Mixed Deck — All CRE Topics Flashcards

In reliability block diagrams, what is the reliability of two components with reliabilities R₁ = 0.9 and R₂ = 0.8 connected in series?

Answer: 0.72

For series systems, system reliability is the product of component reliabilities: R_sys = 0.9 × 0.8 = 0.72.

In reliability testing, the term 'censored data' (or suspended data) refers to:

Answer: Units that were removed from the test before failing

Censored (suspended) data represents test units that were removed or ended the test without experiencing a failure, providing partial life information.

In reliability testing, confidence intervals are used to:

Answer: Quantify uncertainty in reliability point estimates

Confidence intervals provide a range within which the true reliability parameter is expected to fall with a stated probability.

What is a key principle of reliability-centered maintenance (RCM)?

Answer: Determining cost-effective maintenance strategies

A key principle of Reliability-Centered Maintenance (RCM) is to determine the most cost-effective maintenance strategies for equipment based on its operational context and potential failure modes. RCM focuses on understanding the functions of assets and applying appropriate maintenance tasks (e.g., preventive, predictive, run-to-failure) to prevent functional failures. This approach optimizes maintenance resources and improves system reliability.

Which regulatory body enforces the Process Safety Management standard (29 CFR 1910.119) in the United States?

Answer: OSHA

OSHA (Occupational Safety and Health Administration) promulgates and enforces 29 CFR 1910.119, the PSM standard.

A reliability engineer is drafting a Derating Analysis Report. What must be documented for each component to demonstrate compliance?

Answer: Applied stress vs. rated stress and the resulting derating percentage for each stress parameter

Derating reports must show both the applied stress (voltage, current, temperature, etc.) and the rated maximum, along with the calculated derating percentage compared to the program's derating criteria.

In root cause analysis, the '5 Whys' technique is best suited for:

Answer: Simple to moderately complex failures with a single cause chain

The 5 Whys method iteratively asks 'why' to drill down through a cause-and-effect chain, working best when there is a single root cause pathway.

In Total Productive Maintenance (TPM), Overall Equipment Effectiveness (OEE) is calculated as:

Answer: Availability × Performance × Quality

OEE = Availability × Performance × Quality, capturing the three main sources of equipment effectiveness loss.

The cumulative distribution function (CDF) of the Weibull distribution F(t) equals 0.632 when t equals:

Answer: The characteristic life η (eta)

At t = η (the characteristic life), F(η) = 1 − e^(−1) ≈ 0.632 regardless of the shape parameter β.

What role does data collection play in quality improvement?

Answer: It provides objective evidence for identifying trends and measuring progress

Data-driven decision making provides objective evidence, helping identify patterns and measure the impact of improvement efforts.

In a reliability context, which environmental compliance strategy aligns with predictive maintenance to minimize chemical spills?

Answer: Monitoring equipment condition to detect potential leaks before they occur

Condition-based predictive maintenance detects deterioration in seals, pipes, and containment systems before failure, directly reducing the likelihood of environmental releases.

A component shows beach marks on its fracture surface. This is most indicative of:

Answer: Fatigue crack propagation

Beach marks (also called clamshell marks) are macroscopic striations on fracture surfaces that indicate cyclic loading and fatigue crack propagation.

Monte Carlo simulation in reliability analysis is primarily used to:

Answer: Generate simulated failure times mathematically from probability distributions

Monte Carlo simulation randomly samples input distributions to model system behavior and estimate reliability metrics.

What is the purpose of non-destructive testing (NDT) in failure analysis?

Answer: Identify defects without causing damage

Non-destructive testing (NDT) in failure analysis is crucial for identifying defects or discontinuities in materials or components without causing any damage to them. This allows for the examination of failed parts or components without altering their condition, preserving evidence for further analysis. NDT techniques help in understanding the failure mechanism without introducing new damage or compromising the integrity of the sample.

System availability (A) is correctly calculated as:

Answer: MTBF divided by (MTBF plus MTTR)

Availability = MTBF / (MTBF + MTTR), representing the proportion of time a system is operational versus being repaired.

Under OSHA's Process Safety Management (PSM) standard (29 CFR 1910.119), what is the primary trigger for coverage?

Answer: A process involves a highly hazardous chemical at or above a threshold quantity

PSM coverage is triggered when a process contains a highly hazardous chemical at or above the quantity thresholds listed in Appendix A of the standard.

Likelihood ratio confidence bounds in life data analysis are generally preferred over Fisher matrix bounds because they:

Answer: Are more accurate for small samples and highly censored data

Likelihood ratio bounds do not rely on asymptotic normality and therefore perform better for small, censored, or skewed datasets.

A facility subject to EPA's RMP rule must review and update its hazard assessment at least every:

Answer: 5 years

EPA's RMP rule (40 CFR 68.36) requires that the hazard assessment be reviewed and updated at least every five years or whenever the process changes significantly.

Which quantitative risk metric represents the probability of an individual being harmed per year due to a specific hazard?

Answer: Individual risk

Individual risk is expressed as the annual probability that a specific person will be harmed by the hazard.

Which document formally defines the asset functions, performance standards, and failure modes as the foundation for an RCM analysis?

Answer: Failure Mode and Effects Record (Information Worksheet)

The RCM Information Worksheet captures each function, its performance standard, and associated failure modes as the structured input to the decision process.