EN 10305 Precision Steel Tubes and Pipes

EN 10305 is a series of specifications for the technical delivery conditions of precision steel tubes developed by the European Committee for Standardization (CEN). It is mainly applicable to high-precision, high-quality cold-drawn or cold-rolled seamless steel tubes and welded steel tubes, which are widely used in hydraulic systems, automobile manufacturing, mechanical engineering and other fields.

EN 10305 standard classification:

EN 10305 standard is divided into several parts, covering different types of precision steel tubes:

EN 10305-1: Cold-drawn seamless tubes

EN 10305-2: Welded cold-drawn steel tubes

EN 10305-3: Welded cold-finished steel tubes
EN 10305-4: Seamless cold-drawn steel tubes for hydraulic and pneumatic systems (most commonly used)
EN 10305-5: Welded cold-finished square and rectangular steel tubes

EN 10305-6: Welded cold-drawn steel tubes for hydraulic and pneumatic systems

The main features of this standard are:

High precision: Strictly control the outer diameter and wall thickness tolerances of the steel tube to ensure dimensional consistency.
High finish: The inner wall is smooth, reducing fluid resistance, suitable for hydraulic systems.
Excellent mechanical properties: No deformation during cold bending, no cracks during expansion and flattening, suitable for high-pressure environments.

Common materials:
Carbon steel: E235 (ST35), E255 (ST45), E355 (ST52)

China corresponding grades: 10# (ST37.4), 20# (ST45), 16Mn (ST52)

ST35: Low carbon steel, good weldability and cold workability
ST45: Medium carbon steel, moderate strength, used for mechanical structures
ST52: Low alloy high strength steel, excellent pressure resistance

ST37.4: Higher purity, suitable for precision hydraulic pipes

Mechanical properties:
The mechanical properties of EN 10305 steel pipes vary depending on the material and heat treatment status:

Material	Tensile strength (MPa)	Yield strength (MPa)	Elongation (%)	Hardness (HB)
ST35 (E235)	340-470	≥235	≥25	≤140
ST45 (E255)	410-530	≥255	≥21	≤170
ST52 (E355)	490-630	≥355	≥18	≤200

Key performance features:

High precision: outer diameter tolerance ±0.05mm, wall thickness tolerance ±5%.
High finish: no oxide layer on the inner and outer surfaces, Ra≤0.8μm.
Cold processing performance: can withstand cold bending, flaring, flattening without cracking.

High pressure resistance: suitable for hydraulic systems (up to 70MPa) and high-pressure pneumatic pipelines.

Manufacturing process:

Cold drawing/cold rolling process: improve dimensional accuracy and surface finish.
Non-oxidation bright heat treatment (NBK state): eliminate stress, ensure that the steel pipe has no oxide layer during the manufacturing process, and improve the cleanliness and service life of the steel pipe.

Surface treatment: phosphating, galvanizing (white zinc, colored zinc) to enhance corrosion resistance.

In addition, the steel pipe will undergo non-destructive testing to ensure that the quality meets the standards.

Specifications and tolerances:
Specifications: Wide range of outer diameters, from 4mm to larger sizes, to meet various application requirements. Steel pipes with different outer diameters have clear tolerance regulations to ensure the accuracy and consistency of the steel pipes. Wall thickness range: 0.5mm ~ 12mm.

Surface treatment and features:

Surface treatment:
Inner wall treatment: Brushed and high-pressure flushed with special equipment to ensure good inner wall cleanliness.
Outer wall treatment: Anti-rust oil treatment to effectively prevent rusting of steel pipes; dust-proof treatment at both ends to prevent pollution.

Features:
Strong high pressure bearing capacity: Suitable for high-pressure systems to ensure stable operation of the system.
No deformation after cold bending: With good cold bending performance, it can be used in complex environments.
Expansion, flattening without cracks: Various complex deformations and mechanical processing can be performed to ensure the integrity and reliability of the steel pipe.

Application:
EN 10305 steel pipes are widely used in hydraulic systems, automobile manufacturing, machinery manufacturing, petrochemicals, aerospace and other industries that have high requirements for steel pipe precision, finish, cleanliness and mechanical properties.

For example:
Hydraulic and pneumatic systems: high-pressure cylinders, construction machinery, injection molding machines, ship hydraulic pipes.
Automobile manufacturing: brake oil pipes, fuel delivery pipes.

Delivery status:
Common delivery status includes NBK (+N), GBK (+A), BK (+C), BKW (+LC) and BKS (+SR), etc. Choose the appropriate delivery status according to specific needs.

Conclusion:

EN 10305 is the core standard for high-precision steel tubes in Europe, especially suitable for hydraulics, automobiles, machinery and other fields. Its strict dimensional tolerances, excellent surface treatment and mechanical properties make it an ideal choice for high-end industrial applications.

Read more: DIN 17175 Heat-resistant Seamless Steel Pipe or Cold Drawn ERW Pipe