ASTM A333 covers seamless and welded carbon and alloy steel pipe for use in cryogenic environments. During the manufacturing process of these steel pipes, whether using seamless or welding processes, there is no need to add filler metal during the welding process. At the same time, all these steel pipes require microstructural control processing. The standard covers multiple ferritic steel grades, including Grade 1, Grade 3, Grade 4, Grade 6, Grade 7, Grade 8, Grade 9, Grade 10 and Grade 11. Of these grades, Grade 6 is the most commonly used steel grade.
Chemical Requirements:
Composition, %
| Element | Grade 1 | Grade 3 | Grade 6 |
| Carbon, max | 0.30 | 0.19 | 0.30 |
| Manganese | 0.40 – 1.06 | 0.31 – 0.64 | 0.29 – 1.06 |
| Phosphorous, max | 0.025 | 0.025 | 0.025 |
| Sulfur, max | 0.025 | 0.025 | 0.025 |
| Silicon | 0.18 – 0.37 | 0.10 min | |
| Nickel | 3.18 – 3.82 |
Mechanical Properties:
| Grade 1 | Grade 3 | Grade 6 | |
| Tensile Strength, min, psi (MPa) | 55,000 (380) | 65,000 (450) | 60,000 (415) |
| Yield Strength, min, psi (MPa) | 30,000 (205) | 35,000 (240) | 35,000 (240) |
CVN Impact (Charpy) Test:
Minimum Impact Test Temperature
| Grade 1 | -50 (F) | -45 (°C) |
| Grade 3 | -150 (F) | -100 (°C) |
| Grade 6 | -50 (F) | -45 (°C) |
Heat Treatment:
Normalizing by heating to a uniform temperature not less than 1500 °F [815 °C] and cooling in air or in the cooling chamber of an atmosphere-controlled furnace. Or normalized as above and reheated to appropriate tempering temperature at manufacturer's discretion.
For seamless processes only, reheat and control the temperature of hot working and hot finishing operations to the finishing temperature range of 1550 to 1750 °F [845 to 945 °C] and cool in air or in a controlled atmosphere furnace . Initial temperature is not less than 1550 °F [845 °C]. Or processed as above and reheated to appropriate tempering temperature at manufacturer's discretion.
Grades 1, 6, and 10 seamless pipe may be heat treated by heating to a uniform temperature not less than 1500 °F [815 °C], then quenched in a liquid and reheated to the appropriate tempering temperature.
