[Material Requirements] The physical attributes testing of manufactured bricks during pre-shipment testing shall require a minimum Acceptable Quality Limit (AQL) of:

According to API Standard 936, the quality control requirements for manufactured refractory shapes, such as bricks, mandate specific testing protocols before installation. For physical attributes testing conducted on a lot basis, the standard explicitly defines the acceptable quality limit (AQL). This limit is set to ensure a high probability that the percentage of nonconforming items in a given lot does not exceed a specified value. The standard requires that the AQL for this type of testing shall be 4.0%.

A. 1%: This AQL is more stringent than the value specified by API 936 for the physical attribute testing of bricks.
C. 5%: This value is incorrect. The standard explicitly mandates an AQL of 4.0%, not 5.0%.
D. 10%: This AQL is too lenient and would permit a higher defect rate than what is allowable under the API 936 standard for these materials.

1. API Standard 936

Refractory Installation Quality Control—Inspection and Testing Monolithic Refractory Linings and Materials

4th Edition

May 2014.

Section 4.3.2.2: "Physical attributes testing of manufactured shapes shall be performed on a lot basis. The sample size shall be in accordance with Table 1. The acceptable quality limit (AQL) shall be 4.0 %."