API 510 PRESSURE VESSEL
INSPECTOR PRACTICE
EXAM 170 QUESTIONS
Question 1: A pressure vessel shell was 0.500 in. thick �ve years ago and is now 0.475 in. thick. What is the long-term corrosion rate?
Choices:
1) 0.005 in./yr 2) 0.025 in./yr 3) 0.001 in./yr 4) 0.050 in./yr
Correct Answer: 0.005 in./yr
Explanation: Metal loss is 0.500 - 0.475 = 0.025 in. Dividing by 5 years gives a corrosion rate of 0.005 in./yr.Page 1
Question 2: A vessel has an actual thickness of 0.460 in., a required thickness of 0.400 in., and a corrosion rate of 0.003 in./yr. What is the estimated remaining life?
Choices:
1) 30 years 2) 20 years 3) 15 years 4) 10 years
Correct Answer: 20 years
Explanation: Remaining life = (0.460 - 0.400) / 0.003 = 20 years.
Question 3: If the actual thickness is 0.625 in. and the required thickness is 0.500 in., what is the remaining corrosion allowance?
Choices:
1) 0.100 in.2) 1.125 in.3) 0.125 in.4) 0.0625 in.
Correct Answer: 0.125 in.
Explanation: Remaining corrosion allowance equals actual thickness minus required thickness: 0.625 - 0.500 = 0.125 in.Page 2
Question 4: A vessel part is 40 ft below the liquid surface. For a liquid with speci�c gravity 1.0, approximately what static head pressure acts at that elevation?
Choices:
1) 57.7 psi 2) 92.4 psi 3) 40.0 psi 4) 17.3 psi
Correct Answer: 17.3 psi
Explanation: For speci�c gravity 1.0, static head is approximately 0.433 psi/ft. Thus 40 x 0.433 = 17.32 psi.Question 5: A vessel operates at 150 psi and a lower shell course is 30 ft below the reference elevation under liquid of speci�c gravity 1.0. What pressure should be considered at that lower location before other adjustments?
Choices:
1) 163.0 psi 2) 214.9 psi 3) 150.0 psi 4) 180.0 psi
Correct Answer: 163.0 psi
Explanation: Static head is 30 x 0.433 = 12.99 psi. Total pressure is approximately 150 + 12.99 = 163.0 psi.Page 3