1.1 This specification covers minimum wall thickness welded tubes made from carbon and carbon manganese steels listed in , with various grades intended for use in boiler, superheater, heat exchanger, or condenser applications.

1.2 The tubing sizes and thicknesses usually furnished to this specification are 1/4 to 5 in. [6.3 to 127 mm] in outside diameter and 0.015 to 0.375 in. [0.4 to 9.5 mm], inclusive, in wall thickness. Tubing having other dimensions may be furnished provided such tubes comply with all other requirements of this specification.

1.3 Mechanical property requirements do not apply to tubing smaller than 1/8 in. [3.2 mm] in inside diameter or 0.015 in. [0.4 mm] in thickness.

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. The inch-pound units shall apply unless the "M" designation of the specification is specified in the order.

1.5 Optional supplementary requirements are provided and when desired, shall be so stated on the purchase order.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.