Preface
This is the fourteenth edition of CSA Standard B51, Boiler, Pressure Vessel, and Pressure Piping Code. This edition incorporates a number of approved but unpublished revisions since the publication of the thirteenth edition. The fourteenth edition supersedes all previous editions, published in 1939, 1945, 1951, 1955, 1957, 1960, 1965, 1969, 1972, 1975, 1981, 1986, and 1991.
This edition retains the content of the previous edition but has been extensively revised. Some new material has been added.
The CSA B51 Committee works closely with the ASME Boiler and Pressure Vessel Code Committees and with the National Board of Boiler and Pressure Vessel Inspectors, to whom we are indebted for permission to reproduce text and illustrations from their publication National Board Inspection Code (see Appendix B).
It should be understood that this Code is a recommended Standard only and does not have the force of law unless adopted officially by the various jurisdictions. In keeping with CSA standard practice, the Appendices are usually considered to be nonmandatory parts of the Standard. However, the reader is advised to consult the jurisdiction as to the extent of its adoption, as the Code may have been adopted with exemptions, or additions, and may include some Appendices.
The Code is intended mainly to fulfil two purposes: first, to provide for the safe design, construction, installation, operation, inspection, testing, and repair of boilers, pressure vessels, and related equipment; and second, to promote uniform requirements among the jurisdictions.
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B51-95 Part 1 - Boiler, Pressure Vessel, and Pressure Piping Code
Scope
1.1
Except as provided for in Clause 1.2, this Standard applies to all boilers, pressure vessels, fittings, and piping, as provided for by the Act and defined in this Standard.
Notes:
(1) In certain provinces there may be variations in size limitations quoted in this Standard. Consultation with the regulatory authority is recommended.
(2) Cylinders, spheres, tubes, and drums used in transportation are subject to the Transportation of Dangerous Goods Act and Regulations under that Ad; it is not intended that the provisions of this Standard conflict with or supersede the requirements of that Ad or Regulations in regard to the control of these containers when used for transportation by any mode.
(3) Corresponding imperial values to the SI (metric) units are shown in parentheses for information only.
Where nominal pipe sizes are shown they have been retained in nondimensional terms.
(4) All pressures shown in the text are gauge pressures, ie, above atmospheric pressure.
1.2
Requirements for compressed natural gas refuelling station pressure piping systems and containers are covered in CSA Standard 851-95, Part 2 and Part 3.
1.3
This Code does not apply to pressure-retaining components as used in hydraulic elevators.
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B51-95 Part 2 - High Pressure Cylinders for the On-Board Storage of Natural Gas as a Fuel for Automotive Vehicles
Scope
1.1
This Standard sets out minimum requirements for serially produced light-weight refillable gas cylinders, original equipment and conversions, having a water capacity exceeding 20 L (1220 in 3) but not exceeding 1000 L (35.3 ft 3). 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 steel, aluminum, or nonmetallic material, design, or method of manufacture suitable for the specified service conditions.
1.2
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-Nonmetallic liner with resin impregnated continuous filament (all-composite).
1.3
Service conditions to which the cylinders will be subjected are detailed in Clause 4. This Standard is based upon 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 the cylinder shall be defined by the manufacturer and may vary with applications. Definition of service life is based upon filling the cylinders 750 times a year; however, some provisions of this Standard may require modification if a service life of over 20 years is specified. For all cylinders a safe life design principle is used.
For metal and metal-lined cylinders, the cylinder life is based upon the rate of fatigue crack growth. The ultrasonic inspection, or equivalent, of each cylinder or liner is required to ensure the absence of flaws which 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 nonmetallic non-load-bearing liners, the safe life is ensured by appropriate design methods, design qualification testing, and manufacturing controls.
1.4
This Standard does not cover the use of stainless steels or welded metallic cylinders or liners.
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B51-95 Part 3 - Requirements for CNG Refuelling Station Pressure Piping Systems and Ground Storage Vessels
Scope
1.1
CSA Standard 851-95 Part 3 contains mandatory requirements for compressed natural gas (CNG) refuelling station pressure piping systems and ground storage vessels .
1.2
Pressure piping systems covered in this Part 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 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.
1.3
Ground storage vessels covered in this Part are pressure vessels installed at CNG refueling stations and intended to store CNG ready for delivery to vehicle fuel tanks.
