EN 10305-1 Seamless Precision Steel Tube E235 E355 Cold Drawn Tubing For Hydraulic Cylinders
EN 10305-1 seamless precision steel tubes are cold-drawn seamless steel tubes manufactured to European standard specifications for precision applications. These tubes are characterized by precisely defined dimensional tolerances and specified maximum surface roughness, making them ideal for applications requiring high accuracy and reliability
The standard covers circular cross-section tubes with outside diameters up to 380 mm, and may also be applied to other cross-section types. Typical applications span the automotive, furniture, and general engineering industries.
| Specification | Details |
|---|---|
| Standard | EN10305-1 |
| Materials | E215, E235, E255, C35E, C45E, 25CrMo4, 42CrMo4 |
| Type | Seamless cold-drawn precision steel tube |
| Outside Diameter (OD) | ≤ 380 mm (typically 6-114 mm) |
| Wall Thickness (WT) | 0.5 mm – 60 mm |
| Length | 5.8m, 6m, 11.8m, 12m, or cut to size |
| Manufacturing Process | Cold drawn from hot finished seamless tubes |
| Surface Finish | BK, BKW, BKS, GBK, NBK |
- High dimensional accuracy – Tight tolerances on OD, ID, and wall thickness
- Smooth surface finish – Specified maximum surface roughness values
- Excellent mechanical properties – Consistent strength and ductility
- Good machinability – Suitable for further processing (bending, flaring, swaging)
- Pressure rated – Suitable for hydraulic and pneumatic systems
- Full traceability – Inspection documents per EN 10204
- Non-destructive testing – Eddy current, ultrasonic, or flux leakage testing available
EN 10305-1 specifies three main steel grades for precision tubes:
| Steel Grade | Steel Number | C max (%) | Si max (%) | Mn max (%) | P max (%) | S max (%) |
|---|---|---|---|---|---|---|
| E215 | 1.0212 | 0.10 | 0.05 | 0.70 | 0.025 | 0.015 |
| E235 | 1.0308 | 0.17 | 0.35 | 1.20 | 0.025 | 0.015 |
| E355 | 1.0580 | 0.22 | 0.55 | 1.60 | 0.025 | 0.015 |
*Source: EN 10305-1:2016*
| Steel Grade | Yield Strength Rp0.2 (min MPa) | Tensile Strength Rm (MPa) | Elongation A (min %) |
|---|---|---|---|
| E215 | 215 | 290 – 430 | 30 |
| E235 | 235 | 340 – 480 | 25 |
| E355 | 355 | 490 – 630 | 22 |
*Source: EN 10305-1:2016*
Note on Delivery Conditions:
For tubes delivered in cold-finished conditions (BK/BKW), the yield point may be higher:
- BK (cold-finished/hard) : ≥ 80% of tensile strength
- BKW (cold-finished/soft) : ≥ 70% of tensile strength
- GBK/NBK (annealed/normalized): Standard values apply
EN 10305-1 defines five delivery conditions for precision tubes:
| Symbol | Term | Description | Deformability |
|---|---|---|---|
| BK | Cold-finished/hard (as-drawn) | No heat treatment after final cold forming | Low |
| BKW | Cold-finished/soft (lightly cold-worked) | Light finishing pass after heat treatment | Limited cold forming possible |
| BKS | Cold-finished/soft stress-relieved | Stress relieved after cold finishing | Improved for cold forming |
| GBK | Annealed | Annealed in a controlled atmosphere or vacuum | Good |
| NBK | Normalized | Normalized above the upper transformation point | Best |
GBK (+A) = Annealed in controlled atmosphere (bright annealed)
NBK (+N) = Normalized in controlled atmosphere
Precision tubes according to EN 10305-1 feature strictly defined dimensional tolerances:
| Parameter | Tolerance Class |
|---|---|
| Outside Diameter (OD) | ISO 7 (standard), ISO 8, ISO 9 available |
| Wall Thickness (WT) | ±5% to ±10% depending on size |
| Length | ±10mm (standard), closer tolerances available |
| Straightness | 0.5 mm per 1000 mm (standard) |
| Surface Roughness (Ra) | ≤ 1.6µm (for GBK/NBK condition) |
| OD (mm) | Wall Thickness (mm) Range | Common Applications |
|---|---|---|
| 6 | 1.0 – 2.0 | Instrumentation, fuel lines |
| 8 | 1.0 – 2.0 | Hydraulic pilot lines |
| 10 | 1.0 – 2.5 | Pneumatic tubing |
| 12 | 1.0 – 3.0 | Injection pipes |
| 14 | 1.5 – 3.0 | Cylinder tubes |
| 15 | 1.5 – 3.0 | Hydraulic lines |
| 16 | 1.5 – 4.0 | Precision shafts |
| 18 | 1.5 – 4.0 | Telescopic tubes |
| 20 | 2.0 – 5.0 | Piston rods |
| 22 | 2.0 – 5.0 | Hydraulic cylinders |
| 25 | 2.0 – 6.0 | General engineering |
| 28 | 2.5 – 6.0 | Mechanical tubing |
| 30 | 2.5 – 8.0 | Structural applications |
| 32 | 3.0 – 8.0 | Heavy-duty cylinders |
| 35 | 3.0 – 10.0 | Pressure applications |
| 38 | 3.0 – 10.0 | Boiler tubes |
| 40 | 3.0 – 12.0 | Industrial machinery |
| 42 | 3.0 – 12.0 | Automotive components |
| 45 | 3.5 – 14.0 | Heavy machinery |
| 50 | 4.0 – 15.0 | Large cylinders |
| 55 | 4.0 – 16.0 | Special applications |
| 60 | 5.0 – 18.0 | Pressure vessels |
| 63 | 5.0 – 20.0 | Custom applications |
| 70 | 5.0 – 20.0 | Large diameter precision |
| 76 | 6.0 – 25.0 | Thick wall precision |
| 80 | 6.0 – 25.0 | High pressure |
| 89 | 6.0 – 30.0 | Heavy wall |
| 100 | 8.0 – 35.0 | Special order |
| 114 | 8.0 – 40.0 | Maximum standard size |
Sizes up to 380mm OD available upon request.
EN 10305-1 seamless precision steel tubes are used across multiple industries:
Hydraulic Systems – Hydraulic cylinders, piston tubes, telescopic pipes, power steering tubes
Pneumatic Systems – Pneumatic cylinders, air line tubing, control systems
Automotive – Transmission shafts, fuel injection pipes, piston pins, ball cages, steering systems, drive shafts
Mechanical Engineering – Shafts, axles, cylinders, ring-shaped parts, stabilizer pipes
General Engineering – Machine frames, structural components, precision mechanisms
Furniture Industry – Office chair cylinders, adjustable mechanisms, telescopic legs
Special Applications – Heat exchangers, elevator tubes, gas bottles, pit props, pump pipes, textile machinery
Custom tolerances available upon request.
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.