This Standard contains requirements for the material, design, manufacture, and testing of serially produced, refillable Type NGV 2 containers intended only for the storage of compressed natural gas for vehicle operation. These containers are to be permanently attached to the vehicle. This Standard applies to containers up to and including 1000 L (35.4 ft³) water capacity. Type NGV 2 containers are designated as follows: a) Type 1: metal; b) Type 2: resin-impregnated continuous filament with metal liner with a minimum burst pressure of 125% of service pressure. The container is hoop-wrapped; c) Type 3: resin-impregnated continuous filament with metal liner. The container is full-wrapped; and d) Type 4: resin-impregnated continuous filament with a nonmetallic liner. Conformable container types are designated as follows: a) CT1: container or assembly of a non-spherocylindrical or non-spherical (i.e., irregular) shape without a protective shell (i.e., outside wall containing gas pressure); b) CT2: container or assembly of possibly irregular shape within a conformable protective shell that is acting as a shield and not directly assisting the inner container with containing gas pressure; and c) CT3: container or assembly of possibly irregular shape within a conformable protective shell that is acting as a shield and directly assisting the inner container with containing gas pressure. The conformable container types are an additional identifier that is used in combination with the container type. A conformable tank is designated based on the design as a Type 1 (metal) to Type 4 (resin-impregnated continuous filament with a nonmetallic liner) with the additional conformable type identifier. For example, a Type 4 CT2 container would be required to meet the criteria for a Type 4 container as well as the criteria specified for a CT2 container.