ST52 Seamless Tubes – DIN 2391 St52 (1.0580) / EN 10305-1 E355 Precision Steel Tubes
ASC LLP, Mumbai, supplies ST52 seamless tubes: cold-drawn seamless precision steel tubes to DIN 2391 St52 (1.0580), now EN 10305-1 E355. Tubes come in BK, BKW, BKS, GBK and NBK delivery conditions, in metric OD × wall sizes for hydraulic and mechanical use, with EN 10204 3.1 certificates. See our carbon steel tubes.
What are ST52 Seamless Tubes?
St52 is a carbon-manganese steel (C ≤ 0.22%, Mn ≤ 1.60%) with a minimum yield of about 355 MPa in the normalised condition – roughly 50% stronger than ST35. As DIN 2391 St52 (material no. 1.0580), it is cold drawn into seamless precision tubes with close OD and wall tolerances and a clean, smooth bore. DIN 2391 has been replaced by EN 10305-1, where the equivalent grade is E355. Tubes can be certified to either designation.
ST52 Tube vs ST52 Pipe vs St52-3 – Not the Same Thing
| Name | Standard & material no. | Product |
| ST52 seamless tube (this page) | DIN 2391 St52, 1.0580 = EN 10305-1 E355 | Cold-drawn precision tube, about 4 – 120 mm OD |
| ST52 seamless pipe | DIN 1629 St52.0, 1.0421 = EN 10297-1 E355 / P355N | Seamless pipe, 10.2 – 660 mm OD |
| St52-3 | DIN 17100 St52-3, 1.0570 = EN 10025-2 S355J2 | Structural steel (plate, sections, bar) |
| ST52 welded tube | DIN 2393 / EN 10305-2 with E355 | Welded and cold-drawn precision tube |
DIN 2391 Delivery Conditions
- BK (+C) – cold finished / hard: highest strength, little ductility; for parts that are not bent.
- BKW (+LC) – cold finished / soft: a light final pass after heat treatment; limited bending.
- BKS (+SR) – cold finished and stress relieved: high strength with better straightness; good for machining and cylinder tubes.
- GBK (+A) – annealed: soft, for severe bending and forming.
- NBK (+N) – normalised: uniform structure and good ductility; the standard condition for hydraulic lines.
Applications of ST52 Seamless Tubes
- Hydraulics: high-pressure hydraulic lines with compression fittings (NBK) and cylinder tubes (BKS, honed or skived)
- Pneumatics and lubrication: air and oil lines on machines and mobile equipment
- Mechanical engineering: shafts, bushings, rollers and precision machined parts
- Automotive and mobile equipment: steering, shock-absorber and axle components
Read more: why ST52 seamless tubes are ideal for hydraulic systems.
ST52 Tube Size & Weight Chart (Common Hydraulic Sizes)
| OD (mm) | Wall (mm) | ID (mm) | Weight (kg/m) |
| 6 | 1 | 4 | 0.123 |
| 8 | 1.5 | 5 | 0.240 |
| 10 | 1.5 | 7 | 0.314 |
| 12 | 2 | 8 | 0.493 |
| 15 | 2.5 | 10 | 0.771 |
| 16 | 2 | 12 | 0.690 |
| 18 | 2.5 | 13 | 0.956 |
| 20 | 3 | 14 | 1.258 |
| 22 | 2.5 | 17 | 1.202 |
| 25 | 3 | 19 | 1.628 |
| 28 | 3 | 22 | 1.850 |
| 30 | 4 | 22 | 2.565 |
| 38 | 5 | 28 | 4.069 |
| 42 | 4 | 34 | 3.748 |
| 50 | 6 | 38 | 6.510 |
Precision tubes are ordered by OD × wall in mm, not by pipe schedule. The usual range is about 4 – 120 mm OD and 0.5 – 10 mm wall; larger sizes on request. Weights calculated at 7.85 g/cm³.
ST52 Seamless Tube Specifications
| Item | Details |
| Standard | DIN 2391-1 / -2 (replaced by EN 10305-1) |
| Grade | St52, material no. 1.0580 = EN 10305-1 E355 |
| Type | Seamless, cold drawn precision tube |
| Delivery condition | BK, BKW, BKS, GBK, NBK (+C, +LC, +SR, +A, +N) |
| OD tolerance (typical) | ±0.08 mm up to 30 mm OD; ±0.15 – 0.50 mm for 30 – 120 mm OD |
| Wall tolerance | ±10% (min. ±0.1 mm) |
| Length | Random 5 – 7 m or exact cut lengths |
| Surface | Bright, phosphated, oiled or zinc-plated; honed / skived ID on request |
| Certificate | EN 10204 3.1 |
Mechanical Properties of ST52 Tubes by Delivery Condition
| Condition | Tensile Rm (MPa) | Yield ReH (MPa) | Elongation A5 |
| BK (+C) | 640 min. | – | 4% min. |
| BKW (+LC) | 580 min. | – | 7% min. |
| BKS (+SR) | 580 min. | 420 min. | 10% min. |
| GBK (+A) | 490 min. | – | 22% min. |
| NBK (+N) | 490 – 630 | 355 min. | 22% min. |
Hardness and impact values are not specified by DIN 2391 / EN 10305-1; they can be agreed on order.
ST52 Tube Chemical Composition (1.0580 / E355)
| Element | St52 / E355 (%) |
| Carbon (C) | 0.22 max. |
| Silicon (Si) | 0.55 max. |
| Manganese (Mn) | 1.60 max. |
| Phosphorus (P) | 0.025 max. |
| Sulphur (S) | 0.025 max. |
ST52 vs ST35 Tubes & ASTM Alternatives
| Grade | Material no. / EN | NBK tensile / yield (MPa) | Use |
| St35 | 1.0308 / E235 | 340 – 470 / 235 | General hydraulic and mechanical tube |
| St52 | 1.0580 / E355 | 490 – 630 / 355 | Higher-pressure hydraulics, cylinders, stressed parts |
| ASTM A519 / A513 1026 DOM | ASTM | By grade and condition | Nearest ASTM mechanical tubing (similar, not identical) |
Physical Properties
| Property | Value (approx.) |
| Density | 7.85 g/cm³ |
| Modulus of elasticity | ≈ 210 GPa |
| Thermal conductivity | ≈ 45 – 50 W/m·K |
| Magnetic | Yes |
Related Products
Why Buy ST52 Tubes from ASC LLP?
- Correct grade and condition: DIN 2391 St52 / EN E355 in NBK, BKS or other conditions, stated on the 3.1 certificate.
- Hydraulic sizes in metric OD × wall, cut to length.
- Clean, protected tubes: oiled or phosphated, capped and bundled or boxed.
Send OD × wall, delivery condition (e.g. NBK), length and quantity to sales@amardeepsteel.com, call 022-67439130 or contact us. See our full carbon steel range.
Frequently Asked Questions – ST52 Seamless Tubes
What is DIN 2391 St52 tube?
DIN 2391 St52 (material no. 1.0580) is a carbon-manganese steel used for cold-drawn seamless precision tubes, mainly for hydraulic lines, cylinders and mechanical parts. DIN 2391 has been replaced by EN 10305-1, where the equivalent grade is E355.
What is the material number of ST52 tube?
DIN 2391 St52 precision tube is material number 1.0580 (EN 10305-1 E355). It should not be confused with St52-3 structural steel (1.0570, S355J2) or DIN 1629 St52.0 pipe (1.0421).
What are the mechanical properties of ST52 NBK tubes?
In the normalised (NBK / +N) condition, St52 / E355 tubes have a tensile strength of 490–630 MPa, minimum yield strength of 355 MPa and minimum elongation of 22%.
What is the difference between ST52 and ST35 tubes?
ST52 contains more manganese and has higher strength – 490–630 MPa tensile and 355 MPa yield in NBK – compared with 340–470 MPa and 235 MPa for ST35. ST52 is used for higher-pressure hydraulics and more highly stressed parts.
Which ST52 delivery condition is used for hydraulic lines?
NBK (normalised, +N) is the standard condition for hydraulic lines, because it has good ductility for bending and for compression-fitting assembly. BKS (stress-relieved) is often used for cylinder tubes.
How are ST52 tubes sized?
ST52 precision tubes are ordered by outside diameter and wall thickness in millimetres – for example 20 × 3 mm – not by nominal pipe size or schedule.
Global Reach
ASC LLP supplies precision tubes, seamless pipes and fittings to hydraulic, engineering and automotive customers in the USA, Europe, the Middle East and Asia, with secure packing and full documentation. Buyers worldwide rely on our ST52 seamless tubes for certified material and traceability.
Countries We Export To
UNITED STATES, EUROPE, UK, UAE, SAUDI ARABIA, OMAN, KUWAIT, JORDAN, QATAR, INDONESIA, MALAYSIA, BRAZIL, SPAIN, ITALY, FRANCE, GERMANY, BAHRAIN, SRI LANKA, AZERBAIJAN, AUSTRALIA, AUSTRIA, PHILIPPINES, TURKEY, RUSSIA, IRAN, IRAQ, CANADA, KOREA, JAPAN, YEMEN, FINLAND, ZIMBABWE, HUNGARY, PORTUGAL, VIETNAM, MOROCCO, THAILAND, SOUTH AFRICA, MEXICO, SINGAPORE, GREECE, KUWAIT, POLAND, NEW ZEALAND, SWEDEN, SWITZERLAND, BELGIUM, BHUTAN, BANGLADESH, TAIWAN, ROMANIA, CAMBODIA, KAZAKHSTAN, AFGHANISTAN.
