API 936 Exam Domains 2026: Complete Guide to All 4 Content Areas

How the API 936 Body of Knowledge Is Organized

Refractory Personnel Certification (API 936) is built around a Body of Knowledge (BOK) published by the American Petroleum Institute's Individual Certification Programs group. The current BOK and its associated reference set are effective from April 2025 through December 2026, which means anyone preparing for an exam in this window should be studying against the fifth edition of API Standard 936 (March 2024), not an older revision. If you're still confirming what this credential covers before committing to prep materials, What Is API 936? is a good starting point.

Instead of testing candidates on isolated trivia, the BOK groups everything a refractory professional needs to know into four content areas. Each domain reflects a phase of real refractory work: understanding who does what on a job, verifying materials in the lab before they're installed, applying correct material and installation practices, and inspecting the finished work for quality. Knowing the boundaries of each domain lets you target your review instead of re-reading the entire API 936 standard cover to cover.

Domain 1: Roles and Responsibilities

This domain establishes the organizational and procedural context of refractory work: who is accountable for what during design, procurement, installation, and inspection of refractory linings. It is the domain most likely to include questions about documentation flow, communication between owner, contractor, and inspector, and the general responsibilities defined in API Standard 936 itself.

Because this domain is conceptual rather than numerical, it rewards careful reading of the standard's introductory and scope sections rather than memorizing formulas. If you're unsure how much depth this section demands relative to the others, the API 936 Study Guide walks through how to allocate reading time across the standard.

Domain 2: Laboratory Testing Procedures

This is where the ASTM references in the required reading list carry the most weight. Refractory materials must be validated in a lab before and during installation, and this domain tests your familiarity with the standardized test methods used to characterize them.

Because these ASTM standards are dense and use specific terminology, this domain is one where flashcard-style repetition of method names, purposes, and what each test measures pays off disproportionately. Confusing one ASTM number for another is a common, avoidable error on exam day.

Domain 3: Materials and Installation Requirements

This domain is the practical core of the certification: what refractory materials are, how they're classified, and how they must be installed to meet the requirements of API 936 and related guidance in API 975 and API 976. It draws on real installation scenarios, so expect questions framed around field situations rather than pure definitions.

Because this domain spans multiple documents, it's worth cross-referencing terminology between API 936, API 975, and API 976 rather than studying each in isolation. If a term appears differently worded across two references, the exam may test whether you understand the underlying concept, not just one document's phrasing.

Domain 4: Installation Inspection and Quality Control

The final domain shifts from "how to install" to "how to verify installation was done correctly." It covers the inspection checkpoints, acceptance criteria, and quality control practices that determine whether a refractory lining is fit for service before startup.

Domains 3 and 4 overlap conceptually since inspection criteria only make sense once you understand the installation requirements they're checking against. Studying them back to back, rather than as separate silos, tends to reduce confusion on scenario-based questions.

How the Exam Actually Tests These Domains

The API 936 exam consists of 85 total questions, of which 75 are scored and 10 are unscored pretest items you cannot identify during the test. You have 195 minutes to complete the exam, which is closed-book: no personal references, notes, or the standards themselves are permitted at the testing station. Test centers provide a calculator and scratch paper; if you sit for the exam remotely through ProProctor, you'll be given digital equivalents and must complete a system-readiness check beforehand.

Format-wise, the exam is multiple choice, though API has stated it is gradually introducing alternative item types across its Individual Certification Program exams over time. A passing result requires a scaled score of 400 on a 200-500 point scale, meaning your result is not a simple raw percentage of questions answered correctly. For a full breakdown of how scaled scoring works, see API 936 Passing Score: Exactly What You Need to Pass.

According to API's own statistics for the December 2025 administration (reported April 30, 2026), 131 of 181 candidates passed, a 72.4% pass rate. That figure reflects candidates across all four domains combined, not a domain-by-domain breakdown. For more context on what that number means for your own preparation, read API 936 Pass Rate 2026: What the Data Shows and How Hard Is the API 936 Exam? Complete Difficulty Guide.

Sequencing Your Study Across All Four Domains

There's no requirement to take a prep course before sitting for API 936, and candidates can apply regardless of how much petroleum or petrochemical experience they already have. That flexibility means your study plan needs to fill in whatever gaps your background leaves, domain by domain, rather than assuming prior field exposure covers you. A structured pass through all four domains, in the order they build on each other, tends to work better than jumping around.

This sequencing isn't a generic template; it follows the logical dependency between domains, since inspection criteria in Domain 4 only make sense once installation requirements from Domain 3 are solid. If you want a condensed version of this plan alongside a fuller explanation of pacing, the API 936 Study Guide 2026 covers it in more depth, and running practice questions on our practice test platform can help confirm which domains still need work before exam day.

Required References Mapped to Each Domain

Knowing which document to open for which domain saves time during review. Here's how the required references line up against the four content areas.

Because API 936 itself touches three of the four domains, it's worth reading in full at least once before narrowing into domain-specific sections during review. Candidates who skip straight to the ASTM standards without first understanding how API 936 frames roles and inspection often find Domain 1 and Domain 4 questions harder than expected.

Frequently Asked Questions