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Help CenterSteel Pipe & Tube & Precision Steel Tube，10#,20#,35#,45#,16Mn,40Cr,42CrMo,27SiMn,20CrMnTi
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1. Product Overview
Precision steel tubes are finished high-precision seamless steel pipes manufactured from premium steel billets through multiple fine processing procedures including cold rolling/cold drawing, bright annealing, precision straightening, non-destructive testing and precision cleaning. Distinct from ordinary hot-rolled seamless pipes, they feature micron-level dimensional tolerances, mirror-smooth inner and outer surfaces, oxide-free inner bores, leak-proof pressure resistance, and crack-free performance after cold bending, flaring and flattening tests. They serve as core special pipes for hydraulic & pneumatic systems, automotive parts, precision machinery and high-pressure instruments.
Product Classification
Cold-drawn Precision Tubes (BK): Stable dimensions with cost-effective performance, suitable for general mechanical processing and low-pressure hydraulic cylinder barrels.
Cold-rolled Precision Tubes (CK): Higher precision and lower inner surface roughness, applicable to high-pressure oil cylinders and servo systems.
Bright Annealed Precision Tubes (NBK): Heat-treated without oxidation throughout the process, boasting clean inner walls free of scale, which can be directly assembled without secondary grinding.
Honed Precision Tubes (Grade H8/H9): Super-precision honed inner bores with surface roughness Ra ≤ 0.2μm, specially used for high-end oil and air cylinders.
2. Applicable Standards (Domestic & International for Foreign Trade)
Domestic National Standards
GB/T 3639-2020 Cold-drawn or Cold-rolled Precision Seamless Steel Tubes (general structural precision tubes)
GB/T 8713 Precision Seamless Steel Tubes for Hydraulic and Pneumatic Cylinder Barrels (special for oil cylinders)
GB/T 8162, GB/T 8163 (base standard for raw seamless tubes)
International Export Standards
Germany: DIN 2391-2
Europe & America: EN 10305-1, ASTM A519
Custom production per customer requirements for JIS, GOST standards
3. Common Material Grades & Application Scenarios
1. High-quality Carbon Steel (Main Stock Products)
Grade 10#: Excellent plasticity and weldability, used for low-pressure oil pipes and instrument tubes
Grade 20#: Balanced toughness, the most universal material for hydraulic pipelines and automotive brake tubes
Grade 35#: Medium strength, applied to mechanical structural parts and sleeves
Grade 45#: High tensile strength for transmission shafts, heavy-duty cylinder barrels and precision shaft sleeves
2. Alloy Structural Steel (Heavy-load Wear-resistant Conditions)
16Mn(Q345B/C/D), 20Cr, 40Cr, 42CrMo, 27SiMn, 20CrMnTi, 35CrMo. For heavy machinery, construction machinery cylinder barrels, automotive shock absorber tubes and high-pressure hydraulic components.
4. Specification Parameter Range
Outer Diameter: 6mm – 219mm, non-standard customization available
Wall Thickness: 0.5mm – 40mm, both thin and thick wall tubes producible
Single Tube Length: Standard 6m / 9m / 12m, fixed-length cutting available (0.5–12 meters arbitrary length)
Surface Roughness
Standard precision tubes: Inner wall Ra ≤ 0.8μm
Honed cylinder tubes: Inner wall Ra ≤ 0.2–0.4μm
Bright annealed tubes: Oxide-free inner and outer walls with matte metallic bright finish
5. Core Product Performance Advantages
Ultra-high dimensional accuracy: Strict control over inner/outer diameter, wall thickness, straightness and concentricity; straightness ≤ 0.1mm/m. No rough turning required before assembly, greatly cutting customers’ processing costs.
Oxide-free inner and outer walls: Bright annealing eliminates scale and impurities inside tubes, preventing blockage of sealing parts in high-pressure oil circuits and extending service life of oil seals.
Outstanding pressure resistance: Withstand up to 100MPa high pressure without leakage; no cracks during flaring, flattening and cold bending tests with stable deformation performance.
Stable mechanical properties: Refined grain structure with tensile and yield strength 20%–30% higher than ordinary hot-rolled tubes, offering long fatigue life.
Strong processing adaptability: Directly available for turning, milling, grinding, welding, bending and electroplating, removing rough polishing procedures.
Lightweight design: Thinner wall thickness while maintaining equivalent bending and compression strength, effectively reducing overall equipment weight.
6. Complete Production Process Flow
Raw steel billet inspection → Hot piercing to form hollow tube shells → Pickling, phosphating and lubrication → Multi-pass cold rolling / cold drawing forming → Precision fixed-length cutting → Vacuum bright annealing (NBK) → Automatic precision straightening → Eddy current + ultrasonic non-destructive testing → High-pressure inner wall cleaning, degreasing and rust prevention → Plastic end caps fitted on both ends → Anti-rust winding and packaging
7. Main Application Industries
Hydraulic & Pneumatic Industry: Oil cylinder barrels, air cylinder barrels, high-pressure oil pipes, servo valve sleeves, hydraulic pipelines for construction machinery
Automotive Manufacturing: Shock absorber tubes, brake oil pipes, steering shaft sleeves, engine high-pressure fuel pipes, new energy battery cooling pipes
Precision Machinery: Machine tool spindle sleeves, bearing liners, guide pillars and guide sleeves, structural parts for automation equipment
Construction Machinery: High-pressure hydraulic components for excavators, injection molding machines and elevators
Petrochemical Industry: High-pressure instrument impulse tubes and corrosion-resistant conveying pipelines
Aviation & Aerospace: Lightweight high-pressure oil circuits and structural tubes for precision instruments
Medical & Food Equipment: Sanitary precision pipelines made of 316L stainless steel
8. Packaging, Delivery & Commercial Terms
Packaging: Plastic dustproof caps at both tube ends; whole bundles wrapped with anti-rust film and woven bags. Wooden case packaging customized for extra-long or ultra-precision small tubes. Each bundle labeled with material grade, specification and heat batch number.
Loading Ports: Tianjin Port, Qingdao Port, Shanghai Port
Lead Time: 5–7 days for standard stock goods; 7–15 days for customized tubes with special materials and honed fine finishing
Minimum Order Quantity: Minimum 5 tons for bulk orders, small sample orders acceptable
Payment Term: 30% TT advance deposit, 70% balance TT against copy of Bill of Lading (Letter of Credit LC not accepted)
Quality Documents Supplied Alongside Shipment: Material test certificate, mechanical performance report, non-destructive testing certificate and factory inspection certificate
9. Complete Quality Inspection Items
Spectral chemical analysis of incoming billets → Full dimensional tolerance inspection → Visual surface inspection → Eddy current testing (inner wall cracks and lamination defects) → Ultrasonic wall thickness testing → Flattening & flaring mechanical tests → Hardness test → Inner wall cleanliness inspection → Hydrostatic pressure tightness test
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