ASME B16.28 Standard covers ratings, overall dimensions, testing, tolerances, and markings for wrought carbon and alloy steel buttwelding short radius elbows and returns. The term wrought denotes fittings made of pipe, tubing, plate, or forgings.
Fabricated fittings employing intersection welds are not covered by this Standard. Design of such fittings is covered in the ASME B31, Code for Pressure Piping or the ASME Boiler and Pressure Vessel Code.
Referenced Standards. Standards and specifications adopted by reference in this Standard are shown in Annex B, which is part of this Standard. It is not considered practical to identify the specific edition of each standard and specification in the individual references. Instead the specific edition reference is identified in Annex B. 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.
Codes and Regulations. A fitting used under the jurisdiction of the ASME Boiler and Pressure Vessel Code, the ASME Code for Pressure Piping, or a governmental regulation is subject to any limitation of that code or regulation. This includes any maximum temperature limitation or rule governing the use of a material at low temperature.
Criteria for selection of fitting types and materials suitable for particular fluid service are not within the scope of this Standard.
Installation welding requirements are outside the scope of this Standard. Installation welding shall be done in accordance with the applicable piping code or regulation covering the piping system into which the fittings are installed.