API 653 Repair and Alteration 4 — Questions and Answers
Question 1: What does API 653 classify as an 'alteration' as opposed to a 'repair' for aboveground storage tanks?
- Any weld made on the tank after original construction
- A change in tank design, configuration, or service that was not part of the original design (Correct answer)
- Replacing corroded shell plates with identical thickness material
- Repainting the external surface of the tank
Correct answer: A change in tank design, configuration, or service that was not part of the original design
API 653 defines alterations as physical changes or service condition changes outside the original design intent, distinguishing them from like-for-like restorations.
Question 2: When performing a repair using a flush patch on a tank shell, what is the minimum distance the patch edges must be kept from existing shell welds per API 653?
- 1 inch (25 mm)
- 2 inches (50 mm)
- 3 inches (75 mm) (Correct answer)
- 6 inches (150 mm)
Correct answer: 3 inches (75 mm)
API 653 requires flush patch edges to be at least 3 inches (75 mm) from existing welds to avoid creating intersecting or closely spaced weld joints.
Question 3: According to API 653, who is responsible for ensuring that all tank repairs and alterations conform to the standard's requirements?
- The welding contractor performing the work
- The authorized inspector assigned to the tank
- The tank owner/operator (Correct answer)
- The engineer of record for the repair
Correct answer: The tank owner/operator
API 653 places ultimate responsibility for compliance with the standard's repair and alteration requirements on the tank owner/operator.
Question 4: A repair organization plans to use a new welding procedure for tank shell repairs. Per API 653, the procedure must be:
- Approved by the local welding inspectorate before use
- Qualified in accordance with ASME Section IX (Correct answer)
- Submitted to API for review and approval
- Certified by the welding consumable manufacturer
Correct answer: Qualified in accordance with ASME Section IX
API 653 requires that welding procedures be qualified per ASME Section IX, which is the standard reference for welding procedure qualification in pressure equipment.
Question 5: When API 653 allows an 'in-service' repair (repair made while the tank contains product), what is a key prerequisite?
- The repair area must be below the product level to prevent ignition
- Engineering evaluation must confirm structural and safety adequacy for the in-service condition (Correct answer)
- The repair must use only cold-work methods such as mechanical clamps
- In-service repairs are never permitted under API 653
Correct answer: Engineering evaluation must confirm structural and safety adequacy for the in-service condition
API 653 permits in-service repairs only after engineering evaluation confirms that the repair can be safely performed with product present.
Question 6: After completing a repair on a tank shell that involved installation of a new flush patch, what nondestructive examination (NDE) is typically required per API 653?
- Radiographic testing (RT) of all patch welds (Correct answer)
- Vacuum box testing of all patch welds
- Hydrostatic testing of the entire tank
- Magnetic particle testing (MT) of all patch welds
Correct answer: Radiographic testing (RT) of all patch welds
API 653 typically requires radiographic testing of flush patch welds to ensure full penetration weld quality comparable to original construction requirements.
Question 7: Per API 653, what is required when converting a fixed-roof tank to a floating-roof tank as an alteration?
- Only a visual inspection of the shell is needed
- Engineering calculations must verify shell adequacy for the different loading conditions (Correct answer)
- The tank must be demolished and rebuilt to API 650 floating roof specifications
- The change is not permitted under API 653
Correct answer: Engineering calculations must verify shell adequacy for the different loading conditions
Converting roof type changes the loading conditions and requires engineering analysis to confirm the existing shell can safely accommodate the new roof system.
API 653 Repair and Alteration 4
What does API 653 classify as an 'alteration' as opposed to a 'repair' for aboveground storage tanks?