API 653 RECERTIFICATION PRACTICE
EXAM 2 QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2025
1. What is the minimum remaining shell thickness (tmin) allowed without
reinforcement for a tank in service?
A. 0.1 in.
B. 0.1 in. or 40% of the original thickness, whichever is less
C. 0.1 in. or 60% of the original thickness, whichever is more
D. 0.2 in.
• Per API 653, Section 4.3.2.1, the minimum is 0.1 in. or 40% of the original
thickness, whichever is less.
2. The maximum interval for an internal inspection of an aboveground storage
tank is:
A. 5 years
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,B. 10 years
C. 15 years
D. 20 years
• According to API 653, the maximum interval for internal inspection is 20
years if risk-based assessment is favorable.
3. Which document governs the design of new welded tanks for oil storage?
A. API 510
B. API 650
C. ASME Section VIII
D. API 570
• API 650 covers the design, material, fabrication, erection, and testing of
new aboveground welded storage tanks.
4. What type of inspection is required after a major tank repair?
A. Visual only
B. Spot UT
C. Full RT or UT, visual, and hydrotest or NDE substitute
D. API does not require inspection
• Per API 653, repairs require inspection, including possible RT/UT and
hydro/NDE.
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, 5. When calculating the required thickness for a shell course, which factor is
considered?
A. Internal pressure only
B. Shell curvature
C. Hydrostatic head (liquid height)
D. Wind load
• Thickness is governed by hydrostatic pressure from the stored liquid
height.
6. Which equation is commonly used to determine the minimum required
thickness of a tank bottom plate?
A. Barlow’s Formula
B. Poisson's Ratio
C. t = (2.6P + C) / SE
D. Von Mises Equation
• Used for bottom plate thickness calculation based on internal pressure
and other factors.
7. According to API 653, an inspector must be certified under:
A. API 510
B. API 653
C. API 570
D. ASNT Level III
3|Page
EXAM 2 QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2025
1. What is the minimum remaining shell thickness (tmin) allowed without
reinforcement for a tank in service?
A. 0.1 in.
B. 0.1 in. or 40% of the original thickness, whichever is less
C. 0.1 in. or 60% of the original thickness, whichever is more
D. 0.2 in.
• Per API 653, Section 4.3.2.1, the minimum is 0.1 in. or 40% of the original
thickness, whichever is less.
2. The maximum interval for an internal inspection of an aboveground storage
tank is:
A. 5 years
1|Page
,B. 10 years
C. 15 years
D. 20 years
• According to API 653, the maximum interval for internal inspection is 20
years if risk-based assessment is favorable.
3. Which document governs the design of new welded tanks for oil storage?
A. API 510
B. API 650
C. ASME Section VIII
D. API 570
• API 650 covers the design, material, fabrication, erection, and testing of
new aboveground welded storage tanks.
4. What type of inspection is required after a major tank repair?
A. Visual only
B. Spot UT
C. Full RT or UT, visual, and hydrotest or NDE substitute
D. API does not require inspection
• Per API 653, repairs require inspection, including possible RT/UT and
hydro/NDE.
2|Page
, 5. When calculating the required thickness for a shell course, which factor is
considered?
A. Internal pressure only
B. Shell curvature
C. Hydrostatic head (liquid height)
D. Wind load
• Thickness is governed by hydrostatic pressure from the stored liquid
height.
6. Which equation is commonly used to determine the minimum required
thickness of a tank bottom plate?
A. Barlow’s Formula
B. Poisson's Ratio
C. t = (2.6P + C) / SE
D. Von Mises Equation
• Used for bottom plate thickness calculation based on internal pressure
and other factors.
7. According to API 653, an inspector must be certified under:
A. API 510
B. API 653
C. API 570
D. ASNT Level III
3|Page
