This specification covers the carbon steel forgings used for general-purpose piping. Two classes of material are covered, Classes 60 and 70, and classified according to their mechanical properties. Except for flanges of all types, up to and including NPS 4 may be machined from hot-rolled or forged bar. Elbows, return bends, tees, and header tees shall not be machined directly from bar stock. Forgings shall be protected against sudden or too rapid cooling from the rolling or forging while passing through critical range. Heat treatment is neither required nor prohibited, but when applied, it shall consist of tempering, annealing, normalizing, or normalizing and tempering. Heat analysis shall be made to determine the percentage of the following elements: carbon, manganese, phosphorus, silicon, and sulfur. The mechanical properties of the material shall conform to the required tensile properties: tensile strength, yield strength, elongation, and reduction of area.

1.1 This specification covers nonstandard as-forged fittings, valve components, and parts for general service. Forgings made to this specification are limited to a maximum weight of 10 000 lb [4540 kg]. Larger forgings may be ordered to Specification A 266/A 266M.

1.2 Two classes of material are covered, designated as Classes 60 and 70, respectively, and are classified in accordance with their mechanical properties as specified in .

1.3 This specification is expressed in both inch-pound units and SI units. However, unless the order specifies the applicable "M" specification designation (SI units), the material shall be furnished to inch-pound units.

1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.