Overview of Hydraulic Tubes and Rods

The reliability and lifespan of hydraulic systems (such as cylinders, valve blocks, and pipelines) depend significantly on the quality, material, and surface treatment of their tubes and rods. At Hidraulika Szaküzlet, we offer a wide range of products—including hydraulic steel tubes, seamless honed tubes, hard chrome-plated rods, and hot-rolled seamless steel tubes—available from stock in various standards. In this detailed article, we present each main product type, their characteristics, and areas of application.

1. Hydraulic Steel Tubes (St37.4, Galvanized)

Cold-drawn steel tubes made of St37.4 material with Zn-galvanized coating are excellent for creating cylinder housings in low- and medium-pressure hydraulic circuits. The galvanized surface provides corrosion protection, while the factory-smooth inner surface ensures optimal sealing of gaskets and a long service life.

• Material: St37.4, cold-drawn, Zn-galvanized
• Application: Lower-pressure hydraulic circuits, hydraulic cylinder housings
• Available Size Range:
  • Outer Ø: 4 mm – 42 mm
  • Wall Thickness: 1 mm – 5 mm

2. Hot-Rolled Seamless Steel Tubes (EN 10216-1 / EN 10216-3)

Hot-rolled seamless tubes made of P 235 TR1 / S235JRH (EN 10216-1) and P 355 NH / S355 (EN 10216-3) are suitable for hydraulic systems with higher temperature and pressure requirements, as well as for heavy machinery structural components. Our EN 10204 3.1 certification guarantees continuous, tested quality.

• Material:
  • P 235 TR1 / S235JRH (EN 10216-1)
  • P 355 NH / S355 (EN 10216-3)
• Application: Hydraulic systems with higher temperature and pressure requirements, heavy machinery structural components
• Available Size Range:
  • Inner Ø: 12.4 mm – 309.7 mm
  • Outer Ø: 20 mm – 323.9 mm
  • Wall Thickness: 2.3 mm – 25 mm

3. Seamless Honed Tubes (St 52+SR / E 355+SR)

Honed tubes made of St 52+SR (E 355+SR) material, with an internal diameter tolerance of H8–H9 and an Ra ≤ 0.2 µm roughness, provide outstanding precision and low friction. They are specifically recommended for precision cylinders, bearing-mounted components, and environments with low temperature fluctuations.

• Material: St 52+SR (E 355+SR), cold-drawn, then precisely machined by honing
• Application: Precision cylinders, low-friction bearing-mounted components
• Available Size Range:
  • Inner Ø: 30 mm – 350 mm
  • Outer Ø: 35 mm – 406.4 mm
  • Wall Thickness: 4 mm – 37.8 mm

4. Hard Chrome-Plated Round Steel Rods

Chrome-plated rods and tubes are indispensable in high-stress hydraulic systems due to their wear-, corrosion-, and fatigue-resistant surfaces. Below, we present the most important base materials and their variations.

1. 20MnV6 Round Steel (Plain and Induction Hardened)

Material Information:

• 20MnV6 is a vanadium micro-alloyed carbon-manganese steel, typically supplied as cold-drawn or hot-rolled bar stock.
• Mechanical Properties (cold-drawn state): Tensile strength 550–790 MPa, yield strength approx. 430 MPa, elongation ≥ 17 %, Brinell hardness HB ≥ 170.
• Induction Hardened Version: Surface hardness up to HRC 60–65, inner core retains toughness.
• Application: Piston rods, bearing housings, eccentric shafts, especially where a combination of wear and impact resistance is important.

2. 42CrMo4 Alloy Steel (Plain and Hardened)

Material Information (Plain Version):

• 42CrMo4 (EN 1.7225) is a chromium-molybdenum alloy steel that excellently combines strength and toughness even in its plain, pre-heat-treatment state.
• Mechanical Properties (plain state): Tensile strength 650–850 MPa, yield strength ≥ 440 MPa, elongation ≥ 12 %.
• Application: General machine components, shafts, V-belt pulley supports, where consistently high strength is important.

Heat Treatment Characteristics (Hardened Version):

• The rods are first heated to a high temperature, then rapidly cooled and tempered, so the surface hardness reaches HRC 53 (Ø ≤ 60 mm), and the inner core retains sufficient toughness and impact resistance.
• In the case of induction hardening, the surface hardness is also ≥ HRC 53, while the core remains even more flexible due to the heat treatment cycle.
• Application: Heavy-duty piston rods, eccentric shafts, and other high-cyclic components.
• Overall Application: Heavy-duty piston rods and shafts where internal flexibility is critical, as well as components requiring surface hardness.

3. CK45 Carbon Steel (Plain and Hardened)

Material Information:

• CK45 (DIN 1.1191) is a medium carbon steel (C ≈ 0.45 %) with good tensile strength (570–700 MPa) and Brinell hardness (HB 170–210).
• In normalized (plain) state, it offers excellent machinability and weldability; in the induction hardened version, the surface hardness is around HRC 55–60.
• Application: Machine components, eccentric parts, where the surface needs to be partially hardened for higher wear resistance.

4. Stainless Steel Round Rods (1.4301 and 1.4057)

1.4301 (AISI 304):

• Composition: 17.5–19.5 % Cr, 8–10.5 % Ni, C ≤ 0.07 %.
• Mechanics: Tensile strength 520–720 MPa, yield strength ≥ 210 MPa, elongation ≥ 45 %.
• Application: Hydraulic systems in the food and pharmaceutical industries, where corrosion and chemical resistance are paramount.

1.4057 (AISI 431):

• Composition: 15–17 % Cr, 2–2.5 % Ni, 0.12–0.22 % C, minor Mo, Si, P additives.
• Mechanics: Capable of martensitic hardening, as-drawn material HRC 40–50, outstanding torsional strength.
• Application: High-strength, corrosion- and fatigue-resistant shaft solutions, piston rods in contact with chemical media.

5. Chromed Tubes St 52 (EN 10305-1) Cold-Drawn

• Material: Seamless, cold-drawn St 52 steel tube (EN 10305-1) with hard chrome plating.
• Application: Internal wear protection for telescopic tubes and multi-stage hydraulic cylinders, and in hydraulic sections of crane arms and unloading machines.

Product Summary Table

Industrial Standards and Quality

• EN 10216-1 / EN 10216-3: Hot-drawn and cold-drawn seamless tubes
• EN 10305-1: Precision cold-drawn tubes
• EN 10204 3.1: Inspection certificate for batches

All our products are CE- and ISO-certified, and our suppliers are continuously audited.

Ordering and Cutting

Ordering: Tubes and Rods - Hidraulika Szaküzlet - Hydraulics and Pneumatics

Cutting: For orders of non-full lengths, a cutting fee will be added to the total amount according to the following rates:

Pickup: Personal pickup at our specialized store or delivery throughout Hungary and abroad.