TORICH INTERNATIONAL LIMITED
TORICH INTERNATIONAL LIMITED The Steel Tube Maker
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TORICH GB/T 18984 Seamless Steel Tubes For Low-Temperature-Service Piping
Application:For Low-Temperature-Service Piping
Material:16MnDG,10MnDG,09DG,09Mn2VDG,06Ni3MoDG
Unit:mm
| Hot Roll(Extrusion,Expansion)Steel Tube | Cold Drawn(Roll) Steel Tube | ||||||
| Diamension | Tolerance | Diamension | Tolerance | ||||
| Ordinary Level PA | High Level PC | Ordinary Level PA | High Level PC | ||||
Nominal Outer Diameter | ＜76.1 | ±1.25%D | ±0.60 | Nominal Outer Diameter | ＜12.7 | ±0.30 | ±0.10 |
| 76.1~＜139.7 | ±0.80 | 12.7~＜38.1 | ±0.30 | ±0.15 | |||
| 139.7~＜273.1 | ±1.5%D | ±1.20 | 38.1~＜88.9 | ±0.40 | ±0.30 | ||
| 88.9~＜139.7 | ±0.9%D | ±0.40 | |||||
| 273.1~＜323.9 | ±1.60 | 139.7~＜203.2 | ±0.80 | ||||
| 203.2~＜219.1 | ±1.10 | ||||||
| ≥323.9 | ±0.6%D | 219.1~＜323.9 | ±1.60 | ||||
| ≥323.9 | ±0.5%D | ||||||
Nominal Wall Thinckness | All Wall Thickness | +15%S | ±12.5%S | Nominal Wall Thinckness | All Wall Thickness | +12.5%S | ±10%S |
Permissible deviation tolerance of OD and WT
| Classfication | Steel size | Permissible tolerance | |
| W-H | OD | ＜351 | ±1.0%D |
| ≥351 | ±1.25%D | ||
| WT | ≤25 | ±12.5%S | |
| W-C | OD | ≤30 | ±0.20 |
| ＞30~50 | ±0.30 | ||
| ＞50 | ±0.75%D | ||
| WT | ≤3 | ＋12.5%S | |
| ＞3 | ±10%S | ||
Steel grade and chemical composition
| Steel grade | Chemical composition/% | |||||||
| C | Si | Mn | P | S | Ni | Mo | V | |
| 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 | — | — | ≤0.05 |
Longitudinal mechanical properties of steel tubes
| Steel grade | Tensile strength | Lower yield strength Rp0.2/MPa | Elongation A/％ | |||
| S≤16mm | S＞16mm | Sample 1 | Sample 2 | Sample 3 | ||
| 16MnDG | 490~665 | ≥325 | ≥315 | ≥30 | ||
| 10MnDG | ≥400 | ≥240 | ≥35 | |||
| 09DG | ≥385 | ≥210 | ≥30 | |||
| 09Mn2VDG | ≥450 | ≥300 | ≥30 | |||
| 06Ni3MoDG | ≥455 | ≥250 | ≥30 | |||
Testing items and sampling quantity of steel tubes
| Number | Testing items | Sampling quantity |
| 1 | Chemical composition | 1 sample from each furnace |
| 2 | Tensile test | 1 sample from each of two steel tubes on each batch |
| 3 | Hardness test | 1 sample from each of two steel tubes on each batch |
| 4 | Ultrasonic testing | ALL |
| 5 | Hydraulic test | ALL |
