scope:

General

This Standard applies to new valve 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 shall be treated as flanged-end valves. Alternative rules for small valves (NPS 2½ and smaller) are given in Annex G.

Applicability

Standards and Specifications. Standards and specifications adopted by reference in this Standard and the names and addresses of the sponsoring organizations are shown in Annex 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 Annex I. A product made in conformance with a prior edition of reference standards and in all other respects conforming to this Standard will be considered to be in conformance even though the edition reference may have been changed in a subsequent revision of this Standard.

Codes and Regulations. A valve used under the jurisdiction of the ASME Boiler and Pressure Vessel Code, the ASME Code for Pressure Piping, or governmental regulations is subject to any limitation of that code or regulation. This incudes any maximum temperature limitation for a material or rule governing the use of a material at a low temperature.

Time of Purchase, Manufacture, or Installation. The pressure-temperature ratings included in this Standard are applicable, upon its publication, to all valves covered within its scope which otherwise 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 requirements of this edition have been met. However, where such components were installed under the pressure temperature ratings of an earlier edition of ASME B16.5 or ASME B16.34, those ratings shall apply except as may be governed by an applicable Code (see para. 1.2.2)

User Accountability. This Standard cites duties and responsibilities that are to be assumed by the valve user in the areas of, for example, application, installation, system hydrostatic testing, operation, and material selection.

Quality Systems. Requirements relating to the valve manufactures Quality System Programs are described in nonmandatory Annex H.

Service Conditions

Criteria for selection of valve types and materials suitable for particular fluid service are not within the scope of this Standard.

Convention

For the purpose of determining conformance with this standard, the convention for fixing significant digits where limits, maximum and minimum values, are specified shall be ôrounding offÆÆ as defined in ASTM Practice E 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 tolerance do not imply a particular method of measurement.