ASP Risk Assessment and Control 4 — Questions and Answers
Question 1: A facility uses the 'Bow-Tie' analysis method. What does the 'knot' or center of the bow-tie represent?
- A control measure
- The top event or hazardous event (Correct answer)
- A consequence pathway
- A threat source
Correct answer: The top event or hazardous event
In Bow-Tie analysis, the central knot represents the top event — the moment control of the hazard is lost.
Question 2: When applying the hierarchy of controls, substitution is preferred over engineering controls because:
- It is always cheaper to implement
- It eliminates or reduces the hazard at the source rather than containing it (Correct answer)
- It requires less regulatory documentation
- It is easier to train workers on
Correct answer: It eliminates or reduces the hazard at the source rather than containing it
Substitution replaces a hazardous material or process with a less hazardous one, reducing inherent risk rather than just controlling exposure.
Question 3: A safety manager calculates a Risk Priority Number (RPN) of 120 for a hazard. Which FMEA inputs produce this value if severity = 8 and detectability = 5?
- Occurrence = 2
- Occurrence = 3 (Correct answer)
- Occurrence = 4
- Occurrence = 15
Correct answer: Occurrence = 3
RPN = Severity × Occurrence × Detectability; 8 × 3 × 5 = 120.
Question 4: In quantitative risk assessment, 'risk tolerance' criteria are typically expressed as:
- A qualitative color on a risk matrix
- A maximum acceptable individual or societal risk level (e.g., 1×10⁻⁵/year) (Correct answer)
- The number of near-misses per quarter
- OSHA recordable incident rate
Correct answer: A maximum acceptable individual or societal risk level (e.g., 1×10⁻⁵/year)
Quantitative risk tolerance is usually expressed as an annual probability of harm threshold for individuals or populations.
Question 5: Which of the following BEST describes a 'leading indicator' in safety risk management?
- Number of lost-time injuries last quarter
- Workers' compensation costs year-to-date
- Percentage of safety observations completed on schedule (Correct answer)
- OSHA 300 log total recordable cases
Correct answer: Percentage of safety observations completed on schedule
Leading indicators measure proactive activities (like completed observations) that predict future safety performance before incidents occur.
Question 6: A root cause analysis reveals that a pressure relief valve was bypassed because workers lacked time under production pressure. This root cause is BEST categorized as:
- Technical failure
- Organizational/management system failure (Correct answer)
- Human error (skill-based)
- Environmental factor
Correct answer: Organizational/management system failure
Production pressure that leads to bypassing safety devices reflects a management system failure in balancing safety and productivity priorities.
Question 7: OSHA's Process Safety Management (PSM) standard requires a Process Hazard Analysis (PHA) to be revalidated at least every:
- 3 years
- 5 years (Correct answer)
- 7 years
- 10 years
Correct answer: 5 years
29 CFR 1910.119 requires PHA revalidation every five years to ensure the analysis remains current with process changes.
ASP Risk Assessment and Control 4
A facility uses the 'Bow-Tie' analysis method.
What does the 'knot' or center of the bow-tie represent?