Below is a API 510-style mock exam designed specifically with the real exam traps: unit mistakes, wording tricks, code navigation confusion, and calculation pitfalls.
It’s structured like the actual test: mix of calculations + code interpretation + scenario questions.
Q1. Corrosion rate
Thickness decreased from 0.625 in to 0.450 in over 7 years. What is corrosion rate?
→0.025 in/yr
0.015 in/yr
0.018 in/yr
0.030 in/yr
(0625 – 0.450 = 0.175
(0.175 / 7 = 0.025)
Current thickness = 0.300 in
Minimum required = 0.200 in
Corrosion rate = 0.020 in/yr
What is remaining life?
→5 years
B) 4 years
C) 6 years
D) 3 years
(0.100 / 0.020 = 5)
Remaining life = 6.4 years
What is maximum inspection interval?
6.4 years
→3.2 years
2.0 years
4.0 years
(½ remaining life rule)
t = 0.50 in
S = 15000 psi
R = 20 in
E = 0.85
Which is TRUE?
MAWP increases with corrosion
→MAWP decreases with lower E
MAWP independent of thickness
MAWP increases with radius
✔ B (most direct correct relationship)
Liquid height = 18 ft water
What pressure is added?
→7.8 psi
8.1 psi
6.5 psi
9.2 psi
(0.433 × 18 = 7.79 psi)
Original thickness = 0.750 in
Current = 0.525 in
What % loss?
25%
→30%
35%
40%
(0.225 / 0.750 = 30%
Where is corrosion rate primarily addressed?
A) Section 5
B) Section 6
→C) Section 9
D) Section 7
Replacing a nozzle with identical size is:
A) Alteration
→B) Repair
C) Design change
D) Reconstruction
Which governs inspection frequency?
A) ASME VIII
→B) API 510 Section 5
C) API 576
D) API 577
Wet H₂S environment most likely causes:
A) Erosion
→B) Sulfide stress cracking
C) CUI
D) Fatigue
Which detects subsurface defects?
A) PT
B) MT
→C) RT
D) VT
Lowest efficiency occurs when:
A) Full RT performed
B) Spot RT performed
→C) No RT performed
D) Post weld heat treated
UG-27 is used for:
A) Weld qualification
→B) MAWP of cylindrical shells
C) Corrosion rate
D) Inspection intervals
UG-32 relates to:
→A) Heads
B) Corrosion allowance
C) Nozzles
D) Repairs
UG-99 defines:
A) Weld types
→B) Pressure testing
C) Inspection intervals
D) Fatigue limits
If actual pressure exceeds MAWP, vessel is:
A) Acceptable with monitoring
B) Safe
→C) Unsafe for operation
D) Requires NDE only
Thickness = 0.400 in
Minimum = 0.250 in
Corrosion rate = 0.030 in/yr
What is inspection interval?
→2.5 years
3.0 years
2.0 years
1.5 years
(0.150 / 0.030 = 5 → ½ = 2.5)
Corrosion rate calculated in mm/year but required in in/year. What mistake occurs?
A) No issue
B) Overestimation
→C) Unit inconsistency
D) Wrong formula
Hydrotest pressure is based on:
A) Operating pressure only
→B) MAWP × test factor
C) Corrosion rate
D) Inspection interval
A vessel below minimum thickness should:
A) Continue operation
→B) Be immediately de-rated or repaired
C) Be ignored
D) Only be externally inspected