Hydraulic Hard Tube

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What is hydraulic hard tube?

The hydraulic hard tube is a rigid tube used to transmit hydraulic oil and other working media in hydraulic systems. It is usually made of metal materials and has strong rigidity and pressure resistance.

In hydraulic systems, hard tubes are often used to connect components such as hydraulic pumps, cylinders, hydraulic valves, and hydraulic pipelines to achieve the transmission and control of hydraulic energy.

Hydraulic hard tubes can be divided into the following categories according to different surface treatment methods:

⚑ Bright precision tube

⚑ Black phosphated precision tube

⚑ Galvanized precision tube

⚑ Army green passivated precision tube

Manufacturing Standard

✔ DIN 2391

✔ 10305-1/4

Available size range:

✔ OD: 4-60mm

✔ WT: 0.5-8mm

Regular Size Chart

	Wall Thickness (mm)
OD (mm)	1	1.5	2	2.5	3	3.5	4	4.5	5	6	8
6	√	√
8	√	√	√
10	√	√	√
12	√	√	√	√
14	√	√	√	√	√
15	√	√	√	√	√
16	√	√	√	√	√
18		√	√	√	√	√	√
20		√	√	√	√	√	√
22		√	√	√	√	√	√
25			√	√	√	√	√
28			√	√	√	√	√
30			√	√	√	√	√	√	√
32			√	√	√	√	√	√	√
34			√	√	√	√	√	√	√	√
35			√	√	√	√	√	√	√	√
38			√	√	√	√	√	√	√	√
40				√	√	√	√	√	√	√
42				√	√	√	√	√	√	√
45				√	√	√	√	√	√	√
46				√	√	√	√	√	√	√
48				√	√	√	√	√	√	√
50				√	√	√	√	√	√	√
54					√	√	√	√	√	√
60					√	√	√	√	√	√	√

Outside Diameter Tolerance

OD (mm)	DIN Standard (mm)	Special high-precision (mm)
4-30	±0.08	±0.03
31-40	±0.15	±0.03
41-50	±0.2	±0.03
51-60	±0.25	±0.03

Wall Thickness Tolerance

WT (mm)

DIN Standard (mm)

Special high-precision (mm)

0.5-8

±10%

Min. ±0.03

Available Material & Grade

Stainless steel：304，316，904L，Duplex SS，

Carbon steel：St35，St37.4，St45，St52，E215，E235，E355

Chemical Composition of Common Grade

Standard	Grade	C	Mn	P	S	Si
DIN 2391	St35	≤0.17	≥0.4	≤0.025	≤0.025	≤0.35
	St37.4	≤0.17	≥0.35	≤0.040	≤0.040	≤0.35
	St45	≤0.21	≥0.4	≤0.025	≤0.025	≤0.35
	St52	≤0.22	≤1.6	≤0.025	≤0.025	≤0.55
EN 10305	E215	≤0.1	≤0.7	≤0.025	≤0.015	≤0.05
	E235	≤0.17	≤1.2	≤0.025	≤0.015	≤0.35
	E355	≤0.22	≤1.6	≤0.025	≤0.015	≤0.55

Mechanical Properties of Common Grade

Standard	Grade	Tensile Strength, min	Yield Strength, min	Elongation, min
DIN 2391	St35	340-470 MPa	235 MPa	25%
	St37.4	350-480 MPa	235 MPa	25%
	St45	440-570 MPa	255 MPa	21%
	St52	490-630 MPa	355 MPa	22%
EN 10305	E215	290-430 MPa	215 MPa	30%
	E235	340-480 MPa	235 MPa	25%
	E355	490-630 MPa	355 MPa	22%

Performance of Hydraulic Hard Tube

⚑ Strength: high

⚑ Pressure resistance: high

⚑ Corrosion resistance: excellent

⚑ Rigidity: strong

⚑ High temperature resistance: good

⚑ Expansion: low

Manufacturing Process

Purchase raw materials →Physical and chemical properties testing →Surface treatment →Cutting →Hot perforation →Getting tube blanks →Pickling →Cold rolling/cold drawing →Straightening →Surface cleaning and degreasing →Annealing (NBK) →Straightening

→Inspecting dimensional accuracy and surface →Eddy current flaw detection →Physical properties testing →Surface treatment (phosphating, galvanizing, passivation) →Labeling

→Packaging

Surface Roughness

✔ Smooth inner and outer surfaces

✔ Roughness ≤ 4μm

Applications

✔ Engineering machinery

✔ Heavy equipment

✔ Automotive parts

✔ Fluid delivery system

Application Industries

✔ Industrial manufacturing

✔ Automotive industry

✔ Aerospace

✔ Oil and gas

✔ Electricity and energy

✔ Chemical industry

✔ Pharmaceuticals

What is a hydraulic assembly?

A complete hydraulic pipeline system component assembled by a special process using hydraulic assembly pipes and various connectors (such as joints, clamps, flanges, etc.).

Hydraulic Tube Assembly