1.1 This specification covers externally helical, integrally finned aluminum-alloy seamless tubes with finned or unfinned ends, with continuous fins, or with unfinned sections, in outside diameters (diameter over fins) up to 2 in. inclusive.

1.2 Alloy and temper designations are in accordance with ANSI H35.1. The equivalent Unified Numbering System alloy designations are those of Table 1 preceded by A9, for example, A91060 for aluminum 1060 in accordance with Practice E527.

1.3 For acceptance criteria for inclusion of new aluminum and aluminum alloys in this specification, see Annex A2.

1.4 A complete metric companion to Specification B404 has been developed-B404M; therefore, no metric equivalents are presented in this specification.