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Eastern Steel Manufacturing Co.,Ltd is a leading manufacturer and distributor of seamless steel pipe, welded steel pipe, OCTG products and fittings. We supply first-step processing, semi-finished parts and finished parts to help our clients meet fabrication requirements beyond their capacity or to improve operations by moving forward the pre-production processing.

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Seamless Steel Pipe

Seamless Hydraulic Tube, Round cold drawn seamless hydraulic steel tube

Seamless Steel Pipe

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Seamless Hydraulic Tube

Seamless hydraulic tubes for hydraulic systems, hydraulic cylinders, fluid power equipment, and industrial machinery, available in carbon steel, alloy steel, and stainless steel grades.

Size: 4–130 mm OD

Material: E355 (ST52.4), E235 (ST37.4)

Standard: DIN 2391/C (DIN EN 10305-1), DIN 2445/2 (DIN EN 10305-4)

Finishing: NBK (Phosphate and Normalized)

Product Description
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1. Seamless Hydraulic Tube Specifications

Seamless hydraulic tubes are supplied in 4–130 mm outside diameters in E235 (ST37.4) and E355 (ST52.4) grades, with dimensions and finishing according to the applicable DIN standards and order requirements.

1.1 Product Specifications

Item	Specification
Product	Seamless Hydraulic Tube
Outside Diameter	4–130 mm
Material	E235 (ST37.4), E355 (ST52.4)
Standards	DIN 2391/C (DIN EN 10305-1), DIN 2445/2 (DIN EN 10305-4)
Finishing	NBK, phosphate and normalized
Size Format	Metric OD, inch OD, inch nominal bore
Length	6 m; other lengths according to order requirements

1.2 Material Grades

Grade	Equivalent Designation	C	Si	Mn	P	S
E355	ST52.4	≤0.22%	≤0.55%	≤1.60%	≤0.045%	≤0.045%
E235	ST37.4	≤0.17%	≤0.35%	≤1.20%	≤0.045%	≤0.045%

E355 (ST52.4) and E235 (ST37.4) are supplied for hydraulic tube applications with different strength and working-pressure requirements.

1.3 Dimensions & Surface Finish

Tube dimensions are specified by outside diameter, wall thickness, and length, with dimensional tolerances according to the applicable DIN EN 10305 requirements.

The standard finishing is NBK (phosphate and normalized), with oil applied to the inside and outside surfaces. Phosphate treatment provides corrosion protection, while normalizing provides the required mechanical condition for the tube.

2. Hydraulic Tube Materials & Grades

Seamless hydraulic tubes are supplied in E235 (ST37.4) and E355 (ST52.4) grades. Grade selection depends on the required mechanical properties and application requirements.

Grade	Equivalent Designation	Typical Selection
E235	ST37.4	General hydraulic applications
E355	ST52.4	Applications requiring higher strength

For detailed chemical composition and material requirements, refer to the applicable DIN EN 10305 specification.

3. Cold Drawn Seamless Hydraulic Tube

For hydraulic systems, tube dimensional accuracy and surface condition can directly affect assembly, sealing, and service performance. Cold drawing provides tighter control of tube dimensions and a more consistent surface finish than hot-finished production, making cold drawn seamless tube a suitable choice for hydraulic cylinders, fluid-power equipment, and precision hydraulic piping.

Eastern Steel supplies cold drawn seamless hydraulic tubes in E235 (ST37.4) and E355 (ST52.4), with dimensions arranged according to the required outside diameter, wall thickness, length, and applicable DIN specifications.

Cold drawn tubes can be supplied with the NBK finishing specified for the product, including phosphate treatment and normalizing, according to the required specification and order requirements.

Related Guide: Cold Drawn Seamless Hydraulic Tube

4. Pressure Capability & Quality Inspection

Seamless hydraulic tubes are used in pressure-fluid systems where tube dimensions, material grade, mechanical properties, and surface condition need to meet the requirements of the hydraulic application. The pressure capability of a tube depends on its outside diameter, wall thickness, material grade, operating temperature, and applicable design requirements.

For each order, the required tube specifications and inspection requirements can be confirmed according to the applicable standard and project requirements.

Inspection Item	What It Covers
Dimensional Inspection	Outside diameter, wall thickness, and length
Mechanical Testing	Mechanical properties required for the specified grade
Surface Inspection	Surface condition and overall tube quality
Hydrostatic Testing	Pressure integrity when required by the applicable standard or order
Inspection Documentation	MTR, MTC, and other documents according to order requirements

5. Hydraulic Tube Applications

Seamless hydraulic tubes are used in hydraulic and fluid-power systems where reliable pressure performance, controlled dimensions, and consistent tube quality are required. Typical applications include hydraulic cylinders, mobile equipment, industrial machinery, and other hydraulic systems.

Application	Typical Use
Hydraulic Cylinders	Cylinder assemblies and hydraulic actuation systems
Construction Equipment	Excavators, loaders, lifting equipment, and other hydraulic machinery
Mobile Machinery	Hydraulic power and control systems
Industrial Machinery	Hydraulic actuation and fluid-power systems
Agricultural Equipment	Hydraulic cylinders and fluid systems
Fluid Power Systems	Hydraulic circuits and pressure-fluid transmission

6. Seamless Hydraulic Tube Supply from Eastern Steel

Eastern Steel supplies seamless hydraulic tubes for hydraulic, fluid-power, and industrial applications. Orders can be arranged according to required tube dimensions, material grades, finishing conditions, and project specifications.

Supply Capability	Eastern Steel
Product	Seamless Hydraulic Tube
Grades	E235 (ST37.4), E355 (ST52.4)
Manufacturing	Seamless, cold drawn
Outside Diameter	4–130 mm
Length	6 m and according to order requirements
Finishing	NBK, phosphate and normalized
Size Format	Metric OD, inch OD, inch nominal bore
Documentation	MTR, MTC and other documents according to order requirements
Order Type	Standard and project orders
Export Support	Packing, marking and shipping documentation

7. FAQs

Q1. Can seamless hydraulic tubes be used for high-pressure applications?

Yes. Seamless hydraulic tubes are commonly used in pressure-fluid systems. The applicable pressure capability depends on tube outside diameter, wall thickness, material grade, mechanical properties, operating temperature, and system design requirements.

Q2. Can seamless hydraulic tubes be supplied according to project requirements?

Tube dimensions, lengths, finishing conditions, quantities, and other requirements can be confirmed according to the applicable specification and order requirements.

Q3. What documents are provided with seamless hydraulic tube orders?

Depending on the order requirements, documentation may include MTR, MTC when required, packing list, commercial invoice, certificate of origin when required, and other project-specific documents.

Seamless 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	-

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	-