ASTM A333 Gr.3 Seamless Low-Temperature Steel Pipe
Dec 05, 2025
What Is A333 Gr.3 Pipe
A333 Gr.3 is a seamless steel pipe material specifically designed for low-temperature environments within the ASTM A333 standard, belonging to the 3.5 percent nickel series of low-temperature alloy steels. Its core feature is the low-carbon, high-nickel composition design. By precisely controlling the carbon content (0.19 percent maximum) and adding 3.18-3.82 percent nickel, it significantly enhances the steel's low-temperature toughness, enabling it to maintain stable mechanical properties at about minus 100 deg C and effectively prevent low-temperature embrittlement.
Chemical Composition
| Element | Grade 3 |
|---|---|
| Carbon, max | 0.19 |
| Silicon | 0.18-0.37 |
| Manganese | 0.31-0.64 |
| Phosphorus, max | 0.025 |
| Sulfur, max | 0.025 |
| Nickel | 3.18-3.82 |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile strength | 450 MPa (min) |
| Yield strength | 240 MPa (min) |
| Elongation | 15 percent (min) |
| Impact test temperature | Minus 101 deg C (minus 150 deg F) |
Impact energy follows the A333 tables, for example 18 J average for full-size specimens at minus 101 deg C.
Equivalent Material
The equivalent material of A333 Gr.3 is 16MnDG, which complies with the GB/T 18984 standard. This material is specifically designed for low-temperature environments and is commonly used in pressure vessels and heat exchanger piping systems.
A333 vs API 5L
| Comparison item | ASTM A333 | API 5L |
|---|---|---|
| Standard type | Material standard (composition and mechanical properties) | Product standard (dimensions, manufacture, inspection of line pipe) |
| Primary purpose | Low-temperature environments | Transportation of oil, natural gas, and other fluids |
| Core requirements | Low-temperature toughness | Strength, toughness, weldability, corrosion resistance |
| Typical materials | A333 Gr.3 (about 3.5 percent nickel), Gr.6, Gr.8 | X42, X52, X70 (carbon-manganese steels) |
| Manufacturing | Requires normalizing to refine grain | Hot rolling, cold rolling, heat treatment |
Applications
LNG industry: piping in LNG terminals and low-temperature transportation systems. Cryogenic chemical equipment: heat exchange pipes for reactors and condensers in ethylene and propylene production. Oil and gas extraction: platform piping in cold regions, with fatigue resistance extending service life. Gr.3 is also specified for service down to about minus 100 deg C where Grade 6 cannot provide the required toughness.
Frequently Asked Questions
Q: What is A333 Gr.3 pipe? A: A 3.5 percent nickel low-temperature steel pipe per ASTM A333 for service down to about minus 100 deg C.
Q: What is the equivalent material? A: 16MnDG per GB/T 18984.
Q: What is the tensile strength of Gr.3? A: 450 MPa minimum, with 240 MPa minimum yield strength.
Q: What is the impact test temperature? A: About minus 101 deg C (minus 150 deg F).
Q: What is the difference between Gr.3 and Gr.6? A> Gr.3 uses 3.5 percent nickel for toughness to about minus 100 deg C; Gr.6 is nickel-free and limited to about minus 45 deg C.
Q: Where is Gr.3 used? A: LNG terminals, cryogenic chemical plants, and cold-region oil and gas platforms.
Need A333 Gr.3 pipe for your low-temperature project? Contact us with your size and impact-test requirement for a quotation.
