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Help CenterSteel Pipe & Tube & Precision Steel Tube,10#、20#、35#、45#、16Mn、40Cr、42CrMo、35CrMo、20Cr、27SiMn、12Cr1MoV、Cr5Mo、Cr9Mo
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1. Product Overview
Precision steel tubes (precision seamless bright tubes) are processed from high-quality round steel billets or hot-rolled seamless tubes through multiple procedures including cold rolling, cold drawing, bright annealing, precision straightening and non-destructive testing. Compared with ordinary hot-rolled seamless tubes, they feature micron-level dimensional tolerance, mirror-like smooth inner and outer surfaces without oxide layers, excellent pressure resistance without leakage, and stable cold forming performance free of cracking. Secondary turning and boring processes are not required, and the tubes can be directly assembled. They serve as core matching pipes for hydraulic & pneumatic systems, automobiles, precision machinery and construction machinery.
2. Applicable Standards
Domestic Standards
GB/T 3639-2020 Cold-drawn and Cold-rolled Precision Seamless Steel Tubes (for general mechanical structures)
GB/T 8713 Precision Seamless Steel Tubes for Hydraulic and Pneumatic Cylinders
GB/T 8162 Seamless Steel Tubes for Structural Purposes, GB/T 8163 Seamless Steel Tubes for Fluid Transportation
International Export Standards
German Standard: DIN 2391-2
European Standard: EN 10305-1 / EN 10305-4 (special for hydraulic pipelines)
American Standard: ASTM A519, ASTM A179
Japanese Standard: JIS G3459
3. Main Material Grades (Regular Stock, Custom Special Materials Available)
1. High-quality Carbon Steel (Cost-effective, for general hydraulic & mechanical use)
10#, 20#, 35#, 45#, 16Mn (Q345B/C/D)
2. Alloy Structural Steel (High strength, wear resistance, heavy-load working conditions)
40Cr, 42CrMo, 35CrMo, 20Cr, 27SiMn, 12Cr1MoV, Cr5Mo, Cr9Mo
4. Complete Production Flow
Round steel billet → Hot piercing into hollow shell → Pickling to remove oxide scale → Phosphating & saponification for lubrication → Multi-pass cold rolling / cold drawing for diameter & wall thickness reduction → Bright annealing (eliminate internal stress and improve surface finish) → Precision straightening → Fixed-length cutting → Internal & external cleaning and air blowing → Eddy current & ultrasonic non-destructive testing → Full dimensional inspection (outer diameter, inner diameter, wall thickness, straightness, concentricity) → Anti-rust oil coating → Packaging and warehousing
5. Core Technical Parameters & Performance Advantages
1. Ultra-high Dimensional Precision (Core Advantage)
Outer diameter tolerance: ±0.05~±0.20mm (classified into general grade, high grade and ultra-precision grade)
Inner diameter tolerance: H8 / H9 precision tolerance, minimum up to ±0.03mm
Uniform wall thickness: ±3%~±8%, no eccentric wall, stable pressure bearing performance
Straightness: ≤0.1mm/m, concentricity ≤0.1mm, free of bending deformation
Conventional Size Range: Outer diameter 8~650mm, inner diameter 4~500mm, wall thickness 1~100mm
Fixed Length: 2000~12000mm, non-standard lengths cuttable as required
2. Superior Surface Quality
No oxide scale, peeling, pits, cracks or pockmarks on inner and outer walls
Inner wall roughness Ra ≤0.4~0.8μm, extremely low fluid resistance, leak-proof sealing performance
Delivered after bright annealing with silvery metallic luster; no polishing required
3. Excellent Machinability & Mechanical Properties
Pressure resistance: No leakage under high pressure, suitable for high-pressure hydraulic systems
Formability: No cracking or deformation during cold bending, flaring, flattening and stamping
Stable mechanical performance: Controllable uniform tensile strength and yield strength; deliverable under annealed, normalized or stress-relieved states as required
Lightweight design: Over 30% lighter than solid round steel under equivalent bending and torsional strength, saving raw material and processing time
4. Four Optional Delivery Conditions
+C Cold Finished Hard State: High strength and hardness, suitable for structural parts without bending processing
+LC Cold Finished Soft State: Good plasticity, available for arbitrary flaring, bending and stamping
+SR Stress Relieved Annealing: Eliminate cold working stress, no deformation during long-term service
+A Fully Bright Annealed State: Optimal toughness, specially for oil and air cylinders
6. Precision Grade Classification & Corresponding Application Scenarios
| Precision Grade | Outer Diameter Tolerance | Wall Thickness Tolerance | Application Fields |
|---|---|---|---|
| General Grade | ±0.50mm | ±10% | Ordinary mechanical structures, low-pressure fluid pipelines |
| Medium High Grade | ±0.30mm | ±8% | General auto parts, common machine tools |
| High Grade | ±0.20mm | ±5% | Hydraulic cylinders, pneumatic cylinders, shock absorbers |
| Ultra-precision Grade | ±0.10mm | ±3% | Aviation parts, precision instruments, new energy equipment |
7. Main Application Industries
Hydraulic & Pneumatic Equipment (Largest Consumption Field)Excavators, injection molding machines, jacks, hydraulic station cylinder barrels, air cylinder tubes, high-pressure oil pipes, solenoid valve bodies. Smooth inner walls reduce hydraulic oil loss and guarantee stable sealing performance.
Automotive ManufacturingEngine high-pressure fuel pipes, brake oil pipes, shock absorber barrels, steering tie rods, transmission sleeves, new energy battery cooling pipelines.
General Precision MachineryMachine tool spindle sleeves, bearing rings, gear bushings, tooling fixtures, precision instrument housings.
Construction & Mining MachineryHydraulic supports, lifting equipment cylinder tubes, mine high-pressure delivery pipes, heavy-duty mechanical structural components.
Other FieldsRail transit, medical devices, petrochemical fluid transportation, aviation precision fittings, agricultural machinery equipment.
8. Factory Full Inspection Standards
Dimensional Inspection: Random sampling with coordinate measuring machines, micrometers and wall thickness gauges for each batch
Non-destructive Testing: Eddy current testing and ultrasonic testing to detect internal cracks and interlayers
Mechanical Performance Test: Tensile test, flattening test, flaring test and hardness test with mechanical performance reports issued
Metallographic Inspection: Metallographic structure analysis for annealed tubes
Hydrostatic Pressure Test: Hold pressure without leakage (mandatory for cylinder tubes)
Spectral Material Analysis: Chemical composition certificates provided for each batch
9. Packaging & Anti-rust Treatment
Small short-length tubes: Wrapped with plastic protective film, packed in woven bags, both ends sealed with plastic plugs for dust-proof and anti-rust purposes
Large-diameter thick-wall tubes: Coated with anti-rust oil, bundled with steel strips and fitted with end protection caps
Export sea freight packaging: Covered with moisture-proof stretch film, packed in wooden cases or pallets to avoid rust and collision damage during ocean transportation
10. Core Product Value Summary
Cost Reduction & Efficiency Improvement: Ultra-precise dimensions eliminate boring and polishing procedures for clients, cutting costs of cutting tools, labor and raw material loss
Extended Service Life: Uniform wall thickness and defect-free inner walls prevent tube burst and leakage under high pressure
Compatible with Automatic Machining: Qualified straightness and concentricity allow direct processing on CNC lathes
Export Compliance: Full range complies with mainstream European and American industrial standards; complete inspection documents support customs clearance
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