- The written exam is 92 multiple-choice questions, including select-all-that-apply items, delivered through Pearson VUE under exam code NACE-OCAT-001.
- General Knowledge is the largest domain at 24-28%, followed by Evaluate platform corrosion system at 17-22%.
- Safety, Types of oil platforms/rigs & equipment, and the BSEE/A-B-C grading domain are each 4% or less of the blueprint.
- The 2017 O-CAT course manual appears electronically inside the exam; personal reference books are not authorized.
What This Credential Is (and Is Not)
The Offshore Corrosion Assessment Technician (O-CAT) is a credential from the Association for Materials Protection and Performance (AMPP). It is aimed at people who assess corrosion conditions on offshore oil and gas platforms. It is not S-CAT, and it is not a coating-inspector certification, so do not mix study materials from those programs into your review. If you are still orienting yourself, start with What Is O-CAT? and What Does O-CAT Stand For?, then come back to this page as a quick-reference sheet.
This cheat sheet condenses the facts you are most likely to need in the final stretch: format, blueprint ranges, fee mechanics, retake waits, and renewal rules. For deeper explanations of any single item, the linked guides go further, including the O-CAT study guide and the complete domains guide.
Written Exam Snapshot
The written component is a computer-based test. Memorize the numbers in the table below, because they shape how you pace yourself.
| Item | What to Know |
|---|---|
| Delivery | Pearson VUE computer-based test |
| Exam code | NACE-OCAT-001 |
| Question count | 92 multiple-choice questions, including select-all-that-apply items |
| Appointment length | 150 minutes of seat time |
| Built into that time | A four-minute nondisclosure agreement and a six-minute tutorial |
| Reference material | 2017 O-CAT course manual supplied electronically inside the exam |
| Result reporting | Pass/fail; numerical passing score not published |
| Practical component | Separate field assessment on the final day of the five-day course |
Reading the time budget correctly
The 150 minutes is appointment time, not question-answering time. After the NDA and tutorial, you have less than that for the 92 items. A reasonable habit is to treat the exam as a pacing exercise: answer what you know quickly, flag what requires the manual, and return to flagged items with whatever time remains.
Select-all-that-apply items
Some questions ask you to choose every correct option rather than a single best answer. These reward complete knowledge of a topic, not partial recognition. When you review a subject, practice listing all the factors, methods, or conditions that apply rather than recalling one favorite.
The built-in manual is a tool, not a plan
The 2017 course manual is available electronically during the written exam. That helps with lookups, but it does not authorize personal reference books, and searching a long document costs minutes you may not have. Know the manual's structure well enough to find a definition or procedure fast, and rely on memory for the rest. For a sense of how demanding candidates find the exam overall, see How Hard Is the O-CAT Exam?
The practical assessment
A practical field assessment takes place on the final day of the course. Its timing is separate from the written appointment, so do not assume any particular duration from the written exam's 150 minutes. Initial access to both the written and practical examinations is included in course registration.
The Eight Domains and Their Weight Ranges
AMPP publishes the written exam objectives as eight domains with percentage ranges rather than fixed percentages. Keep them as ranges. They are official blueprint figures, and the ranges do not sum to a single clean allocation you should try to reverse-engineer.
| Domain | Published Range |
|---|---|
| Domain 8: General Knowledge | 24-28% |
| Domain 1: Evaluate platform corrosion system | 17-22% |
| Domain 2: Testing Methods | 16-21% |
| Domain 4: Systems and requirements to collect information on platforms | 12-17% |
| Domain 6: Primary corrosion protection systems | 12-17% |
| Domain 3: Safety | 1-4% |
| Domain 7: Role of BSEE and A-B-C- grading system for reporting | 1-4% |
| Domain 5: Types of oil platforms/rigs & equipment | 1-3% |
Key Takeaway
Five domains carry the bulk of the exam: General Knowledge, Evaluate platform corrosion system, Testing Methods, data-collection systems, and primary corrosion protection. The three small domains (Safety, platform types, BSEE/A-B-C grading) are worth a focused pass but should not consume your study calendar.
High-Value Topics by Domain
The domain names tell you the shape of the work: you are expected to evaluate an offshore corrosion system, choose and understand testing methods, gather information in the right way, and know the protection systems that keep platforms from degrading. The boxes below frame what to be able to explain in each area.
Domain 8: General Knowledge (24-28%)
The largest domain, so shortcuts here are expensive. Expect foundational corrosion concepts and terminology that support everything else on the exam.
- Be fluent in the vocabulary used throughout the course manual, since other domains assume it.
- Know why corrosion occurs in marine and offshore environments and how conditions change its severity.
- Practice distinguishing similar terms, because select-all items often hinge on precise definitions.
Domain 1: Evaluate platform corrosion system (17-22%)
This is the assessment core of the credential. Think like the technician on the platform deciding whether a system is performing.
- Be able to walk through how a corrosion system is judged as functioning or deficient.
- Connect observed conditions to likely causes and to what should be documented.
- Link evaluation findings to the reporting framework covered in Domain 7.
Domain 2: Testing Methods (16-21%)
Know what each method measures, why you would choose it, and what its limitations are.
- Study methods as a decision set: which test answers which question.
- Expect scenario items that ask what you would do or use in a given situation.
- Use the electronic manual to confirm procedure details you cannot recall.
Domain 4: Systems and requirements to collect information on platforms (12-17%)
Assessment is only as good as the data behind it. This domain covers the systems and requirements used to gather information on a platform.
- Know what information must be collected and why it matters to the evaluation.
- Understand how records and documentation support later corrosion decisions.
Domain 6: Primary corrosion protection systems (12-17%)
The protection side of the exam. Be able to describe the primary systems used to control corrosion on offshore structures and how you tell whether they are doing their job.
- Pair each protection system with the symptoms that indicate it is failing.
- Be ready to compare systems, since comparison items are natural select-all material.
The three small domains
Safety (1-4%), Types of oil platforms/rigs & equipment (1-3%), and Role of BSEE and A-B-C- grading system for reporting (1-4%) are light on weight but easy points if you have seen the material.
- For BSEE and the A-B-C- grading system, know the agency's role and how the grading scheme is used for reporting.
- For platform types, be able to recognize the major categories of platforms and rigs and their key equipment.
- For Safety, review the basic offshore hazard-awareness material from the course.
For a domain-by-domain walkthrough with more depth, use the O-CAT exam domains guide, and check your recall under timed conditions with the practice questions at the main O-CAT practice test site.
Fees, Retakes and Registration Mechanics
The money and scheduling rules are where candidates most often get confused, so read this section carefully.
- Initial access is bundled. Initial written and practical examination access is included in course registration.
- USD 275 is narrow. The published USD 275 fee applies to written CBT exam-only or retake access. It is not the price of the full course or the whole certification package.
- Verify the charge. The fee document shows conflicting revision dates (July 2026 in extracted text versus June 2024 in its rendered revision date), though both show USD 275. Confirm the current amount at checkout.
- First retake wait. The Examinee User Guide specifies a 30-day wait before the first written CBT retake.
- Later retake waits. Subsequent retakes require a four-month wait.
Eligibility and Renewal at a Glance
| Stage | Requirement |
|---|---|
| Course admission | No prerequisites |
| Experience for certification | 1.5 years of applicable experience |
| Training | Successful completion of the five-day O-CAT course |
| Ethics | Ethics training or an approved equivalent |
| Application | An approved application |
| Examinations | Both the written exam and the practical assessment |
| Validity | Three years |
| Renewal work history | 1.5 years of relevant work during the cycle |
| Renewal PDHs | 24 PDHs, eight per year, across at least two categories |
| Renewal extras | Ethics, an application and fees |
Note the distinction between taking the course and being certified. Anyone can be admitted to the course, but certification itself requires the experience, training, ethics, application and both examinations. The details live in O-CAT requirements, and the broader overview is in O-CAT certification.
Which Domain to Study When
Generic study methods matter less than sequencing. Because the domains build on one another, order your review so that foundations come first and the small domains fill gaps at the end.
General Knowledge first
- It is the largest domain and supplies the vocabulary for everything else.
- Get comfortable navigating the course manual's structure.
Evaluate platform corrosion system and Testing Methods
- These two together carry a large share of the blueprint.
- Practice linking a finding to the method used to confirm it.
Information collection and primary protection systems
- Cover the data-gathering requirements and the protection systems.
- Drill select-all-that-apply items on comparing systems.
Small domains and full review
- Sweep Safety, platform types and BSEE/A-B-C- grading.
- Finish with timed mixed sets and revisit weak areas.
If you want a fuller plan, the O-CAT study guide expands on pacing and practice strategy.
Exam-Day Facts Worth Memorizing
Mental checklist
- The exam is 92 questions, and some are select-all-that-apply.
- Your 150-minute appointment already includes the NDA and tutorial.
- The 2017 manual is available electronically, but personal reference books are not authorized.
- Results come back as pass/fail with no published numerical cut score.
- If you do not pass, the first written retake is 30 days out, then four months for later ones.
On the passing score
Because AMPP does not publish a numerical passing score, any specific number you see quoted elsewhere is not an official figure. Likewise, no pass rate is asserted here. See O-CAT passing score and O-CAT pass rate for how to interpret what is and is not known.
Why the credential matters
The certification is relevant to people working in offshore corrosion assessment, so employers in that space are the natural audience for it. For career context, see O-CAT jobs and whether the certification is worth it. When you are ready to test your recall against exam-style questions, head to the O-CAT practice test.
Frequently Asked Questions
The written exam has 92 multiple-choice questions, including select-all-that-apply items. It is delivered by Pearson VUE under exam code NACE-OCAT-001, and the 150-minute appointment includes a four-minute nondisclosure agreement and a six-minute tutorial.
General Knowledge is the largest domain at 24-28%. Evaluate platform corrosion system (17-22%) and Testing Methods (16-21%) follow. These are published ranges, not fixed percentages.
No. The 2017 O-CAT course manual is supplied electronically inside the written exam, but that does not authorize personal reference books. Learn the manual's layout so lookups are quick.
It is the published fee for written CBT exam-only or retake access, not the full course or certification package. Initial written and practical exam access is included in course registration. The fee document shows conflicting revision dates, so confirm the current charge at checkout.
The Examinee User Guide specifies a 30-day wait for the first written CBT retake and four months for subsequent retakes.