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American Petroleum Institute (API) Individual Certification Programs

API 571 Corrosion and Materials Certification

The credential for people who know how refinery equipment fails — and how to spot, prevent and inspect for every damage mechanism.

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Inspecting vessels? API 510 Pressure Vessel Inspector → · Inspecting piping? API 570 Piping Inspector → · Next step: API 580 Risk Based Inspection →

Questions110 multiple-choice (100 scored, 10 unscored pretest)
Time3 hours 15 minutes, one section
Open book?No — closed-book, and no references are shown on screen
WhereAt a Prometric test center or by Prometric remote proctoring, inside one of three 3-week windows a year
Fee$380 API members · $440 non-members (2026); $390 · $450 (2027)
Who sits itCurrent API 510, 570 or 653 holders qualify automatically; otherwise a degree or diploma plus 1–5 years of petrochemical industry experience within the last 10 years
PassingScaled score 400 on a 200–500 scale; Prometric emails results within 24 hours

About the exam

API 571 certifies inspectors, engineers and corrosion professionals who understand the damage mechanisms that affect fixed equipment in refineries and petrochemical plants. It shows you can name a mechanism from its conditions or appearance and know which materials it attacks. You also know the critical factors that drive it, the units where it shows up, and how to prevent it and inspect for it.

The whole exam is closed-book. API's Body of Knowledge tests RP 571 terms and definitions and every damage mechanism through eight facets: description, affected materials, critical factors, affected units or equipment, appearance or morphology, prevention and mitigation, and inspection and monitoring. Expect mostly recognition and judgment questions, with only a few simple calculations — which mechanism, which material is most susceptible, which NDE method will find it, what stops it.

Our practice follows the single publication in API's Body of Knowledge: API RP 571, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry, 3rd edition (March 2020). It covers all 67 mechanisms, grouped by family: mechanical and metallurgical damage, metal loss, high-temperature corrosion, environment-assisted cracking and refining-specific corrosion.

How we track your progress

Every blueprint domain moves through five levels as you study:

  1. Not startedNo questions answered in this domain yet.
  2. Getting startedFirst questions answered — not enough yet to judge.
  3. DevelopingAt least 5 answered and 50% or better on your recent questions.
  4. ProficientAt least 15 answered and 70% or better on your recent questions.
  5. Exam readyAt least 25 answered, 80% or better recently, and holding up on hard questions.

The exam blueprint

API 571 Body of Knowledge (API RP 571, 3rd edition, March 2020) for the 2026–2027 exam windows — 110 items (100 scored, 10 pretest), closed-book, across 7 areas covering RP 571 terms and all 67 damage mechanisms; weights are QuizMe estimates. Tap a domain to see its topics.

1 Terms, definitions and damage fundamentals about 7% (est.) of the exam
RP 571 terms, definitions and acronymsHow each mechanism is described: the eight BOK facetsCorrosion vs cracking vs metallurgical damageIntergranular vs transgranular crackingAffected units and process flow diagrams (RP 571 Section 4)Related mechanisms and how they are told apart

16 practice questions in this domain so far

2 Mechanical and metallurgical damage about 18% (est.) of the exam
Brittle fracture and strain aging885°F, sigma phase and temper embrittlementCreep, stress rupture and short-term overheatingGraphitization and spheroidizationMechanical, vibration-induced and thermal fatigueThermal shock and refractory degradationErosion/erosion-corrosion and cavitationDissimilar metal weld and stress relaxation crackingGaseous oxygen-enhanced ignition and combustion

40 practice questions in this domain so far

3 Uniform and localized metal loss about 18% (est.) of the exam
Atmospheric corrosion and corrosion under insulationCooling water, boiler water and steam condensate corrosionCO2 corrosion and oxygenated process waterGalvanic and concentration cell corrosionMicrobiologically influenced corrosionSoil corrosion and brine corrosionDealloying and graphitic corrosion of cast ironFlue-gas dew-point corrosionCaustic corrosion

40 practice questions in this domain so far

4 High-temperature corrosion about 15% (est.) of the exam
Sulfidation and the low-silicon carbon steel problemHigh-temperature H2/H2S corrosionHigh-temperature hydrogen attack (HTHA)Oxidation and fuel ash corrosionCarburization, decarburization and metal dustingNitriding

32 practice questions in this domain so far

5 Environment-assisted cracking about 18% (est.) of the exam
Wet H2S damage: blistering, HIC, SOHIC and SSCAmine and carbonate stress corrosion crackingCaustic stress corrosion crackingChloride stress corrosion crackingPolythionic acid stress corrosion crackingAmmonia and ethanol stress corrosion crackingHydrogen embrittlement and hydrogen stress cracking in HFCorrosion fatigueLiquid metal embrittlement and HF SCC of nickel alloys

40 practice questions in this domain so far

6 Refining and process-specific corrosion about 13% (est.) of the exam
Amine corrosionAmmonium bisulfide corrosionAmmonium chloride and amine hydrochloride corrosionHydrochloric acid corrosionNaphthenic acid corrosionSour water corrosion (acidic)Sulfuric, hydrofluoric and phosphoric acid corrosionPhenol and aqueous organic acid corrosionTitanium hydriding

28 practice questions in this domain so far

7 Materials, inspection and mitigation about 11% (est.) of the exam
Choosing the NDE method that finds each damage typePWHT, hardness control and other weld-related mitigationAlloy upgrades and material selectionProcess controls: wash water, inhibitors and neutralizersOperating limits and temperature monitoringPMI and material verificationCoatings, cladding and cathodic protection

24 practice questions in this domain so far

What you get when you access this exam

Free with your QuizMe account.

Damage mechanism questions aligned to the Body of Knowledge

Every question is tagged to one of 7 API 571 areas and its topics, from wet H2S and HTHA to CUI, sulfidation and naphthenic acid. Questions cover all eight facets the exam tests: materials, critical factors, units, appearance, prevention and inspection.

Exam-critical hints

Reveal the concept that unlocks the question: the critical factor, the tell-tale appearance, the material that resists. Every answer comes with a full rationale that explains why the look-alike mechanisms are wrong.

Adaptive testing

Questions steer toward your weakest areas, weighted by our estimate of how much each counts on the real exam, and get harder as you get stronger.

Timed practice exams

Full-length exams at the real pace — 110 questions in 3 hours 15 minutes — with a live pacing indicator and a full review.

Flashcards, case simulations and guides

100 flashcards for mechanisms, materials, temperature ranges and NDE choices, and 6 failure-analysis cases where a unit's conditions, findings and mitigation unfold step by step. Interactive illustrated guides let you explore process units hotspot by hotspot.

Progress for every blueprint area

Each area moves from Not started to Getting started, Developing, Proficient and Exam ready — so you know exactly what to study next.

Test at home or at a center

Apply through API's ICP portal by the deadline for your chosen window. Once approved, you get an authorization to schedule your API 571 exam with Prometric on any open day inside that window — at a test center or by remote proctoring. The application deadline for the December 4–25, 2026 window (October 2, 2026) has passed; the next windows are April 9–30, 2027 (apply by February 4, 2027), August 6–27, 2027 (apply by June 4, 2027) and December 3–24, 2027 (apply by September 30, 2027).

At a Prometric test center

  • API 571 is a single closed-book section — no code books, papers or notes in the room, and nothing is shown on screen.
  • Bring government-issued photo ID; the name must match your API account exactly.
  • A calculator and scratch paper are available at the center.
  • Phones, watches, bags and notes go in a locker.

Remote proctoring from home or office

  • API 571 is one of the ICP exams API offers by Prometric remote proctoring (510, 570 and 653 are not).
  • Run Prometric's system check on the computer you'll use well before exam day, and test your webcam, microphone and connection.
  • Plan a quiet, private room with a clear desk — the proctor checks the room and watches the whole session.
  • Your application is valid for 12 months from the first window you request; moving to a different window means a new application and fees.

Exam-day game plan

How to walk in ready — and how to pace 110 questions in 3.25 hours.

Pacing checkpoints

Hit these and you finish with time to revisit your flagged questions. Our timed practice exams run at this same pace.

28questions0:50
55questions1:38
83questions2:27
110questions3:15

The week before

  • Take one full-length timed practice exam 3–5 days out, then rest.
  • Spend your last sessions on the families you mix up — the cracking mechanisms near welds, and the high-temperature mechanisms — plus anything still below Proficient.
  • For each mechanism, say the eight facets out loud from memory: what it is, materials, critical factors, units, appearance, prevention, inspection, related mechanisms.
  • Walk through the RP 571 process-unit diagrams and name the mechanisms you'd expect at each location.
  • If you're testing remotely, run Prometric's system check again and set up your room.

Exam morning

  • Eat a real breakfast; the exam is 3 hours 15 minutes in one sitting.
  • At a test center, arrive 30 minutes early with ID that matches your API account; remotely, log in early for the check-in.
  • Use the restroom right before you start.

During the exam

  • There are no references, so trust what you know — read every stem for its clues: material, temperature, environment, location and appearance.
  • Rule out look-alikes on purpose: amine vs carbonate vs caustic SCC, HTHA vs H2/H2S corrosion, thermal vs mechanical vs corrosion fatigue.
  • Watch for MOST, LEAST, BEST and NOT — they decide many damage-mechanism questions.
  • Keep to roughly 28 questions every 50 minutes and flag anything slow to come back to.
  • Answer every question — there's no penalty for guessing.
  • 10 questions are unscored pretest items you can't identify.

Keep your head

  • A few nerves sharpen focus. If you freeze, take three slow breaths and reread the stem.
  • You're measured against a fixed standard, not other test-takers.
  • Change an answer only when you find a real reason in the stem.

Keeping your API 571 certification

  • Certification lasts 3 years.
  • Recertify by applying through the ICP portal — no exam, quiz or CPD hours are required, and API says employment verification is not required at this time.
  • Apply from 90 days before your expiration date; recertification fees are $265 for members and $320 for non-members in 2026 ($270 and $330 in 2027).
  • A 90-day grace period after expiry carries late fees.
  • Miss the grace period and the certification lapses — you need a new application and must pass the full exam again.

Official sources and further reading

Ready to start?

220 questions and scenarios across the blueprint — and growing.

Enroll free

API 571 and API 580 are certification programs of the American Petroleum Institute. QuizMe and thinQtank Learning are not affiliated with or endorsed by API or Prometric. API recommended practices are copyrighted — candidates need their own copies of the edition named in API's Body of Knowledge, and our practice items are original, not recalled exam questions. Exam details are summarized from API's published Body of Knowledge, program pages and schedules; fees, dates and editions change — always confirm at api.org before you apply. Our domain weights are estimates; API publishes no percentages.