Risk Assessment & Hazard Analysis Flashcards
7 cards from real SIL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Risk Assessment & Hazard Analysis flashcards as text
In a semi-quantitative risk matrix, a scenario rated 'Unlikely' frequency and 'Catastrophic' consequence would typically fall into which risk category?
Answer: Intolerable or high risk requiring immediate risk reduction
Catastrophic consequence paired with any meaningful frequency typically places a scenario in the intolerable or high-risk region requiring priority risk reduction.
What is the role of 'enabling conditions' in a LOPA scenario?
Answer: They are conditions that must be present for the hazard to result in the worst-case consequence but are not IPLs
Enabling conditions modify the likelihood of a scenario reaching the defined consequence but are not independently acting protection layers; they reduce the scenario frequency without being credited as IPLs.
Which of the following best describes 'consequence modeling' in a QRA?
Answer: Predicting the physical effects (e.g., blast overpressure, thermal radiation) and their impact on people and assets
Consequence modeling uses dispersion, explosion, or fire models to predict the physical extent and severity of a hazardous event's effects on surroundings.
A 'Safeguard' in process safety is considered an Independent Protection Layer (IPL) only if it meets which key criteria?
Answer: It is independent, effective, and auditable/testable
IPL criteria require that the safeguard be independent of the initiating cause, effective in preventing the consequence, and auditable/testable to confirm its availability.
In Failure Mode and Effects Analysis (FMEA), what does 'severity rating' specifically assess?
Answer: The impact of the failure effect on the system, process, or end user
Severity rating in FMEA assesses the seriousness of the effect of the failure mode on the system, operation, or personnel, typically on a scale of 1 to 10.
Which statement correctly describes the relationship between PFD and Risk Reduction Factor (RRF)?
Answer: RRF = 1 / PFDavg
The Risk Reduction Factor is the reciprocal of the average probability of failure on demand; a PFDavg of 0.01 (SIL 2) equals an RRF of 100.
According to IEC 61511, who has the primary responsibility for determining the required SIL for a safety instrumented function?
Answer: The asset owner or operator responsible for the process
IEC 61511 places primary responsibility on the asset owner/operator to perform hazard and risk assessment and determine the required SIL for each SIF.