ASME B16.38-2007 pdf free download.Large Metallic Valves for Gas Distribution.
1.1 Valve Types
This Standard covers requirements for manually operated metallic valves in nominal sizes 2’/2 (DN 65) 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 manufactured metallic valve must possess in order to be considered suitable for use in piping systems indicated above, carrying natural gas, manufactured gas [includes synthetic natural gas (SNG)1, 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 sponsoring 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 1. A product made in conformance with a prior edition of reference standards will be considered to be in conformance, 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 F 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 measurement.
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 limitation 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 pressures.
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 possible removal of the core of the valve with other-thanspecialized tools, e.g., tools other than common wrenches, pliers, etc.
2.7 Gas Resistance
All materials, including lubricants and sealants, shallbe resistant to deterioration when exposed to fuel gasessuch as listed in para.1.2.
2.8 Temperature Resistance
The materials used for valve bodies, plugs, bonnets,unions, and other pressure-containing parts, excludinghandles, shall have a solidus temperature in excess of600°F(427°C).
2.9 Elastomer Components
2.9.1 Air Aging Tests.Elastomer parts that areexposed to fuel gas shall be made of materials that [fol-lowing 70-hr air aging at 212°F (100°C) in accordancewith ASTM D 573] meet elongation, tensile, and hard-ness property requirements as specified in paras. 2.9.1.1and 2.9.1.2.