1.1 This specification covers seamless stainless tubing for use in mechanical applications where corrosion-resistant or high-temperature strength is needed. The grades covered are listed in Table 1, Table 2, and Table 3.

1.2 This specification covers seamless cold-finished mechanical tubing and seamless hot-finished mechanical tubing in sizes up to 12¾ in. [325 mm] in outside nominal diameter (for round tubing) with wall thicknesses as required.

1.3 Tubes shall be furnished in one of the following shapes, as specified by the purchaser: round, square, rectangular, or special.

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

1.5 The values stated in inch-pound units are to be regarded as the standard. Within the text, the SI units are shown in square brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other.

TABLE 1 Chemical Requirements of Austenitic Stainless Steels

^A For small diameter or thin wall tubing or both, where many drawing passes are required, a maximum of 0.040 % carbon is necessary in grades MT-304L and MT-316L. Small outside diameter tubes are defined as those under a 0.500 in. [12.7 mm] outside diameter and light-wall tubes as those under a 0.049 in. [1.2 mm] average wall thickness (0.044 in. [1.1 mm] min wall thickness).

^B The titanium content shall be not less than five times the carbon content and not more than 0.60 %.

^C The columbium plus tantalum content shall be not less than ten times the carbon content and not more than 1.00 %.

TABLE 2 Chemical Requirements of Ferritic and Martensitic Stainless Steels

^A MT446-2 is a lower carbon version of MT446-1, that has a lower tensile strength but improved ductility and toughness.

^B Carbon plus nitrogen = 0.025 max %.

TABLE 3 Chemical Requirements of Austenitic-Ferritic Stainless Steels^A

^A Maximum, unless a range or minimum is indicated. Where ellipses (…) appear in this table, there is no requirement and analysis for the element need not be determined or reported.

^B % Cr + 3.3 X % Mo + 16X % N ≥ 40.