Seamless precision steel tubes & pipes according to DIN 2391, EN 10305-1, EN 10305-4 are widely used as hydraulic steel tubes in various hydraulic systems. So this product is known as hydraulic steel tubes also.
As the first class quality China seamless precision steel tube manufacturer and supplier, our factory produces precision seamless hydraulic steel tubes and pipes in a wide range of dimensions and materials.
Seamless precision hydraulic steel tubing standard / specifications
Our factory is one of the leading China precision steel tube manufacturers, our precision steel hydraulic tubes are produced and supplied according to most popular standards in the world, such as:
- DIN2391 / DIN 2391;
- DIN 2394
- EN 10305-1
- EN 10305-4
- DIN 17175
- Equivalent ASTM standards and other standards.
Size Range
Precision seamless hydraulic steel tube Sizes
As the leading China precision seamless steel tube manufacturer, our factory manufactures and supplies precision cold drawn steel seamless tubes in a wide range of sizes, as below.
- Outer Diameter: 4 mm – 89 mm;
- Wall thickness: 0.5 mm – 15 mm
- Tolerance of our precision tubes are well conformed DIN 2391, EN 10305-1, EN10305-4, and our best tolerance can reach O.D. min. +/-0.03 mm, WT min. +/-0.03 mm.
Here below is the popular dimension list of our DIN 2391 precision seamless steel hydraulic tubing.
| Metric Precision seamless tubing Size List | Imperial Size Precision seamless hydraulic tubing Size List | |||||||||||||
| O.D (mm) | W. T (mm) | O.D (mm) | W. T (mm) | O.D (inch) | W. T (inch) | O.D (mm) | W. T (mm) | |||||||
| 4 | x | 0.5 | 22 | x | 2.5 | 1/4″ | x | 0.035 | 6.35 | x | 0.89 | |||
| 4 | x | 1 | 22 | x | 3 | 1/4″ | x | 0.049 | 6.35 | x | 1.25 | |||
| 5 | x | 1 | 25 | x | 2 | 1/4″ | x | 0.065 | 6.35 | x | 1.65 | |||
| 6 | x | 1 | 25 | x | 2.5 | 3/8″ | x | 0.035 | 9.53 | x | 0.89 | |||
| 6 | x | 1.5 | 25 | x | 3 | 3/8″ | x | 0.049 | 9.53 | x | 1.25 | |||
| 8 | x | 1 | 30 | x | 3 | 3/8″ | x | 0.065 | 9.53 | x | 1.65 | |||
| 8 | x | 1.5 | 32 | x | 2 | 1/2″ | x | 0.035 | 12.7 | x | 0.89 | |||
| 10 | x | 1 | 32 | x | 3 | 1/2″ | x | 0.049 | 12.7 | x | 1.25 | |||
| 10 | x | 1.5 | 34 | x | 3 | 1/2″ | x | 0.065 | 12.7 | x | 1.65 | |||
| 10 | x | 2 | 35 | x | 2 | 5/8″ | x | 0.035 | 15.88 | x | 0.89 | |||
| 12 | x | 1 | 35 | x | 3 | 5/8″ | x | 0.049 | 15.88 | x | 1.25 | |||
| 12 | x | 1.5 | 38 | x | 4 | 5/8″ | x | 0.065 | 15.88 | x | 1.65 | |||
| 12 | x | 2 | 38 | x | 5 | 5/8″ | x | 0.083 | 15.88 | x | 2.11 | |||
| 15 | x | 1 | 38 | x | 6 | 3/4″ | x | 0.035 | 19.05 | x | 0.89 | |||
| 15 | x | 1.5 | 42 | x | 2 | 3/4″ | x | 0.049 | 19.05 | x | 1.25 | |||
| 15 | x | 2 | 42 | x | 3 | 3/4″ | x | 0.065 | 19.05 | x | 1.65 | |||
| 16 | x | 1 | 42 | x | 5 | 3/4″ | x | 0.083 | 19.05 | x | 2.11 | |||
| 16 | x | 1.5 | 45 | x | 3 | 1″ | x | 0.049 | 25.4 | x | 1.25 | |||
| 16 | x | 2 | 48 | x | 3 | 1″ | x | 0.065 | 25.4 | x | 1.65 | |||
| 18 | x | 1 | 48 | x | 5 | 1″ | x | 0.083 | 25.4 | x | 2.11 | |||
| 18 | x | 1.5 | 50 | x | 5 | 1″ | x | 0.12 | 25.4 | x | 3.05 | |||
| 18 | x | 2 | 50 | x | 6 | 1.1/4″ | x | 0.083 | 31.75 | x | 2.11 | |||
| 20 | x | 1 | 60 | x | 3 | 1.1/4″ | x | 0.12 | 31.75 | x | 3.05 | |||
| 20 | x | 1.5 | 60 | x | 5 | 1.1/2″ | x | 0.12 | 38.1 | x | 3.05 | |||
| 20 | x | 2 | 60 | x | 6 | 1.1/2″ | x | 0.165 | 38.1 | x | 4.19 | |||
| 20 | x | 2.5 | 65 | x | 5 | 1.3/4″ | x | 0.18 | 44.45 | x | 4.57 | |||
| 22 | x | 1 | 70 | x | 4 | 2″ | x | 0.12 | 50.8 | x | 3.05 | |||
| 22 | x | 1.5 | 70 | x | 5 | 2″ | x | 0.203 | 50.8 | x | 5.16 | |||
| 22 | x | 2 | 90 | x | 5 | 2-1/2″ | x | 0.18 | 63.5 | x | 4.57 | |||
Materials
DIN2391 seamless precision steel tube Materials
As the professional China precision seamless steel tubing manufacturer, our factory produces and supplies DIN2391 seamless precision tubes in a wide range of materials.
The popular steel grades of our precision pipes including:
- DIN 2391: ST37, ST37.4, ST35, ST52;
- EN 10305-1 / EN 10305-4: E235, E355, E255
- Other steel grades are available upon customer’ request with a certain min. order quantity.
Chemical Compositions
| Standard | Grade | Chemical Components (%) | |||||
| Symbol | Material No. | C | Si | Mn | P | S | |
| DIN2391 | St 30 Si | 1.0211 | ≤0.10 | ≤0.10 | ≤0.55 | ≤0.025 | ≤0.025 |
| St 30 Al | 1.0212 | ≤0.10 | ≤0.05 | ≤0.55 | ≤0.025 | ≤0.025 | |
| St 35 | 1.0308 | ≤0.17 | ≤0.35 | ≥0.40 | ≤0.025 | ≤0.025 | |
| St 45 | 1.0408 | ≤0.21 | ≤0.35 | ≥0.40 | ≤0.025 | ≤0.025 | |
| St 52 | 1.058 | ≤0.22 | ≤0.55 | ≤1.60 | ≤0.025 | ≤0.025 | |
Surface Conditions
DIN2391 precision seamless hydraulic tubing Delivery Condition
Seamless steel precision pipes are produced by either cold drawn or cold rolled or both processes. The precision seamless hydraulic tubes usually are supplied with one of the below delivery conditions:
| Delivery Condition | Symbol | Description |
| Cold finished (hard) | BK | The seamless tubes are not heat treated after the final cold forming and so have a rather high resistance to deformation. |
| Cold finished (soft) | BKW | The final heat treatment is followed by cold drawing involving limited deformation. Appropriate further processing allows a certain degree of cold forming (e.g. bending, expanding). |
| Cold finished and stress-relieved | BKS | The seamless pipes are Heat treated after the last cold drawn or cold roll process. Subject to appropriate processing conditions, the increase in the residual stresses involved enables both forming and machining to a certain degree. |
| Annealed | GBK | The last cold forming process is followed by annealing in a controlled atmosphere. |
| Normalized | NBK | The last cold forming process is followed by annealing above the upper transformation point in a controlled atmosphere. |
Delivery Condition Symbol in accordance with EN10305 and DIN2391.
| Symbol in accordance with EN 10305 | Symbol in accordance with DIN2391 |
| +C | BK |
| +LC | BKW |
| +SR | BKS |
| +A | GBK |
| +N | NBK |
Precision Seamless Steel Tube Surface Treatment
As one of the first class China precision seamless steel tubing manufacturer and supplier, we supply our precision seamless tubes with surface conditions as below.
- Bright Annealed surface: this is also known as NBK seamless steel tubes;
- Galvanized surface: this is known as zinc plated seamless tube also.
The seamless steel pipes are galvanized after the final heat treatment. We supply yellow galvanized precision seamless tubes and white galvanized seamless tubes. - Phosphated treatment:
Bright black color is homogeneously distributed on the phosphated seamless tube surface, and the phosphated seamless tubes have good anti-rust and corrosion resistance performance.
Features
Advantages of Our Precision seamless hydraulic steel tubing
Our precision seamless steel tubing factory manufactures and supplies DIN 2391 precision seamless steel hydraulic tubing with advantages as below.
- With high dimension accuracy, which ensures our precision seamless tubes can tightly connect to the pipe fittings, thus our precision seamless pipes have excellent performance on preventing leakages.
- Our factory’s No deformation after cold bending, no crack after flaring and flattening. The complicated geometrical forming and machining can be realized.
- High cleanness , no oxidization on the outer surface and inside surface after heat treatment.
- Our factory’s cold drawn seamless steel tubes are free of rust, with no cracks and without other defects on both inner and outer wall.
- With the phosphated or galvanized surface, our DIN2391 precision steel hydraulic tubes has good performance of anti-rust.
- Our factory’s DIN 2391 precision seamless steel tube can work under high pressure, our precision seamless steel pipes are widely used as hydraulic steel tubes in various hydraulic lines and systems.
Applications
DIN 2391 /EN 10305 Precision Steel Tubing Applications
As the professional China precision seamless steel tube suppliers, our factory manufactured and supplied a huge number of our seamless steel precision tubes to many customers in China and abroad.
Our precision seamless pipes are used for hydraulic systems, automobiles, Diesel Engine, machinery, and other areas which require high precision, cleanness, and high mechanical properties performance.
And the seamless steel precision galvanized tubes and phosphated tubes are widely used in hydraulic systems, machines and facilities, other applications which require good rust proof and corrosion resistance performance.
Photos of DIN 2391 / EN 10305 precision seamless steel hydraulic tubes
