What is Hydraulic Steel Pipe?

What is Hydraulic Steel Pipe?

Hydraulic steel pipe is basically divided into the hydraulic system with fluid pipe and oil cylinder, also known as honing tube, and cold drawn or cold rolled precision seamless steel pipe also contains hydraulic tube.
Hydraulic pipe after finishing, no oxidation bright heat treatment of raw materials (NBK), nondestructive testing, steel pipe inner hole through high pressure washing, pickling, block on both ends of the steel tube inside and outside wall with anti-rust oil antirust processing, used as a dustproof. To produce steel pipes with high precision, finish good, tube inside and outside wall without oxidation layer, steel pipe can bear the high pressure of fluid flow through, and the steel tube cold bending deformation, flaring, flattening without cracks.Mechanical properties can be bending deformation under any Angle.

Honed Tubes for Hydraulic/ Pneumatic Cylinder

The honed tubes suitable for various kinds of Precision Mechanical Tube, Honed Cylinder Tubing and Hydraulic Cylinder, Construct use Multi Joint Tube, Steel Axis Pipe, Injection Machine and Robotic Arm. This tubing is ready to use for hydraulic cylinder applications without further ID processing.

honed tube - What is Hydraulic Steel Pipe?

Grade:

ST 52,ST52.3,CK45, E355, 16Mn, STKM13C, SAE1020, SAE1026, SAE1045

Size range

Inside diameter from 40 to 1000mm, Max length 20 meters.

Straightness: 0.5 /1000

Tolerance EXT: DIN 2391

Tolerance INT: ISO H8

Roughness(Ra): 0.2 to 0.4µ

Type:

cold drawing, normalizing treatment, honing.

Chemical composition(%)

Si(Max) Mn (Max) C Max) P (Max.) S (Max)
0.55 1.60 0.22 0.025 0.25

Mechanical properties:

Tensile strength
Min
Yield Point
Min
Elongation
% Min
580 N/mm2 420 N/mm2 10

 

Marking: YaangID, OD

Length: unfixed length or fixed length

Package: banding with steel strips, braiding parcel at outside

Conservation: Anti rust oiled coating on the inside and outside of the surface, plastic caps at both ends.

Impact test: -20℃, 27 J (only for special requirement)

High precision cold drawn tube (ready to honed tube) can also be supplied. 

Tolerance standard:

ID(mm) TOLERANCE(mm)
H7 H8

H9

H10

30

+0.021/0

+0.033/0

+0.052/0

+0.084/0

30 – 50

+0.025/0

+0.039/0

+0.062/0

+0.100/0

50 – 80

+0.030/0

+0.046/0

+0.074/0

+0.120/0

80 – 120

+0.035/0

+0.054/0

+0.087/0

+0.140/0

120 – 180

+0.040/0

+0.063/0

+0.100/0

+0.160/0

180 – 250

+0.046/0

+0.072/0

+0.115/0

+0.185/0

250 – 315

+0.052/0

+0.081/0

+0.130/0

+0.210/0

315 – 700

+0.057/0

+0.089/0

+0.140/0

+0.230/0

Precision Seamless Pipe

Precision seamless pipe is a pipe material producing by a cold drawn process with high precision and high-quality finish.

precision seamless tubes 1 - What is Hydraulic Steel Pipe?

CDS is popular in the hydraulics, being used to make hollowed chrome plated telescopic cylinders and hydraulic rods. It is also popular for large bore, heavy walled, high pressure hydraulic cylinders. Cold Drawn Seamless tubes also find uses in heavy equipment manufacturing such as cranes and garbage trucks.

precision seamless tubes 2 - What is Hydraulic Steel Pipe?

Due to the characteristics of high-precision, in precision machinery manufacturing, auto parts, hydraulic cylinders, construction (steel sleeve) industry has a very wide range of applications.

General process of cold drawing

A considerable proportion of the seamless tubes and pipes manufactured through the cold roll piercing technology undergo subsequent cold forming. The principal reasons behind cold drawing are:

precision seamless tubes 3 - What is Hydraulic Steel Pipe?
  • Achievement of closer wall thickness and diameter tolerance
  • Improvement in surface finish
  • To enhance serviceability
  • No premature failure
  • Suitable for critical forming Such as 180˚ Bends
  • Enhancement of mechanical properties of the tube
  • Expansion of product mix towards the lower end of the OD and wall thickness scales.
seamless process colddraw - What is Hydraulic Steel Pipe?

Cold drawn steel tube is with hot-rolled steel coil as raw material, and tandem cold rolling pickled to remove oxide scale, its finished rolling hard roll, rolling hard volumes due to the continuous cold deformation caused by cold hardening strength, hardness increased indicators declined tough plastic, stamping performance will deteriorate, which can only be used for simple deformation of the parts.

Pipe weld cracks often follow different mechanisms can be divided into two types of thermal cracking and cold cracking. It is produced by the thermal cracking of a liquid to a solid state crystallization process in the weld metal, mostly generated in the weld metal. The main causes of its low-melting substance is present in the weld, which weakens the contact between the grains when subjected to high welding stress, it is easy to cause breakdown between the grains. Weldments and welding rod containing S, Cu impurities such a long time, it is prone to hot cracking.

Thermal cracking characteristic distribution along the grain boundaries. When the crack through the surface and the outside world, it is a clear tendency hydrogenation. Cold cracks are generated in the cooling process after welding, mostly produced in the base metal or base metal and the weld fusion line junction. The main reason is due to its generation or the weld heat affected zone formed within the quenched structure, under high stress, causing rupture of grains, the higher the carbon content of the welding elements, or more easily hardened alloy steel, the most prone to cold cracking. Excessive weld melt into hydrogen, can also cause cold cracking. A defect of the most dangerous cracks, which in addition to reducing the cross-section than the bearing, but also produce severe stress concentration at the crack will gradually expand in use, may eventually lead to the destruction member. So welded structures are generally not permitted the existence of such defect has been found to be a shovel to re-welding.

Steel pipe internal defects of weld lack of penetration is refers to the workpiece and the weld metal or weld layer between local incomplete fusion of a defect. Incomplete penetration welds weakened section of the work, causing serious stress concentration, greatly reduce joint strength, it is often a source of weld cracking. Weld slag sandwiched nonmetallic slag, that is called slag. Weld slag reduces work-section, resulting in stress concentration will reduce weld strength and toughness.

Porosity of the weld metal at high temperatures, the absorption due to too much gas or gas dissolved within the cell is generated by the reaction of metallurgical, too late when the bath is discharged is cooled and solidified, and the weld hole is formed inside or the surface, i.e. pores. The presence of pores reduces the effective work of the weld cross-section, to reduce the mechanical strength of the joint. If penetrating pores or continuity exists, it will seriously affect the tightness of the weldment. After cracking during welding or welding metal in the welded joints appearing partial rupture area called crack. Cracks may occur in the weld may also be produced in the weld heat affected zone on both sides. Sometimes occurs on the metal surface, the metal may be generated internally.

Cold formed steel

Cold-formed steel refers to the use plates or strip bent in a cold state of the various cross-sectional shape of the finished steel. Cold-formed steel is an economical lightweight thin-walled steel cross-section, also called cold-formed steel profiles. Bending section steel is the main material of light steel structure. It has a hot rolling can produce all kinds of thin, reasonable shape and complex cross section.

Hot forging and cold forging

Hot forging means forging blank metal above the recrystallization temperature carried out.

Cold forming performance

Cold forming is not performed in the case of heating the material for punching, bending, stretching and other processing methods. Cold forming processes are cold heading, cold rolled, forging and so on.

The advantages of cold-rolled tube

Cold-rolled tube refers to steel product that is through cold drawing, cold-formed, cold drawn, cold plate or strip processed at room temperature.

Annealing and quenching of cold drawn steel

The annealing of cold drawn steel is commonly used in the production of preliminary heat treatment process. The annealing of cold drawn steel is commonly used in the production of preliminary heat treatment process.

Application of ASTM A179 Cold Drawn Seamless Tubes

ASTM A179 cold drawn seamless carbon steel pipe is mainly used in various sectors of the metal structure facilities, mainly after the rust of steel pieces immersed in 440 – 460 ℃ melting zinc solution, so that the steel surface attached to the zinc layer, which play a preservative purpose.

Weld cold crack

Welded joints cooled to a lower temperature ( for steel, in the martensitic transformation start temperature Ms less ) generated by the weld cracking.

THERE ARE THREE BASIC PROCESSES EMPLOYED FOR THE COLD DRAWING OF TUBE:

  • Hollow drawing
  • Stationery drawing or floating plug drawing and
  • Drawing over a mandrel (also known as drawing on-the-bar)
Annealing

After the goods are cold drawn to sizes, the tubes are put on annealing furnace for heat treatment and normalising.

Straightening

Post annealing, the goods are passed through a seven roller straightening machine to achieve proper straightening of the tubes.

Eddy current

Post straightening, each tube is passed through eddy current machine to detect for surface cracks and other defects . Only the tubes that pass eddy current are fit for delivery to customers.

Finishing

Each tube is either oiled with corrosion resistant oil or varnished for surface protection and corrosion resistant as per customers requirement, each tube end is covered by plastic end caps to avoid damage in transit, the marking and specs are put and the goods are ready for dispatch.

Technical standard

The seamless precision steel tubes can be used for a wide range of precision mechanical spare for car and cylinder accord to standard:

DIN 2391-1 Cold Drawn or Cold Rolled Steel Tube

DIN 2391 standard specifies the Seamless steel tubes used forMechanical and Automobile. The main products of steel / steel grade: DIN2391-1(ST35, ST45, ST52).

Features Specifications

OD(mm) Wall Thickness Unit(mm)
2 2.5 3 3.5 4 4.5 5 6 6.5-7 7.5-8 8.5-9 9.5-10 11 12
Φ25-Φ28
Φ32
Φ34-Φ36
Φ38
Φ40
Φ42
Φ45
Φ48-Φ60
Φ63.5
Φ68-Φ73
Φ76
Φ80
Φ83
Φ89
Φ95
Φ102
Φ108
Φ114
Φ121
Φ127
Φ133
Φ140
Φ146
Φ152
Φ159
Φ168

Grade and Chemical Composition(%)

Grade
Chemical Composition(%):
C max Si max Mn P max S max
St 35 0.17 0.35 ≥0.40 0.025 0.025
St 45 0.21 0.35 ≥0.40 0.025 0.025
St 52 0.22 0.55 ≤1.60 0.025 0.025

Steel grade Chemical Composition(%):
Steel name Steel number C max Si max Mn P max S max Al min
E215 1.0212 0.10 0.05 0.70 0.025 0.025 0.025
E235 1.0308 0.17 0.35 1.20 0.025 0.025
E355 1.0580 0.22 0.55 1.60 0.025 0.025

Mechanical Properties(Mpa)


Steel grade
BK BKW BKS GBK NBK
RmN/mm
min
min RmN/mm
min
min N/mm
min
ReH
N/mm
min
min N/mm
min
min N/mm
min
ReH
N/mm
min
min
St35 480 6 420 10 420 315 14 315 25 340-470 235 25
St45 580 5 520 8 520 375 12 390 21 440-570 235 21
St52 640 4 580 7 580 420 10 490 22 490-630 355 22 

Steel grade Minimum values for the delivery condition
Steel name Steel number + C + LC + SR + A + N
Rm Mpa A% Rm Mpa A% Rm Mpa ReH Mpa A% ReH Mpa A% Rm Mpa ReH Mpa A%
E215 1.0212 430 8 380 12 380 280 16 280 30 290-430 215 30
E235 1.0308 480 6 420 10 420 350 16 315 25 340-480 235 25
E355 1.0580 640 4 580 7 580 450 10 450 22 490-630 355 22

EN 10305-1 seamless precision steel tube

EN 10305 is for seamless precision steel tube applications.
Yaang offers an extensive range of EN 10305 seamless precision steel tube.

EN 10305 european standard specifies the technical delivery conditions for seamless cold drawn steel pipe of circular cross section used in hyhydraulic and pneumatic power systems.

Tubes according to this EN 10305 European standard are characterised by having precisely defined tolerances on dimensions and a specified surface roughness. The allowed pressure rates and temperatures are the responsibility of the customer in accordance with the state of the art and in application of the safety coefficients specified in the application regulations, codes or standards.

Standard and Steel grade:

  • EN10305-1 E215
  • EN10305-1 E235
  • EN10305-1 E355

EN 10305 seamless precision steel tube shall be manufactured from hot finished seamless tubes by cold drawning. Other suitable methods of cold working are permitted. The tubes shall be delivered in the delivery condition +N which means that after the final cold drawing operation the tubes are normalized in a controlled atmosphere.

NBK means protective heat-treating under the non-oxidation enviroment to get a bright and smooth surface for the tubes. 

Chemical composition(%) of EN 10305-1

Steel grade
Name
 Steel
Number
 C(% max)  Si(% max)  Mn(% max)  P(% max)  S(% max)
 E215  1.0212  0.10  0.05  0.70  0.025  0.015
 E235  1.0308  0.17  0.35  1.20  0.025  0.015
 E355  1.0580  0.22  0.55  1.60  0.025  0.015

Mechanical and technological properties of EN 10305-1

 Yield strength
(min Mpa)
 Tensile strength
(min Mpa)
 Elongation
(min %)
 215  290-430  30
 235  340-480  25
 355  490-630  22

Note:

  • The yield point for the annealed (GBK)condition on delivery is at least 50% of the (ultimate) tensile strength. Depending upon the degree of deformation in the drawing operation, the yield point of tubes delivered in the cold-finished/hard (BK)and cold-finished/soft(BKW) conditions, may be increased to a level close to the tensile strength.
  • In calculating the yield point, the following values are recommended : cold-finished/hard condition on delivery ≥ 80% of the tensile strength, cold-finished/soft condition on delivery ≥ 70% of the tensile strength.

Quality grade of EN 10305-1

The tubes are supplied in the following quality grades:

A) precision steel tubes intended primarily for mechanical stressing, without any particular quality requirement and without acceptance test certificate.
B) precision steel tubes intended primarily for mechanical stressing, with special quirement and exclusively with acceptance test certificate.
C) precision steel tubes with special requirement according to section 12. Theses requirements and corresponding tests must be agreed, with the customer having to specify his requirements at the time of enquiry and on ordering.

Condition on delivery of EN 10305-1:

Term Symbol Explanation
Cold-finished/hard
(cold-finished as-drawn)
BK No heat treatment after the last cold-forming process. The tubes therefore have only low deformability.
Cold-finished/soft
(lightly cold-worked)
BKW After the last heat treatment there is a light finishing pass (cold drawing) With proper subsequent processing, the tube can be cold-formed (e.g. bent, expanded) within certain limits.
Annealed GBK After the final cold-forming process the tubes are annealed in a controlled atmosphere or under vacuum.
Normalized NBK The tubes are annealed above the upper transformation point in a controlled atmosphere or under vacuum.

DIN17175/EN10216 standard specification

DIN 17175 steel pipes are used in boiler installations, high-pressure pipelines and tank construction and special machinery for both high temperature and high-pressure devices. This alloy steel pipe is just a big class,and it has many classifivations.We mainly produce DIN 17175 ST35.8,DIN 17175 ST45.8, and 10CrMo910 steel pipes.

Features Specifications

OD(mm)  Wall Thickness Unit(mm)
2 2.5 3 3.5 4 4.5 5 6 6.5-7 7.5-8 8.5-9 9.5-10 11 12
Φ25-Φ28                
Φ32                
Φ34-Φ36                
Φ38                
Φ40                  
Φ42                  
Φ45                
Φ48-Φ60              
Φ63.5              
Φ68-Φ73                
Φ76        
Φ80        
Φ83        
Φ89        
Φ95        
Φ102        
Φ108        
Φ114          
Φ121          
Φ127          
Φ133          
Φ140            
Φ146            
Φ152            
Φ159            
Φ168            

Chemical composition and Mechanical Property DN17175

Grade

Chemical Composition

Mechanical Property

C Si Mn P≤ S≤

Cr

Mo

(MPa)

(MPa)

(%)

St35.8 ≤0.17 0.10~
0.35
0.40~
0.80
0.030 0.030 / / 360~480 ≥235 ≥25
St45.8 ≤0.21 0.10~
0.35
0.40~
1.20
0.030 0.030 / / 410~530 ≥255 ≥21
15Mo3 0.12~
0.20
0.10
~0.35
0.40~
0.80
0.030 0.030 / 0.25~
0.35
460~600 ≥270 ≥20

Chemical composition and Mechanical Property of EN10216-2

Grade

Chemical Composition

Mechanical Property

C

Si

Mn

P≤

S≤

Cr≤

Mo

(MPa)

(MPa)

L t
195GH ≤0.13 ≤0.35 ≤0.70 0.025 0.020 0.30 ≤0.08 320~440 ≥195 ≥27 ≥25
P235GH ≤0.16 ≤0.35 ≤1.20 0.025 0.020 0.30 ≤0.08 360~500 ≥235 ≥25 ≥23
P265GH ≤0.20 ≤0.40 ≤1.40 0.025 0.020 0.30 ≤0.08 410~570 ≥265 ≥23 ≥21
20MnNb6 ≤0.22 0.15~
0.35
1.00~ 1.50 0.025 0.020 500~650 ≥355 ≥22 ≥20
16Mo3 0.12~
0.20
≤0.35 0.40~ 0.90 0.025 0.020 0.30 0.25~
0.35
450~600 ≥280 ≥22 ≥20

Application: 
Used in hydraulic & pneumatic cylinder ,automobile and other mechanical device.

Feature: 
high precision and high brightness, the inner and outer surface of the tubes have high cleanness without oxid, mechanical properties of the final tubes also come out excellent, promising no leakage under high pressure, no deformation after cold-bent and no cracks when flaring and flattening, ensuring the efficient operation in all service.

NBK means protective heat-treating under the non-oxidation enviroment to get a bright and smooth surface for the tubes. ?

DIN 2391-81 Part 2 Seamless Precision steel tubes (DIN2391-81)

Standard DIN 2391 defines the technical delivery conditions for seamless precision steel tubes according to DIN 2391 Part 1 which are made from the steel grades listed in section 5.
Tubes according to this Standard are mainly used where accuracy to dimension and, possibly, small wall thicknesses and good surface condition are required.

Chemical composition(%)

Code
number
Material number Mfg. Process C
max
Si
max
Mn
max
P
max
S
max
St35 1.0308 S 0.17 0.35 0.4 0.05 0.05
St45 1.0408 S 0.21 0.35 0.4 0.05 0.05
St52 1.0508 S 0.22 0.55 1.6 0.05 0.05

Mechanical and technological properties

Code number Material number Cold-finished hard(BK) Cold-finished/soft (BKW) 3)
Rm(Mpa) A(%) Rm(Mpa) A(%)
St 35/E235 1.0308 480 6 420 10
St 45 1.0408 580 5 520 8
St 52/E355 1.0508 640 4 580 7

Code number Cold finished (soft)(BKW) Annealed (GBK) Normalized (NBK)
Rm(Mpa) ReH (Mpa) A(%) Rm(Mpa) A(%) Rm (Mpa) ReH (Mpa) A(%)
St 35/E235 420 315 14 315 25 340-470 235 25
St 45 520 375 12 390 21 440-570 255 21
St 52/E355 580 450 10 490 22 490-630 355 22

Note:

  • The yield point for the annealed (GBK)condition on delivery is at least 50% of the (ultimate) tensile strength.
  • Depending upon the degree of deformation in the drawing operation, the yield point of tubes delivered in the cold-finished/hard (BK)and cold-finished/soft(BKW) conditions, may be increased to a level close to the tensile strength.
  • In calculating the yield point, the following values are recommended : cold-finished/hard condition on delivery ≥ 80% of the tensile strength, cold-finished/soft condition on delivery ≥ 70% of the tensile strength.

Quality grade

The tubes are supplied in the following quality grades :

A) precision steel tubes intended primarily for mechanical stressing, without any particular quality requirement and without acceptance test certificate.
B) precision steel tubes intended primarily for mechanical stressing, with special quirement and exclusively with acceptance test certificate.
C) precision steel tubes with special requirement according to section 12. Theses requirements and corresponding tests must be agreed, with the customer having to specify his requirements at the time of enquiry and on ordering.

Steel pipe hydrostatic testing

hydrostatic testing - What is Hydraulic Steel Pipe?

For hydrostatic testing purposes, there are two: one is the process of hydraulic test to test whether the leaking pipe, that test tube sealing performance;

Another is confirmatory hydrostatic test to test the strength of steel adequacy. In general, low and medium pressure boiler pipe hydrostatic test is part of the process of the hydrostatic test, which is the density of material testing and inspect and whether the material is a continuous dense; it is not verify the strength tests. From the intensity of mechanics of materials theory, seamless steel components are thin and long, and its diameter is very small, even for thin-walled capillary tubes can withstand great pressure. That is to say, when low and medium pressure boiler tubes test pressure, even when there are deep cracks, can not happen leaking.

Hydrostatic test is that many product specification test methods are available. This test can detect leakage of liquid from the inner wall of the case outward can be observed with the naked eye or with a pressure drop to determine. Hydrostatic test can not be found through-wall defects but very close or very close to the wall thickness in depth but not yet fully penetrated defects. Conducted for each pipe eddy current inspection after the low and medium pressure boiler pipe hydrostatic testing is not necessary to replace the hydrostatic test eddy current testing.

Steel pipe hydrostatic testing procedure is as follows:

  • test section at the end of block, slow water injection, the tube gas discharge.
  • after the steel tube filled with water, water tightness checks.
  • made slow progress in steel pressure appropriate USES manual pump, booster time should not less than 10 min.
  • stop pressure after test pressure, observe the 10 min, must not exceed 0.02 MPa pressure drop; Then put the testing pressure drop to the working pressure, steel pipe for visual inspection, leak-proof is not qualified.
  • after arrival, steel pipe pressure, leakage and pressure drop more than a specified value, check the steel tube, after the reason to discharge the leakage, as stipulated in the above to test again, until it meets the requirements.
  • the temperature is lower than 5 ℃ under the environment of water pressure and water capacity, reliable antifreezing measures should be taken, after the test, water should be put.

How to order a hydraulic steel pipe?

The following information shall be provided to order a stub end:

  1. Size of Pipe: Nominal inner diameter (ID), pipe “schedule” (wall thickness), length
  2. Specs and material grade
  3. Execution: seamless / welded (wx)
  4. Any special pipe end requirements?
  5. Quantity

For example, a 1 inch pipe would be as follows:

1″ SCH 40 x 20′

Therefore, the measured size of this pipe is 1.315″OD x .133″WT x 20′

This is where the nominal inner diameter (ID) comes in.  In this case the ID 1.049″ will be the inner diameter measurement.   The OD size is different for each Size ID; For example 3-1/2″ Pipe will have a 4″ Diameter. This is another aspect of pipe buying that most novices find confusing.

Some other important things to note about sizes:  Once the pipe size is higher than 14,” the size called out is actually the outer diameter (OD), instead of the inner diameter, as described above. This remains the OD size from then on, even to the largest-offered pipes.

However, there are still a couple of other exceptions to this rule. For the wall thickness, Sch 40 and Sch STD (Standard) is the same up until the 12″ Pipe.  For pipes larger than that, the schedule switches to Sch 40S (STD) or what is referred to as “True Sch 40.”

For example in the case of 12″ Pipe sizes would be as follows:

STD or Sch 40s

12″ SCH 40s = 12.750″OD x .375″WT

or Sch 40 (True Schedule 40)

12″ SCH 40 = 12.750″OD x .405″WT

This also applies to Sch 80 and Sch 80S.

Source: China Hydraulic Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@pipelinedubai.com

Please notice that you might be interested in the other technical articles we’ve published:

References:

  • https://www.yaang.com
  • https://www.steeljrv.com/how-to-get-high-quality-precision-seamless-pipe.html

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