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Free API510 Practice Questions

10 free, exam-style API 510 Pressure Vessel Inspector (API510) practice questions with answers and explanations. No signup required. Work through them below, then take the full free API510 practice test to study every exam domain.

Question 1

Calculate the MAWP for a cylindrical shell using UG-27: R = 24 in., t = 0.500 in., S = 15,000 psi, E = 0.85. Use P = (S × E × t) / (R + 0.6 × t).

  1. 248 psi
  2. 263 psi
  3. 278 psi
  4. 300 psi
Show answer & explanation

Correct answer: B - 263 psi

Question 2

Per Table UW-12, what is the joint efficiency for a Category A, Type 1 joint with spot radiography (RT-2)?

  1. 0.70
  2. 0.80
  3. 0.85
  4. 1.00
Show answer & explanation

Correct answer: C - 0.85

Question 3

A PQR was qualified using SMAW with E7018 (F-No. 4) electrode. Can this PQR support a WPS using E7024 (F-No. 1)?

  1. Yes, both are E70xx electrodes with similar mechanical properties
  2. Yes, F-Number changes are non-essential variables in SMAW processes
  3. No, changing F-Number is an essential variable requiring a new PQR
  4. Yes, if the authorized inspector approves the electrode substitution
Show answer & explanation

Correct answer: C - No, changing F-Number is an essential variable requiring a new PQR

Question 4

A vessel is made of Type 316L stainless steel. Surface cracking is suspected. Which NDE method should be used?

  1. Magnetic particle testing (MT)
  2. Liquid penetrant testing (PT)
  3. Either MT or PT - both work equally well
  4. Ultrasonic thickness measurement
Show answer & explanation

Correct answer: B - Liquid penetrant testing (PT)

Question 5

A vessel has t_actual = 0.550 in., t_required = 0.400 in., and CR = 0.012 in./yr. What is the remaining life and the maximum internal inspection interval?

  1. RL = 10 years, Interval = 5 years
  2. RL = 12.5 years, Interval = 6.25 years
  3. RL = 12.5 years, Interval = 10 years
  4. RL = 15 years, Interval = 7.5 years
Show answer & explanation

Correct answer: B - RL = 12.5 years, Interval = 6.25 years

Question 6

The key distinction between a repair and an alteration is that a repair:

  1. Maintains the original material specifications and thickness requirements
  2. Does NOT change the design conditions (pressure, temperature)
  3. Restores equipment to its original operating parameters without design modifications
  4. Returns the component to its as-built condition without altering rated capacities
Show answer & explanation

Correct answer: B - Does NOT change the design conditions (pressure, temperature)

Question 7

A 304 stainless steel vessel operating at 200°F in a chloride-containing environment develops branching transgranular cracks. Which damage mechanism is indicated?

  1. Caustic SCC
  2. Amine SCC
  3. Chloride SCC
  4. Wet H₂S cracking
Show answer & explanation

Correct answer: C - Chloride SCC

Question 8

During an inspection, a spring-loaded PRV on a vessel with MAWP = 250 psi is found to have a nameplate set pressure of 300 psi. This is:

  1. Acceptable - PRVs are always set above MAWP
  2. NOT acceptable - the PRV set pressure exceeds the MAWP
  3. Acceptable for fire case only
  4. Acceptable if the operating pressure is below 200 psi
Show answer & explanation

Correct answer: B - NOT acceptable - the PRV set pressure exceeds the MAWP

Question 9

API 510 considers safe operation of a pressure vessel to be the ultimate responsibility of:

  1. The authorized inspector
  2. The repair organization
  3. The owner-user
  4. The vessel manufacturer
Show answer & explanation

Correct answer: C - The owner-user

Question 10

Which PMI method can identify carbon content in addition to alloy composition?

  1. X-ray Fluorescence (XRF)
  2. Optical Emission Spectrometry (OES)
  3. Chemical spot testing methods
  4. Visual examination techniques
Show answer & explanation

Correct answer: B - Optical Emission Spectrometry (OES)

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