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Free API653 Practice Questions

10 free, exam-style API 653 Aboveground Storage Tank Inspector (API653) practice questions with answers and explanations. No signup required. Work through them below, then take the full free API653 practice test to study every exam domain.

Question 1

The API 653 scope includes all of the following tank components EXCEPT:

  1. Tank foundation settlement monitoring systems
  2. Piping beyond the first flange
  3. External floating roof seals and fittings
  4. Tank shell corrosion allowance calculations
Show answer & explanation

Correct answer: B - Piping beyond the first flange

Question 2

If the original weld type on an existing tank is NOT KNOWN, what joint efficiency must be used?

  1. 0.60
  2. 0.80
  3. 0.70
  4. 0.90
Show answer & explanation

Correct answer: C - 0.70

Question 3

A tank shell has a remaining life of 16 years and the bottom has a remaining life of 8 years. What is the governing internal inspection interval?

  1. 4 years (bottom: ½ × 8)
  2. 8 years (shell: ½ × 16)
  3. 10 years (maximum)
  4. 16 years (shell remaining life)
Show answer & explanation

Correct answer: A - 4 years (bottom: ½ × 8)

Question 4

A carbon steel tank storing 60% sulfuric acid shows minimal corrosion, while a similar tank storing 20% sulfuric acid shows severe corrosion. This is because:

  1. The 20% tank has thinner plates
  2. The 60% tank has cathodic protection
  3. The 20% tank is at higher temperature
  4. The 60% concentration forms a protective film
Show answer & explanation

Correct answer: D - The 60% concentration forms a protective film

Question 5

Compared to API 510 and API 570, the API 653 welding scope is:

  1. Broader - it includes more processes and base metals
  2. The most restricted - only SMAW/GMAW and P-No. 1
  3. Less restricted - it includes all welding processes
  4. Identical in scope
Show answer & explanation

Correct answer: B - The most restricted - only SMAW/GMAW and P-No. 1

Question 6

If a tank has 4 courses and the calculated maximum fill heights are: Course 1 = 36 ft, Course 2 = 34 ft, Course 3 = 38 ft, Course 4 = 42 ft, the overall maximum fill height is:

  1. 34 ft
  2. 38 ft
  3. 42 ft
  4. 36 ft
Show answer & explanation

Correct answer: A - 34 ft

Question 7

The vacuum box testing procedure involves:

  1. Filling the tank with water and observing for leaks
  2. Applying a magnetic field to detect defects
  3. Applying penetrant to the weld surface
  4. Applying soap solution, placing vacuum box over weld, and observing for bubbles
Show answer & explanation

Correct answer: D - Applying soap solution, placing vacuum box over weld, and observing for bubbles

Question 8

All of the following are types of settlement evaluated per API 653 Annex B EXCEPT:

  1. Edge settlement
  2. Localized settlement remote from the shell
  3. Foundation tilt settlement
  4. Differential settlement near the shell
Show answer & explanation

Correct answer: C - Foundation tilt settlement

Question 9

A tank bottom shows pitting in areas directly under deposits. The MOST likely damage mechanism is:

  1. Corrosion under insulation
  2. Concentration cell corrosion
  3. Stress corrosion cracking
  4. Galvanic corrosion
Show answer & explanation

Correct answer: B - Concentration cell corrosion

Question 10

The PRIMARY distinction between a repair and a reconstruction is:

  1. Repair follows API 653 rules; reconstruction requires API 650 compliance
  2. Repair involves welding; reconstruction does not
  3. There is no meaningful distinction
  4. Cost - reconstruction is always more expensive
Show answer & explanation

Correct answer: A - Repair follows API 653 rules; reconstruction requires API 650 compliance

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