API 653 Welding Inspection 3 — Questions and Answers
Question 1: What is the primary purpose of a weld procedure qualification test (PQR) per ASME Section IX?
- To certify the welder's skill level
- To prove the weld procedure will produce sound welds meeting mechanical requirements (Correct answer)
- To satisfy insurance company documentation requirements
- To determine the maximum allowable working pressure of the vessel
Correct answer: To prove the weld procedure will produce sound welds meeting mechanical requirements
A PQR documents the actual variables used and test results to demonstrate that a welding procedure will produce welds with acceptable mechanical properties.
Question 2: Which type of weld discontinuity is considered LEAST acceptable in a tank shell butt weld per API 650 acceptance criteria?
- Minor undercut not exceeding 1/32 inch
- Weld reinforcement of 3/16 inch
- Cracks of any length or type (Correct answer)
- Porosity cluster less than 1/4 inch diameter
Correct answer: Cracks of any length or type
Cracks of any type or size are never acceptable in tank shell welds because they propagate under cyclic loading and can cause catastrophic failure.
Question 3: During inspection of a fillet weld on a nozzle-to-shell attachment, the throat size is found to be less than specified. What is the FIRST action an inspector should take?
- Accept the weld if it passes visual inspection
- Document the deficiency and require repair or additional weld passes (Correct answer)
- Grind the weld flush to improve appearance
- Apply a sealant to compensate for reduced throat size
Correct answer: Document the deficiency and require repair or additional weld passes
An undersized fillet weld does not meet design requirements and must be documented, then repaired by adding weld metal to achieve the specified throat size.
Question 4: What is 'interpass temperature' and why is it controlled during tank weld repairs?
- The temperature of the plate before welding begins, controlled to prevent distortion
- The maximum temperature of the weld between passes, controlled to maintain mechanical properties (Correct answer)
- The temperature differential between the inside and outside of the tank shell
- The ambient temperature inside the tank during hot work
Correct answer: The maximum temperature of the weld between passes, controlled to maintain mechanical properties
Interpass temperature is the weld metal temperature between successive passes; exceeding the maximum limit can reduce toughness and cause grain coarsening.
Question 5: When inspecting a tank annular plate weld repair, which measurement is critical to verify proper weld quality?
- The weld crown height above the floor plate
- Full penetration through the annular plate thickness (Correct answer)
- The distance from the weld to the tank shell
- The width of the heat-affected zone
Correct answer: Full penetration through the annular plate thickness
Annular plate butt welds must achieve full penetration through the plate thickness to ensure structural integrity at the tank base.
Question 6: A welder qualification test requires the welder to weld in the 6G position. Which positions does this qualification cover?
- Flat (1G) only
- Flat and horizontal (1G and 2G)
- Flat, horizontal, and vertical (1G, 2G, and 3G)
- All positions including overhead (1G, 2G, 3G, and 4G) (Correct answer)
Correct answer: All positions including overhead (1G, 2G, 3G, and 4G)
The 6G position (45° inclined fixed pipe) is the most comprehensive qualification and qualifies a welder for all pipe welding positions per ASME Section IX.
Question 7: Per API 653, what NDE method is required for detecting surface cracks in a weld on a non-magnetic (austenitic stainless steel) tank shell?
- Magnetic particle testing (MT)
- Liquid penetrant testing (PT) (Correct answer)
- Eddy current testing (ET)
- Acoustic emission testing (AET)
Correct answer: Liquid penetrant testing (PT)
Liquid penetrant testing (PT) is required for surface crack detection on non-magnetic materials since magnetic particle testing cannot be used on non-ferromagnetic metals.
API 653 Welding Inspection 3
What is the primary purpose of a weld procedure qualification test (PQR) per ASME Section IX?