ASME B16.38-2007 pdf download.Large Metallic Valves for Gas Distribution Manually Operated, NPS 2 1 / 2 (DN 65) to NPS 12 (DN 300), 125 psig (8.6 bar) Maximum.
1 SCOPE 1.1 Valve Types This Standard covers requirements for manually oper- ated metallic valves innominalsizes 2 1 ⁄ 2 (DN65) through 12 (DN 300) having the inlet and outlet on a common centerline. These valves are intended for controlling the flow of gas from open to fully closed positions, for use in distribution and service lines where the maximum gage pressure does not exceed 125 psig (8.6 bar). Valve seats, seals, and stem packing may be nonmetallic. 1.2 Application This Standard sets forth the minimum capabilities, characteristics, and properties that a newly manufac- tured metallic valve must possess in order to be consid- ered suitable for use in piping systems indicated above, carrying natural gas, manufactured gas [includes syn- thetic natural gas (SNG)], and liquefied petroleum gases (distributed as a vapor, with or without the admixture of air) or mixtures thereof. 1.3 Referenced Standards Standards and specifications adopted by reference in this Standard and the names and addresses of the spon- soring organizations are shown in Mandatory Appendix I. It is not considered practical to refer to a specific edition of each of the standards and specifications in the individual references. Instead, the specific edition references are included in Mandatory Appendix I. A product made in conformance with a prior edition of reference standards will be considered to be in confor- mance, even though the edition reference may be changed in a subsequent revision of the standard. 1.4 Quality Systems Nonmandatory requirements relating to the product manufacturer’s Quality System Program are described in Nonmandatory Appendix A. 1.5 Convention For the purpose of determining conformance with this Standard, the convention for fixing significant digits where limits, maximum or minimum values, shall be “rounded off” as defined in ASTM Practice E 29. This requires that an observed or calculated value shall be rounded off to the nearest unit in the last right-hand digit used for expressing the limit. Decimal values and tolerances do not imply a particular method of mea- surement. 1.6 Codes and Regulations A valve used under the jurisdiction of a Federal Regulation, such as CFR Title 49, Part 192; the ASME Code for Pressure Piping, such as ASME B31.8; or the National Fuel Gas Code, Z223.1, is subject to any limita- tion of that code or regulation. 1.7 Definitions NPS: nominal pipe size NVS: nominal valve size one bar: 100 kPa PTFE: materials that comply with ASTM D 4894, Specification for Polytetrafluoroethylene (PTFE) Granular Molding and Extrusion Materials All pressures, unless otherwise stated, are gage pres- sures. 2 CONSTRUCTION 2.1 Conformance 2.1.1 Each completed and assembled valve at the time of manufacture and marked with the designation B16.38 shall be capable of meeting the requirements set forth in this Standard. 2.1.2 Classes 125 and 150 valves (depending upon their design) shall meet the requirements of one of the following standards: MSS SP-67, MSS SP-70, MSS SP-72, MSS SP-78, MSS SP-80, MSS SP-84, ASME B16.34, and ASME B16.42 (see Mandatory Appendix I). 2.2 Tamperproof Features Where valves are specified to be tamperproof, they shall be designed and constructed to minimize the possi- ble removal of the core of the valve with other-than- specialized tools, e.g., tools other than common wrenches, pliers, etc.
2.8 Temperature Resistance The materials used for valve bodies, plugs, bonnets, unions, and other pressure-containing parts, excluding handles, shall have a solidus temperature in excess of 600°F (427°C). 2.9 Elastomer Components 2.9.1 Air Aging Tests. Elastomer parts that are exposed to fuel gas shall be made of materials that [fol- lowing 70-hr air aging at 212°F (100°C) in accordance with ASTM D 573] meet elongation, tensile, and hard- ness property requirements as specified in paras. 188.8.131.52 and 184.108.40.206. 220.127.116.11 Tensile tests shall be conducted in accor- dance with ASTM D 412. Three dumbbells shall be air aged 70 hr at 212°F (100°C) in accordance with ASTM D 573. The dumbbells shall have a thickness of 0.08 in. ± 0.008 in. (2 mm ± 0.2 mm). The average of the three individual tests for the aged dumbbells shall exceed 60% retention of ultimate elongation and 60% retention of tensile strength at break. The average of the three individual tests for the nonaged dumbbells shall be the basis for the percent calculation. 18.104.22.168 Hardness tests shall be conducted using specimens in accordance with ASTM D 395, Type 2. Three specimens shall be air aged 70 hr at 212°F (100°C) in accordance with ASTM D 573. The average of the three individual tests for the aged specimens shall not show a hardness change of more than ±10 Shore A hard- ness points relative to the average hardness of the non- aged specimens. 2.9.2 Swell Tests. Elastomer parts that are exposed to fuel gas shall be made from materials that after 70-hr exposure to N-hexane at 74°F (23°C), in accordance with ASTM D 471, meet the volume change, elongation, and tensile property requirements as specified in paras. 22.214.171.124 and 126.96.36.199.