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Question 1

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Which ASTM test method is used to measure the abrasion resistance of refractory materials at room temperature?

ASTM C113

ASTM C133

ASTM C181

ASTM C704

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2026 Statistics

Key Facts: API 936 Exam

85 Qs

Exam Questions

75 scored + 10 pretest

3 hr 15 min

Time Limit

Closed-book

~70%

Passing Score

Set scaled score

$450-$625

Exam Fee

Member / nonmember

3 years

Validity

Recertification required

API 936

Primary Reference

Dec 2023 BOK

The API 936 exam has 85 multiple-choice questions (75 scored plus 10 unscored pretest items) with a 3 hour 15 minute time limit in closed-book format. You must achieve a set passing scaled score, benchmarked to approximately 70% correct. The exam fee is $450 for API members and $625 for nonmembers. Testing is offered during four approximately 3-week windows per year at Prometric centers, with remote proctoring available. The current Body of Knowledge is the December 2023 edition based on API Standard 936, API TR 978/979/980, and ASTM C113/C133/C181/C704.

Sample API 936 Practice Questions

Try these sample questions to test your API 936 exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which ASTM test method is used to measure the abrasion resistance of refractory materials at room temperature?

A.ASTM C113

B.ASTM C133

C.ASTM C181

D.ASTM C704

Explanation: ASTM C704 is the Standard Test Method for Abrasion Resistance of Refractory Materials at Room Temperature. It measures volume loss in cubic centimeters when 1000 grams of silicon carbide grit is blasted at the specimen surface under controlled conditions. Lower volume loss indicates higher abrasion resistance. Exam tip: C704 is one of the four ASTM methods explicitly listed in the API 936 Body of Knowledge and is the most frequently tested on the exam because FCC and regenerator refractories rely on abrasion resistance.

2According to ASTM C133, which two mechanical properties are measured on refractory specimens?

A.Cold crushing strength and modulus of rupture

B.Abrasion resistance and thermal shock

C.Workability index and water content

D.Permanent linear change and density

Explanation: ASTM C133 is the Standard Test Methods for Cold Crushing Strength (CCS) and Modulus of Rupture (MOR) of Refractories. CCS is measured by compressing a cubic or cylindrical specimen until failure, while MOR is measured in three-point bending on a prismatic bar. Both tests are performed at room temperature on dried or fired specimens. Exam tip: CCS is typically the first mechanical acceptance criterion on refractory data sheets and is a common qualification metric under API 936 Section 6.

3ASTM C113 measures which property of refractory brick?

A.Reheat change (permanent linear change after heating)

B.Cold crushing strength

C.Modulus of elasticity

D.Thermal conductivity

Explanation: ASTM C113 is the Standard Test Method for Reheat Change of Refractory Brick. It measures the permanent linear change of a specimen after it has been heated to a specified temperature and cooled back to room temperature. This indicates whether a refractory will expand or shrink permanently in service. Exam tip: Reheat change is commonly reported as a percentage and is a key stability indicator for brick and shapes used in FCC and fired heater service.

4ASTM C181 is used to determine which property of plastic refractories?

A.Abrasion resistance

B.Workability index

C.Cold crushing strength

D.Bulk density

Explanation: ASTM C181 is the Standard Test Method for Workability Index of Fireclay and High-Alumina Plastic Refractories. The workability index is a measure of the consistency and formability of a plastic refractory mix and is determined using a standard impact device. It helps predict how easily the material can be rammed into place. Exam tip: C181 applies only to plastic (rammable) refractories, not to castables or gun mixes.

5In ASTM C704 abrasion testing, what mass of silicon carbide grit is used to abrade each specimen?

A.500 grams

B.750 grams

C.1000 grams

D.1500 grams

Explanation: ASTM C704 specifies 1000 grams of silicon carbide grit blasted at the specimen surface under controlled air pressure, nozzle distance, and angle. The result is reported as the volume loss in cubic centimeters, with lower values indicating better abrasion resistance. Exam tip: The 1000-gram value is frequently tested — it is the single constant that defines the test and candidates should commit it to memory.

6What is the reported result of an ASTM C704 abrasion test on a refractory specimen?

A.Mass loss in grams

B.Volume loss in cubic centimeters

C.Surface roughness in micrometers

D.Percent weight loss

Explanation: ASTM C704 reports abrasion resistance as the volume loss in cubic centimeters, calculated from the mass loss divided by the bulk density of the specimen. Reporting volume instead of mass normalizes results across materials with different densities so that abrasion behavior can be compared directly. Exam tip: A typical FCC abrasion-resistant castable target is 6 cubic centimeters or less by ASTM C704.

7How many specimens are typically required per sample for ASTM C704 abrasion testing to report an average result?

A.1

B.3

C.5

D.10

Explanation: ASTM C704 generally requires five specimens per sample. Reporting the average of five individual volume-loss values reduces the influence of localized hard spots or voids in any one specimen and gives a more reliable abrasion value. Exam tip: Five specimens is a commonly tested numerical detail — remember it along with the 1000 gram grit charge.

8Which ASTM test method would an inspector cite to verify the modulus of rupture of a refractory castable specimen?

A.ASTM C704

B.ASTM C181

C.ASTM C133

D.ASTM C113

Explanation: Modulus of rupture (MOR), a three-point bending test, is specified together with cold crushing strength (CCS) in ASTM C133. The test uses a prismatic bar supported on two lower knives with load applied at the center until fracture. Exam tip: CCS and MOR are both in C133 — do not confuse MOR with abrasion (C704) or reheat change (C113).

9Which of the following materials is classified as a shaped refractory?

A.Firebrick and fused cast shapes

B.Gunning mix

C.Castable refractory

D.Ceramic fiber blanket

Explanation: Shaped refractories are pre-formed products such as firebricks, tiles, and fused cast shapes that are manufactured to specific dimensions and fired before shipment. Unshaped refractories include castables, gunning mixes, plastics, and ramming mixes that are formed in place during installation. Exam tip: The shaped versus unshaped distinction is a common definitional question in the Laboratory Testing and Installation categories of the API 936 BOK.

10In API 936 terminology, what does PLC typically refer to on a refractory data sheet?

A.Programmable logic controller

B.Permanent linear change

C.Pre-cast liner component

D.Primary lining class

Explanation: On a refractory data sheet, PLC stands for Permanent Linear Change — the irreversible dimensional change after heating and cooling, typically measured per ASTM C113. It is reported as a percentage and may be positive (expansion) or negative (shrinkage). Exam tip: A refractory with large negative PLC can develop shrinkage cracks in service; this is why PLC is an important qualification parameter in API 936 material acceptance.

About the API 936 Exam

The API 936 Refractory Personnel certification is administered by the American Petroleum Institute Individual Certification Programs (ICP) and qualifies inspectors to oversee the installation, inspection, testing, and repair of monolithic refractory linings used in refineries and petrochemical facilities. The closed-book, computer-based exam is based on API Standard 936 (Refractory Installation Quality Control Guidelines) together with API TR 978, 979, and 980 and four ASTM test methods (C113, C133, C181, C704). Certification is widely required for inspectors working on FCC units, sulfur recovery units, reformers, fired heaters, and other refractory-lined equipment. The credential is valid for three years and is recognized globally in the refining and petrochemical industries.

Questions

85 scored questions

Time Limit

3 hours 15 minutes

Passing Score

Set passing scaled score

Exam Fee

$450 member / $625 nonmember (API ICP via Prometric)

API 936 Exam Content Outline

20%

Laboratory Testing Procedures

ASTM C113 reheat change, C133 CCS/MOR, C181 workability index, C704 abrasion, density, PLC, specimen preparation, and acceptance criteria

20%

Applicator and Material Qualification

Gunning, casting, ramming, hand packing qualification; test panels and mockups; optimal water content; mixing; environmental controls

25%

Installation

Anchor welding and layout, surface preparation, gunite variables, flash set, vibration casting, production sampling, and ramming procedures

20%

Inspection

Visual and NDT methods, hammer and sonic testing, radiography, core sampling, portable abrasion, acceptance criteria, and repair procedures

15%

Post-Installation

Dryout requirements, membrane curing, heatup and cooldown schedules, temperature probe placement, and heating rates for refractory classes

How to Pass the API 936 Exam

What You Need to Know

Passing score: Set passing scaled score
Exam length: 85 questions
Time limit: 3 hours 15 minutes
Exam fee: $450 member / $625 nonmember

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

API 936 Study Tips from Top Performers

1Memorize the four ASTM test methods cold: C113-14 reheat change (permanent linear change after heat exposure), C133-97 cold crushing strength and modulus of rupture (specimen dimensions and load rate), C181-11 workability index for plastic refractories, and C704-15 abrasion resistance (measured as volume loss in cubic centimeters from 1000 grams of silicon carbide grit)

2Know the anchor layout rules from API 936 Section 8 — typical V-anchor or hex-mesh spacing is roughly 1.5 to 2 times the lining thickness, anchor height is typically two-thirds of the lining thickness, and anchor welds must be visually inspected and magnetic-particle or dye-penetrant tested per the job specification

3Master the gunning quality variables per API 936 Section 8 and API TR 980 — air pressure at the nozzle (commonly 60 to 90 psi), water pressure (above air pressure), nozzle distance from the substrate (about 3 feet or 1 meter, perpendicular impact), and rebound control (rebound should not be reincorporated into the in-place lining)

4Drill heatup and cooldown schedules from API 936 Annex A and API TR 980 — typical castable dryout uses a ramp of about 50 degrees F per hour with holds at 250 degrees F, 500 degrees F, and 1000 degrees F; know which temperature holds are mandatory and why (free water, chemically combined water, and ceramic bond formation)

5For inspection, memorize the hammer testing logic (dull or drummy sound indicates delamination or voids), acceptance crack-width criteria in API 936 Section 9 (typically 1/16 inch maximum for dense castables with repair beyond that), and the use of portable abrasion testing per ASTM C704 as a field verification tool for as-installed quality

Frequently Asked Questions

What score do I need to pass the API 936 exam?

API uses a set scaled score for API 936, benchmarked to roughly 70 percent correct on the 75 scored questions (the 10 pretest items are unscored). API does not publish a raw-percent cutoff, and candidates only receive a pass or fail result — no numerical score is shown to passing candidates. Failing candidates receive a diagnostic report showing performance by BOK category (Laboratory Testing, Applicator and Material Qualification, Installation, Inspection, Post-Installation) so they can focus their restudy.

Is the API 936 exam open-book or closed-book?

API 936 is strictly closed-book. You cannot bring API Standard 936, ASTM test methods, calculators, notes, or any reference material into the Prometric testing room. All content must be memorized — this is a major difference from API 510, 570, and 653, which are partially open-book. With 75 scored questions in 3 hours 15 minutes, you have about 2.6 minutes per question, which means recognition and recall from prior study must be strong.

How hard is the API 936 exam?

API 936 is considered advanced because it is closed-book and spans both laboratory testing detail (ASTM C704 abrasion, C133 CCS, C181 workability) and field installation variables (gunite rebound, flash set, anchor patterns, dryout rates). The hardest topics for most candidates are quantitative ASTM test parameters, heatup and cooldown rates by refractory class, and anchor welding/layout requirements per API 936 Annex A. Candidates with hands-on refractory installation or inspection experience have the highest pass rates.

Which references are used on the API 936 exam?

The December 2023 Body of Knowledge lists API Standard 936 (Refractory Installation Quality Control Guidelines) as the primary reference, along with API TR 978 (Manufacture, Properties, and Selection), API TR 979 (Applications of Refractory Lining Materials), and API TR 980 (Installation and Dryout). Four ASTM test methods are also on the exam: C113-14 (reheat change), C133-97 (CCS and MOR), C181-11 (workability index), and C704-15 (abrasion resistance). All these are closed-book — you must memorize the specifics.

What jobs can I get with API 936 certification?

API 936 is required or strongly preferred for refractory inspectors, refractory project specialists, turnaround inspectors, and third-party quality surveillance personnel working on FCC units, sulfur recovery units, reformers, fired heaters, and CO boilers in refineries and petrochemical plants. Typical salaries range from $85,000 to $150,000 depending on location, experience, and willingness to travel for turnarounds. Many refractory contractors and inspection firms require API 936 as a condition of field assignment on major turnarounds.

How do I prepare for the API 936 exam?

Start by obtaining API Standard 936, API TR 978, TR 979, TR 980, and the four ASTM test methods. Read API 936 cover-to-cover twice, paying close attention to Sections 6 (inspection), 7 (installation), 8 (mockups), 9 (testing), and the annexes on dryout schedules. Take a structured API 936 prep course, complete at least 300 practice questions, and build flashcards for ASTM test parameters and heatup rates. Plan on 80 to 140 hours over 8 to 16 weeks for most working inspectors.