers or the Health and Safety Committee that the risk assessments are no longer valid.
• New information is discovered by the industry, showing some risks which were previously unknown.
• Significant changes are made to working arrangements, such as shift patterns and break times.

Question 23

Organisations are required to reduce risks to “as low as is reasonably practicable” (ALARP), what does ALARP means?

Answer 23

This is a balancing act with the level of risk on one side and the costs in terms of time, effort, money needed for rectification on the other side.

ALARP allows for grossly disproportionate actions to be deemed unnecessary.

Question 24

How can a series system reliability be improved?

Answer 24

• Replace the least reliable components with more reliable components. There are usually one or two weak links in the system which lowers the overall reliability.
• Simplify the system so there are fewer components. The fewer components there are, the less can go wrong!
• Change the system so that there are redundancies and back-up system. However, this would no longer be a series system.

Question 25

Identify the objective of a Failure Mode and Effects Analysis (FMEA)

Answer 25

• The objective of FMEA is to analyse each component of a system in order to identify the possible causes of its failure and the effects of the failure on the system as a whole.
• It is a Reductionist approach to System Failure Analysis.
• Risk Priority Number (RPN) is a measure used when assessing risk to help identify critical failure modes associated with your design or process.

Question 26

Identify the term RPN in Failure Mode and Effects Analysis (FMEA)

Answer 26

Risk Priority Number (RPN) is a measure used when assessing risk to help identify critical failure modes associated with the system or process.

RPN = Likelihood (L) x Severity (S) x (D)

Where:

(D) is the likelihood of failure detection and can be ranked e.g.

Ranking 1 - “Almost Certain”

Ranking 10 - “Absolute Uncertainty”

Question 27

Outline the methodology of FMEA

Answer 27

The methodology of FMEA includes breaking a system down into its component parts and identifying all possible causes of failure of the component; assessing the probability of failure and its effects on the system as a whole; identifying how the failures might be detected for example by a sensor; assessing the probability of failure; allocating a risk priority code to each component based on severity, the probability of failure and the effectiveness of detection; devising actions to reduce the risk to a tolerable level and documenting the results of the exercise in the conventional tabular format.

Question 28

Identify the formula for calculating Series Systems reliability

Answer 28

Rs = R1 x R2 x R3 x … x Rn

Question 29

Identify the formula for calculating Parallel Systems Reliability

Answer 29

Rs= 1 - (1 - R1) x (1 - R2) x (1 - R3) x … (1 - Rn)

Question 30

Define a “common mode failure” and give an example

Answer 30

Is where one event causes multiple systems to fail or where one fault causes multiple parts of the system to fail. These are often random failures caused by environmental conditions or ageing.

For example, in 1980 the Alexander L. Kielland platform in the North Sea capsized and sank due to a power failure originated by heavy weather conditions. killing 123 people

Question 31

Give the various ways of improving system reliability

Answer 31

1. Use of Reliable Components.
2. Parallel Redundancy.
3. Standby Systems.
4. Quality Assurance.
5. Minimising Failures to Danger (or use of fail-safe designs), eg. fail to close valves.
6. Planned Preventative Maintenance (PPM).

Question 32

Identify the methodology of the fault tree analysis (FTA)

Answer 32

• Deductive method
• Uses sets of symbols used in logic diagrams (logic gates), e.g. AND gate, OR gate
• Uses events symbols, e.g. basic, intermediate
• Starts with a top-event (loss causing event)
• Top-down approach (establish and upside down tree)
• The immediate and necessary events for the top-event are identified
• The tree is further downwards developed to obtain all the possible primary cause events.

Question 33

Use and limitations of an FTA

Answer 33

• FTA is used for analysis of events which may have multiple causes.
• The probability / frequency of the “top event” can be quantified provided there is sufficient data on the probabilities / frequencies of the underlying events.
• It also helps identify critical stages where intervention might be most effective (to reduce the probability of the top event).
• Complex events require skill to work out
• and of course the top event probability calculation is only as good as the data which is input into the calculation.

Question 34

What does quantification of the Fault Tree means?

Answer 34

Quantification of the Fault Tree means that we try to express the Top Event in terms of :

1. How likely it is to happen (the ‘probability’), or
2. How frequently do we expect it to occur (the ‘failure rate’).

Question 35

Define Reliability

Answer 35

• Reliability is the probability that a device, system, or process will perform its prescribed duty without failure for a given time when operated correctly in a specified environment.

Reliability ends up with failure!

Question 36

Give the main features of a FTA

Answer 36

• A method for representing the logical combinations of various system states which lead to a particular outcome (top event).
• At system level, the Fault Tree analyses the combination of failures that could occur (human error, hardware and software) to create the “top event” (the undesired outcome).
• It is deductive and adopts the reductionist approach (examines the individual components of a system) to analyses probability of failure.
• The FTA adopts a top-down approach where an undesired outcome is identified and the specific events leading to it are determined.
• The FTA process uses logic gates “AND” and “OR” to analyse the events.
• THE FTA is worked backwards from the top event until the lowest level errors/events are identified.
• This procedure is repeated for each sub-event and cause until the basic causes are identified at the bottom of the tree.

Question 37

Identify the purpose of an FTA?

Answer 37

• The main purpose of the fault tree analysis is to help identify potential causes of system failures before the failures actually occur. It can also be used to evaluate the probability of the top event using analytical or statistical methods.
• The purpose of the FTA is to improve the reliability and safety of the system.

Question 38

Identify the methodology of FMEA

Answer 38

• Assemble the team.
• Establish the ground rules and assumptions.e.g. responsibilities, failure definition, ranking severity methodology, etc.
• Gather and review relevant information.
• Identify the item(s) or process(es) to be analyzed (scope)
• Identify the function(s), failure(s), effect(s), cause(s) and control(s) for each item or process to be analyzed.
• Evaluate the risk associated with the issues identified by the analysis.
• Prioritize and assign corrective actions (using RPN concept).
• Perform corrective actions and re-evaluate risk.
• Record, distribute, review and update the analysis, as appropriate.