ASTM A268/A268M Stainless Steel Tubing
ASTM A268/A268M
Standard Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service
1. Scope
1.1 This specification covers a number of grades of nominal-wall-thickness, stainless steel tubing for general corrosion-resisting and high-temperature service. Most of these grades are commonly known as the “straight-chromium” types and are characterized by being ferromagnetic. Two of these grades, TP410 and UNS S 41500 (Table 1), are amenable to hardening by heat treatment, and the high-chromium, ferritic alloys are sensitive to notch-brittleness on slow cooling to ordinary temperatures. These features should be recognized in the use of these materials. Grade TP439 is used primarily for hot-water tank service and does not require post-weld heat treatment to prevent attack of the heat affected zone.
1.2 An optional supplementary requirement is provided, and when desired, shall be so stated in the order.
1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.
2. Referenced Documents
2.1 ASTM Standards:
A 480/A 480M Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate,Sheet, and Strip
A 763 Practices for Detecting Susceptibility to Intergranular Attack in Ferritic Stainless Steels
A 1016/A 1016M Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes
E 213 Practice for Ultrasonic Examination of Metal Pipe and Tubing
E 273 Practice for Ultrasonic Examination of the Weld Zone of Welded Pipe and Tubing
3. Terminology
3.1 Lot Definitions:
3.1.1 For flange and flaring requirements, the term lot applies to all tubes, prior to cutting, of the same nominal size and wall thickness that are produced from the same heat of steel. If 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. If the final heat treatment is in a continuous furnace, the number of tubes of the same size and from the same heat in a lot shall be determined from the size of the tubes as given in Table 2.
3.1.2 For tensile and hardness test requirements, the term lot applies to all tubes, prior to cutting, of the same nominal diameter and wall thickness that are produced from the same heat of steel. If 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. If the final heat treatment is in a continuous furnace, 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.
4. Ordering Information
4.1 It is the responsibility of the purchaser to specify all requirements that are necessary for material ordered under this specification. Such requirements may include, but are not limited to, the following:
4.1.1 Quantity (feet, metres, or number of lengths),
4.1.2 Name of material (seamless or welded tubes),
4.1.3 Grade (Table 1),
4.1.4 Size (outside diameter and nominal wall thickness),
4.1.5 Length (specific or random),
4.1.6 Optional requirements (hydrostatic or nondestructive electric test, Section 16),
4.1.7 Test report required (Certification Section of Specification A 1016/A 1016M),
4.1.8 Specification designation,
4.1.9 Intergranular corrosion test, and
4.1.10 Special requirements.
5. General Requirements
5.1 Material furnished under this specification shall conform to the applicable requirements of Specification A 1016/A 1016M unless otherwise provided herein.
6. Manufacture
6.1 The tubes shall be made by the seamless or welded process with no filler metal added.
7. Heat Treatment
7.1 As a final heat treatment, tubes shall be reheated to a temperature of 1200 °F [650 °C] or higher and cooled (as appropriate for the grade) to meet the requirements of this specification.
7.2 The martensitic grade UNS S 41500 shall be reheated to a temperature of 950 °F [510 °C] or higher and cooled as appropriate to meet the requirements of this specification.
8. Chemical Composition
8.1 The steel shall conform to the chemical requirements prescribed in Table 1.
TABLE 1 Chemical Requirements
A For small diameter or thin walls, or both, tubing, where many drawing passes are required, a carbon maximum of 0.015 % is necessary. Small outside diameter tubes are defined as those less than 0.500 in. [12.7mm] in outside diameter and light wall tubes as those less than 0.049 in. [1.2 mm] in average wall thickness (0.040 in. [1 mm] in minimum wall thickness).
B Plate version of CA6NM.
C Carbon plus nitrogen = 0.30 max.
D Nickel plus copper.
E Carbon plus nitrogen = 0.025 % max.
F Cb/(C + N) = 12 min.
9. Product Analysis
9.1 An analysis of either one billet or one length of flatrolled stock or one tube shall be made from each heat. The chemical composition thus determined shall conform to the requirements specified.
9.2 The product analysis tolerance of the Chemical Requirements Table of A 480/A 480M shall apply. The product analysis tolerance is not applicable to the carbon content for material with a specified maximum carbon of 0.04 % or less.
9.3 If the original test for product analysis fails, retests of two additional billets, lengths of flat-rolled stock or tubes shall be made. Both retests for the elements in question shall meet the requirements of the specification; otherwise all remaining material in the heat or lot shall be rejected or, at the option of the producer, each billet or tube may be individually tested for acceptance. Billets, lengths of flat-rolled stock or tubes which do not meet the requirements of the specification shall be rejected.
10. Tensile Requirements
10.1 The material shall conform to the tensile properties prescribed in Tables 3 and 4.
A For tubing smaller than 1 ⁄ 2 in. [12.7 mm] in outside diameter, the elongation values given for strip specimens in Table 2 shall apply. Mechanical property requirements do not apply to tubing smaller than 1 ⁄ 8 in. [3.2 mm] in outside diameter or with walls thinner than 0.015 in. [0.4 mm].
B For longitudinal strip tests a deduction of 0.90 % for TP446–1 and S 44735 and 1.00 % for all other grades shall be made from the basic minimum elongation for each 1 ⁄ 32 in. [0.8 mm] decrease in wall thickness below 5 ⁄ 16 in. [8 mm]. The following table gives the computed minimum values:
A Calculated elongation requirements shall be rounded to the nearest whole number.
Note—The above table gives the computed minimum values for each 1 ⁄ 32 in.[0.8 mm] decrease in wall thickness. Where the wall thickness lies between two values shown above, the minimum elongation value shall be determined by the following equation:
where:
E = elongation in 2 in. or 50 mm, %.
t = actual thickness of specimen, in.[mm].
11. Hardness Requirements
11.1 The tubes shall have a hardness number not to exceed those prescribed in Table 5.
A Editorially corrected October 2000.
B Rockwell hardness, C scale.
12. Permissible Variations in Dimensions
12.1 Variations in outside diameter, wall thickness, and length from those specified shall not exceed the amounts prescribed in Table 6.
A When tubes as ordered require wall thicknesses 3 ⁄ 4 in. [19 mm] or over, or an inside diameter 60 % or less of the outside diameter, a wider variation in wall thickness is required. On such sizes a variation in wall thickness of 12.5 % over or under will be permitted. For tubes less than 1 ⁄ 2 in. [12.7 mm] in inside diameter which cannot be successfully drawn over a mandrel, the wall thickness may vary 615 % from that specified.
B These tolerances apply to cut lengths up to and including 24 ft [7.3 m]. For lengths greater than 24 ft [7.3 m], the above over tolerances shall be increased by 1 ⁄ 8 in.[3 mm] for each 10 ft [3 m] or fraction thereof over 24 ft, or 1 ⁄ 2 in. [13 mm], whichever is lesser.
C Ovality provisions of 12.2 apply.
12.2 The permissible variations in outside diameter given in Table 6 are not sufficient to provide for ovality in thin-walled tubes, as defined in the Table. In such tubes, the maximum and minimum diameters at any cross section shall deviate from the nominal diameter by no more than twice the permissible variation in outside diameter given in Table 6; however, the mean diameter at that cross section must still be within the given permissible variation.
12.3 When the specified wall is 2 % or less of the specified outside diameter, the method of measurement is in accordance with the agreement between the purchaser and the manufacturer (see Note 1).
NOTE 1—Very thin wall tubing may not be stiff enough for the outside diameter to be accurately measured with a point contact test method, such as with the use of a micrometer or caliper. When very thin walls are specified, “go”–“no go” ring gages are commonly used to measure diameters of 1 1 ⁄ 2 in. [38.1 mm] or less. A0.002-in. [0.05-mm] additional tolerance is usually added on the “go” ring gage to allow clearance for sliding. On larger diameters, measurement is commonly performed with a pi tape. Other test methods such as optical test methods may also be considered.
13. Surface Condition
13.1 All tubes shall be free of excessive mill scale, suitable for inspection. A slight amount of oxidation will not be considered as scale. Any special finish requirements shall be considered to agreement between the manufacturer and the purchaser.
14. Mechanical Tests Required
14.1 Tension Tests—One tension test shall be made on a specimen 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.
14.2 Flaring Test (for Seamless Tubes)— One test shall be made on specimens from one end of one tube from each lot of finished tubes. The minimum expansion of the inside diameter shall be 10 %. For tubes over 8 in. [203.2 mm] in outside diameter, or tubes with wall thickness 3 ⁄ 8 in. [9.52 mm] and over, the flattening test may be performed instead of the flaring test unless the flaring test is specified in the purchase order.
14.3 Flange Test (for Welded Tubes)— One test shall be made on specimens from one end of one tube from each lot of finished tubes. For tubes over 8 in. [203.2 mm] in outside diameter, or tubes with wall thickness 3 ⁄ 8 in. [9.52 mm] and over, the flattening test may be performed instead of the flange test unless the flange test is specified in the purchase order.
14.4 Hardness Test—Brinell or Rockwell hardness tests shall be made on specimens from two tubes from each lot.
14.5 When more than one heat is involved, the tension,flaring, flanging, and hardness test requirements shall apply to each heat.
14.6 Reverse Flattening Test—For welded tubes, one reverse flattening test shall be made on a specimen from each 1500 ft [450 m] of finished tubing.
15. Intergranular Corrosion Test
15.1 If intergranular corrosion testing is specified in the purchase order, the test shall be made in accordance with Practices A 763, using samples prepared as agreed upon between the seller and the purchaser.
16. Hydrostatic or Nondestructive Electric Test
16.1 Each tube, seamless or welded, 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.
17. Product Marking
17.1 In addition to the marking described in Specification A 1016/A 1016M, the marking shall indicate whether the tubing is seamless or welded.
18. Keywords
18.1 ferritic stainless steel; seamless steel tube; stainless steel tube; steel tube; welded steel tube
Standard Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service
1. Scope
1.1 This specification covers a number of grades of nominal-wall-thickness, stainless steel tubing for general corrosion-resisting and high-temperature service. Most of these grades are commonly known as the “straight-chromium” types and are characterized by being ferromagnetic. Two of these grades, TP410 and UNS S 41500 (Table 1), are amenable to hardening by heat treatment, and the high-chromium, ferritic alloys are sensitive to notch-brittleness on slow cooling to ordinary temperatures. These features should be recognized in the use of these materials. Grade TP439 is used primarily for hot-water tank service and does not require post-weld heat treatment to prevent attack of the heat affected zone.
1.2 An optional supplementary requirement is provided, and when desired, shall be so stated in the order.
1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.
2. Referenced Documents
2.1 ASTM Standards:
A 480/A 480M Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate,Sheet, and Strip
A 763 Practices for Detecting Susceptibility to Intergranular Attack in Ferritic Stainless Steels
A 1016/A 1016M Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes
E 213 Practice for Ultrasonic Examination of Metal Pipe and Tubing
E 273 Practice for Ultrasonic Examination of the Weld Zone of Welded Pipe and Tubing
3. Terminology
3.1 Lot Definitions:
3.1.1 For flange and flaring requirements, the term lot applies to all tubes, prior to cutting, of the same nominal size and wall thickness that are produced from the same heat of steel. If 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. If the final heat treatment is in a continuous furnace, the number of tubes of the same size and from the same heat in a lot shall be determined from the size of the tubes as given in Table 2.
3.1.2 For tensile and hardness test requirements, the term lot applies to all tubes, prior to cutting, of the same nominal diameter and wall thickness that are produced from the same heat of steel. If 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. If the final heat treatment is in a continuous furnace, 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.
TABLE 2 Number of Tubes in a Lot Heat Treated by the Continuous Process
| 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 |
|
Less than 2 in. [50.8 mm] but over 1 in. [25.4 mm] in outside diameter or over 1 in. [25.4 mm] in outside diameter and under 0.200 in. [5.1 mm] in wall thickness |
not more than 75 tubes |
| 1 in. [25.4 mm] or less in outside diameter | not more than 125 tubes |
4. Ordering Information
4.1 It is the responsibility of the purchaser to specify all requirements that are necessary for material ordered under this specification. Such requirements may include, but are not limited to, the following:
4.1.1 Quantity (feet, metres, or number of lengths),
4.1.2 Name of material (seamless or welded tubes),
4.1.3 Grade (Table 1),
4.1.4 Size (outside diameter and nominal wall thickness),
4.1.5 Length (specific or random),
4.1.6 Optional requirements (hydrostatic or nondestructive electric test, Section 16),
4.1.7 Test report required (Certification Section of Specification A 1016/A 1016M),
4.1.8 Specification designation,
4.1.9 Intergranular corrosion test, and
4.1.10 Special requirements.
5. General Requirements
5.1 Material furnished under this specification shall conform to the applicable requirements of Specification A 1016/A 1016M unless otherwise provided herein.
6. Manufacture
6.1 The tubes shall be made by the seamless or welded process with no filler metal added.
7. Heat Treatment
7.1 As a final heat treatment, tubes shall be reheated to a temperature of 1200 °F [650 °C] or higher and cooled (as appropriate for the grade) to meet the requirements of this specification.
7.2 The martensitic grade UNS S 41500 shall be reheated to a temperature of 950 °F [510 °C] or higher and cooled as appropriate to meet the requirements of this specification.
8. Chemical Composition
8.1 The steel shall conform to the chemical requirements prescribed in Table 1.
TABLE 1 Chemical Requirements
| Grade | TP405 | TP410 | TP429 | TP430 | TP443 | TP446–1 | TP446–2 A | ... | TP409 |
|
UNS Designation |
S40500 | S41000 | S42900 | S43000 | S44300 | S44600 | S44600 | S40800 | S40900 |
| Element | |||||||||
| C, max | 0.08 | 0.15 | 0.12 | 0.12 | 0.20 | 0.20 | 0.12 | 0.08 | 0.08 |
| Mn, max | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.50 | 1.50 | 1.00 | 1.00 |
| P, max | 0.040 | 0.040 | 0.040 | 0.040 | 0.040 | 0.040 | 0.040 | 0.045 | 0.045 |
| S, max | 0.030 | 0.030 | 0.030 | 0.030 | 0.030 | 0.030 | 0.030 | 0.045 | 0.030 |
| Si, max | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Ni | 0.50 max | .... | .... | .... | 0.75 max | 0.75 max | 0.50 max | 0.80 max | 0.50 max |
| Cr | 11.5–14.5 | 11.5–13.5 | 14.0–16.0 | 16.0–18.0 | 18.0–23.0 | 13.0–27.0 | 23.0–27.0 | 11.5–13.0 | 10.5–11.7 |
| Mo | .... | .... | .... | .... | .... | .... | .... | .... | .... |
| Al | 0.10–0.30 | .... | .... | .... | .... | .... | .... | .... | .... |
| Cu | .... | .... | .... | .... | 0.90–1.25 | .... | .... | .... | .... |
| N | .... | .... | .... | .... | .... | 0.25 | 0.25 | .... | .... |
| Ti | .... | .... | .... | .... | .... | .... | .... |
12 * C min; 1.10 max |
6 3 C min; 0.75 max |
TABLE 1 Continued
A For small diameter or thin walls, or both, tubing, where many drawing passes are required, a carbon maximum of 0.015 % is necessary. Small outside diameter tubes are defined as those less than 0.500 in. [12.7mm] in outside diameter and light wall tubes as those less than 0.049 in. [1.2 mm] in average wall thickness (0.040 in. [1 mm] in minimum wall thickness).
B Plate version of CA6NM.
C Carbon plus nitrogen = 0.30 max.
D Nickel plus copper.
E Carbon plus nitrogen = 0.025 % max.
F Cb/(C + N) = 12 min.
9. Product Analysis
9.1 An analysis of either one billet or one length of flatrolled stock or one tube shall be made from each heat. The chemical composition thus determined shall conform to the requirements specified.
9.2 The product analysis tolerance of the Chemical Requirements Table of A 480/A 480M shall apply. The product analysis tolerance is not applicable to the carbon content for material with a specified maximum carbon of 0.04 % or less.
9.3 If the original test for product analysis fails, retests of two additional billets, lengths of flat-rolled stock or tubes shall be made. Both retests for the elements in question shall meet the requirements of the specification; otherwise all remaining material in the heat or lot shall be rejected or, at the option of the producer, each billet or tube may be individually tested for acceptance. Billets, lengths of flat-rolled stock or tubes which do not meet the requirements of the specification shall be rejected.
10. Tensile Requirements
10.1 The material shall conform to the tensile properties prescribed in Tables 3 and 4.
TABLE 3 Tensile Requirements
| Grade and UNS Designation |
Tensile strength,min, ksi [MPa] |
Yield strength,min, ksi [MPa] |
Elongation A,B in 2 in. or 50 mm,min, % |
|
TP405 S40500 |
60 [415] | 30 [205] | 20 |
|
. . . S40800 |
55 [380] | 30 [205] | 20 |
|
TP410 S41000 |
60 [415] | 30 [205] | 20 |
|
TP429, TP430, and TP430 Ti S429000, S 43000, and S 43036 |
60 [415] | 35 [240] | 20 |
|
TP443 S44300 |
70 [485] | 40 [275] | 20 |
|
TP446-1 S44600 |
70 [485] | 40 [275] | 18 |
|
TP446-2 S44600 |
65 [450] | 40 [275] | 20 |
|
TP409 S40900 |
55 [380] | 25 [170] | 20 |
|
TP439 S43035 |
60 [415] | 30 [205] | 20 |
| S43932 | 60 [415] | 30 [205] | 20 |
|
. . . S41500 |
115 [795] | 90 [620] | 15 |
|
TPXM-27 S44627 |
65 [450] | 40 [275] | 20 |
|
TPXM-33 S44626 |
68 [470] | 45 [310] | 20 |
|
18Cr-2Mo S44400 |
60 [415] | 40 [275] | 20 |
|
29-4 and 29-4-2 S44700 and S44800 |
80 [550] | 60 [415] | 20 |
|
26-3-3 S44660 |
85 [585] | 65 [450] | 20 |
|
25-4-4 S44635 |
90 [620] | 75 [515] | 20 |
|
. . . S44735 |
75 [515] | 60 [415] | 18 |
|
28-2-3.5 S32803 |
87 [600] | 72 [500] | 16 |
| S40977 | 65 [450] | 41 [280] | 18 |
| S43940 | 62 [430] | 36 [250] | 18 |
| S42035 | 80 [550] | 55 [380] | 16 |
|
TP468 S46800 |
60 [415] | 30 [205] | 22 |
A For tubing smaller than 1 ⁄ 2 in. [12.7 mm] in outside diameter, the elongation values given for strip specimens in Table 2 shall apply. Mechanical property requirements do not apply to tubing smaller than 1 ⁄ 8 in. [3.2 mm] in outside diameter or with walls thinner than 0.015 in. [0.4 mm].
B For longitudinal strip tests a deduction of 0.90 % for TP446–1 and S 44735 and 1.00 % for all other grades shall be made from the basic minimum elongation for each 1 ⁄ 32 in. [0.8 mm] decrease in wall thickness below 5 ⁄ 16 in. [8 mm]. The following table gives the computed minimum values:
TABLE 4 Minimum Elongation Values
| Wall Thickness | Elongation A in 2 in. or 50 mm, min, % | |||
| in. | mm |
TP446–1 and S 44735 |
S41500 |
All Other Grades |
| 5 ⁄ 16 [0.312] | 8 | 18 | 15 | 20 |
| 9 ⁄ 32 [0.281] | 7.2 | 17 | 14 | 19 |
| 1 ⁄ 4 [0.250] | 6.4 | 16 | 14 | 18 |
| 7 ⁄ 32 [0.219] | 5.6 | 15 | 13 | 17 |
| 3 ⁄ 16 [0.188] | 4.8 | 14 | 12 | 16 |
| 5 ⁄ 32 [0.156] | 4 | 13 | 11 | 15 |
| 1 ⁄ 8 [0.125] | 3.2 | 13 | 11 | 14 |
| 3 ⁄ 32 [0.094] | 2.4 | 12 | 10 | 13 |
| 1 ⁄ 16 [0.062] | 1.6 | 11 | 9 | 12 |
| 0.062–0.035, excl | 1.6–0.9 | 10 | 8 | 12 |
| 0.035–0.022, excl | 0.9–0.6 | 10 | 8 | 11 |
| 0.022–0.015, incl | 0.6–0.4 | 10 | 8 | 11 |
A Calculated elongation requirements shall be rounded to the nearest whole number.
Note—The above table gives the computed minimum values for each 1 ⁄ 32 in.[0.8 mm] decrease in wall thickness. Where the wall thickness lies between two values shown above, the minimum elongation value shall be determined by the following equation:
| Grade | Equation |
| TP446–1 and S 44735 | E = 28.8t + 9.00 [E = 1.13t + 9.00] |
| S41500 | E = 24t + 7.5 |
| All other grades | E = 32t + 10.00 [E = 1.25t + 10.00] |
where:
E = elongation in 2 in. or 50 mm, %.
t = actual thickness of specimen, in.[mm].
11. Hardness Requirements
11.1 The tubes shall have a hardness number not to exceed those prescribed in Table 5.
TABLE 5 Hardness Requirements.
| Grade | UNS Designation |
Brinell Hardness, max |
Rockwell Hardness, B Scale, max |
| TP405 | S40500 | 207 | 95 |
| . . . | S40800 | 207 | 95 |
| TP410 | S41000 | 207 | 95 |
|
TP429, TP430, and TP430 TI |
S42900, S 43000, and S 43036 |
190 | 90 |
| TP443 | S44300 | 207 | 95 |
|
TP446-1 and TP446-2 |
S44600 | 207 | 95 |
| TP409 | S40900 | 207 | 95 |
| TP439 | S43035 A | 190 | 90 |
| S43932 | 190 | 90 | |
| . . . | S41500 | 295 B | 32 |
|
TPXM-33 and TPXM-27 |
S44626 and S44627 |
241 | 100 |
| 18CR-2Mo | S44400 | 217 | 95 |
| 29-4 and 29-4-2 |
S44700 and S44800 |
207 | 100 |
| 26-3-3 | S44660 | 265 | 25 B |
| 25-4-4 | S44635 | 270 | 27 B |
| . . . | S44735 | . . . | 100 |
| 28-2-3.5 | S32803 | 240 | 100 |
| . . . | S40977 | 180 | 88 |
| . . . | S43940 | 180 | 88 |
| . . . | S42035 | 180 | 88 |
A Editorially corrected October 2000.
B Rockwell hardness, C scale.
12. Permissible Variations in Dimensions
12.1 Variations in outside diameter, wall thickness, and length from those specified shall not exceed the amounts prescribed in Table 6.
TABLE 6 Permissible Variations in Dimensions
| Group |
Size, Outside Diameter, in.[mm] |
Permissible Vari- ations in Outside Diameter, in. [mm] |
Permissible Variations in Wall Thickness, A % |
Permissible Variations in Cut Length, in. B [mm] |
Thin-Walled Tubes C | |
| 1 |
Up to 1 ⁄ 2 [12.7], excl |
±0.005 [0.13] | ±15 | 1 ⁄ 8 [3] | 0 | . . . |
| 2 | 1 ⁄ 2 to 1 1 ⁄ 2 [12.7 to 38.1], excl | ±0.005 [0.13] | ±10 | 1 ⁄ 8 [3] | 0 |
less than 0.065 in. [1.6 mm] nominal |
| 3 |
1 1 ⁄ 2 to 3 1 ⁄ 2 [38.1 to 88.9], excl |
±0.010 [0.25] | ±10 | 3 ⁄ 16 [5] | 0 |
less than 0.095 in. [2.4 mm] nominal |
| 4 |
3 1 ⁄ 2 to 5 1 ⁄ 2 [88.9 to 139.7], excl |
±0.015 [0.38] | ±10 | 3 ⁄ 16 [5] | 0 |
less than 0.150 in. [3.8 mm] nominal |
| 5 |
5 1 ⁄ 2 to 8 [139.7 to 203.2], incl |
±0.030 [0.76] | ±10 | 3 ⁄ 16 [5] | 0 |
less than 0.150 in. [3.8 mm] nominal |
A When tubes as ordered require wall thicknesses 3 ⁄ 4 in. [19 mm] or over, or an inside diameter 60 % or less of the outside diameter, a wider variation in wall thickness is required. On such sizes a variation in wall thickness of 12.5 % over or under will be permitted. For tubes less than 1 ⁄ 2 in. [12.7 mm] in inside diameter which cannot be successfully drawn over a mandrel, the wall thickness may vary 615 % from that specified.
B These tolerances apply to cut lengths up to and including 24 ft [7.3 m]. For lengths greater than 24 ft [7.3 m], the above over tolerances shall be increased by 1 ⁄ 8 in.[3 mm] for each 10 ft [3 m] or fraction thereof over 24 ft, or 1 ⁄ 2 in. [13 mm], whichever is lesser.
C Ovality provisions of 12.2 apply.
12.2 The permissible variations in outside diameter given in Table 6 are not sufficient to provide for ovality in thin-walled tubes, as defined in the Table. In such tubes, the maximum and minimum diameters at any cross section shall deviate from the nominal diameter by no more than twice the permissible variation in outside diameter given in Table 6; however, the mean diameter at that cross section must still be within the given permissible variation.
12.3 When the specified wall is 2 % or less of the specified outside diameter, the method of measurement is in accordance with the agreement between the purchaser and the manufacturer (see Note 1).
NOTE 1—Very thin wall tubing may not be stiff enough for the outside diameter to be accurately measured with a point contact test method, such as with the use of a micrometer or caliper. When very thin walls are specified, “go”–“no go” ring gages are commonly used to measure diameters of 1 1 ⁄ 2 in. [38.1 mm] or less. A0.002-in. [0.05-mm] additional tolerance is usually added on the “go” ring gage to allow clearance for sliding. On larger diameters, measurement is commonly performed with a pi tape. Other test methods such as optical test methods may also be considered.
13. Surface Condition
13.1 All tubes shall be free of excessive mill scale, suitable for inspection. A slight amount of oxidation will not be considered as scale. Any special finish requirements shall be considered to agreement between the manufacturer and the purchaser.
14. Mechanical Tests Required
14.1 Tension Tests—One tension test shall be made on a specimen 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.
14.2 Flaring Test (for Seamless Tubes)— One test shall be made on specimens from one end of one tube from each lot of finished tubes. The minimum expansion of the inside diameter shall be 10 %. For tubes over 8 in. [203.2 mm] in outside diameter, or tubes with wall thickness 3 ⁄ 8 in. [9.52 mm] and over, the flattening test may be performed instead of the flaring test unless the flaring test is specified in the purchase order.
14.3 Flange Test (for Welded Tubes)— One test shall be made on specimens from one end of one tube from each lot of finished tubes. For tubes over 8 in. [203.2 mm] in outside diameter, or tubes with wall thickness 3 ⁄ 8 in. [9.52 mm] and over, the flattening test may be performed instead of the flange test unless the flange test is specified in the purchase order.
14.4 Hardness Test—Brinell or Rockwell hardness tests shall be made on specimens from two tubes from each lot.
14.5 When more than one heat is involved, the tension,flaring, flanging, and hardness test requirements shall apply to each heat.
14.6 Reverse Flattening Test—For welded tubes, one reverse flattening test shall be made on a specimen from each 1500 ft [450 m] of finished tubing.
15. Intergranular Corrosion Test
15.1 If intergranular corrosion testing is specified in the purchase order, the test shall be made in accordance with Practices A 763, using samples prepared as agreed upon between the seller and the purchaser.
16. Hydrostatic or Nondestructive Electric Test
16.1 Each tube, seamless or welded, 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.
17. Product Marking
17.1 In addition to the marking described in Specification A 1016/A 1016M, the marking shall indicate whether the tubing is seamless or welded.
18. Keywords
18.1 ferritic stainless steel; seamless steel tube; stainless steel tube; steel tube; welded steel tube