Description:
​Hydraulic steel tubes are made of material E235 (ST 37.4) or E355 (ST 52.4) according to DIN EN 10305-4 (DIN 2445/2) or DIN EN 10305-1 (DIN 2391/C). The material is +N (NBK) annealed, phosphate and oiled internally and externally. The tube ends closed with plastic plugs with continuous marking along the entire tube length. The tubes are delivered with 3.1. certification on EN 10204.​

Size Range (Metric)	6MM to 190MM
Size Range (Inch OD)	1/8" to 4"
Dimension Standard	DIN EN 10305-1 (DIN 2391/C) DIN EN 10305-4 (DIN 2445/2)
Material	E355 (ST52.4)​ E235 (ST37.4)
Finishing	NBK (Phosphate and Normalized)
Origin	China

Catalogue:
Hydraulics Steel Tubes

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Literature:
Hydraulics Steel Tubes

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Product Information of Hydraulic Steel Tubes

1. Introduction:
​​
Chuan Kok maintains a large stock of hydraulic tubes in steel material. The hydraulic tube is a cylinder-shaped tubing device that connects to hydraulic systems, allowing fluids to flow between and inside components. They usually hold a length of about 6 meters. These steel tubes are in accordance with DIN 2391, the standard specification of steel tubes for precision application such as hydraulic and pneumatic power systems, and DIN 2445, the standard specification of seamless steel tubes for dynamic loads.
​
Steel tubes are available in two kinds of steel material, ST37.4 (E235N) and ST52.4 (E355N). Different materials result from differences in the working pressure that the material can withstand. Grade ST52.4 is a higher grade compared to grade ST37.4, and a higher grade of material quality can reduce wall thickness and weight while maintaining the same working pressure.

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Hydraulic Steel Tubes in Difference Size

​2. Hydraulic Steel Pipe Attributes:

​Different material grades will lead to differences in attributes. For ST37.4, tensile strength ranges from 340 N/mm² to 480 N/mm², while for ST52.4, the tensile strength ranges from 490 N/mm² to 630 N/mm². Higher tensile strength means higher working pressures with reduced wall thickness, thus leading to reduced tube weight.
 
The two different steel grades also lead to different yield strengths. The minimum yield strength for ST37.4 is 235 MPa and for ST52.4 it is 355 MPa. However, for steel tubes with an outside diameter that is less than 30MM and a thickness that is less than 3.0MM, the minimum yield strength is 10 MPa lower.
 
There are also differences in chemical composition between ST37.4 and ST52.4. For example, the maximum carbon content for ST37.4 is 0.17%, while the maximum carbon content for ST52.4, is 0.22%. The high carbon content will make the steel harder and stronger through heat treatment. However, it will also cause the steel material to be less ductile and reduce the melting point. 

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

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​3. Hydraulic Steel Tube Finishing:

The finishing of tubes under ST37.4 and ST52.4 are NBK, where tubes are normalized, phosphated, and oiled inside and outside. Normalizing is a type of heat treatment process. Heat treatment is done to change its mechanical properties such as hardness, yield strength, and ductility.
 
In the normalizing process, steel is heated to a temperature about 55˚C. This process will be continued over a period of time for a transformation namely grain refinement to occur. The steel then will be air-cooled in a room temperature. This results in the steel becoming stronger and harder. Besides, this cold drawn process brings advantages of tight dimensional tolerances, increased material strength, and improved machinability for the tube. Thus, hydraulic tubes are appropriate for use in high-performance pipe systems.

Galvanizing the tubes is also another technique. Zinc is added as an additional coating to the tubes to improve their anti-rust properties. Galvanizing can be done in a variety of ways, yet this hot-dip approach is the most popular and commonly used. The hot-dip galvanization process applies a thick layer of zinc to the melted tube before painting. Electro-galvanizing can be employed when a lighter form of zinc is needed on the tube's surface.
 
Hydraulic tubes can be produced in two ways: seamless or welded. As they are pulled from a billet, our hydraulic tubes are manufactured from a seamless method and do not have a weld-join or a seam.

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4. Pressure Rating:

​At room temperature, allowable working pressures are determined using DIN 2413. The maximum permissible running pressure and required wall thickness are determined by the yield and tensile stress values. The actual yield and tensile stress values of the tubes and pipes are validated using true copy material certifications.

° 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

​To calculate the allowed working pressure at increased temperatures, multiply the allowable working pressure of the tube outer diameter and thickness by the rating factor after determining the temperature measurement. ​​

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5. Difference Between Hydraulic Tubes and Hydraulic Hoses:

Characteristics	Hydraulic Steel Tubes	Hydraulic Hose
Workability and Expansion	Ability to work and maintain shape ​under high heat.	Low-level of heat resistance. When the temperature is high, they have a tendency to expand.
​Cost	Less expensive and easily available for purchase	Expensive
Durability	Highly durable	Has a limited time for use

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6. Installation:

Hydraulic tubes can be welded using standard welding processes. A bending radius of 3x the exterior tube outer diameter is suggested when cold bending tubes using an instrument tube bender or by hand.  Welding Filler should be chosen in line with DIN EN 1600 and DIN EN 12072 part 1, taking into consideration the welding skill sets and application type.

There are 4 steps for hydraulics steel tubes installation:

STEP 1: Cut the tube - You can use a wheel cutter or a mechanical cutter to cut the tube

STEP 2: Bend the tube - This is usually done using a hydraulic tube bender or by hand

STEP 3:​ Welding - There are three steps of welding: the weld bevel process, selecting the proper welding procedures, and inspecting your work after welding.

STEP 4: Installation - After both the hydraulic component and the associated equipment have been installed, this step is completed. After you've clarified the sequence and the pipe scheme, you may use a pipe clamp to minimize tube vibration while the flow passes through.

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7. Outer Diameter and Tube Thickness Specifications:

The specifications of the tube outer diameter and tube wall thickness are according to EN 10305-4. Below Hydraulic Steel Tubes Literature will  shows the preferred outside diameter, inside diameter, and wall thickness.

​For more information regarding hydraulic steel tubes and their application, please refer to en.wikipedia.org/wiki/Hydraulic_machinery#Hose.2C_tubes_and_pipes

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8. Hydraulic Tube (ST37.4 NBK) Working Pressure Table: 

 

No.	Description	Working Pressure (Bar)	Burst Pressure (Bar)	IMPA CODE
1	4MM OD x 1.0MM THK x 6 MTR	707	1755	710701
2	5MM OD x 1.0MM THK x 6 MTR	565	1404	-
3	6MM OD x 1.0MM THK x 6 MTR	471	1170	710702
4	6MM OD x 1.5MM THK x 6 MTR	707	1755	710703
5	8MM OD x 1.0MM THK x 6 MTR	353	878	710704
6	8MM OD x 1.5MM THK x 6 MTR	530	1316	710705
7	8MM OD x 2.0MM THK x 6 MTR	707	1755	710706
8	8MM OD x 2.5MM THK x 6 MTR	883	2194	-
9	10MM OD x 1.0MM THK x 6 MTR	283	702	710707
10	10MM OD x 1.2MM THK x 6 MTR	339	845	710708
11	10MM OD x 1.5MM THK x 6 MTR	424	1053	710709
12	10MM OD x 2.0MM THK x 6 MTR	565	1404	710710
13	10MM OD x 2.5MM THK x 6 MTR	707	1755	-
14	12MM OD x 1.0MM THK x 6 MTR	236	585	710711
15	12MM OD x 1.2MM THK x 6 MTR	283	702	710712
16	12MM OD x 1.5MM THK x 6 MTR	353	878	710713
17	12MM OD x 2.0MM THK x 6 MTR	471	1170	710714
18	12MM OD x 2.5MM THK x 6 MTR	589	1463	-
19	12MM OD x 3.0MM THK x 6 MTR	707	1755	-
20	14MM OD x 1.5MM THK x 6 MTR	303	752	-
21	14MM OD x 2.0MM THK x 6 MTR	404	1003	-
22	14MM OD x 2.5MM THK x 6 MTR	505	1254	-
23	14MM OD x 3.0MM THK x 6 MTR	606	1504	-
24	14MM OD x 4.0MM THK x 6 MTR	807	2006	-
25	15MM OD x 1.0MM THK x 6 MTR	188	468	-
26	15MM OD x 1.2MM THK x 6 MTR	226	562	710715
27	15MM OD x 1.5MM THK x 6 MTR	283	702	710716
28	15MM OD x 2.0MM THK x 6 MTR	377	936	710717
29	15MM OD x 2.5MM THK x 6 MTR	471	1170	710718
30	15MM OD x 3.0MM THK x 6 MTR	565	1404	-
31	16MM OD x 1.5MM THK x 6 MTR	265	658	710719
32	16MM OD x 2.0MM THK x 6 MTR	353	878	710720
33	16MM OD x 3.0MM THK x 6 MTR	530	1316	-
34	18MM OD x 1.5MM THK x 6 MTR	236	585	710721
35	18MM OD x 2.0MM THK x 6 MTR	314	780	710722
36	18MM OD x 2.5MM THK x 6 MTR	393	975	710723
37	18MM OD x 3.0MM THK x 6 MTR	471	1170	-
38	20MM OD x 2.0MM THK x 6 MTR	283	702	710724
39	20MM OD x 2.5MM THK x 6 MTR	353	878	710725
40	20MM OD x 3.0MM THK x 6 MTR	424	1053	710726
41	20MM OD x 3.5MM THK x 6 MTR	495	1229	-
42	20MM OD x 4.0MM THK x 6 MTR	565	1404	-

 

 

No.	Description	Working Pressure (Bar)	Burst Pressure (Bar)	IMPA CODE
43	20MM OD x 4.5MM THK x 6 MTR	636	1580	-
44	20MM OD x 5.0MM THK x 6 MTR	707	1755	-
45	22MM OD x 2.0MM THK x 6 MTR	257	638	710727
46	22MM OD x 2.5MM THK x 6 MTR	321	798	-
47	22MM OD x 3.0MM THK x 6 MTR	385	957	710728
48	22MM OD x 4.0MM THK x 6 MTR	514	1276	-
49	25MM OD x 2.0MM THK x 6 MTR	226	562	710729
50	25MM OD x 2.5MM THK x 6 MTR	283	702	710730
51	25MM OD x 3.0MM THK x 6 MTR	339	842	710731
52	25MM OD x 3.5MM THK x 6 MTR	396	983	-
53	25MM OD x 4.0MM THK x 6 MTR	452	1123	-
54	25MM OD x 5.0MM THK x 6 MTR	565	1404	-
55	28MM OD x 2.0MM THK x 6 MTR	202	501	-
56	28MM OD x 2.5MM THK x 6 MTR	252	627	710732
57	28MM OD x 3.0MM THK x 6 MTR	303	752	-
58	28MM OD x 4.0MM THK x 3 MTR	404	1003	-
59	28MM OD x 5.0MM THK x 6 MTR	505	1254	-
60	30MM OD x 2.0MM THK x 6 MTR	188	468	-
61	30MM OD x 2.5MM THK x 6 MTR	236	585	710733
62	30MM OD x 3.0MM THK x 6 MTR	283	702	-
63	30MM OD x 4.0MM THK x 6 MTR	377	936	-
64	30MM OD x 5.0MM THK x 6 MTR	471	1170	-
65	35MM OD x 2.0MM THK x 6 MTR	161	401	-
66	35MM OD x 2.5MM THK x 6 MTR	202	501	710734
67	35MM OD x 3.0MM THK x 6 MTR	242	602	-
68	35MM OD x 4.0MM THK x 6 MTR	323	802	710735
69	35MM OD x 5.0MM THK x 6 MTR	404	1003	-
70	38MM OD x 3.0MM THK x 6 MTR	223	554	-
71	38MM OD x 4.0MM THK x 6 MTR	297	739	-
72	38MM OD x 5.0MM THK x 6 MTR	372	924	-
73	42MM OD x 2.0MM THK x 6 MTR	135	334	-
74	42MM OD x 3.0MM THK x 6 MTR	202	501	-
75	42MM OD x 4.0MM THK x 6 MTR	269	669	710736
76	42MM OD x 5.0MM THK x 6 MTR	336	836	-
77	50MM OD x 3.0MM THK x 6 MTR	170	421	-
78	50MM OD x 5.0MM THK x 6 MTR	283	702	-
79	60MM OD x 3.0MM THK x 6 MTR	141	351	-
80	60MM OD x 5.0MM THK x 6 MTR	236	585	-
81	65MM OD x 6.0MM THK x 6 MTR	261	648	-
82	75MM OD x 3.0MM THK x 6 MTR	113	281	-
83	1/8"NB x 2.41MM THK x 6 MTR	649	1611	-
84	1/4"NB x 3.02MM THK x 6 MTR	618	1536	-

 

 

No.	Description	Working Pressure (Bar)	Burst Pressure (Bar)	IMPA CODE
85	3/8"NB x 3.2MM THK x 6 MTR	523	1298	-
86	1/2"NB x 3.0MM THK x 6 MTR	391	971	-
87	3/4"NB x 3.0MM THK x 6 MTR	312	774	-
88	1"NB x 3.5MM THK x 6 MTR	291	723	-
89	1"NB x 4.55MM THK x 6 MTR	378	939	-
90	1 1/4"NB x 4.85MM THK x 6 MTR	321	797	-
91	1 1/2"NB x 5.08MM THK x 6 MTR	295	734	-
92	2 1/2"NB x 6.3MM THK x 6 MTR	NIL	580	-
93	1/4"OD x 1.2MM THK x 6 MTR	534	1327	-
94	1/4"OD x 1.5MM THK x 6 MTR	668	1658	-
95	3/8"OD x 1.22MM THK x 6 MTR	362	899	-
96	3/8"OD x 1.5MM THK x 6 MTR	445	1105	-
97	1/2"OD x 1.5MM THK x 6 MTR	334	829	-
98	3/4"OD x 2.0MM THK x 6 MTR	297	737	-
99	3/4"OD x 2.64MM THK x 6 MTR	392	973	-
100	1"OD x 3.0MM THK x 6 MTR	334	829	-
101	1 1/4"OD x 3.0MM THK x 6 MTR	267	663	-
102	1 1/4"OD x 3.25MM THK x 6 MTR	289	719	-

 

9. Hydraulic Tube (ST52.4 NBK) Working Pressure Table: 

No.	Description	Working Pressure (Bar)	Burst Pressure (Bar)	IMPA CODE
103	10MM OD x 2.0MM THK x 6 MTR	799	1919	710710
104	12MM OD x 2.0MM THK x 6 MTR	666	1599	710714
105	14MM OD x 1.5MM THK x 6 MTR	428	1028	-
106	14MM OD x 2.0MM THK x 6 MTR	571	1371	-
107	15MM OD x 1.5MM THK x 6 MTR	400	959	710716
108	15MM OD x 2.0MM THK x 6 MTR	533	1279	710717
109	15MM OD x 2.5MM THK x 6 MTR	666	1599	710718
110	16MM OD x 1.5MM THK x 6 MTR	375	899	710719
111	16MM OD x 2.0MM THK x 6 MTR	500	1199	710720
112	16MM OD x 3.0MM THK x 6 MTR	749	1799	-
113	18MM OD x 1.5MM THK x 6 MTR	333	800	710721
114	18MM OD x 2.0MM THK x 6 MTR	444	1066	710722
115	20MM OD x 2.0MM THK x 6 MTR	400	959	710724
116	20MM OD x 2.5MM THK x 6 MTR	500	1199	710725
117	20MM OD x 3.0MM THK x 6 MTR	599	1439	710726
118	22MM OD x 2.0MM THK x 6 MTR	363	872	710727
119	25MM OD x 2.0MM THK x 6 MTR	320	768	710729
120	25MM OD x 2.5MM THK x 6 MTR	400	959	710730
121	25MM OD x 3.0MM THK x 6 MTR	480	1151	710731
122	25MM OD x 4.0MM THK x 6 MTR	639	1535	-
123	25MM OD x 5.0MM THK x 6 MTR	799	1919	-
124	28MM OD x 2.0MM THK x 6 MTR	285	685	-
125	28MM OD x 3.0MM THK x 6 MTR	428	1028	-
126	30MM OD x 2.0MM THK x 6 MTR	266	640	-
127	30MM OD x 3.0MM THK x 6 MTR	400	959	-
128	30MM OD x 4.0MM THK x 6 MTR	533	1279	-
129	35MM OD x 3.0MM THK x 6 MTR	343	822	-
130	35MM OD x 4.0MM THK x 6 MTR	457	1096	710735
131	38MM OD x 3.0MM THK x 6 MTR	315	757	-
132	38MM OD x 4.0MM THK x 6 MTR	421	1010	-
133	38MM OD x 5.0MM THK x 6 MTR	526	1262	-
134	42MM OD x 3.0MM THK x 6 MTR	285	685	-
135	42MM OD x 4.0MM THK x 6 MTR	381	914	710736
136	42MM OD x 5.0MM THK x 6 MTR	476	1142	-
137	45MM OD x 5.0MM THK x 6 MTR	444	1066	-
138	50MM OD x 5.0MM THK x 6 MTR	400	959	-
139	50MM OD x 6.0MM THK x 6 MTR	480	1151	-
140	50MM OD x 10.0MM THK x 6 MTR	799	1919	-
141	54MM OD x 6.0MM THK x 6 MTR	444	1066	-
142	60MM OD x 5.0MM THK x 6 MTR	333	800	-
143	60MM OD x 6.0MM THK x 6 MTR	400	959	-

 

No.	Description	Working Pressure (Bar)	Burst Pressure (Bar)	IMPA CODE
144	65MM OD x 8.0MM THK x 6 MTR	492	1181	-
145	66MM OD x 8.5MM THK x 6 MTR	515	1236	-
146	76.1MM OD x 6.3MM THK x 6 MTR	331	794	-
147	80MM OD x 10.0MM THK x 6 MTR	500	1199	-
148	90MM OD x 5.0MM THK x 6 MTR	222	533	-
149	90MM OD x 10.0MM THK x 6 MTR	444	1066	-
150	97MM OD x 12.0MM THK x 6 MTR	494	1187	-
151	100MM OD x 10.0MM THK x 6 MTR	400	959	-
152	115MM OD x 15.0MM THK x 6 MTR	521	1251	-
153	120MM OD x 12.0MM THK x 6 MTR	400	959	-
154	130MM OD x 15.0MM THK x 6 MTR	461	1107	-
155	150MM OD x 15.0MM THK x 6 MTR	400	959	-
156	190MM OD x 20.0MM THK x 6 MTR	421	1010	-
157	2"OD x 5.9MM THK x 6 MTR	464	1114	-
158	2"OD x 6.0MM THK x 6 MTR	472	1133	-

 

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Product Catalogue in pdf:

Hydraulic Steel Tubes

Product Literature in pdf:

Hydraulic Steel Tubes

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FAQ Of Hydraulic Steel Tubes

What are the diameter sizes available? What is the standard length for hydrailics steel
tubes?

​The sizes of hydraulics steel tubes range from 4mm to 130mm outer diameter. They typically have a length of 6 meter long.

What are the functions of hydraulics steel tubes?

The function of hydraulic steel tube is to convey liquid fluids to among hydraulics components, fittings, valves, flanges, and other tools. They are suitable in high performance piping system application.

What are the chemical composition for hydraulics steel tubes?​

​Hydraulics steel tubes consist of Carbon (C), Silicon (Si), Manganese (Mn), Phosphorus (P), Sulfur (S).

What are the material specifications of hydraulics steel tubes?

There are two types of material grade which are ST52.4 and ST37.4. Compared to ST37.4, ST52.4 has higher tensile strength and
higher permissible working pressures by reduced tube wall thickness. It leads to reduced system overall weight.

What is the finishing used by hydraulics tubes?

The hydraulics steel tubes surface finishing is NBK where the tubes are phosphate and normalized which is corrosion resistance.

Is hydraulics steel tubes suitable for welding?

Yes. Tubes of ST37.4 and ST52.4 are suitable for welding according to usual techniques.

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