CSA/ANSI NGV 2-2016 Compressed natural gas vehicle fuel containers.
12 Batch tests
Batch testing shall be conducted on finished containers or liners that are representative of normal production and are complete with identification marks. The test containers and liners, as appropriate, shall be randomly selected from each batch. If more containers are subjected to the tests than are required by this Standard, all results shall be documented.
When the test results fail to meet requirements, the container or liner batch shall be rejected. One retest of a rejected batch is authorized if an improper test was made due to the presence of a defect in the specimen. A batch shall be 100 percent inspected to remove defective containers or liners from the batch. A second sample shall then be permitted to be selected from the batch and tested. The batch is considered acceptable if the second sample meets the batch criteria.
12.2 Batch material tests
The container or liner shall meet the requirements of the design when subjected to the following tests.
a) Dimensions checked against the design.
b) For metal containers and liners, tensile test two specimens in accordance with the appropriate method specified under Clause 6.2.4.
c) For steel containers and liners, three impact tests in accordance with the method specified under Clause 6.2.2.
12.3 Coated containers
When a protective coating is a part of the design, the following tests shall be performed (in order) on a finished container or a representative test panel from each coating batch:
a) Coating thickness tests shall be in accordance with the following appropriate test method ASTM D1186, ASTM D1400, ASTM D4138. Containers that do not meet the manufacturer’s specified coating thickness requirement may be recoated after appropriate surface preparation without prior restripping.
b) The coating adhesion test in accordance with ASTM D3359, shall provide a minimum rating of 4 when measured using either Test Method A or B of ASTM D3359, as appropriate.
Repair of tested surfaces is permitted to a manufacturer’s approved procedure.
Where the coating fails to meet the requirements, the batch shall be 100 percent inspected to remove similarly defective containers. The coating on all defective containers may be stripped, using a method that does not affect the integrity of containers, and re-coated. The coating batch test shall then be repeated.CSA/ANSI NGV 2 pdf download.