This standard is issued under the fixed designation A 249/A 249M; 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 specification covers nominal-wall-thickness welded tubes made from the austenitic steels listed in Table 1, with various grades intended for such use as boiler, superheater, heat exchanger, or condensed tubes.
1.2 Grades TP304H, TP309H, TP309HCb, TP310H, TP310HCb, TP316H, TP321H, TP347H, and TP348H are modifications of Grades TP304, TP309S, TP309Cb, TP310S, TP310Cb, TP316, TP321,TP347, and TP348, and are intended for high-temperature service such as for superheaters and reheaters.
1.3 The tubing sizes and thicknesses usually furnished to this specification are 1/8 in. [3.2 mm] in inside diameter to 5 in. [127 mm] i outside diameter and 0.015 to 0.320 in. [o.4 to 8.1 mm], inclusive, in wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of this specification.
1.4 Mechanical property requirements do not apply to tubing smaller tan 1/8 in. [3.2 mm] in inside diameter or 0.015 in. [0.4 mm] in thickness.
1.5 Optional supplementary requirements are provided and, when one or more of these are desired, each shall be so stated in the order.
1.6 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. The inch-pound units shall apply unless the "M" designation of this specification is specified in the order.
1.7 The following safety hazards caveat pertains only to the test method described in the Supplementary Requirement of this specification. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate of regulatory limitations prior to use. A specific warning statement is given in Supplementary Requirement S7, Note 5.