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

According to API Std 936, cold crushing strength tests for non-erosive service require:

“For non-erosive service, a minimum of two specimens per sample shall be tested for cold crushing strength.”

— API Std 936, Section 6.4.2, Cold Crushing Strength​

This ensures adequate verification of mechanical integrity without the more stringent criteria used for erosive applications. Therefore, Option B is correct.

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Hydrationrefers to the chemical reaction between water and cement components in refractory concretes (hydraulic bonded castables), resulting in the formation ofcalcium-aluminate hydrates, which are responsible for initial strength—known asgreen strength. This strength enables the lining to be demolded and eventually dried without mechanical failure.

Hydration is not related to final heat resistance or dryout; those come later during the firing or heat-up stages. It is distinct from setting in air-setting refractories or sintering in ceramic-bonded types.

TR 980 outlines curing and dryout best practices for monolithic refractories. For high-purity low-cement castables, gradual heat-up is necessary to avoid thermal shock and cracking:

“A minimum 24-hour air cure at ambient temperature should be followed by a controlled dryout ramp not exceeding 50°F (28°C) per hour up to 600°F (316°C).”

— TR 980, Section 6.4.2​

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According to API 936, thecontractoris responsible for submitting adetailed dryout procedure. This procedure must be reviewed and approved by the owner or the owner’s representative. While manufacturers may provide guidance, the contractor is accountable for ensuring the procedure aligns with project specifications, material requirements, and environmental conditions.

Theinspector’s responsibilities, as defined in API 936, include visual and mechanical inspection of installed linings.Hammer testingis one such non-destructive method used to detect delamination, voids, and rebound areas by listening for variations in sound. It is a practical method during and after installation.

Other tasks like providing compliance documentation or water testing are typically done by the contractor or laboratory personnel.

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.

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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According to API Std 936, when applying refractory via pneumatic gunning, the angle below the horizontal must be controlled to avoid rebound and poor bonding.

“For downward gunning, the maximum angle below the horizontal shall be 30°.”

— API Std 936, Section 6.6.2.1​

This restriction ensures proper adherence and consolidation of refractory materials.

According to API TR 980, a form must be able to support its own weight and the pressure from the refractory material:

“Formwork shall be self-supporting and capable of withstanding the static and dynamic loads imposed during installation.”

— API TR 980, Section 4.2.1, Form Requirements​

Transparency and chemical resistance are not required characteristics for refractory formwork in installation.

API 936 mandates specific AQL values during pre-shipment testing:

“Physical property test results shall meet the specified requirements with a minimum AQL of 5.0 percent.”

— API Std 936, Section 5.2.4​

Hence, the correct AQL for physical property verification of pre-shipment brick testing is 5%.

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