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Hydraulic Tubes

Hydraulic Tubes – DIN 2391 / EN 10305 Manufacturer in India

Cold Drawn · Seamless · Precision Hydraulic Tubing
Inox Steel India

Inox Steel India is a leading manufacturer, stockist, and exporter of Hydraulic Tubes manufactured in accordance with DIN 2391 and EN 10305 standards.

These tubes are engineered for high-pressure hydraulic circuits, hydraulic cylinder manufacturing, heavy-duty machinery, automotive systems, precision assemblies, and load-bearing fluid transfer systems.

Hydraulic tubes operate under demanding conditions involving:

  • High-pressure hydraulic oil
  • Pulsating pressure cycles
  • Vibration & mechanical fatigue
  • Bending, flaring, and forming stress
  • Abrasion and internal cleanliness requirements
  • Precise OD/ID for seamless fittings and connectors

Our cold-drawn precision tubes ensure outstanding dimensional accuracy, smooth bore finish, high tensile strength, and excellent performance in hydraulic and pneumatic systems.

We supply hydraulic tubes in ST35, ST37.4, ST45, ST52, E235, and E355 grades, fully compliant with European standards.

Table of Contents

What Are Hydraulic Tubes & Why DIN / EN Standards Are Preferred

Hydraulic tubes must withstand:

  • High working pressure (up to 400–600 bar)
  • Continuous dynamic load
  • Hydraulic oil compatibility
  • Shock loads & cyclic pressure impact
  • Tight OD/ID tolerance for fittings

Hence, the industry prefers DIN 2391 and EN 10305 because these standards guarantee:

  • Precise dimensional tolerances
  • High tensile & yield strength
  • Smooth internal bore (low friction)
  • Cold-drawn seamless integrity
  • Excellent formability for bending, flaring, honing & machining

Overview of Hydraulic Tube Standards

DIN 2391 – Seamless Precision Hydraulic Tubes

Common grades:

  • ST35
  • ST37.4
  • ST45
  • ST52

Key advantages:

  • Close OD tolerance
  • Excellent surface finish
  • High pressure handling capacity
  • Widely used in hydraulics & fuel lines

EN 10305 – Precision Steel Tubes

Types:

  • EN 10305-1
  • EN 10305-2
  • EN 10305-4

Grades:

  • E235
  • E355

Advantages:

  • Superior dimensional accuracy
  • Ideal for high-pressure hydraulics
  • Smooth ID for fluid-power systems
  • Excellent bending & forming characteristics

Manufacturing Process — Precision Hydraulic Tubes

1. Cold Drawing
Achieves tight OD, WT, and ID tolerances.

2. Normalizing / Stress Relieving
Ensures uniform mechanical properties.

3. Bright Annealing / Phosphating
Enhances corrosion resistance and internal cleanliness.

4. OD Finishing & Straightening
Perfect straightness for hydraulic assembly.

5. Inner Surface Cleaning
Essential for hydraulic oil purity.

6. NDT Testing
Eddy current & UT test ensure leak-proof tubes.

Applications by Standard / Grade / Service Pressure

DIN 2391 ST35 / ST37.4 (E235)

ApplicationPressureMediaIndustries
Hydraulic & Pneumatic LinesMediumHydraulic oil, airAutomotive · Machinery
Fuel Injection LinesMedium-HighDiesel, petrolAutomotive
Brake & Steering LinesMediumBrake fluidCommercial Vehicles
Heat Exchanger PipingMediumOil, waterHVAC · Industrial
General Machine HydraulicsMediumHydraulic oilManufacturing

DIN 2391 ST45 / EN 10305 E355

ApplicationPressureIndustries
Hydraulic Cylinder Outer TubesHighConstruction · Mining
Telescopic Cylinder TubesHighMaterial Handling
High-Pressure Feed LinesHighPress Machines
Earthmoving EquipmentHighExcavators, Loaders
CNC Hydraulic AssembliesHighAutomation Systems

DIN 2391 ST52 / EN 10305 E355 — Ultra-High Pressure

ApplicationPressureMediaIndustries
Hydraulic Cylinder TubesVery HighHydraulic oilConstruction · Mining
Hydraulic Power PacksVery HighMineral oilsIndustrial Hydraulics
Heavy-Duty Mobile HydraulicsVery HighPressure fluidsEarthmoving
Impact & Load-Shock SystemsVery HighOilSteel Mills
Marine Hydraulic SteeringVery HighHydraulic oilMarine

Dimensional Range

  • Outside Diameter (OD): 4 mm – 120 mm
  • Wall Thickness (WT): 0.5 mm – 12.5 mm
  • Length: 6M · 12M · Custom
  • Delivery Conditions: NBK, BK, BKS, BKW
  • Finishes: Phosphated · Bright · Oiled · Pickled
  • Tube Types: Seamless · Honed · Skived & Roller Burnished

Indicative Price Range — 2025

GradeConditionPrice (INR/kg)Price (USD/kg)Applications
ST35 / E235NBK₹85 – ₹135$1.10 – $1.65Medium Pressure Lines
ST37.4BK₹95 – ₹150$1.25 – $1.90Auto Hydraulics
ST45 / E355NBK/BK₹110 – ₹170$1.35 – $2.20High Pressure
ST52 / E355NBK/BKS₹120 – ₹185$1.50 – $2.50Cylinder Tubes

Testing & Quality Assurance

  • Tensile strength, yield strength, hardness
  • Flattening & flaring tests
  • Eddy current, UT & hydrostatic tests
  • Internal cleanliness verification
  • OD/WT tolerance & straightness checks
  • EN 10204 3.1 / 3.2 certification

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