1.1 This specification covers welded stainless steel tubing for mechanical applications where appearance, mechanical properties, or corrosion resistance is needed. The grades covered are listed in Table 1.

1.2 This specification covers as-welded or cold-reduced mechanical tubing in sizes to 16 in. (406.4 mm) outside dimension, and in wall thicknesses 0.020 in. (0.51 mm) and over.

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

1.4 Supplementary requirements of an optional nature are provided and when desired shall be so stated in the order.

1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

TABLE 1 Chemical Requirements

Grade	Composition, %
Grade	Carbon, max	Manga- nese, max	Phos- phorus, max	Sulfur, max	Silicon, max	Nickel	Chromium	Molybdenum	Titanium	Columbium + Tantalum
Austenitic
MT-301	0.15	2.00	0.040	0.030	1.00	6.0-8.0	16.0-18.0	...	...	...
MT-302	0.15	2.00	0.040	0.030	1.00	8.0-10.0	17.0-19.0	...	...	...
MT-304	0.08	2.00	0.040	0.030	1.00	8.0-11.0	18.0-20.0	...	...	...
MT-304L	0.035^A	2.00	0.040	0.030	1.00	8.0-13.0	18.0-20.0	...	...	...
MT-305	0.12	2.00	0.040	0.030	1.00	10.0-13.0	17.0-19.0	...	...	...
MT-309S	0.08	2.00	0.040	0.030	1.00	12.0-15.0	22.0-24.0	...	...	. . .
MT-309S-Cb	0.08	2.00	0.040	0.030	1.00	12.0-15.0	22.0-24.0	...	...	^B
MT-310S	0.08	2.00	0.040	0.030	1.00	19.0-22.0	24.0-26.0	...	...	...
MT-316	0.08	2.00	0.040	0.030	1.00	10.0-14.0	16.0-18.0	2.0-3.0	...	...
MT-316L	0.035^A	2.00	0.040	0.030	1.00	10.0-15.0	16.0-18.0	2.0-3.0	...	...
MT-317	0.08	2.00	0.040	0.030	1.00	11.0-14.0	18.0-20.0	3.0-4.0	...	...
MT-321	0.08	2.00	0.040	0.030	1.00	9.0-13.0	17.0-20.0	...	^C	...
MT-330	0.15	2.00	0.040	0.030	1.00	33.0-36.0	14.0-16.0	...	...	...
MT-347	0.08	2.00	0.040	0.030	1.00	9.0-13.0	17.0-20.0	...	...	^B
Ferritic
MT-429	0.12	1.00	0.040	0.030	1.00	0.50 max	14.0-16.0	...	...	...
MT-430	0.12	1.00	0.040	0.030	1.00	0.50 max	16.0-18.0	...	...	...
MT-430-Ti	0.10	1.00	0.040	0.030	1.00	0.075 max	16.0-19.5	...	5 × C min,	...
									0.75 max

^A For small diameter or thin walls, or both, where many drawing passes are required, a carbon content of 0.040 % max is necessary in grades MT-304L and MT-316L. Small outside diameter tubes are defined as those less than 0.500 in. (12.7 mm) in outside diameter and light wall tubes as those less than 0.049 in. (1.24 mm) in average wall thickness.

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

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