Pass the API ICP Programs API-936 Questions and answers with ValidTests

PerAPI Std 936, friable materials are defined as:

“Friable: A term applied to a material that is easily reduced to a powdery or granular state by crushing or rubbing.”

—API Std 936, Section 3: Definitions​

This is a key property considered in refractory evaluation because friability can indicate material weakness after installation.

Therefore:

A (friable materials)is the correct and technically defined term.

The other terms refer to distinct classes of materials not defined this way.

In API 936, it is specified that as-installed specimens of gunned refractory linings are to be cut from the installation using adiamond saw. This ensures precision and avoids thermal or mechanical damage to the specimen, which could otherwise alter the properties being tested such as density or strength.

This practice is consistent with ASTM standards (e.g., ASTM C133, ASTM C704) referenced in API 936 for the preparation of physical specimens.

Applicator qualification testingis a term used in API 936 to describe the testing required to evaluate whether installation equipment and personnel can achieve the required physical properties (e.g., density, strength) in the final refractory. This testing often involves a mock-up or practice panel where variables like rebound, compaction, and finish are assessed.

The objective is to ensure:

Installation consistency across shifts or crews

Operator competence with specific materials

Adequate equipment settings (nozzles, air pressure, etc.)

Applicator qualification must be completed before production installation begins and is separate from material qualification or final as-installed testing.

API 936 establishes quality assurance testing frequencies based on usage, service condition, and criticality of application. Forerosion service refractory, which is subject to high-velocity particle impingement (e.g., in FCCU units), the standard testing frequency isone sample per 2 tons or less. This ensures that each significant quantity used in fabrication is represented by a test sample to verify compressive strength, density, and abrasion resistance.

Failure to meet this frequency may risk undetected variability in raw material batches or mixing inconsistencies.

The correct ASTM designation for testingcold crushing strength (CCS)of refractory materials isASTM C133. This test determines the load at which a sample fails under compressive stress and is essential for assessing the structural integrity of castable and formed refractories.

ASTM C113 relates to permanent linear change.

ASTM C704 is for abrasion resistance.

ASTM C417 is not related to CCS in this context.

When the owner does not provide explicit temperature criteria for mixing and placement, the refractory manufacturer’s instructions prevail:

“If not specified by the owner, the refractory manufacturer’s published recommendations shall be followed for temperature limits of both material and mixing water.”

— API TR 980, Section 4.5.2​

Thus, Option B is correct.

The term “production run” is defined by API 936 as follows:

“Production Run: The quantity of material manufactured using the same formulation in an uninterrupted manufacturing operation.”

— API Std 936, Section 3: Terms and Definitions​

This distinguishes it from a test sample (a subset), a pallet (a packaging unit), or a bag (a smaller containment unit). The production run forms the batch basis for qualification and traceability.

Per API Std 936 Section 6.3.2.1, qualification trials for castable refractories require strict control over water content. The variation must be within ±1.0% of the manufacturer’s recommended water addition to ensure consistency and reliability in performance.

"Acceptance of the test results from the cast sample trial shall be contingent on the mix water being within ±1.0 % of that recommended by the manufacturer."

— API Std 936, Section 6.3.2.1​

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For linings intended for erosive service, API 936 requires testing that includes specimens that experience real service wear simulation:

“For erosive service, bulk density shall be determined using the abrasion resistance test specimens and the linear change specimens.”

— API Std 936, Section 6.4.3​

Thus, both abrasion plates and linear change bars are used to evaluate density in erosion-sensitive applications.

API 936 requires a specific level of surface cleanliness before lining application:

“All surfaces to be lined shall be cleaned in accordance with SSPC-SP 7/NACE No. 4 (Brush-Off Blast Cleaning).”

— API Std 936, Section 5.3.2.1​

This brush-off blast cleaning ensures adequate bonding without aggressive surface treatment.

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