This 2026 practice question bank prepares candidates for the API 510 Pressure Vessel Inspector certification exam administered by the American Petroleum Institute (API). The questions below are referenced to the API 510 Body of Knowledge (BOK), with primary code references to API 510 Pressure Vessel Inspection Code (In-service Inspection, Rating, Repair, and Alteration), API RP 572 (Inspection Practices for Pressure Vessels), API RP 576 (Inspection of Pressure-Relieving Devices), API RP 577 (Welding Inspection and Metallurgy), API RP 580 (Risk-Based Inspection), API 579-1/ASME FFS-1 (Fitness-for-Service), and ASME BPVC Sections V, VIII Div 1, and IX.
\nThe API 510 exam is administered as a computer-based test (CBT) at Prometric centers in two parts:
\nCorrect Answer: C
Explanation: Per API 510 Section 6.4, external inspection intervals shall not exceed 5 years or the required internal/on-stream inspection interval, whichever is less. Insulated vessels follow the same rule with CUI considerations.
Correct Answer: A
Explanation: API 510 Section 6.5.1 limits the internal (or on-stream) inspection interval to the lesser of one-half the remaining corrosion life or 10 years. RBI-based intervals can extend this with proper justification under API 580.
Correct Answer: A
Explanation: Long-term corrosion rate (LTCR) = (t-initial − t-actual) / (years between t-initial and t-actual). Short-term rate (STCR) uses the period between the previous and current inspection. The greater rate is generally used for remaining life calculations.
Correct Answer: B
Explanation: API 510 Section 8 requires a documented repair plan, qualified WPS/PQR per ASME IX, qualified welder/welding operator, applicable NDT, and post-weld heat treatment (PWHT) where required by original construction code or alteration analysis.
Correct Answer: B
Explanation: MAWP is the maximum pressure at which the weakest component will safely operate, calculated using current measured thickness minus the future corrosion allowance (FCA). MAWP is updated when corrosion or alterations change the rating.
Correct Answer: A
Explanation: Risk = PoF × CoF. PoF accounts for damage mechanisms, inspection effectiveness, and remaining life; CoF accounts for safety, environmental, and business impact. The risk matrix drives inspection planning per API 580/581.
Correct Answer: A
Explanation: API 510 Section 6.6 and API 576 typically require PRV testing/inspection every 5 years (clean services) or 10 years (RBI-justified). PRVs in severe or fouling service may require more frequent inspection.
Correct Answer: A
Explanation: ASME VIII Div 1 UG-27: t = PR / (SE − 0.6P) for circumferential stress (governs thin-walled cylinders). The alternate formula t = PR / (2SE + 0.4P) for longitudinal stress is rarely governing. Joint efficiency E depends on RT.
Correct Answer: A
Explanation: On-stream inspection uses external NDT (UT, RT, profile RT, guided wave UT, PEC) to assess vessel condition without entry. Per API 510, on-stream may substitute for internal inspection if the inspector and engineer can determine vessel integrity to the same degree.
Correct Answer: A
Explanation: Authorized inspectors must hold current API 510 certification with required experience (4-year degree + 1 yr, or 2-year degree + 2 yrs, or HS + 3 yrs, etc.) and operate under a quality system. PE is required only when API 510 specifies engineer involvement.
Correct Answer: A
Explanation: Remaining life = (t-actual − t-min) / corrosion rate = (12 − 10) / 0.1 = 20 years (without FCA) or (12 − 10 − 1.6) / 0.1 = 4 years if FCA must be retained. API 510 uses the more conservative number for inspection planning.
Correct Answer: A
Explanation: Per API 510, an alteration changes the design conditions (T, P, MAWP), vessel rating, or geometry (e.g., adding a nozzle). A repair restores the vessel to a condition suitable for safe operation without changing the rating. Alterations require engineering review.
Correct Answer: A
Explanation: Hot tapping is welding (typically a nozzle) onto a pressurized line or vessel and then drilling through. API RP 2201 governs hot tap procedures including burn-through prevention, hazard analysis, and procedure qualification.
Correct Answer: B
Explanation: Weld overlay (build-up) repairs are permitted as permanent repairs under API 510 Section 8, requiring qualified WPS, qualified welders, NDT, and PWHT if mandated by base metal P-number or carbon equivalent rules.
Correct Answer: B
Explanation: Fillet welded patches are permitted as temporary repairs per API 510 Section 8.1.5 with limits on size, design analysis, NDT, and a defined service period until a permanent repair can be made.
Correct Answer: B
Explanation: ASME VIII Div 1 UCS-56 specifies PWHT requirements based on material P-number and nominal thickness. Common rule: P-No. 1 carbon steel typically needs PWHT above 19 mm (3/4 in) thickness; lower-alloy steels at lesser thickness.
Correct Answer: A
Explanation: API 579 organizes Fitness-for-Service assessments in three levels: Level 1 (conservative tables/formulas), Level 2 (more detailed calculations with material properties), Level 3 (advanced FEA / probabilistic). The inspector typically performs Level 1; engineers Level 2 and 3.
Correct Answer: A
Explanation: Chloride stress corrosion cracking (Cl-SCC) of austenitic stainless steel (304/316) occurs typically above 60°C in chloride-bearing solutions. Insulation chlorides leaching with water is a common source. API RP 581 lists SCC mechanisms.
Correct Answer: A
Explanation: API RP 577 and API 571 cover hydrogen damage: HIC (blistering and crack networks in wet H2S), SSC (sulfide stress cracking in hard welds and HAZ), HSC (hydrogen stress cracking), and HTHA (high-temperature hydrogen attack — Nelson curves).
Correct Answer: A
Explanation: Hydrostatic test pressure after major repair/alteration is typically 1.3 × MAWP × (Sa/Sd) per ASME VIII Div 1 UG-99, where Sa/Sd is the stress ratio at test/design temperatures. Alternative NDT and engineering analysis may substitute.
Correct Answer: A
Explanation: UT thickness is the workhorse NDT for vessel wall measurement. Spot UT at TML (thickness measurement locations) and scanning UT (corrosion mapping) are both used. Profile RT, PAUT corrosion mapping, and PEC for through-insulation are also acceptable.
Correct Answer: A
Explanation: TMLs are placed at expected damage locations based on the dominant damage mechanism, geometry (shells, heads, knuckle radii, nozzles, manways), inlet/outlet, level lines, and historical thinning. API RP 572 provides guidance on TML selection.
Correct Answer: A
Explanation: The authorized inspector is responsible for verifying inspection, repair, and alteration activities meet API 510 and applicable code. Design and reratings involve the engineer (PE or qualified equivalent).
Correct Answer: A
Explanation: ASME VIII Div 1 Table UW-12 gives joint efficiencies based on joint type (Type 1 butt weld, Type 2 single-V, etc.) and radiography category (Full, Spot, None). Typical values: E=1.0 for Type 1 with full RT; E=0.85 with spot; E=0.70 with no RT.
Correct Answer: A
Explanation: ASME VIII Div 1 UG-119 requires the nameplate to include manufacturer, MAWP, design temperature, MDMT, year of construction, manufacturer’s serial number, and the appropriate ASME code stamp (U, UM, etc.).
Correct Answer: A
Explanation: Sulfidation is high-temperature corrosion of iron-based alloys by sulfur compounds, typically above 260°C. The McConomy curves and modified McConomy provide thinning rate vs. temperature, sulfur content, and material. Common in crude distillation and FCC units.
Correct Answer: A
Explanation: Pressure cycles, thermal cycles, and vibration can initiate and propagate fatigue cracks, particularly at stress concentrations (nozzles, weld toes). API RP 579-1 Part 14 provides fatigue assessment procedures.
Correct Answer: A
Explanation: MDMT is the lowest expected metal temperature considering operation, startup, shutdown, and upsets. Material toughness must be sufficient at MDMT per UCS-66 charts. Brittle fracture risk increases as temperature drops below MDMT.
Correct Answer: A
Explanation: Temporary repairs are limited in scope and time. API 510 Section 8.1.5 requires them to be replaced with a permanent repair by the next scheduled turnaround or as documented in the engineering and inspector-approved repair plan.
Correct Answer: A
Explanation: ASME IX requires a welder performance qualification (WPQ) including production of a test coupon and acceptable NDT (RT or bend testing). The WPQ has essential variables that, if changed, may require requalification. Welders must maintain continuity (typically welding within the 6 months prior).
A: API 510 requires combinations like: BS in engineering plus 1 year, or 2-year engineering degree plus 2 years, or high school plus 3 years of NDT/inspection-related experience. Verify the current API ICP requirements.
\nA: 3 years to a reduced recertification exam (open-book only), then 6 years for the full recertification exam. Continuous practice as an inspector is also required.
\nA: No. API 510 certifies you as a vessel inspector (a code-driven role); ASNT certifies you in NDT methods (UT, RT, MT, PT, etc.). Many inspectors hold both. See our ASNT vs PCN comparison for NDT body certifications and our ASNT certification page for ASNT routes.
\nA: Yes. API 510 is widely recognized globally, especially in oil & gas. In Europe, PED-driven Notified Body assessments may also apply. In Saudi Aramco SAES requirements explicitly reference API 510 inspectors.
\nA: API 510 covers pressure vessels; API 570 covers in-service piping. See our API 510 vs API 570 comparison.
\nA: No. Atlantis NDT does not run API 510 exam-preparation courses. Our API 510 pressure vessel inspection support is ASNT Level III technical work on vessel programmes — RBI, FFS and data review — not exam coaching.
\nA: API exams are administered through Prometric test centers worldwide (computer-based test). Online proctoring options have been piloted; verify the latest with API ICP at the time of registration.
\nA: Industry averages range from 50 to 65% first attempt. Candidates from structured prep courses typically report 80%+ first try.
\nA: In the US, $90,000 to $140,000/year base, plus offshore/turnaround premiums. In the Middle East, $7,000 to a modest cost/month tax-free for experienced inspectors. Salary scales with API 570 + 653 stacking.
\nA: Yes — welding procedure and welder performance qualification under ASME IX is a major open-book topic. Tab QW-200 (WPS/PQR), QW-300 (welder performance), and QW-400 (essential variables tables).
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