Complaint
ASTM A268 is Standard specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service, the grades contain TP410, TP405, TP420, TP430, TP430Ti, TP403, TP409, TP444, TP439 and TP446, it covers standard specification for a number of grades of nominal-wall-thickness, welded ferritic and martensitic stainless steel tubing for general corrosion-resisting and high-temperature service, ASME SA268 is alternative standard.
The tubes shall be made by the seamless or welded process with no filler metal added, tubes shall be reheated to a temperature of 1200.F [650.C] or higher and cooled to meet the requirements of this specification, All tubes shall be free of excessive mill scale, suitable for inspection. A slight amount of oxidation will not be considered as scale.
| Standard | ASTM A268, ASME SA268 |
|---|---|
| Tube Type | Both Welded And Seamless |
| Grades | ASTM A268 TP 410, ASTM A268 TP 430, ASTM A268 TP 439 |
| Outside Diameter | 1/4″ (6.25mm) To 8″ (203mm) |
| Wall Thickness | 0.02″ (0.5mm) To 0.5″(12mm) |
| Application | Heat Exchanger, Heater, Condenser |
The steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, aluminum, copper, nitrogen, titanium, and columbium, most of these grades are commonly characterized by being ferromagnetic.
| Grade: | TP410 | TP430 | TP439 |
|---|---|---|---|
| UNS | S41000 | S43000 | S43035 |
| C, Max | 0.15 | 0.12 | 0.07 |
| Mn,Max | 1.00 | 1.00 | 1.00 |
| P, Max | 0.04 | 0.04 | 0.040 |
| S, Max | 0.03 | 0.03 | 0.030 |
| Si, Max | 1.00 | 1.00 | 1.00 |
| Ni | … | … | 0.50max |
| Cr | 11.5-13.5 | 16.0-18.0 | 17.00-19.00 |
| Mo | … | … | … |
| Al | … | … | 0.15 |
| Cu | … | … | … |
| N | … | … | 0.04 |
| Ti | … | … | 0.20+4(C+N)Min, 1.10max |
ASTM A268 mainly contains 400 series Ferritic and Martensitic stainless steel grades, without or with slight Nickel element, so they have advantages on price compared to 304 or 316L stainless steel, that is the common used grade.
Variations in outside diameter, wall thickness, and length from those specified shall not exceed the amounts prescribed below.
| Outside Diameter, In.[Mm] | OD Tolerance, In.[Mm] | Wall Thickness, % | Thin Wall Tubes |
|---|---|---|---|
| Up To1⁄2, [12.7], Excl | ±0.005 [0.13] | ±15 | |
| 1⁄2 To 11⁄2 [12.7 To 38.1], Excl/Td>
| ±0.005 [0.13] | ±10< | Less Than 0.065 In. [1.6 Mm] Nominal |
| 11⁄2 To 31⁄2 [38.1 To 88.9], Excl | ±0.010 [0.25] | ±10 | Less Than 0.095 In. [2.4 Mm] Nominal |
| 31⁄2 To 51⁄2 [88.9 To 139.7], Excl | ±0.015 [0.38] | ±10 | Less Than 0.150 In. [3.8 Mm] Nominal |
| 51⁄2 To 8 [139.7 To 203.2], Incl | ±0.030 [0.76] | ±10 | Less Than 0.150 In. [3.8 Mm] Nominal |
The steel shall conform to the following tensile properties: tensile strength, yield strength, and elongation.
| Grade | Tensile Strength, Min, Ksi [MPa] | Yield Strength, Min, Ksi [MPa] | ELONGATION. MIN, % |
|---|---|---|---|
| TP410 | 55 [380] | 30 [205] | 20 |
| TP430 | 60 [415] | 35 [240] | 20 |
| TP439 | 60 [415] | 30 [205] | 20 |
The tubes shall have a hardness number that will not exceed the prescribed Brinell and Rockwell hardness values, TP410, TP430 and TP439 max Rockwell hardness 90, Test report required certification conform to Specification A1016/A1016M.
Several mechanical tests shall be conducted, namely:
