This standard is issued under the fixed designation A 731/A 731M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon ( ュ) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification2 covers seamless, welded feritic, and martensitic stainless steel pipe intended for high-emperature and general corrosive service.
1.2 Most of the grades are commonly known as the straight chromium type and are characterized as being ferromagnetic.
1.3 High-chromium, ferritic alloys are highly sensitive to notch brittleness on slow cooling to ordinary temperatures. This features should be recognized in the use of this material in the as-welded condition in sections thicker than 0.250 in. [6.4 mm].
1.4 Optional supplementary requirements are provided for pipe where a greater degree of testing is desired. These supplementary requirements call for additional tests to be made and, when desired, one or more of these may be specified in the order.
1.5 The values sated 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; Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the "M" designation of this specification is specified in the order.
NOTE 1ΑThe dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as "nominal diameter," :size," and "nominal size."
