Carbon Steel Precision Tube
Carbon steel precision tubes deliver exceptional dimensional accuracy, smooth surface finish, and reliable mechanical properties for hydraulic systems, automotive components, precision machinery, and instrumentation. Manufactured by cold drawing or cold rolling over a mandrel, these tubes offer tighter tolerances and superior concentricity compared to standard hot-rolled seamless pipe. Huaxia-Steel supplies DIN 2391 and EN 10305-1 precision tubes in diameters from 4 mm to 120 mm with EN 10204 3.1 mill test certificates.
Product Specifications
| Parameter | Specification |
|---|---|
| Outside diameter | 4 mm – 120 mm |
| Wall thickness | 0.5 mm – 10 mm |
| Length | Fixed 3,000 – 12,000 mm; random 4,000 – 8,000 mm; cut-to-length available |
| Tolerance (OD ≤ 30 mm) | ±0.10 mm (EN 10305-1 E235/E355, DIN 2391 ST35/ST52) |
| Tolerance (OD 30 – 60 mm) | ±0.15 mm |
| Tolerance (OD > 60 mm) | ±0.5 % or ±0.20 mm, whichever is greater |
| Wall thickness tolerance | ±10 % or ±0.10 mm, whichever is greater |
| Straightness | ≤ 1.0 mm per 1,000 mm |
| Surface roughness (Ra) | ≤ 4.0 µm (bright annealed), ≤ 6.3 µm (cold drawn) |
| Ovality | ≤ 50 % of OD tolerance |
Available Grades and Standards
| Standard | Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Application |
|---|---|---|---|---|
| DIN 2391 | ST35 | ≥ 235 | 340 – 470 | General precision tubing, low pressure |
| DIN 2391 | ST37.4 | ≥ 235 | 340 – 470 | Hydraulic lines, automotive fuel injection |
| DIN 2391 | ST52 | ≥ 355 | 490 – 630 | High-pressure hydraulics, shock absorbers |
| EN 10305-1 | E235 | ≥ 235 | 340 – 480 | General engineering, pneumatic cylinders |
| EN 10305-1 | E355 | ≥ 355 | 490 – 630 | Heavy-duty hydraulics, precision shafts |
| ASTM A519 | 1020 | ≥ 290 | ≥ 420 | Mechanical tubing, North American market |
| ASTM A519 | 1045 | ≥ 380 | ≥ 580 | High-strength precision components |
| JIS G3445 | STKM 13A | ≥ 290 | ≥ 390 | Japanese machinery and automotive |
Manufacturing Process
Our precision tubes are produced through a controlled cold-drawing process:
- Hot-rolled mother tube: Produced by seamless piercing or electric resistance welding, inspected by Eddy Current and Ultrasonic testing.
- Cold drawing: The mother tube is drawn through a die and over a mandrel at room temperature, reducing diameter and wall thickness while improving surface finish and dimensional accuracy.
- Bright annealing (optional): Heat treatment in a controlled atmosphere furnace restores ductility and produces a bright, oxide-free surface.
- Straightening: Rotary straightening machines achieve ≤ 1.0 mm/m straightness.
- Cutting and inspection: Cut to specified length, followed by dimensional inspection, surface check, and mechanical testing.
Applications
- Hydraulic and pneumatic cylinders: Honed precision tube serves as the cylinder barrel for construction equipment, agricultural machinery, and industrial presses.
- Automotive: Fuel injection lines, brake lines, shock absorber tubes, and steering rack housings.
- Precision machinery: Linear motion shafts, spindle housings, and bearing races requiring tight tolerances.
- Instrumentation: Pressure gauges, flow meters, and analytical equipment tubing.
- Food and pharmaceutical: When supplied with additional passivation or electro-polishing, precision tube meets sanitary standards for process equipment.
Quality Assurance
- EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 available with third-party witness.
- 100 % dimensional inspection: OD, wall thickness, length, straightness, and ovality.
- 100 % Eddy Current or Ultrasonic testing for wall integrity.
- Chemical analysis by optical emission spectrometry (OES) on each heat.
- Mechanical testing: tensile test, flattening test, and flare test on each batch.
- Optional: pressure test, corrosion test, and microscopic examination.
Packaging and Shipping
- Each tube end is capped with plastic plugs to prevent contamination and moisture ingress.
- Bundles are wrapped in oiled paper and VCI film for sea-freight corrosion protection.
- Wooden crates or steel frames for diameters below 20 mm to prevent bending.
- Bulk shipment in 20-foot or 40-foot containers with proper dunnage and lashing.
- Shipping marks include heat number, grade, dimensions, quantity, and destination port.
Request a quotation for carbon steel precision tube. Provide outside diameter, wall thickness, length, grade, and delivery condition (cold drawn / bright annealed). Huaxia-Steel offers cut-to-length service, honing, and chrome plating as value-added options. Contact us for pricing and lead time.
