ASME B16.34-2020 pdf download

ASME B16.34-2020 pdf download.Valves – Flanged, Threaded, and Welding End.
This Standard applies to new construction and covers pressure- temperature ratings, dimensions, tolerances, materials, nondestructive examination requirements, testing, and marking for cast, forged, and fabricated flanged, threaded, and welding end and wafer or flangeless valves of steel, nickel-base alloys, and other alloys shown in Table 1. Wafer or flangeless valves, bolted or through- bolt types, that are installed between flanges or against a flange are treated as flanged-end valves. Alternative rules for NPS 2/2 and smaller valves are given in Mandatory Appendix V. 1.2 Applicability 1.2.1 Standards and Specifications. Standards and specifications adopted by reference in this Standard and the names and addresses of the sponsoring organi- zations are shown in Mandatory Appendix VII. It is not considered practical to refer to a specific edition of each of the standards and specifications in the individual clause references. Instead, the specific edition references are included in Mandatory Appendix VII. A product made in conformance with a prior edition of reference standards and in all other respects conforming to this Standard shall be considered to be in conformance even though the edition reference may have been changed in a subsequent revision of this Standard. 1.2.2 Time of Purchase, Manufacture, or Installation. The pressure-temperature ratings included in this Stan- dard are applicable, upon publication, to all valves covered within its scope that meet its requirements. For unused valves, valves that have been maintained in inventory, the manufacturer may certify conformance to this edition provided that it can be demonstrated that all require- ments of this edition have been met. However, where such components were installed under the pressure- temperature ratings of an earlier edition of ASME B16.34, those ratings shall apply except as may be governed by an applicable Code or regulation.
2.1.4 Limited Class Valves. Welding- or threaded-end valves NPS 2%/ and smaller that conform to the require- ments of Mandatory Appendix V may be designated Limited Class valves. Pressure-temperature ratings shall not exceed the values calculated in accordance with Mandatory Appendix V. Limited Class ratings shall not be used for flanged-end valves. 2.1.5 Intermediate Rated Valves. A Standard Class or Special Class welding or threaded end valve or a Standard Class 400 fanged-end valve may be assigned an inter- mediate pressure-temperature rating or Class in accor- dance with para. 6.1.4, provided all other applicable requirements of this Standard are met. Correspondingly, an intermediate pressure rating or Class for Limited Class valves having welding ends or threaded ends may be assigned pressure-temperature ratings as determined by the method described in Mandatory Appendix V in conjunction with the interpolation procedure described in para.6.1.4. 2.1.6 Valves Fabricated by Welding. A valve made wholly or partly from segments of castings, forgings, bars, plates, or tubular product welded together will merit the applicable pressure-temperature rating only if (a) it conforms to all applicable requirements of this Standard (b) weld fabrication and heat treatment of welds are in accordance with the ASME Boiler and Pressure Vessel Code (ASME BPVC), Section VIII, Division 12 (c) nondestructive examination of welds is in accor- dance with ASME BPVC, Section VIII, Division 1, as required to warrant a joint efficiency, E, not less than (1) 0.80 for flanged-end and Standard Class welding- end valves larger than NPS 6 (2) 1.00 for Special Class welding-end or threaded- end valves in all sizes (see para. 8.3.3) B16.34, those ratings shall apply except as may be governed by an applicable Code or regulation.2.4 Guidance for the Use of Flanged Valve Ratings Application of flanged-end valves at either high or low temperatures or in a service subject to rapid fluid temperature variations entails some risk of flanged joint leakage. Guidance in this regard is provided in ASME B16.5 and more extensively in ASME PCC-1. Precau- tions regarding the bolting of raised face flanges to cast iron flanges are given in ASME B16.5 and ASME B16.47. 2.5 Variances Except as provided in paras. 2.5.1, 2.5.2, and 2.5.3, the pressure-temperature ratings are the maximum allow- able working pressure for the corresponding tempera- ture. 2.5.1 Safety Valves, Relief Valves, or Rupture Disk Operation. Under conditions of safety valve, relief valve, or rupture disk operation, pressure may exceed the rated pressure for a valve furnished under this Stan- dard by no more than 10% of that defined by the pressure- temperature rating. Such conditions are necessarily of limited duration. Damage that may result from pressure excursions in excess of the aforementioned is solely the responsibility of the user. merit the applicable pressure-temperature rating only if (a) it conforms to all applicable requirements of this Standard (b) weld fabrication and heat treatment of welds are in accordance with the ASME Boiler and Pressure Vessel Code (ASME BPVC), Section VIII, Division 12 (c) nondestructive examination of welds is in accor- dance with ASME BPVC, Section VIII, Division 1, as required to warrant a joint efficiency, E, not less than (1) 0.80 for flanged-end and Standard Class welding- end valves larger than NPS 6 (2) 1.00 for Special Class welding-end or threaded- end valves in all sizes (see para. 8.3.3) B16.34, those ratings shall apply except as may be governed by an applicable Code or regulation.