EAST AI Hydraulic Manufacturer
Since 2006
 |
Bored Tube
EAST AI
ST52
Product Description
ST52 steel (DIN 2391 / EN 1.0570 S355) is a high-quality structural steel with an excellent balance of strength and ductility. It offers outstanding machinability, weldability, and impact resistance, making it ideal for hydraulic components.
| Element | Content |
|---|---|
| Carbon (C) | ≤ 0.22 |
| Silicon (Si) | ≤ 0.55 |
| Manganese (Mn) | ≤ 1.60 |
| Phosphorus (P) | ≤ 0.025 |
| Sulfur (S) | ≤ 0.025 |
| Property | Value |
|---|---|
| Tensile Strength | 490 – 630 MPa |
| Yield Strength | ≥ 355 MPa |
| Elongation | ≥ 20% |
| Impact Energy | ≥ 27 J (at 20°C) |
The combination of high yield strength and excellent ductility allows the ST52 bored tube to withstand high pressure, vibration, and dynamic loads without cracking or deformation.
Producing an ST52 bored tube requires precision machining and strict quality control to achieve both strength and surface accuracy.
High-quality ST52 seamless steel pipes are selected as the base material. The tubes are inspected for surface defects, dimensional uniformity, and chemical composition before processing.
The inner bore is processed using deep-hole boring machines that remove excess material from the tube’s inner wall. This process ensures accurate inner diameters, high roundness, and precise wall thickness.
Depending on customer requirements, the tubes can undergo quenching and tempering (Q+T) to improve hardness, tensile strength, and fatigue resistance for high-pressure hydraulic systems.
After boring, the inner surface is finished to a fine surface roughness of Ra ≤ 0.8 μm, which reduces friction and improves seal life in hydraulic applications.
Each ST52 bored tube is subjected to rigorous inspection, including:
Ultrasonic flaw detection
Dimensional and straightness testing
Mechanical property verification
Surface roughness and hardness measurement
This ensures that every tube meets strict quality standards before delivery.
| Parameter | Specification / Range |
|---|---|
| Material Grade | ST52 / ST52.3 / ST52.4 |
| Inner Diameter (ID) | 50 mm – 800 mm |
| Outer Diameter (OD) | 80 mm – 1000 mm |
| Length | Up to 8000 mm |
| Surface Roughness | Ra ≤ 0.8 μm |
| Roundness Tolerance | ≤ 0.03 mm |
| Straightness | ≤ 1:1000 |
| Heat Treatment | Normalized / Q+T Optional |
Custom dimensions and machining (such as grooving, porting, or flange welding) are available according to specific engineering needs.
ST52 steel has superior mechanical strength, allowing bored tubes to perform reliably under high internal pressure and heavy load conditions. It ensures structural stability in large hydraulic systems.
The precision boring process achieves a highly smooth bore, minimizing piston wear and improving hydraulic cylinder sealing performance.
The tight tolerance and controlled machining ensure consistent straightness and roundness across the entire tube length, essential for precise hydraulic cylinder assembly.
ST52 material is easily machinable and weldable, making it suitable for secondary processing like port machining, thread cutting, or custom cylinder design.
Due to its excellent fatigue resistance and anti-corrosion performance (after protective coating or plating), the tube maintains stable operation over long service cycles.
Compared to honed tubes or skived & roller burnished tubes, bored tubes are more economical for large-diameter or heavy-duty cylinders that require structural strength rather than ultra-fine precision.
ST52 bored tubes are widely used in industries requiring high-pressure fluid power systems. Their strength and machinability make them ideal for both industrial and mobile hydraulic equipment.
Mining Machinery: Dump trucks, drilling rigs, and loaders
Construction Equipment: Excavators, bulldozers, and cranes
These applications demand a robust material capable of withstanding high stress, vibration, and long working cycles, which ST52 bored tubes fully meet.
EASTAI applies strict inspection and testing procedures to guarantee product reliability and consistency.
Quality Assurance Includes:
100% ultrasonic flaw detection
Dimensional tolerance verification
Hardness and tensile testing
Surface finish inspection
All test results are documented and traceable to ensure transparency and confidence in product quality.
Each ST52 bored tube is carefully packed to prevent corrosion and mechanical damage during shipment.
Standard Packaging:
Anti-rust oil coating on the inner and outer surfaces
Plastic film and woven fabric wrapping
Wooden or steel-frame crates for export
Fumigation-free packaging and pallet options available
EASTAI maintains a strong stock capability of over 10,000 tons, ensuring fast delivery — typically within 7 to 15 days for standard dimensions.
Since 2002, EASTAI has been a professional manufacturer and supplier of hydraulic cylinder materials, specializing in honed tubes, skived and roller burnished tubes, chrome plated rods, and bored tubes.
Over 18 years of manufacturing experience
GL (Germanischer Lloyd) Approval of Material Manufacturers (AMM)
Factory area of more than 8,000 m²
Comprehensive inventory and fast delivery
Advanced boring and straightening machines
Full material traceability and inspection reports
Excellent after-sales service and technical support
EASTAI provides one-stop hydraulic tube solutions for global customers in over 50 countries, trusted by OEMs and engineering companies worldwide.
