Description
GB/T 18984 06Ni3MoDG & 06Ni9DG Low-Temperature Seameless Tubes
Material
Low-temperature seamless tubes manufactured to GB/T 18984 are alloy steel pipes designed for service down to –196 °C. The “DG” designation denotes enhanced impact toughness at subzero temperatures, achieved through controlled alloying (notably Ni and Mo) and thermal-mechanical processing.
Specifications
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Outer Diameter (OD): 10 mm – 219 mm
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Wall Thickness (WT): 1.5 mm – 30 mm
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Length: 2 m – 12 m (customizable)
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Surface Finish: Cold-drawn or hot-rolled, ultrasonic tested
Chemical Composition (wt %)
| Grade | C (max) | Si | Mn | P (max) | S (max) | Ni | Mo | V (max) |
|---|---|---|---|---|---|---|---|---|
| 16MnDG | 0.12–0.20 | 0.20–0.55 | 1.20–1.60 | 0.025 | 0.025 | – | – | – |
| 10MnDG | ≤ 0.13 | 0.17–0.37 | ≤ 1.35 | 0.025 | 0.025 | – | – | ≤ 0.07 |
| 09DG | ≤ 0.12 | 0.17–0.37 | ≤ 0.95 | 0.025 | 0.025 | – | – | ≤ 0.07 |
| 09Mn2VDG | ≤ 0.12 | 0.17–0.37 | ≤ 1.85 | 0.025 | 0.025 | – | – | ≤ 0.12 |
| 06Ni3MoDG | ≤ 0.08 | 0.17–0.37 | ≤ 0.85 | 0.025 | 0.025 | 2.5–3.7 | 0.15–0.30 | ≤ 0.05 |
| 06Ni9DG | ≤ 0.10 | 0.10–0.35 | ≤ 0.90 | ≤ 0.015 | ≤ 0.008 | 8.5–9.5 | – | – |
Mechanical Properties
| Grade | Tensile Strength R<sub>m</sub> (MPa) | Yield Strength R<sub>p0.2</sub> (MPa) | Elongation A (%) |
|---|---|---|---|
| 16MnDG | 490–665 | ≥ 315–325 | ≥ 30 |
| 10MnDG | ≥ 400 | ≥ 240 | ≥ 35 |
| 09DG | ≥ 385 | ≥ 210 | ≥ 35 |
| 09Mn2VDG | ≥ 450 | ≥ 300 | ≥ 30 |
| 06Ni3MoDG | ≥ 455 | ≥ 250 | ≥ 30 |
| 06Ni9DG | ≥ 690 | ≥ 515 | ≥ 22 |
Key Features
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Excellent Low-Temperature Toughness: Impact-tested to –196 °C without brittle fracture.
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High Strength: Alloying with Ni (and Mo for 06Ni3MoDG) yields superior yield and tensile levels.
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Corrosion Resistance: Seamless construction minimizes defects; alloying enhances general corrosion resistance.
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Thermal Conductivity: Optimized for efficient heat exchange in cryogenic systems.
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Fabrication Friendly: Available hot-rolled or cold-drawn; meets stringent dimensional tolerances.
Standards
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GB/T 18984-2016: Seamless steel tubes for low-temperature service
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ASTM A333/A333M: Standard specification for low-temperature carbon and alloy steel tubes
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JIS G3460: Alloy steel tubes for low-temperature service
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EN 10216-4: Alloy steel tubes for pressure purposes
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GOST 9941-81: Russian standard for low-temperature seamless pipes
Applications
Seamless low-temperature tubes are used wherever cryogenic service and pressure containment converge:
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LNG & LPG Infrastructure: Storage tanks, transfer lines, vaporizers.
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Air Separation Plants: Cryogenic distillation columns, heat exchangers.
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Chemical & Petrochemical: Ethylene/propylene refrigeration circuits, ammonia synthesis coolers.
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Pharmaceutical & Food Processing: Freeze-drying equipment, refrigerated storage.
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Industrial Cryogenics: Super-cold storage, research-grade cryostats, superconducting magnet cooling.
