AS NZS 4645.2:2018 pdf download.Gas distribution networks Part 2: Steel pipe systems.
2.2 MATERIALS AND COMPONENTS IDENTIFICATION
Materials and components shall be identified in accordance with AS/NZS 4645.1.
2.3 PIPE THREADS, THREADED PIPE FITTINGS, FLANGED PIPE JOINTS AND WELDED PIPE JOINTS
Pipe threads, threaded pipe fittings, flanged pipe joints and welded pipe joints shall conform with Table 2.3.Attention should be given during the design to prevent galvanic corrosion of dissimilar metals joined in buried systems. This includes the joining of the same materials where replacement of a section would see existing piping being connected to new piping.
The use of expansion joints should be avoided. However, where an expansion joint is used, it shall meet the functional requirements and shall be installed in accordance with the manufacturer’s instructions.
2.4 VALVES. FITTINGS AND ACCESSORIES
2.4.1 General
Valves, fittings and accessories shall be manufactured in accordance with a design based on a Standard as nominated in Table 2.1(A). Where the component is to be joined by welding it shall be made of a steel that can be successfully welded on site. Valves, fittings and accessories shall be capable of withstanding the service conditions for which the system is designed. Where the valves, fittings and accessories are to be incorporated in the piping system after it has been pressure tested, they shall—(a) be pressure tested to the same pressure as the piping system; or (b) have pressure and temperature ratings at least equivalent to those of’ the pipe to which they are to be attached.
2.4.2 Flanges and flanged fittings
Flanges and flanged fittings shall conf’orm with a Standard nominated in Table 2.1(A) and the following requirements: (a) Stubs on weld neck flanges that have dimensions conforming with ASME B 16.5 shall be taper bored where they are to be attached to thin wall pipe. (h) The flange thickness of slip-on flanges with a rectangular cross-section shall provide a strength of not less than that of the corresponding hubbed flange specified ASME 816.5, as determined by calculations made in accordance with AS 1210. (c) Bolting of steel flanges shall conform to ASME B 16.5 or BS 4882. Bolting of’ flanges in accordance with AS 2129 shall conform with AS 2528. NOTE: Additional items are included as notes at bottom of Table 2.1(A).
2.4.3 Gaskets and ring joints
Gaskets and ring joints shall conform with a Standard nominated in Table 2.1(A) and the following properties: (a) Resistance to the gases that will be distributed. (b) Rated to withstand the MAOP of the gas distribution network. (c) Rated for the full range of operating temperatures of the gas distribution network. (d) Retain the physical and chemical properties necessary for safe use.
2.4.4 Valves
Valves shall conform with Standards nominated in Table 2.1(A) and the following requirements: (a) Lubricants and sealants shall be suitable for the service conditions. Working pressure ratings of steel parts of valves shall apply within the temperature range of —30°C to +60°C. Resilient plastic materials used for seats and seals shall be capable of withstanding the design pressure and temperature. Parts in contact with gas shall be of materials that are compatible with the gas. The bodies of valves shall be pressure tested to the relevant requirements of API Spec ÔD and shall not leak. The seat of valves shall conform with APi Spec 6D.
Other than non-return valves, a means shall exist for indicating the setting of the valve (e.g. closed, a third open). Valves shall be indelibly marked, on the body or on a permanently attached nameplate, giving the following information: (i) Manufacturer’s name or trademark. (ii) Class designation or the maximum working pressure for which the valve has been designed. (iii) Body material designation (and the end connection material where more than one type is used). (iv) Nominal valve size.
2.5 COATING FoR BURIED METAL MAINS OR SERVICES
All below ground mains or services shall be coated to prevent external corrosion for the operational life or conditions. Coatings shall conform with a Standard nominated in Table 2.1(A) and the following requirements: The coating system used shall be appropriate for underground service and the operating conditions.AS NZS 4645.2 pdf download.