1.1 This specification covers electric-resistance-welded carbon and alloy steel tubing for use as mechanical tubing.

1.2 This specification covers mechanical tubing made from hot- or cold-rolled steel.

1.3 This specification covers round, square, rectangular, and special shape tubing.

1.4 Optional supplementary requirements are provided and when desired, shall be so stated in the order.

1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text the SI units are shown in brackets or parenthesis. The values stated in each system may not be exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. The inch-pound unts shall apply unless the "M" designation of this specification is specified in the order. In this specification hard or rationalized conversions apply to diameters, lengths and tensile properties. Soft conversion applies to other SI measurements.