Seamless Hydraulic Tube

Seamless Hydraulic Tube

Seamless Hydraulic Tubes are specialized steel tubes designed for high-pressure hydraulic systems where precision, strength, and reliability are paramount. Available in outer diameters from 4mm to 130mm, these tubes are manufactured from high-quality materials such as E355 (ST52.4) and E235 (ST37.4). Complying with international standards DIN 2391/C (DIN EN 10305-1) and DIN 2445/2 (DIN EN 10305-4), these tubes provide outstanding performance in fluid conveyance across various industrial and mechanical applications.

Key Features:

The seamless hydraulic tubes feature NBK finishing—phosphated and normalized—which not only improves corrosion resistance but also enhances the material’s strength and ductility. Internally and externally oiled, the tubes are protected against rust during storage and transportation. Their chemical composition varies between E355 and E235, directly affecting the allowable working pressure and mechanical behavior. For example, E355 provides higher strength, making it suitable for more demanding pressure conditions.

Importance and Applications:

These hydraulic tubes are critical in hydraulic systems, serving as conduits for transferring fluids between components such as valves, pumps, actuators, flanges, and fittings. Because they operate under varying pressures and temperatures, it is essential that these tubes possess excellent mechanical strength, consistent wall thickness, and resistance to corrosion and deformation. They are widely used in construction machinery, agricultural equipment, automotive systems, and industrial hydraulics.

Manufacturing and Normalizing Process:

The seamless hydraulic tube manufacturing process includes hot rolling, cold drawing, surface treatment, and normalization. The normalizing process involves heating the tube to a specific temperature and then allowing it to cool in the air. This treatment enhances the material’s toughness, making it stronger, more ductile, and easier to form or weld. It also stabilizes the microstructure, ensuring consistent performance under pressure.

Pressure Ratings and Performance:

Pressure ratings for these tubes are calculated using DIN 2413 standards, factoring in actual yield and tensile strength verified through material certificates. Working pressure is affected by temperature, and reduction factors are applied at elevated temperatures. For instance, the strength drops to 89% at 150°C and to 83% at 200°C, requiring careful selection based on operating conditions. This ensures safe and reliable performance in high-stress environments.