B51-03 (R2007)

Part 1 1 Scope 1.1 Except as indicated in Clause 1.2, Part 1 of this Standard applies to all boilers, pressure vessels, pressure piping, and fittings, as provided for by the Act (as defined in Clause 3) and identified in Part 1 of this Standard. Notes: 1) In certain provinces there may be variations in the size limitations specified in Part 1 of this Standard. The regulatory authority should be consulted. 2) All pressures specified in Part 1 of this Standard are gauge pressures above atmospheric pressure. 1.2 Requirements for compressed natural gas cylinders and refuelling station pressure piping systems and containers are covered in Parts 2 and 3 of this Standard. 1.3 This Standard does not apply to a)pressure-retaining components in hydraulic elevators; b)pressure-containment devices for gas-filled switchgear and controlgear; and c)pressure vessels for the transportation of dangerous goods regulated by Transport Canada. 1.4 Where any clause of Part 1 of this Standard is at variance with the referenced codes and standards, the requirements of Part 1 of this Standard govern. 1.5 In CSA Standards, .shall. is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; .should. is used to express a recommendation or that which is advised but not required; and .may. is used to express an option or that which is permissible within the limits of the standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Legends to equations and figures are considered requirements. 1.6 The values given in SI (metric) units are the standard. The values given in parentheses are for information only. Nominal pipe sizes are expressed in non-dimensional terms. PART 2 1 Scope 1.1 This Standard sets out minimum requirements for serially produced lightweight refillable gas cylinders, both original equipment and conversions, having a water capacity exceeding 20 L (0.71 ft3) but not exceeding 1000 L (35.3 ft3). The cylinders are intended only for the on-board storage of high-pressure compressed natural gas as a fuel for automotive vehicles to which the cylinders are to be fixed. Cylinders may be of any material (steel, aluminum, or non-metallic), or constructed in accordance with any design or method of manufacture, suitable for the specified service conditions. 1.2 The cylinders covered by this Standard are designated as follows: a) CNG-1 ? metal; b) CNG-2 ? metal liner reinforced with resin-impregnated continuous filament (hoop-wrapped); c) CNG-3 ? metal liner reinforced with resin-impregnated continuous filament (fully wrapped); and d) CNG-4 ? non-metallic liner with resin-impregnated continuous filament (all-composite). 1.3 The service conditions to which the cylinders will be subjected are detailed in Clause 4. This Standard is based on a working pressure for natural gas as a fuel of 200 bar (2900 psi) settled at 15 °C (59°F), with a maximum filling pressure of 260 bar (3770 psi). Other working pressures can be accommodated by adjusting the pressure by the appropriate factor (ratio). For example, a 250 bar working pressure system will require pressures to be multiplied by 1.25. The service life of a cylinder is defined by the manufacturer and may vary with different applications. The definition of service life is based on filling a cylinder 1000 times a year. The maximum service life of CNG-2, CNG-3, and CNG-4 cylinders is 20 years. For all cylinders a ?safe life? design principle is used. For metal and metal-lined cylinders, the cylinder life is based on the rate of fatigue crack growth. Ultrasonic or equivalent inspection of each cylinder or liner is required to ensure that there are no flaws that exceed the maximum allowable size determined by fracture mechanics. This approach permits the optimized design and manufacture of lightweight cylinders for natural gas vehicle service. For all-composite cylinders with non-metallic non-load-bearing liners, safe life is ensured by appropriate design methods, design qualification testing, and manufacturing controls. 1.4 This Standard does not cover stainless steel or welded metal cylinders or liners. 1.5 Where any clause of Part 2 of this Standard is at variance with the referenced standards, the requirements of Part 2 of this Standard govern. 1.6 Type CNG-1 steel cylinders may be requalified for further service in accordance with the procedure described in Annex B of Part 2 of this Standard. 1.7 The values given in SI (metric) units are the standard. The values given in parentheses are for information only. Part 3 1 Scope 1.1 1.1.1 The pressure piping systems covered in Part 3 of this Standard are those systems a) between the termination of the utility's piping, usually at the meter, and the inlet to the compressor assembly at a compressed natural gas (CNG) refuelling station, if the design pressure exceeds 414 kPa (60 psi); and b) from the inlet to the compressor assembly through to the dispenser nozzle, except for the mechanical parts of the compressor and any subsystems designed for 414 kPa (60 psi) or less. 1.1.2 The ground storage vessels covered in Part 3 of this Standard are pressure vessels that are installed at CNG refuelling stations and intended to store CNG at pressure for delivery to vehicle fuel tanks. 1.2 Where any clause of Part 3 of this Standard is at variance with the referenced standards, the requirements of Part 3 of this Standard govern. 1.3 The values given in SI (metric) units are the standard. The values given in parentheses are for information only.