Tight-tolerance seamless tubes are engineered for hydraulic, mechanical, and fluid-power systems requiring strict dimensional control, high burst pressure resistance, and reliable mechanical performance. Unlike standard commercial tubes, precision cold-drawn and cold-rolled seamless tubes maintain tight control over outer diameter (OD), inner diameter (ID), and wall thickness uniformity, eliminating eccentric wall variation and internal surface defects.
Engineering Highlights:
• Dimensional accuracy up to ISO H8/H9 or custom tolerances (+-0.03 mm to +-0.05 mm).
• Seamless structure with no weld seam weak points.
• Controlled surface finish (Ra <= 0.8 um internal/external available).
• Stable microstructure achieved through controlled-atmosphere heat treatment.
Specifications
|
Parameter |
Standard Range / Specification |
|
Production Process |
Cold Drawn (CD) / Cold Pilgered & Bright Annealed (NBK) |
|
Outer Diameter (OD) |
6 mm - 219 mm |
|
Wall Thickness (WT) |
0.5 mm - 20 mm |
|
Length Options |
Fixed length 3 m - 12 m or random lengths |
|
Dimensional Tolerance |
OD/ID: +-0.05 mm (stricter tolerances available upon review) |
|
Surface Condition |
Pickled, Phosphated, Polished, or Bright Annealed (oxygen-free atmosphere) |
|
Executive Standards |
EN 10305-1, ASTM A519, DIN 2391, JIS G3445 |
Material & Manufacturing
Material integrity begins with verified billet selection and precise reduction ratios during cold processing.
Material Grades Available:
• Carbon & Alloy Steel: E355 (St 52), E235, SAE 1020, AISI 4140, 20CrMo, 42CrMo.
• Stainless Steel: TP304/304L, TP316/316L, 321.
In-House Manufacturing Capabilities:
• Cold Pilgering & Drawing Benches: Multi-pass drawing ensures precise wall thickness reduction, uniform grain structure, and enhanced tensile strength.
• Controlled Atmosphere Annealing: Roller-hearth furnaces with protective nitrogen/hydrogen atmosphere prevent surface oxidation and scale formation, delivering a clean, bright finish that reduces downstream machining time.
• Straightening & Cutting: Multi-roll precision straightening machines control camber to within 1.0 mm / 1000 mm, paired with burr-free rotary cutting.
Quality Inspection
Every production lot undergoes rigorous destructive and non-destructive testing before release. Testing protocols align strictly with EN 10204 3.1 material test reports.
Inspection & Testing Protocols:
Eddy Current Testing (ET): 100% inline or offline automated testing for longitudinal defects and wall integrity.
Dimensional Verification: Laser micrometers and air gauges monitor OD/ID continuously across the tube length.
Mechanical Testing: Tensile strength, yield strength, elongation, and Rockwell/Brinell hardness testing per production lot.
Metallographic Analysis: Grain size and decarburization depth evaluation.
Surface Roughness Measurement: Profilometer checks for strict Ra limits on honed or bright-annealed tubes.
Applications
Engineered for critical functional performance in dynamic systems:
Hydraulic & Pneumatic Systems: Cylinder barrels, piston rods, and high-pressure fluid transfer lines requiring zero leakage under cyclic pressure.
Automotive Components: Fuel injection rails, steering columns, drive shafts, and suspension components.
Industrial Machinery: Bearing sleeves, spindle housings, and precision rollers.
Instrumentation & Energy: High-temperature/high-pressure sensor housings and heat exchanger tubes.
Customization & Supply
Custom Manufacturing:
Non-standard dimensions, specific mechanical property ranges (e.g., quenched and tempered), and custom fixed-length cutting with tight length tolerances (+-0.5 mm).
Packaging & Logistics:
Anti-rust oiled exterior, heavy-duty plastic caps fitted to both ends to prevent debris ingress, bundled with high-tensile steel strapping, and wrapped in moisture-resistant woven fabric or packed in sturdy wooden crates for safe international transit.
FAQ
Q: What is the standard minimum order quantity (MOQ) for custom-sized tubes?
A: MOQ depends on the steel grade and dimension. Typically, custom production runs start at 1 metric ton per size to cover tooling and machine setup parameters. Stock items feature flexible MOQ.
Q: Do you provide EN 10204 3.1 Material Test Reports?
A: Yes. Every shipment includes a traceable 3.1 certificate detailing chemical composition, mechanical test results, and NDT inspection confirmation.
Q: Can you supply tubes with internal honing for hydraulic cylinders?
A: Yes. We supply cold-drawn tubes ready for internal honing, as well as finished honed or roller-burnished tubes meeting ISO H8/H9 bore tolerances.
Q: What is the difference between bright annealed (NBK) and as-drawn (BK) conditions?
A: BK tubes retain cold-work hardness with higher tensile strength but lower elongation. NBK tubes are stress-relieved in a controlled atmosphere furnace, restoring ductility and providing a scale-free bright surface suitable for bending and flare testing.
Q: How do you prevent rust during ocean freight?
A: Tubes are coated with a protective anti-rust oil film, plastic caps are fitted to both ends, and bundles are wrapped in moisture barrier material. VCI (Volatile Corrosion Inhibitor) packaging is available for long-transit ocean shipments.
Q: What are your standard delivery lead times?
A: For items in stock, dispatch takes 7-10 days. For custom production orders, lead times range from 30 to 45 days depending on raw material availability and processing requirements.
Request a Quote
Provide your specifications below to receive a technical proposal and commercial quotation within 24 hours.
Required RFQ Details for Fast Processing:
• Steel Grade / Standard (e.g., E355, AISI 4140, EN 10305-1)
• Dimensions: Outer Diameter (OD) x Wall Thickness (WT) x Length
• Order Quantity (Metric Tons or Pieces)
• Surface Condition & End Finish Requirements
• Target Port of Destination (for freight estimation)
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