ST52 Pipes and Tubes
Where structural and mechanical hollow sections must handle heavy loads, high internal pressures, or demanding cyclic stresses, ST52 pipes and tubes stand out as the high-strength workhorse of the DIN 17100 carbon steel family. With a minimum yield strength of 355 MPa and tensile strength reaching 630 MPa, ST52 tubulars deliver the load-bearing capacity that lower-strength grades like ST37 cannot provide — enabling leaner section designs without increasing pipe dimensions or wall thickness.
In pipe and tube form, ST52 is produced both seamlessly and as welded hollow sections, covering the full range from precision mechanical tubes for hydraulic and engineering applications to large-diameter structural pipes for heavy construction and industrial frameworks. Its robust combination of strength, weldability, and machinability has made it a trusted specification in German engineering, heavy machinery, and international structural fabrication for decades.
Mechanical Properties
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 490 – 630 | MPa |
| Yield Strength (min.) | 355 | MPa |
| Elongation (min.) | 20 | % |
| Charpy Impact (0 °C, normalized) | ≥ 27 | J |
| Brinell Hardness | 163 – 190 | HB |
| Density | 7.85 | g/cm³ |
| Modulus of Elasticity | 210 | GPa |
Chemical Composition
| Element | Max. Content (%) |
|---|---|
| Carbon (C) | 0.22 |
| Silicon (Si) | 0.55 |
| Manganese (Mn) | 1.60 |
| Phosphorus (P) | 0.035 |
| Sulfur (S) | 0.035 |
| Nitrogen (N) | 0.012 |
| Carbon Equivalent (CE) | ~0.40 |
Precision Tubes vs Structural Hollow Sections — When to Specify Which
| Requirement | Precision Cold-Drawn Tube | Structural Hollow Section |
|---|---|---|
| Tight bore tolerance | ✓ Essential | Not applicable |
| Hydraulic cylinder barrel | ✓ Standard form | Not suitable |
| Structural column / beam | Not standard | ✓ Standard form |
| Surface finish (inner bore) | Honed / skived | Mill finish |
| Governing standard | DIN 2391 / EN 10305 | EN 10210 / EN 10219 |
| Cost | Higher | Lower |
Product Types & Manufacturing Routes
- Seamless Pipes & Tubes (DIN 1629 / EN 10210): Hot-pierced and rolled without a longitudinal weld seam. Seamless ST52 pipe provides uniform wall thickness, higher pressure capacity, and consistent mechanical properties around the full pipe circumference. The standard form for hydraulic cylinders, mechanical engineering tubes, structural columns, and high-stress tubular applications.
- Precision Cold-Drawn Tubes (DIN 2391 / EN 10305): Cold-drawn seamless ST52 tubes with tight dimensional tolerances on OD, ID, and wall thickness. Used for hydraulic cylinder barrels, pneumatic cylinders, mechanical precision tubes, and any application requiring close bore and wall tolerances that hot-finished pipe cannot achieve.
- Structural Hollow Sections — SHS / RHS / CHS (EN 10210 / EN 10219): Welded square, rectangular, and circular hollow sections produced from ST52 / S355 coil. The standard product for structural columns, trusses, crane frames, and portal structures in heavy industrial and construction applications.
- ERW Welded Pipes (DIN 1626): Electric resistance welded pipes for structural and fluid-conveying applications where seamless specification is not required and cost efficiency is the priority.
Applications
- Hydraulic Cylinder Barrels: Cold-drawn precision ST52 tube is the global standard material for hydraulic cylinder barrels. The tight ID tolerance, smooth bore, and 355 MPa yield strength combine to provide the dimensional accuracy and pressure resistance that hydraulic cylinder performance demands.
- Heavy Machinery Structural Frames: SHS and RHS ST52 hollow sections for main structural frames, cross-members, and chassis tubes of mobile cranes, excavators, agricultural machinery, and industrial plant.
- Mechanical Engineering Tubes: Precision ST52 tubes used as shafts, sleeves, bearing housings, and structural tubes in industrial machinery and mechanical engineering assemblies.
- Construction Structural Columns: Hot-finished and seamless ST52 CHS and SHS sections for primary columns, portal legs, and truss chords in heavy industrial buildings, warehouses, and structural frameworks.
- Mining Equipment Structures: Structural ST52 tubes for boom arms, crowd cylinders, dipper handles, and main frame members of mining shovels, draglines, and bucket wheel excavators.
- Pile Casings & Foundation Tubes: Large-diameter seamless ST52 pipe used as pile casing, casing pipes, and open-ended pile sections in civil and industrial foundation engineering.
- Agricultural & Construction Machinery: Boom tubes, stabilizer legs, and structural frame members in telehandlers, backhoes, and agricultural equipment requiring high strength in compact section sizes.
Weldability & Processing
ST52 pipes and tubes weld well with all standard arc welding processes — SMAW, GMAW, FCAW, SAW, and GTAW. The CE of approximately 0.40 is within the good weldability range. For wall thicknesses below 25 mm at ambient temperature, standard shop welding practice applies without mandatory preheating. Above 25 mm wall thickness, a preheat of 100–150 °C is recommended.
For structural hollow sections used in crane and impact-critical applications, welding consumables must carry a specified impact classification matching the application’s toughness requirement. Precision cold-drawn ST52 tubes used in hydraulic cylinder fabrication are typically joined to end caps and ports by high-restraint welded joints, where preheat discipline is especially important to avoid HAZ cracking.
Dimensional Range
| Product Form | OD / Size Range | Wall Thickness |
|---|---|---|
| Seamless Pipe (DIN 1629 / EN 10210) | 21.3 mm – 610 mm OD | 3.2 mm – 100 mm |
| Precision Cold-Drawn Tube (DIN 2391) | 6 mm – 250 mm OD | 1.0 mm – 50 mm |
| CHS Hot-Finished (EN 10210) | 26.9 mm – 508 mm OD | 3.2 mm – 40 mm |
| SHS Hot-Finished (EN 10210) | 40 × 40 mm – 400 × 400 mm | 3.0 mm – 40 mm |
| RHS Hot-Finished (EN 10210) | 50 × 30 mm – 500 × 300 mm | 3.0 mm – 40 mm |
| ERW Pipe (DIN 1626) | 21.3 mm – 508 mm OD | 2.0 mm – 20 mm |
Manufacturing Standards & Equivalents
- DIN 17100 — Primary material standard for ST52
- DIN 1629 — Seamless circular tubes of non-alloy steels
- DIN 2391 — Seamless precision steel tubes
- DIN 1626 — Welded circular tubes of non-alloy steels
- EN 10210-1 — Hot-finished structural hollow sections
- EN 10219-1 — Cold-formed welded structural hollow sections
- EN 10305-1 — Precision steel tubes — seamless cold-drawn
Quality Assurance
- Mechanical Testing: Mechanical Testing — Tensile strength (490–630 MPa), yield strength (min. 355 MPa), and elongation (min. 20%) are verified on every heat per DIN or EN testing standards. For normalized ST52 pipe, Charpy V-notch impact testing at 0 °C confirms toughness compliance for structural and crane applications.
- Dimensional Accuracy: Dimensional Accuracy — For structural hollow sections, OD, wall thickness, length, straightness, and squareness are verified against EN 10210 or EN 10219 tolerances. For precision cold-drawn tubes, ID, OD, wall thickness, ovality, and straightness are measured to DIN 2391 / EN 10305 tolerances — the tighter dimensional requirements that make precision tubes suitable for hydraulic cylinder service.
- Weldability Tests: Weldability Tests — Carbon equivalent is verified per heat. Weld procedure qualifications per EN ISO 15614-1 include tensile, bend, and, where specified, Charpy impact testing of weld and HAZ samples to confirm joint performance at the specified service conditions.
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Industry We Serve
- Oil & Gas industries
- Chemical process industries
- Pump and valve in high pressure component
- Food industries
- Pulp and paper industry
- Aerospace industry
- Power plant
- Mechanical component
- Sugar industry
- Cement industry