High-Precision Seamless Steel Pipe & Tube
Our Precision Steel Pipes are manufactured through advanced cold drawing and hot rolling processes, ensuring inner and outer walls with no oxide layer. Known for high pressure resistance without leakage, exceptional smoothness, and high precision (internal and external diameter control within +/- 0.01 mm).
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Size Range: OD: 6mm – 325mm | WT: 0.5mm – 60mm | Length: 5.8m, 6m, 11.8m, 12m (Random or Fixed).
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Standards: EN 10305, ASTM A106-2006, BS 1139, DIN 2391, DIN 2445.
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Heat Treatment/Delivery Conditions: NBK (+N), GBK (+A), BK (+C), BKW (+LC), BKS (+SR).
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Applications: Widely used in manufacturing pneumatic/hydraulic components (cylinders), mechanical structures, automotive parts, and precision machinery.
Description
1. Product Description & Application
Precision steel tube is a high-precision steel tube material processed by cold drawing or hot rolling. Because the inner and outer walls of precision steel pipes have no oxide layer, they feature high pressure resistance without leakage, high precision, high smoothness, cold bending without deformation, and flaring/flattening without cracks. They are mainly used to produce pneumatic or hydraulic components, such as cylinders (the oil cylinder can be a seamless tube or a welded tube).
Applications
The internal and external diameter can be controlled within +/- 0.01 mm. Under the guarantee of identical anti-bending and torque strength, the weight of the precision pipe is lighter. It is widely used in manufacturing precision machinery parts, engineering structures, automotive parts, and hydraulic equipment. It is also commonly used to produce various kinds of conventional weapons, barrels, shells, bearings, and more.
2. General Specification & Tolerances
| Size | OD | 6 – 325mm | Tolerance | -0.035 — +0.045mm |
| ID | 2 – 250mm | Tolerance (WT) | ±0.035mm (depends on sizes) | |
| WT | 1 – 32mm (Extended up to 60mm) | |||
| Length | Random or fixed length (5.8/6/11.8/12m) | Length Tolerance | +0 – 3.5mm | |
| Straightness | 0.15:1000, 0.4:1000, 0.5:1000, 1:1000 or customized | |||
| Surface Roughness | Ra 0.02 — 0.4μm | |||
Precision Steel Pipe Size Tolerances
- Hot Rolling: Tolerance of OD is +/- 0.1%.
- Cold Drawn: Tolerance allowed in below conditions:
- Diameters 6mm to 10mm: Normal tolerance condition +/- 0.2%, Premium tolerance condition +/- 0.15%.
- Diameters 10mm to 30mm: Normal tolerance condition +/- 0.4%, Premium tolerance condition +/- 0.2%.
- Diameters 30mm to 50mm: Normal tolerance condition +/- 0.45%, Premium tolerance condition +/- 0.3%.
- Outer diameters above 50mm: Normal tolerance condition +/- 0.1%, Premium tolerance condition +/- 0.8%.
3. Standards & Material Grades
Precision Chrome-Molybdenum Steel Tube
| Standard | GB | ASTM | JIS | DIN |
|---|---|---|---|---|
| GRADE | 15Cr | 5115 | SCR415 | 15Cr3 |
| 20Cr | 5120 | SCR420H | 20Cr4 | |
| 30Cr | 5130 | SCR430 | 28Cr4 | |
| 35Cr | 5132 | SCR430H | 34Cr4 | |
| 40Cr | 5140 | SCR440 | 41Cr4 | |
| 12CrMo / 15CrMo | A-387CR / 41.494.18 | A-387CR / 4125 | 13CrMo44 / 16CrMo44 | |
| 20CrMo / 25CrMo | 4125 / 4130 | 4130 / SCR420H | 20CrMo4 / 25CrMo4 | |
| 30CrMo / 35CrMo | SCR420H / 4140 | 4140 / 4140 | 34CrMo4 / 42CrMo4 | |
| 42CrMo | A-387CR |
Chemical Composition (%)
| Grade | C | Si | Mn | P | S |
|---|---|---|---|---|---|
| 20# | 0.17-0.24 | 0.17-0.37 | 0.35-0.65 | 0.035 | 0.035 |
| 45# | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | 0.035 | 0.035 |
| SKTM13C-T(25Mn) | 0.22-0.29 | 0.17-0.37 | 0.70-1.00 | 0.035 | 0.035 |
| 27SiMn | 0.24-0.32 | 1.10-1.40 | 1.10-1.40 | 0.035 | 0.035 |
| E355 | ≤0.22 | ≤0.55 | ≤1.6 | 0.025 | 0.025 |
| Q345B | ≤0.2 | ≤0.5 | 1.00-1.60 | 0.030 | 0.030 |
| Q345D | ≤0.2 | ≤0.5 | 1.00-1.60 | 0.030 | 0.030 |
| SAE1026 | 0.22-0.28 | 0.15-0.35 | 0.60-0.90 | 0.040 | 0.050 |
4. Delivery Conditions & Mechanical Properties
| Delivery Condition | Steel Grade | Rm MPa (Tensile) | ReH MPa (Yield) | Elongation A5(%) |
|---|---|---|---|---|
| BKS (Cold Drawn & Stress-Relieved) |
ST45 | ≥ 520 | ≥ 375 | ≥ 15 |
| ST52(E355) | ≥ 600 | ≥ 520 | ≥ 14 | |
| SAE1026 | ≥ 600 | ≥ 510 | ≥ 15 | |
| 45# | ≥ 600 | ≥ 520 | ≥ 10 | |
| 20# | ≥ 520 | ≥ 375 | ≥ 15 | |
| BK (Cold Finished) |
ST45 | ≥ 550 | – | ≥ 5 |
| ST52(E355) | ≥ 640 | – | ≥ 5 | |
| SAE1026 | ≥ 640 | – | ≥ 5 | |
| 45# | ≥ 640 | – | ≥ 5 | |
| 20# | ≥ 550 | – | ≥ 8 |
5. Manufacturing Process Flow
As we know, most precision steel pipes undergo hot rolled and cold drawn processes. In contrast, cold rolling is more complicated. Not only do the pipes need to be continuously rolled by three rollers, but mandatory tests must also be conducted after extrusion to guarantee the exceptional quality of the precision materials.
Raw Material Inspection → Remove Oxide Layer → Visual Inspection → Heating → Hot Rolling → Pickling and Passivation (Phosphating) → Grinding → Lubrication and Drying → Cold Rolling (Internal and external extraction) → Remove Oil → Ends Cutting → Inspection → Marking → Packing and Storage.
6. Packing & Loading
Pipes are packed in bundles with plastic bags, thin films, and wooden pallets. We ensure standard seaworthy export packing or custom packing as per client demands.
- 20ft GP Container: 5898mm (Length) x 2352mm (Width) x 2393mm (High) | Capacity: 24-26 CBM
- 40ft GP Container: 12032mm (Length) x 2352mm (Width) x 2393mm (High) | Capacity: 54 CBM
- 40ft HC Container: 12032mm (Length) x 2352mm (Width) x 2698mm (High) | Capacity: 68 CBM
