API 510 Standards & Best Practices 5 — Questions and Answers
Question 1: API 510 requires thickness measurements to be taken at locations most susceptible to corrosion. Which factor most influences the selection of these measurement locations?
- Accessibility for inspection personnel
- Known or anticipated damage mechanisms based on process conditions (Correct answer)
- Proximity to nozzle connections
- Locations specified in the original fabrication drawing
Correct answer: Known or anticipated damage mechanisms based on process conditions
Thickness measurement locations should be selected based on knowledge of the damage mechanisms expected given the specific process fluid and operating conditions.
Question 2: According to API 510, what is the correct action when an inspector finds a crack in a pressure vessel during an internal inspection?
- Record the crack size and continue the inspection without immediate action
- Evaluate the crack using FFS methods or remove it from service until repairs are made (Correct answer)
- Apply a temporary weld repair and schedule a follow-up inspection within 30 days
- Reduce the MAWP by 10% and continue operation
Correct answer: Evaluate the crack using FFS methods or remove it from service until repairs are made
Cracks found during inspection must be evaluated using fitness-for-service methods or the vessel must be removed from service until appropriate repairs are completed.
Question 3: In API 510, what does the term 'corrosion allowance' represent?
- The maximum corrosion rate allowed per year before retirement
- The extra thickness added during fabrication to accommodate anticipated metal loss during service life (Correct answer)
- The minimum wall thickness below which the vessel must be retired
- The tolerance permitted on shell plate thickness during fabrication
Correct answer: The extra thickness added during fabrication to accommodate anticipated metal loss during service life
Corrosion allowance is thickness added at fabrication beyond the calculated required thickness to allow for expected corrosion over the vessel's intended service life.
Question 4: Under API 510, an owner/operator wants to use external inspection in lieu of internal inspection. What condition must be met?
- The vessel must be less than 10 years old
- The vessel must be equipped with a corrosion monitoring coupon system
- The authorized inspector must determine that internal entry is impractical and that external methods can adequately assess conditions (Correct answer)
- The vessel must be operating below 50% of its MAWP
Correct answer: The authorized inspector must determine that internal entry is impractical and that external methods can adequately assess conditions
External inspection may substitute for internal inspection only when the authorized inspector determines internal entry is impractical and external NDE methods can adequately evaluate vessel condition.
Question 5: According to API 510, which of the following best describes the role of the 'Inspector' versus the 'Authorized Inspection Agency (AIA)'?
- The inspector is the AIA's legal representative; the AIA performs all physical inspections
- The AIA employs or qualifies the authorized inspector; the inspector carries out actual inspection work (Correct answer)
- The AIA sets inspection intervals; the inspector sets the MAWP
- The inspector owns the vessel; the AIA provides insurance certification
Correct answer: The AIA employs or qualifies the authorized inspector; the inspector carries out actual inspection work
The AIA is the organization that employs or qualifies the authorized inspector; the authorized inspector is the individual who actually performs inspection activities.
Question 6: Under API 510, what is the primary purpose of conducting a hydrostatic test after a repair or alteration?
- To verify the accuracy of corrosion rate calculations
- To confirm that the pressure boundary remains leak-tight and structurally sound at the test pressure (Correct answer)
- To recalibrate pressure relief valves to the new operating pressure
- To remove scale and debris from inside the vessel
Correct answer: To confirm that the pressure boundary remains leak-tight and structurally sound at the test pressure
A hydrostatic test after repair or alteration verifies that the pressure boundary is leak-tight and that the vessel can safely sustain the required test pressure.
Question 7: According to API 510, when must an authorized inspector be consulted before proceeding with a repair?
- Only when the repair involves a full shell plate replacement
- Before any repair work begins on pressure boundary components (Correct answer)
- Only when the repair requires post-weld heat treatment
- When the vessel is more than 20 years old
Correct answer: Before any repair work begins on pressure boundary components
API 510 requires that the authorized inspector be consulted and approve the repair method before any repair work begins on pressure boundary components.
API 510 Standards & Best Practices 5
API 510 requires thickness measurements to be taken at locations most susceptible to corrosion.
Which factor most influences the selection of these measurement locations?