Risk-Based Inspection and Management Flashcards
7 cards from real API 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-Based Inspection and Management flashcards as text
Under API 581, what is the significance of 'thinning' as a damage mechanism category?
Answer: It encompasses general and localized metal loss that reduces wall thickness, affecting structural integrity and failure probability
Thinning in API 581 covers all forms of general and localized metal loss—including corrosion, erosion, and mechanical wear—that progressively reduce wall thickness and increase failure probability.
What does a high 'probability of failure' (PoF) ranking indicate in an RBI assessment?
Answer: The equipment has a relatively higher likelihood of failure compared to other equipment in the plant
A high PoF ranking means the equipment is more likely to fail relative to other plant equipment, not that failure is imminent; it drives prioritization of inspection resources.
In the context of RBI, what is 'Corrosion Under Insulation' (CUI) and why is it particularly challenging to manage?
Answer: CUI is external corrosion that occurs beneath insulation and is difficult to inspect without insulation removal
CUI occurs on the external surface of insulated equipment where moisture intrusion causes corrosion that is hidden beneath insulation, making routine visual inspection ineffective.
According to API 580, what type of data is typically collected during the 'data collection' phase of an RBI program?
Answer: Process conditions, material specifications, equipment history, inspection records, and damage mechanism susceptibility
Data collection for RBI requires technical inputs including process fluid data, equipment design data, materials of construction, operating history, and prior inspection findings.
What does the API 581 'risk plot' (risk matrix) typically display on its axes?
Answer: Probability of failure (PoF) on one axis and consequence of failure (CoF) on the other
The API 581 risk plot displays PoF on one axis and CoF on the other, creating a visual representation that allows equipment to be ranked by risk level.
Which NDE method is most effective for detecting stress corrosion cracking (SCC) in austenitic stainless steel equipment identified through RBI?
Answer: Eddy Current Testing or Phased Array Ultrasonic Testing (PAUT)
Phased Array UT and Eddy Current Testing are effective at detecting tight SCC cracks in stainless steel, whereas visual testing and PMI cannot reveal subsurface cracking.
In API 581 RBI, what is the effect of performing a 'highly effective' inspection on the calculated probability of failure?
Answer: It reduces the damage factor, thereby lowering the calculated PoF and extending the next inspection interval
A highly effective inspection reduces the uncertainty about damage state, which lowers the damage factor and thus the PoF, allowing the next inspection to be scheduled further in the future.