scope:

SCOPE AND BASES OF THE CASE

General Construction Description.

This construction method uses a laminate of continuous unidirectional filaments of a specified glass or carbon fiber with a specified resin that is circumferentially wound in a systematic manner under controlled tension over a cylindrical metallic layer and cured in place. Openings are not permitted in the laminate. Metallic ends and nozzles that meet the requirements of Section VIII, Division 3 complete the construction; see Figs. 1, 2, and 3.

Construction Rules.

Each CRPV shall comply with all existing rules of Section VIII, Division 3 unless otherwise stated as additional requirements and exemptions in this Case.

Metallic Layer.

The outside diameter of the metallic layer in the reinforced area shall not exceed 60 in. (1.52 m). The thickness of the metallic layer shall not be less than 0.25 in. (6 mm).

Service Life.

Service life for CRPV constructed under the rules of this Case shall be limited to twenty years from the date of manufacture as noted on Form CRPV-1A.

Application Specific Tests and Other Requirements.

This Case does not include requirements or rules for tests that may be appropriate for certain applications (e.g., fire tests, drop tests, projectile impact tests). For some applications, it may be necessary to consider additional conditions such as exposure to fire and projectile impact damage. These vessels shall not be used in over-the-road (i.e., truck) transportation service.

Maximum Design Pressure.

The internal design pressure for CRPV shall not be greater than 15,000 psi (103 MPa).

Service Pressure and Working Pressure.

In some standards and regulations used in ambient temperature compressed gas transport service, the term "service pressure" is used to indicate the pressure in the vessel at a temperature of 68°F (20°C). In other standards and regulations, the term "working pressure" is used with the same definition. In these standards and regulations it is generally allowable for the service or working pressure to be exceeded as the gas is heated beyond 68°F (20°C) during filling or due to atmospheric heating. For pressure vessels to be used in transport service constructed to this Case, the service pressure and the working pressure shall be the maximum expected pressure at a temperature of 68°F (20°C). The service pressure or the working pressure or both shall be defined in the User's Design Specification. The expected pressure due to heating during filling or atmospheric heating shall not exceed the design pressure of the vessel.

Protective Layer.

The User's Design Specification shall state whether a protective layer for the composite wrap is needed and, if so, shall specify the performance requirements for that layer (see Table 5a, Scratches). The User's Design Specification shall state whether the CRPV will be exposed to sunlight in service. If so, the Manufacturer shall apply a UV barrier coating.

Requirements for Cyclic Pressure Qualification Test.

In addition to the total number of operating cycles during the life of the CRPV, the User's Design Specification shall state the number of operating pressure cycles that will occur at a metal or composite temperature colder than 30°F (0°C) and the number of operating pressure cycles that will occur at a metal or composite temperature warmer than 110°F (45°C).

Laminate Tensile Strength and Elastic Modulus.

The User's Design Specification shall state the required minimum tensile strength and the nominal elastic modulus for the laminate in the maximum property direction (parallel to the fiber direction).