ASME B16.34:2020 pdf free download

ASME B16.34:2020 pdf free download.Valves -Flanged,Threaded, and Welding End.
2.1.4 Limited CLass VaLves. Welding- or threaded-end valves NPS 2 and smaller that conform to the requirements 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.
2J.5 Intermediate Rated VaLves. A Standard Class or Special Class welding-or threaded-end valve or a Standard Class 400 flanged-end valve may be assigned an intermediate pressure-temperature rating or Class in accordance with para. 61.4. 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 accordance 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)
(3) 1.00 for valves in cryogenic service
These requirements are not applicable to seal welds or attachment welds such as for backseat bushings, seat rings, lifting lugs, and auxiliary connections.
2.2 Rating Temperature
The temperature shown for a corresponding pressure rating Is the temperature of the pressure-containing shell of the component. In general, this temperature Is the same as that of the contained fluid. Use of a pressure rating corresponding to a temperature other than that of the contained fluid Is the responsibility of the user, subject 2.3 Temperature Effects
2.3.1 High Temperature.Application at temperaturesin the creep range will result in decreasing bolt loads asrelaxation of flanges, bolts, and gaskets takes place.Flanged joints subject to thermal gradients may likewisebe subject to decreasing bolt loads. Decreased bolt loadsdiminish the capacity of the flanged joint to sustain loadseffectively without leakage.At elevated temperatures,flanged joints, and in particular Class 150, may developleakage problems unless care is taken to avoid imposingsevere external loads or severe thermal gradients.