API 510 Exam Prep: Study Guide & Tips [2026]

API 510 Exam Prep: Complete Study Guide & Success Tips 2026

This is an independent study guide for the API 510 Pressure Vessel Inspector exam, written from the published API Body of Knowledge (BOK) and program page. Atlantis NDT does not run API exam preparation courses; the guide is here so candidates can plan their own study. Always check the current BOK and Publications Effectivity Sheet on api.org before you start, because the referenced editions change by exam window.

API 510 Exam Overview

Exam Format and Structure (from api.org)

• Total questions: 170 multiple-choice (140 scored, 30 unscored pretest questions you cannot identify)
• Time: about 7.5 hours including tutorial and a break: a closed-book part (110 questions) and an open-book part (60 questions, with the references provided electronically)
• Delivery: in person at Prometric test centers only; remote proctoring for API 510, 570 and 653 ended with the September 2024 window
• Scoring: API reports a scaled score; it does not publish a fixed "percent correct" pass mark
• Results: Prometric emails a score report, typically within 24 hours; API then posts final results to the ICP portal
• Fees and retakes: set by API (a reschedule/retest application and fee apply if you do not pass or miss your appointment); check the current schedule on api.org

Pass Rates

API publishes program statistics from time to time on its ICP statistics pages. We do not repeat unverified pass-rate figures here; if you need a number, use the latest API ICP statistics PDF and note its date. See our pass-rate explainer for how to read those reports.

Content Breakdown and Study Allocation

Referenced Documents (API 510 BOK)

Document	What to focus on
API 510 (current edition per effectivity sheet)	Definitions, inspector and engineer roles, inspection plans, intervals, corrosion rate and remaining life, pressure testing, repairs, alterations, rerating, records
API RP 571	Damage mechanisms listed in the BOK: appearance, critical factors, affected units, inspection and monitoring
API RP 572 (incl. Annex B)	Inspection practices for pressure vessels
API RP 576	Pressure-relieving device inspection and testing
API RP 577	Welding processes, weld inspection, metallurgy
API RP 578	Material verification (PMI) programs
ASME Section VIII Div. 1	Thickness calculations for shells and heads, joint efficiency, MAWP, hydrotest and pneumatic test pressures, impact-test exemption curves
ASME Section V	General NDE requirements in the articles listed in the BOK
ASME Section IX	Reviewing a WPS/PQR for compliance with essential variables
ASME PCC-2	Repair methods named in the BOK

API does not publish percentage weightings per topic. A realistic study budget for working inspectors is often quoted at 80-150 hours over 6-12 weeks, but it depends heavily on your experience with ASME VIII calculations.

Core Content Review by Topic

Section 1: API 510 Code Requirements

• Roles: owner-operator, authorized pressure vessel inspector, pressure vessel engineer, repair organization, examiner, inspection supervisor.
• Intervals (fixed-limit method): external visual at the lesser of 5 years or the internal/on-stream interval; internal or on-stream at the lesser of one-half remaining life or 10 years; if remaining life is under 4 years, the interval may be the full remaining life up to 2 years. RBI per API RP 580 may set other intervals. There is no annual or 12-month external requirement.
• On-stream in lieu of internal: know the conditions (e.g., corrosion rate under 0.005 in./yr, remaining life over 10 years, at least 5 years of similar-service history, no environmental cracking or hydrogen damage).
• Records: permanent and progressive; no fixed retention period.
• Pressure testing: not part of routine inspection; normally after alterations and after repairs if the inspector requires. Know the test-pressure rules referenced in the code and in ASME VIII (UG-99 hydrotest, UG-100 pneumatic).
• Thickness data: CMLs are chosen for the credible damage mechanisms; the code does not set a fixed number of readings per vessel.
• Corrosion rate: long-term = (t initial - t actual) / years between; short-term = (t previous - t actual) / years between. Remaining life = (t actual - t required) / corrosion rate.

Worked example: corrosion rate 0.010 in./yr, actual 0.312 in., required 0.188 in. Remaining life = 0.124 / 0.010 = 12.4 years. Maximum internal interval = lesser of 6.2 years (one-half) or 10 years = 6.2 years.

Section 2: NDE Methods (API RP 572, RP 577, ASME V)

UT thickness: longitudinal velocity in carbon steel about 0.233 in./microsecond (5,920 m/s); calibrate on blocks of the same material across the thickness range; dual-element probes for corroded surfaces; know temperature effects on readings.

MT: ferromagnetic materials only; wet fluorescent MT is preferred for internal crack detection (e.g., wet H2S service).

PT: surface-breaking discontinuities on non-porous materials, including austenitic stainless steels.

RT: volumetric weld examination and profile radiography; know image quality indicators and density requirements from ASME V Article 2 as listed in the BOK.

Angle-beam UT/PAUT/TOFD: crack detection and sizing; often used in lieu of RT where permitted.

Section 3: ASME Section VIII Div. 1 Calculations

• Shell thickness (circumferential stress): t = PR / (SE - 0.6P)
• Heads: ellipsoidal, torispherical and hemispherical formulas as listed in the BOK
• Joint efficiency: depends on joint type and extent of radiography (e.g., Type 1 full RT 1.0, spot RT 0.85, no RT 0.70)
• Corrosion allowance: extra thickness added to the required thickness at design. Required thickness for remaining-life calculation is the pressure (or structural) minimum, without the corrosion allowance.
• Impact testing: use of UCS-66 exemption curves and the MDMT rules listed in the BOK

Section 4: Damage Mechanisms (API RP 571)

Study the mechanisms listed in the current BOK (e.g., sulfidation, wet H2S damage, CUI, chloride SCC, caustic embrittlement, brittle fracture, creep, high-temperature hydrogen attack, erosion). For each: affected materials, critical factors, appearance and the inspection methods that find it. Fitness-for-service assessment is not part of the API 510 BOK; you only need to know that the code refers damage beyond its own rules to an FFS evaluation.

Section 5: Repair, Alteration and Rerating

Know who authorizes and accepts repairs and alterations, the welding requirements (qualified WPS/PQR and welders per ASME IX), preheat and PWHT alternatives listed in API 510, NDE and pressure-test requirements after repairs and alterations, and the rerating steps (calculations, testing, nameplate/stamping).

Study Strategy and Timeline

Example 8-Week Plan (about 12-18 hours per week)

• Week 1: Download the current BOK and effectivity sheet; read API 510 cover to cover; list every definition and every number (intervals, percentages, temperatures).
• Week 2: API 510 calculations: corrosion rates, remaining life, intervals, MAWP; repeat until automatic.
• Week 3: ASME VIII Div. 1: shell and head thickness, joint efficiency, hydrotest/pneumatic test pressures, UCS-66.
• Week 4: API RP 571 mechanisms listed in the BOK.
• Week 5: API RP 572, RP 576 and RP 578.
• Week 6: API RP 577 and ASME IX (WPS/PQR review); ASME V articles in the BOK.
• Week 7: ASME PCC-2 items in the BOK; mixed practice questions, closed-book first.
• Week 8: Timed full-length practice (closed then open book), review weak areas.

Study Materials

• The referenced documents themselves, in the editions on the effectivity sheet (buy or borrow licensed copies)
• API's published BOK and sample questions where available
• Free practice sets such as our API 510 practice questions
• Third-party prep courses exist; choose one that teaches to the current effectivity sheet

Test Day Tips and Strategy

Time Management

• Closed-book part: answer the recall questions quickly, flag calculations and return to them.
• Open-book part: know where things are in each document so you search rather than read; practice with electronic copies, because that is how references are provided.
• Final pass: check calculations for units and for whether the question asks for t required, t actual or remaining life.

Question Analysis Strategy

• Identify which document the question comes from before answering
• Watch for "lesser of" and "whichever is less" wording in interval questions
• Common errors: using design thickness instead of required thickness; mixing short-term and long-term rates; forgetting the 2-year rule when remaining life is under 4 years

Frequently Asked Questions (FAQ)

Q1: How many hours should I study to pass the API 510 exam?

A: Most candidates plan roughly 80-150 hours, more if ASME VIII calculations are new to you. There is no official figure.

Q2: Can I use a calculator during the exam?

A: An on-screen calculator is provided in the Prometric testing software. Check the current API candidate guidance for any rules on personal calculators.

Q3: What score do I need to pass?

A: API uses a scaled passing score; it does not publish a fixed percentage. Your report shows a scaled score.

Q4: Should I take a prep course?

A: It is optional. Experienced inspectors often self-study with the referenced codes; others prefer a course. Atlantis NDT does not offer API exam prep.

Q5: What if I fail the exam?

A: Submit a reschedule/retest application for a later window and pay the retest fee; check api.org for current limits on attempts per application.

Q6: Are there any shortcuts for difficult topics?

A: Build one summary sheet of every number in API 510 (intervals, test pressures, temperatures) and one sheet of formulas; drill them daily.

Q7: What's the best way to prepare for calculation questions?

A: Work every formula listed in the BOK from the source documents, with units, until you can do them closed-book.

Q8: Do I need to memorize ASME Section VIII tables?

A: No. Tables and lengthy references are for the open-book part, where the documents are provided on screen. Formulas and concepts listed in the BOK should be known for the closed-book part.

Q9: How are exam results reported?

A: Prometric emails a scaled-score report (typically within 24 hours); API uploads final results to the ICP portal and issues certificates once the application has no deficiencies.

Q10: Is the API 510 exam the same difficulty as API 570 and 653?

A: All three use the same 170-question, closed-plus-open-book format, but the referenced codes differ (ASME B31.3 for 570, API 650/653 for 653). Difficulty depends on your background.

Conclusion

Study from the current BOK and effectivity sheet, master the API 510 interval and remaining-life calculations and the ASME VIII formulas, and practice searching the open-book references. For the code itself, read our API 510 code guide; for eligibility and recertification see the API 510 certification page.