Hydraulic Steel Tubes
Hydraulic steel tube is designed to convey liquid fluids to among hydraulics components, fittings, valves, flanges, and other tools. It is made of material E355 (ST 52.4) or E235 (ST 37.4). These two grades have different chemical composition. This helps to control the working pressure.
Hydraulic tube is made according to DIN 2391/C (DIN EN 10305-1) or DIN 2445/2 (DIN EN 10305-4) standards and it is available in millimeters, inches outer diameter, and inches nominal bore size.
Hydraulic tube is made according to DIN 2391/C (DIN EN 10305-1) or DIN 2445/2 (DIN EN 10305-4) standards and it is available in millimeters, inches outer diameter, and inches nominal bore size.
Size |
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Material Specifications |
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Dimension Specifications |
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Finishing |
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Hydraulic Steel Tubes Catalogue

Hydraulics Steel Tubes |
What are Hydraulic Tube Specification
1. What is hydraulic tube?
The hydraulic tube is cylinder-like shaped tubing device that when attach to hydraulic systems, allow for the passage of fluids within and among components. The tube standard specifies dimensions for cold drawn finishing and seamless precision steel tubes. Cold drawn process provides the tube with close dimensional tolerances, increase material strength and enhanced machinability. Therefore, hydraulic tubes are suitable in high performance piping system application.
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They typically have a length of approximately 6 meter long. To order tubes, user has to measure the tube outside diameter and inside diameter. Where the wall thickness is of significance, the tubes may ordered in terms of outside diameter and wall thickness or inside diameter and wall thickness.
2. What is the material of hydraulic tube?
There are two type of material grade, ST52.4 and ST37.4. ST52.4 is high tensile strength tube means it has higher permissible working pressures by reduced tube wall thickness, and leading to reduced system overall weight. Please refer to chemical composition for ST52.4 and ST37.4 tube material:
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Chemical Composition (%) |
Carbon (C) |
Silicon (Si) |
Manganese (Mn) |
Phosphorus (P) |
Sulfur (S) |
E355 (ST52.4) |
⩽ 0.22 |
⩽ 0.55 |
⩽ 1.6 |
⩽ 0.045 |
⩽ 0.045 |
E235 (ST37.4) |
⩽ 0.17 |
⩽ 0.35 |
⩽ 1.2 |
⩽ 0.045 |
⩽ 0.045 |
Tensile strength ranges for ST52.4 from 490 N/mm² to 630 N/mm², while the ranges for ST37.4 are from 340 N/mm² to 480 N/mm². Different steel grades lead to different yield strengths too. The minimum yield strength for ST52.4 is 355 MPa and while for ST37.4 is 235 MPa. However, if the steel tubes with a thickness that is smaller than 3.0MM and an outside diameter that is smaller than 30MM and, the minimum yield strength is 10 MPa lower
3. How to make hydraulic tube?
The tubes surface finishing is NBK, where the tubes are phosphate and normalized which provides corrosion resistance. It is oiled inside and outside. Normalize process creates tougher metal product. During normalizing, metals will be heated at a high temperature, and it allowed to naturally cool back down to room temperature by exposure after heating. Metals that have been through this process are more formable, harder and ductile.
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Galvanize coating is available upon request. Galvanise hydraulic tube comes with protective coating layer of zinc to make them longer lifetime. There are two types of galvanize, hot dipped galvanized and cold dipped galvanized.
There are two options of tube production, seamless or welded. Our hydraulic tubes are made from seamless process and it comes without a weld-join or a seam as it is drawn form a billet.
There are two options of tube production, seamless or welded. Our hydraulic tubes are made from seamless process and it comes without a weld-join or a seam as it is drawn form a billet.
4. Hydraulic tube pressure ratings?
Allowable working pressures are calculated using as per DIN 2413 at normal temperature. The yield and tensile stress values utilize to determine the maximum allowable running pressure and wall thickness required. The tubes and pipes are delivered the actual yield and tensile stress values are verified from the true copy material certificates. Pressure reduction factors at various temperatures show below:
Allowable working pressures are calculated using as per DIN 2413 at normal temperature. The yield and tensile stress values utilize to determine the maximum allowable running pressure and wall thickness required. The tubes and pipes are delivered the actual yield and tensile stress values are verified from the true copy material certificates. Pressure reduction factors at various temperatures show below:
° C |
-40 |
120 |
150 |
175 |
200 |
250 |
° F |
-40 |
248 |
302 |
347 |
392 |
482 |
Rating Factor |
0.90 |
1.0 |
0.89 |
0.89 |
0.83 |
NA |
To determine allowance working pressure at elevated temperature, multiply allowable working pressure of the tube outer diameter and thickness at the rating factor after identify temperature reading.
5. How do you build a hydraulic line?
Hydraulic tubes are suitable for welding according to usual techniques. A bending radius of 3x the external tube outer diameter is recommended for cold bending of tubes with instrument tube bender or manual hand bending. Welding Filler should be selected in accordance to DIN EN 1600 and DIN EN 12072 part 1 taking into account of the welding skill sets and type of application.
Here is the 4 simple steps process of hydraulic tube installation guidelines: |
Step 1: Cut the tube - You can either do this with a wheel cutter or mechanically cut the tube.
Step 2: Bend the tube - This is mostly done using hydraulic tube bender or manually bending.
Step 3: Welding - To weld, you go through three processes, the weld bevel process, choosing the appropriate welding methods and lastly carefully check your handiwork after welding.
Step 4: Installation - This is done when both the hydraulic component and connected equipment has been installed. After clarifying the sequence and become familiar with the pipe scheme, using a pipe clamp, you can reduce the tube vibration when flow went through.
Step 2: Bend the tube - This is mostly done using hydraulic tube bender or manually bending.
Step 3: Welding - To weld, you go through three processes, the weld bevel process, choosing the appropriate welding methods and lastly carefully check your handiwork after welding.
Step 4: Installation - This is done when both the hydraulic component and connected equipment has been installed. After clarifying the sequence and become familiar with the pipe scheme, using a pipe clamp, you can reduce the tube vibration when flow went through.
Hydraulic Steel Tubes Catalogue

Hydraulics Steel Tubes |