API 653 Inspection Planning 2 — Questions and Answers
Question 1: According to API 653, what is the primary purpose of a risk-based inspection (RBI) program for aboveground storage tanks?
- To eliminate the need for internal inspections entirely
- To prioritize inspection resources based on likelihood and consequence of failure (Correct answer)
- To extend inspection intervals beyond API 653 maximum limits
- To replace visual inspections with ultrasonic testing only
Correct answer: To prioritize inspection resources based on likelihood and consequence of failure
RBI programs prioritize inspection resources by evaluating both the likelihood and consequence of failure, allowing more frequent inspection of higher-risk tanks.
Question 2: When planning a tank inspection, which document provides the historical record of previous inspections, repairs, and alterations?
- The API 653 standard itself
- The tank inspection file or permanent record (Correct answer)
- The process safety management plan
- The environmental compliance report
Correct answer: The tank inspection file or permanent record
The tank inspection file or permanent record contains historical data on all previous inspections, repairs, alterations, and maintenance activities.
Question 3: Under API 653, who is responsible for determining the inspection interval for an aboveground storage tank?
- The tank manufacturer
- A qualified API 653 inspector or engineer (Correct answer)
- The local fire marshal
- The insurance company underwriter
Correct answer: A qualified API 653 inspector or engineer
A qualified API 653 inspector or authorized inspection engineer is responsible for setting inspection intervals based on corrosion rates and risk factors.
Question 4: Which factor is MOST critical when establishing the external inspection interval for a tank in a coastal marine environment?
- The tank's original design pressure
- Accelerated external corrosion due to salt air exposure (Correct answer)
- The product's flash point temperature
- The tank's original construction date
Correct answer: Accelerated external corrosion due to salt air exposure
Coastal marine environments accelerate external corrosion significantly due to salt air, requiring more frequent external inspections to monitor metal loss.
Question 5: According to API 653, the minimum thickness required for continued service is calculated based on which primary variable?
- The tank's original wall thickness only
- The maximum allowable working stress and tank diameter (Correct answer)
- The product's specific gravity and viscosity
- The number of previous inspection cycles
Correct answer: The maximum allowable working stress and tank diameter
Minimum required thickness for continued service is determined by the maximum allowable working stress, tank diameter, and applicable design equations from API 650 Appendix A.
Question 6: When planning an internal inspection, API 653 requires that the inspector review which document to understand potential hazards before entry?
- The tank nameplate only
- The material safety data sheet (SDS) for the stored product (Correct answer)
- The original construction drawings only
- The local building permit
Correct answer: The material safety data sheet (SDS) for the stored product
Reviewing the SDS for the stored product is essential before entry to understand toxicity, flammability, and other hazards present in the tank.
Question 7: API 653 stipulates that tanks storing highly corrosive products should have their internal inspection intervals determined primarily by:
- A fixed 10-year schedule regardless of conditions
- Measured corrosion rates and remaining life calculations (Correct answer)
- The owner's budgetary constraints
- The age of the tank in years
Correct answer: Measured corrosion rates and remaining life calculations
For highly corrosive service, inspection intervals must be based on actual measured corrosion rates and calculated remaining corrosion allowance life.
API 653 Inspection Planning 2
According to API 653, what is the primary purpose of a risk-based inspection (RBI) program for aboveground storage tanks?