Wall Thickness		Elongation in 2 in.or 50 mm, min, %
in.	mm	S44400,T23, T24, T91 Types 1 and 2,T92, T115, T122, and T911	T 36	All Other Ferritic Grades
5/16 [0.312]	8	20	15	30
9/32[0.281]	7.2	19	14	29
1/4 [0.250]	6.4	18	13	27
7/32 [0.219]	5.6	17	12	26
3/16 [0.188]	4.8	16	11	24
5/32 [0.156]	4	15	10	23
1/8 [0.125]	3.2	14	9	21
3/32 [0.094]	2.4	13	8	20
1/16 [0.062]	1.6	12	7	18
0.062 to 0.035, excl	1.6 to 0.9	12	7	17
0.035 to 0.022, excl	0.9 to 0.6	11	6	17
0.022 to 0.015 incl	0.6 to 0.4	11	6	16

 
9.1.3 One tension test shall be made on a specimen from one tube for lots of not more than 50 tubes. Tension tests shall be made on specimens from two tubes for lots of more than 50 tubes. See 15.2.
9.2 Hardness Requirements:
9.2.1 The material shall conform to the hardness requirements given in Table 4. See 15.2.
9.2.2 Brinell, Vickers, or Rockwell hardness tests shall be made on specimens from two tubes from each lot. See 15.2.
9.3 Flattening Test—One flattening test shall be made on specimens from each end ofone finished tube, not the one used for the flaring test, from each lot. See 15.1.
9.4 Flaring Test—One flaring test shall be made on specimens from each end of one finished tube, not the one used for the flattening test, from each lot. See 15.1.
9.5 Mechanical property requirements do not apply to tubing smaller than 1 ⁄ 8 in. [3.2 mm] in inside diameter or thinner than 0.015 in. [0.4 mm] in thickness.


10. Hydrostatic or Nondestructive Electric Test
10.1 Each tube shall be subjected to the nondestructive electric test or the hydrostatic test. The type of test to be used shall be at the option of the manufacturer, unless otherwise specified in the purchase order.
 
 
11. Forming Operations
11.1 Tubes, when inserted in a boiler or tube sheet, shall stand expanding and beading without showing cracks or flaws.Superheater tubes when properly manipulated shall stand all forging, welding, and bending operations necessary for application without developing defects. See Note 1.
NOTE 1—Certain of the ferritic steels covered by this specification will harden if cooled rapidly from above their critical temperature. Some will air harden, that is, become hardened to an undesirable degree when cooled in air from high temperatures, particularly chromium-containing steels with chromium of 4 % and higher. Therefore, operations that involve heating such steels above their critical temperatures, such as welding,flanging, and hot bending, should be followed by suitable heat treatment.
 
 
12. Repair by Welding
12.1 Repair welding shall be performed in conformance with Specification A1016/A1016M.
12.2 All repair welds in T91 shall be made with one of the following welding processes and consumables: SMAW, A5.5/A5.5M E90XX-B9; SAW, A5.23/A5.23M EB9 + neutral flux;GTAW, A5.28/A5.28M ER90S-B9; and FCAWA5.29/A5.29M E91T1-B9. In addition, the sum of the Ni+Mn content of all welding consumables used to weld repair T91 Types 1 and 2 shall not exceed 1.0 %.
12.3 All repair welds in T92, T911, and T122, shall be made using welding consumables meeting the chemical requirements for the grade in Table 1.
 
 
13. Permissible Variations from the Specified Wall Thickness
13.1 Permissible variations from the specified minimum wall thickness shall be in accordance with Specification A1016/A1016M.
13.2 Permissible variations from the specified average wall thickness shall be 6 10 % of the specified average wall thickness for cold formed tubes and, unless otherwise specified by the purchaser, shall be in accordance with Table 6 for hot formed tubes.

NPS [DN] Designator	Tolerance in %, from specified
	Over	Under
1 ⁄ 8 to 2 1 ⁄ 2 [6 to 65] incl, all t/D ratios A	20	12.5
Above 2 1 ⁄ 2 [65], t/D ≤5 % A	22.5	12.5
Above 2 1 ⁄ 2 [65], t/D >5 % A	15	12.5

 
A t = specified wall thickness
D = specified outside diameter
 
 
14. Surface Condition
14.1 Ferritic alloy cold-finished steel tubes shall be free of scale and suitable for inspection. A slight amount of oxidation is not considered scale.
14.2 Ferritic alloy hot-finished steel tubes shall be free of loose scale and suitable for inspection.
14.3 Stainless steel tubes shall be pickled free of scale.When bright annealing is used, pickling is not necessary.
14.4 Any special finish requirement shall be subject to agreement between the supplier and the purchaser.
 
 
15. Sampling
15.1 For flattening, flaring, and grain size requirements, the term lot applies to all tubes, prior to cutting, of the same size (see 4.1.7) that are produced from the same heat ofsteel. When final heat treatment is in a batch-type furnace, a lot shall include only those tubes of the same size and from the same heat that are heat treated in the same furnace charge. When the final heat treatment is in a continuous furnace or when the heat-treated condition is obtained directly by quenching after hot forming, the number of tubes ofthe same size and from the same heat in a lot shall be determined from the size ofthe tubes as prescribed in Table 7.

Size of Tube	Size of Lot
2 in. [50.8 mm] and over in outside diameter and 0.200 in. [5.1 mm] and over in wall thickness	not more than 50 tubes
2 in. [50.8 mm] and over in outside diameter and under 0.200 in. [5.1 mm] in wall thickness	not more than 75 tubes
Less than 2 in. [50.8 mm] but over 1 in. [25.4 mm] in outside diameter	not more than 75 tubes
1 in. [25.4 mm] or less in outside diameter	not more than 125 tubes

 
15.2 For tensile and hardness test requirements, the term lot applies to all tubes prior to cutting, of the same size (see 4.1.7) that are produced from the same heat of steel. When final heat treatment is in a batch-type furnace, a lot shall include only those tubes of the same size and the same heat that are heat treated in the same furnace charge. When the final heat treatment is in a continuous furnace, or when the heat-treated condition is obtained directly by quenching after hot forming,a lot shall include all tubes of the same size and heat, heat treated in the same furnace at the same temperature, time at heat, and furnace speed; or all tubes of the same size and heat,hot formed and quenched in the same production run, except as prescribed in 9.1.3.
 
 
16. Product Marking
16.1 In addition to the marking prescribed in Specification A1016/A1016M, the marking shall include: the condition, hot finished or cold finished; and the wall designation, minimum wall or average wall.
16.2 For the austenitic stainless steels having a grain size requirement (see Table 3) the marking shall also include the heat number and heat-treatment lot identification.
16.3 When either T2 or T12 are ordered with higher sulfur contents as permitted by Note B of Table 1, the marking shall include the letter, S, following the grade designation: T2S or T12S.
16.4 For T91, the marking shall also include the type.
 
 
17. Keywords
17.1 alloy steel tubes; austenitic stainless steel; boiler tubes;ferritic stainless steel; heat exchanger tubes; high-temperature applications; seamless steel tubes; steel tubes; superheater tubes; temperature service applications-high