【国外标准】 Standard Specification for Wrought-Carbon Steel Butt-Welding Piping Fittings with Improved Notch Toughness

This guide covers standard specification for wrought-carbon steel butt-welding seamless or welded fittings specially processed to ensure better notch toughness. Heat treatment shall be required for all types of fittings. Fittings with mandatory radiographic examination of welds shall be included. Cast fittings and fittings formed from all weld metal, shall not be included. Heat or cast analysis shall be conducted wherein the material shall conform to the required chemical components for carbon, manganese, phosphorus, sulfur, silicon, vanadium, chromium, nickel, molybdenum, copper, and lead. The fittings, as represented by tensile test specimens taken subsequent to final heat treatment, shall conform to the specified values of tensile strength, yield strength, and elongation for the applicable grades of steel. Mechanical tests such as tension test and transverse guided weld bend test shall be performed on the fittings.1.1 This specification covers wrought-carbon steel butt-welding seamless or welded fittings specially processed to ensure better notch toughness than that to be expected in fittings manufactured to the requirements of Specification A234/A234M.1.1.1 Included are elbows, caps, tees, reducers, and other type fittings covered by ASME B16.9.1.1.2 Heat treatment is required for all fittings.1.1.3 Fittings with mandatory radiographic examination of welds are included.1.1.4 Supplementary requirements are provided for use when additional testing or examination is desired.1.1.5 Cast fittings, and fittings formed from all weld metal, are not included.1.2 Several type of fittings are provided, as follows:Type Heat TreatmentRequired Weld SeamFinish (5.3.2) RadiographyRequired? 30 normalize UW-35 no31 normalize UW-35 yes32 normalize UW-35 and ground flush yes40 normalize and temper UW-35 no41 normalize and temper UW-35 yes42 normalize and temper UW-35 and ground flush yes50 quench and temper UW-35 no51 quench and temper UW-35 yes52 quench and temper UW-35 and ground flush yes1.3 It shall be the responsibility of the purchaser to determine whether material meeting the requirements of this specification is satisfactory for the service application.1.4 This specification is expressed in both inch-pound units and SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.