Hydraulic Steel Tubes

HYDRAULIC STEEL TUBES

Material Specification	ST37.4 (E235) ST52.4 (E355)
Dimension Specification	DIN EN 10305-4 (DIN 2445/2) DIN EN 10305-1 (DIN 2391/C)
Outer Diameter Size	4 to 130mm external diameter
Finishing	Normalized / Phosphate (NBK)

Hydraulic steel tubes are a major component that allows free passage of fluids in pipes, valves, and other hydraulic machines. Hydraulic tubes are suitable for use in various hydraulic machines and require low maintenance. The tube is available in DIN 2445/2 (DIN EN 10305-4) or DIN 2391/C (DIN EN 10305-1) standards and measured in inches nominal bore size (NB) or outer diameter (OD) and millimeters (MM).

Produced with two different materials, E235 (ST 37.4) or E355 (ST 52.4), the synthetic elements help regulate pressure in the hydraulics. Without a change in the working pressure, the latter has an advantage of the increased mass and density depletion over the former.

1. What is Hydraulic system and how does it work?

With the invention of more machinery in the 18th century, hydraulic systems were built to replace a steam hammer. This further led to hydraulic systems being used in operating systems such as cranes, elevators, ports, steel production, etc. The hydraulic system was developed from Pascal's Law, a French mathematician, Blaise Pascal. The law states that an enclosed fluid can transmit pressure to all parts of the container without altering the weight. This propelled the research. This drove the research by Joseph Bramah to invent the hydraulic press (system) in 1795. Today, hydraulic systems are well-known and used by many construction companies, machinery, and automobiles.

Hydraulic tubes are cylindrically shaped tools found in hydraulic systems that aid liquids' flow to and from other components. The hydraulic system comprises several elements, with four classified as major parts: pump, reservoir, valve, and actuators. These components direct the storage of liquid, pressure application, conversion of energy, control, and fluids movement.

EN 10305-4 Hydraulic Steel Tubes

2. What is Hydraulic Tube?

DIN 2391C Hydraulic Steel Tubes

The Hydraulic tubes are finished through a cold drawn method, mostly used in shaping steel bars (stainless and carbon). This method gives the hydraulic tubes more straightness, strength, increased tolerance, and efficiency. Also, it has seamless precision, which makes it light weighted. These two qualities make the tubes suitable for use in all machines, including sophisticated ones.

In length, the tubes are 6 meters long. Purchasing the right tube size of hydraulic tubes is very important in achieving the optimum use and maintaining the system's efficiency. Failure to do this may result in damage to other parts and cavitation. The measurement of the inner and outer diameter is needed for determining the size of the tube. This is combined with the thickness of the wall. That is inner diameter + thickness of the wall or outer diameter + thickness of the wall.

The hydraulic tube is made up of two different materials – ST37.4 or ST52.4. ST37.4 tube has anti-rust quality, bright heat light, clean inner walls, pressure-resistant, and no oxidation.

The chemical composition for the ST37.4 material is as follows:

Material	Carbon	Silicon	Manganese	Phosphorus	Sulfur
ST 37.4	≤ 0.17%	≤ 0.35%	≤ 1.2%	≤ 0.0045	≤ 0.0045

The tensile strength for the product ranges between 340 N/mm2, and it has a minimum yield strength of 235MPa. A steel tube with an outer diameter of less than 30MM and thickness less than 3.0MM will result in tensile strength of 225MPa.

For the ST52.4 material, the chemical composition is shown in the table below:

Material	Carbon	Silicon	Manganese	Phosphorus	Sulfur
ST 52.4	≤ 0.17%	≤ 0.35%	≤ 1.2%	≤ 0.0045	≤ 0.0045

The tensile strength is higher than ST37.4, which ranges from 490N/mm2 to 630N/MM2. For yield strength, it has a minimum of 355MPa.

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3. What is Hydraulic Tube?

Hydraulic tubes and hoses serve the same purpose in a hydraulic machine. However, it may not be easy to ascertain the best amongst these two materials.

Hydraulic Tubes

Ability to work and maintain shape under high heat

Less expensive and easily available for purchase

Highly durable

Description

Workability
and Expansion

Cost

Durability

Hydraulic Hose

Low-level of heat resistance. Tend to expand when the heat level is high.

Expensive

Has a limited time for use

These differences have made the hydraulic tubes more opted for when using hydraulic machines.

4. What is Hydraulic Tube made of?

Hydraulic Steel Tubes 6 Meters Long

While making a hydraulic tube, two methods can be used – welding or a seamless method. The welding process involves a combination of metal pieces using heat. This softens the metal and allows bending to the desired shape easily. The process has been long-existing and can be used in several ways.

The seamless method is used when a tube is connected to another without any trace of welding. This is possible because the tubes have a thread at the ends, which can be quickly joined to another through threading. A seamless pipe is more robust and lasts longer than welded tubes. Our tubes are made from the seamless method, making it more durable and able to withstand more pressure.

The tube surface is finished with NBK (normalized). With this method, the tubes are exposed to protective heat treatment in an oxidation-free area to achieve the tubes' shiny, smooth, and glossy surface area. The tube is also greased thoroughly internally and externally, and melted ions are left to cool down after heating naturally. This also gives the tubes an anti-rust property and enhances the strength of the tubes.

Galvanization of the tubes is also available. To increase the tubes' anti-rust quality, zinc is applied for an extra coating of the tube. There are several methods of galvanizing, however, the hot-dip method is mostly used. The Hot-dip galvanization method drops a thick size of the zinc on the melted tube, and this is applied before painting. The electro-galvanizing can be used when a lighter form of zinc is needed on the tube's surface.

5. What is the pressure rating for Hydraulic Tubing?

The pressure ratings are measured using as per DIN 2413 while working with moderate temperatures. Actual yield and tensile stress values can be found on certificates of the materials. However, the table on the right shows several temperatures for reduction of pressure:

Working pressure allowed in elevated temperature is calculated by rating factor thickness multiplied by working pressure allowed for the tube's outer diameter.

C (in degree)	F (in degree)	Rating Factor
40	-40	0.90
120	248	1.00
150	302	0.89
175	347	0.89
200	392	0.83
250	482	NA

6. How do you build a Hydraulic Line?

Setting up a hydraulic line can be done using simple steps. Materials to be used are wheel cutter, hydraulic tube bender, safety goggles, pipe clamp, lubricant, and gloves (optional).

Before the process begins, ensure you have the right size of the hydraulic tubes for your machine. Then, follow the following steps

Hydraulic Steel Tubes ST37.4

STEP 1
The first step is cutting the tubes. You have to cut the tubes to the desired length, and this can be done using a wheel cutter or an engine.

STEP 2
The next step is bending the hydraulic tube. You can bend the tube manually or make use of a hydraulic tube bender for this step.

STEP 3
After cutting, the next step is welding. Welding requires joining two metal materials with heat. The welding process is split into three stages – beveling, selecting the desired welding process, and checking for errors. The bevel process involves changing the structure of metals to be joined. This gives a stronger weld and reduces the probability of developing issues as time proceeds.

After this, you select the method of welding to use. Remember to use your safety goggles and gloves to avoid accidents.

After the process, check for loopholes or faulty areas before use.

STEP 4
The last way is the installation of the hydraulic line welded.