API 653 Inspection Planning 3 — Questions and Answers
Question 1: According to API 653, what is the maximum interval for an internal inspection if the corrosion rate is not known and cannot be determined?
- 5 years
- 10 years (Correct answer)
- 15 years
- 20 years
Correct answer: 10 years
When the corrosion rate is unknown and cannot be determined from historical data, API 653 limits the internal inspection interval to 10 years.
Question 2: In API 653 inspection planning, what does the term 'remaining life' refer to?
- The age of the tank from its original construction date
- The estimated time until the tank reaches minimum acceptable thickness (Correct answer)
- The time remaining on the original manufacturer's warranty
- The number of inspection cycles the tank has undergone
Correct answer: The estimated time until the tank reaches minimum acceptable thickness
Remaining life is the estimated time until the tank wall reaches the calculated minimum required thickness based on current thickness and corrosion rate.
Question 3: Before conducting an inspection, API 653 requires that the inspector assess the tank's service history to identify which of the following?
- The tank's purchase price and depreciation schedule
- Changes in product stored, operating conditions, or known damage mechanisms (Correct answer)
- The number of employees who have operated the tank
- The tank's insurance coverage limits
Correct answer: Changes in product stored, operating conditions, or known damage mechanisms
Service history review identifies changes in stored product, temperature, pressure, or damage mechanisms that could affect inspection scope and findings.
Question 4: Which API 653 inspection category involves examination of the tank from the outside without removing the product or entering the tank?
- Internal inspection
- In-service inspection (Correct answer)
- Out-of-service inspection
- Foundation inspection
Correct answer: In-service inspection
In-service inspection is conducted while the tank remains in operation, examining external surfaces, appurtenances, and foundation without product removal.
Question 5: According to API 653, which condition would MOST likely trigger an unscheduled inspection outside the normal interval?
- Routine scheduled maintenance completion
- Discovery of a leak, unusual settlement, or significant corrosion (Correct answer)
- Completion of the annual safety meeting
- Change of shift supervisor
Correct answer: Discovery of a leak, unusual settlement, or significant corrosion
Unscheduled inspections are triggered by abnormal conditions such as leaks, unusual settlement, significant corrosion findings, or other integrity concerns.
Question 6: When planning thickness measurements for a tank bottom, API 653 recommends which scanning pattern to detect bottom corrosion accurately?
- Measuring only the center of the bottom
- A systematic grid or scan pattern covering the entire bottom (Correct answer)
- Measuring only along the shell-to-bottom weld
- Random spot measurements at five locations
Correct answer: A systematic grid or scan pattern covering the entire bottom
API 653 requires a systematic grid or scanning pattern across the entire tank bottom to ensure representative coverage and detection of localized corrosion.
Question 7: API 653 requires that inspection records be retained for at least how long after the tank is permanently removed from service?
- 2 years
- 5 years (Correct answer)
- The life of the tank plus 5 years
- Indefinitely as long as the site operates
Correct answer: 5 years
API 653 requires inspection records to be retained for the life of the tank plus 5 years after permanent removal from service.
API 653 Inspection Planning 3
According to API 653, what is the maximum interval for an internal inspection if the corrosion rate is not known and cannot be determined?