ASME B16.34:1996 pdf download VALVES一FL ANGED, THREADED, AND WELDING END
1 SCOPE
1.1 General
This Standard applies to new valve constructionand covers pressure-temperature ratings, dimensions,tolerances. materials, nondesfructive examination requtrements, tesfing, and marking for cast, forged, andfahricated flanged, threaded, and welding end and waferor flangeless valves of steel. nickel-base alloys, andother alioys shown in Tabie i. Wafer or fiangeiessvalves, bolted or through-bolt types, that are installedbetween flanges or against a flange shall be treated asflanged-end valves. Alternative rules for small valves(NPS 2% and smaller) are given in Annex G.
1.2 Applicability
1.2.1 Standards and Specifications. Standardsand specifications adopted by reference in this Standardand the names and addresses of the sponsoring organiza.tions are shown in Annex l. It is not considered practicalto refer to a specific edition of each of the standardsand specifications in the individuai references. insteadthe specific edition references are included in AnnexI A product made in conformance with a prior editionof reference standards and in all other respects conforming to this Standard will be considered to be in conformance even though the edition reference may havcbeen changed in a subsequent revision of this Standard.
1.2.2 Codes and Regulations. A valve used un.der the jurisdiction of the ASME Boiler and PressureVessel Code, the ASME Code for Pressure Piping. orgovernmental regulations is subject to any limitationof that code or regulation. This incudes any maximumtemperature limitation for a materiai or ruie governingthe use of a material ar a low temperature.
1.2.3 Time of Purchase, Manufacture, or in.stallation. The pressure-temperature ratings includedin this Standard are applicable, upon its publication,to all valves covered within its scope which otherwisemeet its requirements. For unused valves, valves thathave been maintained in inventory, the manufacturermay certify conformance to this edition provided thatit can be demonstrated that all requirements of this edition have been met. However, where such components were installed under the pressure temperatureratings of an earlier edition of ASME B16.5 or ASMEB16.34, those ratings shall apply except as may begoverned by an applicable Code (see para. 1.2.2)
1.2.4 User Accountability.This Standard citesduties and responsibilities that are to be assumed bythe valve user in the areas of, for example, applicationinstallation,system hydrostatic testing, operation, andmateria! selection.
1.2.5 Quality Systems. Requirements relating tothe valvc manufacturcs Quality System Programs aredescribed in nonmandatory Annex H.
1.3 Service Conditions
Critcria for selection of valve types and materialssuitablc for particular fluid service are not within thescope of this Standard.
1.4 Convention
For the purpose of determining conformance withthis Standard, the convention for fixing significant digitswhere limits, maximum and minimum values, are specified shall be “rounding off’ as defined in ASTMPractice E 29. This requires that an observed or calcu-lated value shall be rounded off to the nearest unit inthe last right-hand digit used for expressing the limitDecima! values and tolerance do not imply a particularmethod of measurement.
2 PRESSURE-TEMPERATURE RATINGS
2.1 General
Pressure-temperature ratings are designated by classnumbers. Each class numher is further identified asStandard, Special, or Limited Class. Ratings are tabu-lated in Tables 2 for Standard and Special (lass 150,300，400，600，900，1500，2500,and 4500. Ratingsfor Limited Class are determined hy the method ofAnnex .
(a) Flanged end-valves shall be rated only as Standard Class.