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NEBOSH PSM study materials
NEBOSH PSM study resources

NEBOSH PSM practice questions

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Question 1Process safety management fundamentals and leadership

In process safety management, what is the primary purpose of a process hazard analysis (PHA)?

  1. To calculate the financial cost of a plant shutdown
  2. To identify, evaluate and control hazards associated with a process Correct answer.
  3. To record employee attendance during training
  4. To schedule routine maintenance activities

Explanation

A PHA is a systematic study that identifies and evaluates hazards and their consequences, and recommends controls. It is a core element of any PSM programme because it drives risk reduction decisions. Financial, scheduling and administrative records fall outside its scope.

Question 2Process safety management fundamentals and leadership

Which leadership behaviour best demonstrates visible commitment to process safety?

  1. Issuing an annual safety policy without follow-up
  2. Delegating all safety decisions to the lowest operational level
  3. Reducing safety budgets to protect production targets
  4. Personally participating in safety reviews and acting on findings Correct answer.

Explanation

Visible leadership means leaders actively engage in safety activities such as reviews and audits, and demonstrate that findings are acted upon. This builds trust and reinforces safety as a core value. Passive or cost-cutting behaviours undermine the safety culture.

Question 3Process safety management fundamentals and leadership

What does the term 'safety culture' most accurately describe?

  1. The set of written safety procedures held by an organisation
  2. The number of incidents recorded over a year
  3. The physical barriers installed to protect equipment
  4. The shared values, attitudes and behaviours relating to safety Correct answer.

Explanation

Safety culture refers to the shared values, beliefs, attitudes and behaviours that determine how safety is actually managed day to day. It is distinct from documented procedures or physical hardware, though it influences both. Incident counts are outcomes, not the culture itself.

Question 4Process safety management fundamentals and leadership

Which of the following is a leading indicator of process safety performance?

  1. Count of reportable process incidents
  2. Frequency of safety-critical device overrides Correct answer.
  3. Total days lost due to accidents
  4. Number of lost-time injuries last year

Explanation

Leading indicators measure proactive activities or conditions that predict future outcomes, such as how often safety-critical devices are bypassed. Lagging indicators, by contrast, record events that have already occurred. Override frequency signals weakening control before an incident happens.

Question 5Process safety management fundamentals and leadership

A senior manager wants to strengthen the 'management of change' (MOC) element of PSM. Which action most directly supports this?

  1. Increasing the frequency of fire drills
  2. Requiring formal review and approval before any process modification Correct answer.
  3. Reducing the number of contractors on site
  4. Publishing the company's safety policy on the intranet

Explanation

MOC requires that changes to processes, equipment or procedures be reviewed and authorised before implementation to ensure hazards are addressed. Drills, policy publication and contractor numbers relate to other PSM elements. Formal pre-change review is the defining control for MOC.

Question 6Process safety management fundamentals and leadership

Which element of PSM ensures workers understand the hazards and safe operating limits of the process they run?

  1. Process safety information Correct answer.
  2. Compliance auditing
  3. Emergency planning
  4. Incident investigation

Explanation

Process safety information compiles data such as chemistry, maximum intended inventory and safe operating limits, which underpins training and operating procedures. It is the foundation from which operators learn the hazards and limits of their process. The other elements serve different functions.

Question 7Process safety management fundamentals and leadership

What is the main objective of a pre-startup safety review (PSSR)?

  1. To negotiate supplier contracts
  2. To determine the annual operating budget
  3. To confirm that a new or modified facility is safe to start up Correct answer.
  4. To evaluate employee performance appraisals

Explanation

A PSSR is conducted before introducing hazardous chemicals to confirm that construction and equipment meet design specifications and that safety systems are in place. It acts as the final check before commissioning. It is unrelated to budgeting, appraisals or procurement.

Question 8Process safety management fundamentals and leadership

A leader wishes to promote a 'just culture' within a PSM environment. Which approach best reflects this?

  1. Discouraging staff from reporting minor deviations
  2. Distinguishing between honest error and reckless behaviour when responding to events Correct answer.
  3. Concealing incident details to protect the organisation's image
  4. Disciplining every employee involved in any near miss

Explanation

A just culture balances accountability with learning by treating honest mistakes differently from wilful or reckless conduct. This encourages reporting and honest disclosure. Blanket punishment or concealment suppresses the information needed for improvement.

Question 9Process safety management fundamentals and leadership

Which of the following best describes the role of a process safety key performance indicator (KPI)?

  1. To guarantee that no incidents will occur
  2. To serve as a legal substitute for permits
  3. To provide a measurable signal of process safety performance over time Correct answer.
  4. To replace the need for engineering controls

Explanation

KPIs are measurable metrics that track whether process safety controls are functioning and improving. They inform decision-making but cannot replace engineering controls or legal permits, and no metric can guarantee the absence of incidents. Their value lies in tracking performance trends.

Question 10Process safety management fundamentals and leadership

During a leadership site walk, an operator reports a corroded pipe near a high-pressure line. What is the most appropriate immediate leadership response?

  1. Log and escalate the finding for prompt engineering assessment Correct answer.
  2. Note it for the next annual budget cycle
  3. Tell the operator to raise it in writing later
  4. Ignore it because it is outside the walk's scope

Explanation

Leaders should act on hazards identified during walkarounds by logging and escalating them for timely assessment and control. Prompt action reinforces that reported hazards are valued and addressed. Deferring or ignoring findings erodes trust and leaves risk uncontrolled.

Question 11Process safety management fundamentals and leadership

What is the fundamental purpose of an incident investigation within PSM?

  1. To satisfy insurance paperwork only
  2. To assign blame to the most senior manager
  3. To identify root and contributing causes to prevent recurrence Correct answer.
  4. To justify reducing the workforce

Explanation

Incident investigation seeks to uncover root and contributing causes so that corrective actions can prevent similar events. It is a learning process rather than a blame exercise. Its purpose is prevention, not administrative or staffing decisions.

Question 12Process safety management fundamentals and leadership

Which statement best captures the concept of 'process safety' as distinct from occupational safety?

  1. It focuses solely on slips, trips and falls
  2. It applies only to office environments
  3. It addresses the prevention of major incidents involving loss of containment of hazardous materials or energy Correct answer.
  4. It concerns only personal protective equipment use

Explanation

Process safety focuses on preventing and mitigating major accidents such as fires, explosions and toxic releases arising from loss of containment. Occupational safety more broadly addresses worker injuries like slips and falls. The two overlap but have different primary concerns.

Question 13Process safety management fundamentals and leadership

An organisation wants to build a 'learning organisation' approach to process safety. Which practice most supports this goal?

  1. Relying only on regulatory inspections for feedback
  2. Systematically sharing lessons from incidents and audits across sites Correct answer.
  3. Restricting access to incident reports to senior managers
  4. Discouraging staff from questioning established procedures

Explanation

A learning organisation systematically captures and disseminates lessons from incidents, audits and near misses so that knowledge spreads and recurs. Shared learning turns individual experience into organisational improvement. Restricting information or discouraging questions blocks learning.

Question 14Process safety management fundamentals and leadership

What is the primary role of operating procedures within a PSM programme?

  1. To document marketing strategies
  2. To provide clear, stepwise instructions that keep the process within safe limits Correct answer.
  3. To record the personal opinions of supervisors
  4. To replace operator training entirely

Explanation

Operating procedures give clear instructions for safely conducting activities, including steps to stay within safe operating limits and respond to deviations. They support consistent, safe operation. They complement rather than replace training and have no marketing role.

Question 15Process safety management fundamentals and leadership

A manager is designing a training programme for operators on a hazardous process. Which principle best ensures the training is effective?

  1. Using generic content unrelated to the specific plant
  2. Delivering training once at induction and never repeating it
  3. Basing training content on the actual process hazards and verifying competence Correct answer.
  4. Relying on operators to train themselves without assessment

Explanation

Effective training is grounded in the specific hazards and process safety information of the plant, and it verifies that operators have achieved competence. Refresher training maintains skills over time. Generic or unverified training fails to build reliable competence.

Question 16Process safety management fundamentals and leadership

What does 'mechanical integrity' address within a PSM programme?

  1. The assurance that critical equipment is designed, maintained and tested to function as intended Correct answer.
  2. The financial integrity of supplier contracts
  3. The integrity of marketing data
  4. The personal integrity of managers

Explanation

Mechanical integrity ensures that safety-critical equipment such as vessels, piping and relief devices is properly designed, installed, inspected, tested and maintained. This keeps protective hardware reliable. It has no connection to financial, personal or marketing matters.

Question 17Process safety management fundamentals and leadership

A leader notices that near-miss reports have fallen sharply although operations have increased. What is the most reasonable interpretation and response?

  1. Recognise reporting may be suppressed and investigate barriers to reporting Correct answer.
  2. Discipline staff for failing to report
  3. Assume operators are too busy to have near misses
  4. Conclude that safety has improved and reduce reporting channels

Explanation

A decline in near-miss reporting during increased activity often signals under-reporting rather than genuine improvement. Leaders should investigate whether fear, complexity or lack of feedback is discouraging reports. Reducing channels or punishing staff would worsen the problem.

Question 18Process safety management fundamentals and leadership

Which of the following best describes the purpose of emergency planning within PSM?

  1. To prepare an effective response that mitigates consequences if a major incident occurs Correct answer.
  2. To eliminate the need for hazard controls
  3. To satisfy staff social events
  4. To replace routine inspections

Explanation

Emergency planning prepares personnel and resources to respond effectively and mitigate consequences when a major incident occurs. It complements, but does not replace, prevention measures such as hazard controls and inspections. Its focus is consequence mitigation.

Question 19Process safety management fundamentals and leadership

A PHA team is using a hazard study method that systematically examines deviations from design intent using guide words such as 'more' and 'less'. Which method is being applied?

  1. Bow-tie analysis
  2. Job safety analysis
  3. HAZOP Correct answer.
  4. Layer of protection analysis

Explanation

HAZOP applies guide words to process parameters to systematically identify deviations from design intent and their causes and consequences. Bow-tie and LOPA analyse risk differently, and job safety analysis focuses on task steps. The guide-word approach is characteristic of HAZOP.

Question 20Process safety management fundamentals and leadership

Which leadership action most effectively sustains a strong process safety culture over the long term?

  1. Integrating process safety metrics into performance reviews and decisions Correct answer.
  2. Removing safety from the agenda of management meetings
  3. Holding a single annual safety briefing
  4. Rewarding only production output regardless of safety performance

Explanation

Embedding process safety metrics into performance reviews and decision-making makes safety a standing priority and aligns incentives with safe operation. Culture is sustained through consistent, ongoing reinforcement. Isolated briefings or production-only rewards weaken it.

Question 21Process safety management fundamentals and leadership

What is the essential purpose of a permit-to-work system in a hazardous process facility?

  1. To record annual leave requests
  2. To authorise and control high-risk work through formal checks before it begins Correct answer.
  3. To serve as a substitute for engineering controls
  4. To replace operator training requirements

Explanation

A permit-to-work system formally authorises specific high-risk tasks after verifying that hazards are identified and controls are in place. It provides a documented check before work starts. It does not replace training, engineering controls or routine administration.

Question 22Process safety management fundamentals and leadership

Which statement best reflects the principle of 'inherent safety' in process design?

  1. Reducing or eliminating hazards by substituting, minimising or moderating hazardous materials and conditions Correct answer.
  2. Adding more alarms to warn operators of hazards
  3. Increasing the quantity of hazardous inventory for efficiency
  4. Relying solely on operator vigilance

Explanation

Inherent safety seeks to eliminate or reduce hazards at source through substitution, minimisation, moderation and simplification, rather than controlling them with add-on devices. This makes the process safer by design. Alarms and vigilance are add-on controls, not inherent measures.

Question 23Process safety management fundamentals and leadership

What is the role of a 'safety case' in a major hazard facility?

  1. To record the plant's profit and loss
  2. To list the names of all visitors to the site
  3. To present a structured argument and evidence that major accident risks are adequately controlled Correct answer.
  4. To replace all operating procedures

Explanation

A safety case is a documented, structured argument supported by evidence that major accident hazards are identified and their risks adequately controlled. It demonstrates safety management to regulators and stakeholders. It does not replace operating procedures or serve administrative purposes.

Question 24Process safety management fundamentals and leadership

A leader wants to ensure that corrective actions from audits are actually completed. Which practice best achieves this?

  1. Reviewing actions only after an incident occurs
  2. Leaving actions to individual discretion without tracking
  3. Assigning owners, deadlines and tracking completion to closure Correct answer.
  4. Closing actions once they are written down

Explanation

Effective corrective action management assigns clear ownership and deadlines and tracks each action through to verified closure. This ensures recommendations translate into real risk reduction. Untracked or prematurely closed actions leave hazards in place.

Question 25Process safety management fundamentals and leadership

Which of the following best explains why leadership should set clear process safety roles and responsibilities across the organisation?

  1. To ensure accountability and avoid gaps in safety-critical activities Correct answer.
  2. To increase the number of managers on site
  3. To shift all safety duties to contractors
  4. To reduce the need for written procedures

Explanation

Clearly defined roles and responsibilities ensure every safety-critical activity has an accountable owner, preventing gaps and overlaps. This supports consistent execution of the PSM programme. It is not about headcount, reducing procedures or offloading duties.

Question 26Process safety management fundamentals and leadership

Which concept describes the acceptable level of risk that a company formally adopts for its major hazard operations?

  1. Hazard identification threshold
  2. Risk tolerance criteria Correct answer.
  3. Consequence severity index
  4. Exposure frequency baseline

Explanation

Risk tolerance (or risk acceptance) criteria define the level of risk an organisation is prepared to live with for its activities. They provide the benchmark against which identified hazards and proposed controls are judged. Other measures describe hazards or exposure but do not set an acceptance benchmark.

Question 27Process safety management fundamentals and leadership

In PSM leadership, what does 'management of change' primarily aim to control?

  1. The frequency of internal audit cycles
  2. The risk introduced by modifications to process plant or procedures Correct answer.
  3. The rotation of shift personnel across operating units
  4. The documentation of routine maintenance tasks

Explanation

Management of change is a formal process for identifying and controlling hazards created when equipment, chemicals, technology or procedures are altered. The intent is that change does not silently erode the safety basis of the plant. Routine maintenance records, staffing rotation and audit scheduling are separate activities.

Question 28Process safety management fundamentals and leadership

A plant manager wants to demonstrate visible process safety leadership. Which action is the strongest evidence of genuine commitment?

  1. Displaying safety slogans prominently across the site
  2. Issuing a safety policy once and then focusing on production targets
  3. Personally chairing regular process safety reviews and following up actions Correct answer.
  4. Delegating all process safety decisions to the engineering department

Explanation

Visible leadership is demonstrated through sustained personal engagement, such as chairing reviews and tracking actions to closure. This shows process safety is a management priority rather than a delegated or symbolic matter. Slogans, one-off policies and full delegation do not provide that evidence.

Question 29Process safety management fundamentals and leadership

Which document typically defines the process safety roles, accountabilities and reporting lines across a major hazard site?

  1. The process safety management system description Correct answer.
  2. The emergency response plan
  3. The operating manual
  4. The incident register

Explanation

The PSM system description sets out how the elements of the management system fit together, including who is accountable for each. It is the framework document that assigns roles and reporting relationships. Operating manuals, emergency plans and incident registers are subordinate documents serving specific functions.

Question 30Process safety management fundamentals and leadership

A supervisor observes that a control room operator has bypassed an interlock to keep production running. Applying PSM principles, what is the most appropriate immediate response?

  1. Adjust the alarm setpoint so the interlock trips less often
  2. Restore the safeguard and investigate why the bypass occurred Correct answer.
  3. Discipline the operator and take no further action
  4. Record the bypass in the shift log and review it at the next monthly meeting

Explanation

Safety-critical safeguards must be restored promptly, and the underlying reason for the bypass must be understood and corrected. Investigation addresses both the immediate hazard and the systemic cause. Logging without action, discipline alone, or weakening the safeguard all leave the risk in place.

Question 31Process safety management fundamentals and leadership

Which leadership behaviour most directly undermines a positive process safety culture?

  1. Participating personally in hazard study reviews
  2. Publishing process safety performance data openly to the workforce
  3. Rewarding fast turnaround at the expense of safety-critical checks Correct answer.
  4. Encouraging workers to stop work when conditions appear unsafe

Explanation

Reward systems that favour speed over safety-critical checks signal that production outranks safety, which erodes trust and encourages risk-taking. Culture is shaped strongly by what leaders measure and reward. The other behaviours all reinforce openness and safety priority.

Question 32Process safety management fundamentals and leadership

What is the primary purpose of a process hazard analysis (PHA) revalidation?

  1. To replace the need for management of change
  2. To confirm that the original study team is still employed
  3. To verify that the assumptions and safeguards in the original study remain valid Correct answer.
  4. To satisfy insurance requirements for annual reporting

Explanation

Revalidation checks whether the process, its safeguards and the underlying assumptions have changed since the last study, so that the hazard analysis stays current. It is a periodic refresh of the risk picture. It does not depend on team continuity, is not merely an insurance formality, and does not substitute for change control.

Question 33Process safety management fundamentals and leadership

A site introduces a new contractor to carry out hot work in a process area. Which PSM requirement is most directly engaged?

  1. Compliance auditing
  2. Contractor safety management Correct answer.
  3. Mechanical integrity
  4. Process hazard analysis

Explanation

Bringing a contractor onto a hazardous site triggers contractor safety management, which covers selection, training, hazard communication and supervision of contractor work. Hot work permitting then applies within that framework. The other elements may be relevant in the background but are not the primary requirement engaged.

Question 34Process safety management fundamentals and leadership

How should a leader treat a worker who self-reports an error that could have led to a process safety event?

  1. Thank the worker and use the report as a learning opportunity Correct answer.
  2. Withhold the report from the investigation team to protect the worker
  3. Apply the same sanction as for a deliberate violation
  4. Record the report only if the error caused actual harm

Explanation

Under a just culture, honest errors are distinguished from reckless or deliberate violations and are treated as learning opportunities. Encouraging self-reporting improves the flow of safety information. Equating errors with violations, suppressing information, or requiring harm before recording all discourage reporting.

Question 35Process safety management fundamentals and leadership

Which measure is a leading indicator of process safety performance?

  1. Number of reportable releases in the past year
  2. Number of overdue safety-critical maintenance tasks Correct answer.
  3. Cost of process safety incidents
  4. Total recordable injury rate

Explanation

Leading indicators measure preventive activity and the health of barriers before loss occurs; overdue safety-critical maintenance shows degrading protection. Lagging indicators such as releases, injury rates and incident costs record harm after the fact. Leaders use leading indicators to intervene early.

Question 36Process safety management fundamentals and leadership

What distinguishes a process safety event from a typical occupational injury?

  1. It is reportable only to the insurance provider
  2. It always involves a fatality
  3. It occurs only during maintenance activities
  4. It involves loss of containment or loss of control of a hazardous process Correct answer.

Explanation

Process safety events involve loss of containment or loss of control of hazardous energy or material, with potential for major accident consequences such as fire, explosion or toxic release. Occupational injuries concern harm to an individual during a task. Severity, timing and reporting route do not define the distinction.

Question 37Process safety management fundamentals and leadership

A leader wants to strengthen the organisation's process safety competency. Which approach is most consistent with PSM expectations?

  1. Rely on experienced operators to train newcomers informally
  2. Provide a single induction session for all staff regardless of role
  3. Define required competencies for each role and verify them periodically Correct answer.
  4. Outsource all technical training to equipment vendors

Explanation

Competency management requires defined, role-specific knowledge and skills with periodic verification that individuals remain competent. This ensures personnel understand hazards and controls relevant to their duties. Informal handover, generic induction and full vendor outsourcing do not provide verified, role-specific competence.

Question 38Process safety management fundamentals and leadership

A leader is deciding how to allocate limited resources among several identified process safety risks. Which principle should guide the decision?

  1. Address the risk with the highest likelihood regardless of consequence
  2. Defer all action until the next scheduled audit
  3. Prioritise risks by their combined likelihood and consequence, considering barrier strength Correct answer.
  4. Fund the cheapest corrective actions first

Explanation

Risk-based prioritisation weighs both the likelihood and the severity of consequences, together with the adequacy of existing barriers, so that resources target the greatest risk. Focusing on likelihood alone, cost alone or deferral can leave major hazards uncontrolled.

Question 39Process safety management fundamentals and leadership

How does a leader best ensure that process safety lessons from an incident at another company are applied at their own site?

  1. Add the external incident to the site's lagging indicator count
  2. Commission a structured review of the external lesson against local operations and track resulting actions Correct answer.
  3. Circulate the incident report by email and take no further action
  4. Wait until a similar incident occurs locally before acting

Explanation

Learning from external events requires a structured comparison with local plant, procedures and safeguards, followed by tracked corrective actions. Simply circulating reports rarely changes practice. Waiting for a local event forfeits the opportunity to prevent it.

Question 40Process safety management fundamentals and leadership

Which statement best explains why leadership commitment is considered the foundation of a PSM programme?

  1. It determines the resources, priorities and behaviours that make every other PSM element effective Correct answer.
  2. It guarantees that no process safety incidents will occur
  3. It removes the need for formal hazard analysis
  4. It satisfies the documentation requirements of regulators

Explanation

Leadership sets the priorities, allocates resources and models the behaviours on which all other PSM elements depend. Without that foundation, elements such as hazard analysis and mechanical integrity tend to become paper exercises. Commitment does not remove the need for technical analysis or guarantee the absence of incidents.

Question 41Process safety hazards and risk assessment

Which of the following best describes the purpose of a Hazard and Operability (HAZOP) study?

  1. To calculate the frequency of accidental releases using fault trees
  2. To determine the financial cost of process safety incidents
  3. To verify that installed safety systems meet their required integrity
  4. To systematically identify deviations from design intent and their consequences Correct answer.

Explanation

A HAZOP uses guide words applied to process parameters to identify deviations from design intent and examine their causes and consequences. It is a qualitative, systematic brainstorming technique rather than a quantitative frequency or cost analysis.

Question 42Process safety hazards and risk assessment

In a HAZOP, the guide word 'NO' applied to the parameter 'flow' typically generates which deviation?

  1. More flow than intended
  2. No flow at all Correct answer.
  3. Reverse flow
  4. Fluctuation in flow

Explanation

Guide words modify the design parameter to reveal deviations. 'NO' combined with 'flow' produces the deviation 'no flow', which prompts examination of causes such as pump failure or blockage.

Question 43Process safety hazards and risk assessment

Which risk assessment technique is most appropriate for a continuous, well-understood process where the objective is to rank hazards and prioritise further study?

  1. Preliminary hazard analysis Correct answer.
  2. Fault tree analysis
  3. Layer of Protection Analysis
  4. Hazard and Operability study

Explanation

Preliminary hazard analysis is a screening tool used early to identify and rank hazards so that resources can be directed to the most significant ones. It is suited to well-understood situations where detailed deviation analysis is not yet warranted.

Question 44Process safety hazards and risk assessment

A fault tree analysis is described as a deductive technique because it:

  1. Starts from basic events and works upward to the top event
  2. Uses guide words to examine process deviations
  3. Starts from a defined top event and works downward to identify causes Correct answer.
  4. Relies on expert judgement to assign likelihood scores

Explanation

Fault tree analysis begins with an undesired top event and logically decomposes it through AND and OR gates to identify the combinations of basic events that can cause it. This top-down reasoning is what makes it deductive.

Question 45Process safety hazards and risk assessment

In an event tree analysis, what does each branch point represent?

  1. A layer of protection and its integrity level
  2. A consequence severity category
  3. A basic event that initiates the sequence
  4. A mitigating system or function that may succeed or fail Correct answer.

Explanation

Event tree analysis is inductive: it starts from an initiating event and follows the success or failure of each subsequent mitigating system or function. Each branch point therefore represents a response that determines the outcome.

Question 46Process safety hazards and risk assessment

Which statement correctly describes the relationship between hazard and risk?

  1. Risk is the inherent property of a substance, while hazard depends on exposure
  2. Risk exists only when a hazard has already caused harm
  3. Hazard is the potential for harm, while risk combines likelihood and severity of that harm Correct answer.
  4. Hazard and risk are interchangeable terms in process safety

Explanation

A hazard is a source or situation with potential for harm, whereas risk expresses the likelihood and severity of harm arising from that hazard. The same hazard can present different risks depending on exposure and controls.

Question 47Process safety hazards and risk assessment

In a risk matrix, a hazard with a severity of 'major' and a likelihood of 'rare' is generally treated as:

  1. Irrelevant because the likelihood is low
  2. Requiring evaluation and possible additional controls Correct answer.
  3. Unacceptable under all circumstances
  4. Always acceptable without further action

Explanation

Risk matrices combine severity and likelihood to give a risk level. A major-severity, rare-likelihood combination typically falls in a middle band requiring evaluation and possibly further controls, rather than automatic acceptance or rejection.

Question 48Process safety hazards and risk assessment

Which of the following is a characteristic of an inherently safer design approach?

  1. Minimising the quantity of hazardous material in the process Correct answer.
  2. Increasing the number of operating procedures
  3. Relying on operator vigilance to prevent deviations
  4. Adding alarms and trips to manage a hazardous inventory

Explanation

Inherently safer design seeks to eliminate or reduce hazards at source, for example by minimising hazardous inventory. This reduces risk without relying on add-on controls or human intervention.

Question 49Process safety hazards and risk assessment

A HAZOP team is examining a vessel where the design intent is 'maintain pressure at 5 bar'. A guide word application reveals the deviation 'pressure higher than design'. Which of the following is the most appropriate next step for the team?

  1. Identify credible causes and consequences, then evaluate existing safeguards Correct answer.
  2. Record the deviation and move immediately to the next node
  3. Recommend immediate shutdown of the plant
  4. Calculate the exact probability of vessel rupture

Explanation

For each deviation the HAZOP team identifies credible causes, examines consequences, and evaluates whether existing safeguards are adequate. Recommendations follow only if safeguards are judged insufficient.

Question 50Process safety hazards and risk assessment

Which of the following best describes a bow-tie diagram?

  1. A tabular record of deviations and their causes
  2. A chart linking an initiating event to consequences via threats, top event, and barriers Correct answer.
  3. A hierarchical breakdown of system functions
  4. A plot of incident frequency against severity

Explanation

A bow-tie diagram places the top event at the centre, with threats and preventive barriers on the left and consequences and mitigating barriers on the right. It provides a visual representation of barrier management across the hazard.