EN 10025 & Longitudinally Submerged Arc Welded Pipe: A European Framework
EN 10025 is a European Standard that covers hot-rolled structural steel products-specifically plates, sheet, and strip. Crucially, EN 10025 is not a pipe or tube standard. It does not specify manufacturing processes, dimensions, or testing requirements for finished pipe.
However, it is the fundamental material standard for the steel plate used to manufacture longitudinally Submerged Arc Welded (SAW) pipe in Europe. The finished pipe product itself would be manufactured and tested to a separate product standard, such as EN 10219 (cold-formed welded structural hollow sections) or EN 10224 (tubes for water pipelines), but made from plate conforming to EN 10025.
This is a key conceptual difference from ASTM standards (like A53, A139), which are typically product standards that include both material and manufacturing requirements.
Technical Specification Tables for Base Material (EN 10025)
Table 1: Common Steel Grades Under EN 10025 (For Pipe Production)
These are the material designations for the plate used as the "raw material" for SAW pipe.
| Steel Grade & Standard | Yield Strength, min (ReH) | Tensile Strength (Rm) | Key Characteristics & Common Pipe Applications |
|---|---|---|---|
| S235JR / J0 / J2 (EN 10025-2) | 235 MPa | 360-510 MPa | General structural steel, basic applications (e.g., light structural tubes, non-critical piping). |
| S275JR / J0 / J2 (EN 10025-2) | 275 MPa | 410-560 MPa | Common for general structural hollow sections (to EN 10219). |
| S355JR / J0 / J2 / K2 (EN 10025-2) | 355 MPa | 470-630 MPa | The most widely used grade for structural and mechanical tubing. Offers good strength and weldability. |
| S420ML / S460ML (EN 10025-4) | 420 / 460 MPa | 500-680 / 530-720 MPa | Thermomechanically rolled, fine-grain steel with guaranteed toughness for more critical structures. |
| S690QL / S890QL (EN 10025-6) | 690 / 890 MPa | 770-940 / 940-1100 MPa | Quenched & tempered, very high-strength steels for specialized, highly loaded structural applications. |
*Note: The suffix indicates impact toughness and testing temperature (e.g., JR = 27J at +20°C, J0 = 27J at 0°C, ML = 40J at -50°C, QL = Quenched & Tempered).*
Table 2: Chemical Composition Examples (Maximum % - EN 10025-2)
Illustrative for common non-alloy steels.
| Steel Grade | C (max) | Si (max) | Mn (max) | P (max) | S (max) | N (max) |
|---|---|---|---|---|---|---|
| S235JR | 0.17 - 0.20* | 0.035 | 1.40 | 0.035 | 0.035 | 0.012 |
| S275JR | 0.18 - 0.22* | 0.035 | 1.50 | 0.035 | 0.035 | 0.012 |
| S355J2 | 0.20 - 0.24* | 0.035 | 1.60 | 0.035 | 0.035 | 0.012 |
| *Maximum carbon content depends on product thickness. CEV (Carbon Equivalent Value) limits also apply for weldability. |
How It Works: From EN 10025 Plate to Finished SAW Pipe
A complete specification for a European SAW pipe requires two standards:
Material Standard: EN 10025 (defines the steel plate properties).
Product/Manufacturing Standard: Defines the pipe's geometry, tolerances, weld quality, and testing.
Common Product Standards for SAW Pipe using EN 10025 plate:
EN 10219-1/-2: Cold formed welded structural hollow sections of non-alloy and fine grain steels.
Example: A square structural column: EN 10219 - S355J2H
EN 10224: Non-alloy steel tubes and fittings for the conveyance of water and other aqueous liquids.
Example: A water pipeline: EN 10224 - P235 (made from S235 plate)
EN 10217-1: Welded steel tubes for pressure purposes - Part 1: Non-alloy steel tubes with specified room temperature properties.
Example: A pressure tube: EN 10217-1 - P235 (made from S235 plate)
EN 10210-1/-2: Hot finished welded structural hollow sections (can also use SAW for large sizes).
Project-Specific Specification: For large-diameter, custom pipes (e.g., penstocks, piles), a detailed project spec will directly call for plate to EN 10025 S355ML, and then define the SAW manufacturing and testing requirements.
Table 3: Hypothetical SAW Pipe Specification Using EN 10025 Material
| Component | Specification | Notes |
|---|---|---|
| Base Material | EN 10025-2: S355J2 | Plate must be certified to this grade. |
| Product Standard | EN 10219-2 | For cold-formed structural hollow sections. |
| Manufacturing Process | Longitudinal Submerged Arc Welding (SAW) | As per the factory's qualified procedure. |
| Testing | As per EN 10219 (e.g., flattening test, tensile test on weld, visual inspection). | The product standard dictates the tests on the finished tube. |
| Marking | EN 10219 - S355J2H - [Manufacturer] - Size | The 'H' indicates it is a hollow section. |
Key Comparison: European (EN) vs. American (ASTM) Approach
| Aspect | European System (EN) | American System (ASTM) |
|---|---|---|
| Philosophy | Modular. Material standards (EN 10025) are separate from product standards (EN 10219, 10224, etc.). | Integrated. Most ASTM pipe standards (A53, A500, A139) combine material and product requirements in one document. |
| Material Designation | Based on Minimum Yield Strength (e.g., S355) and Toughness (e.g., J2). | Based on Grade (A, B, C) or Minimum Tensile Strength (e.g., A53 Gr B, A139 Gr C = 70ksi tensile). |
| Traceability | The steel mill provides the EN 10025 Certificate for the plate/coil. The pipe mill provides the EN 10219 (or other) Certificate for the finished pipe. | A single Mill Test Report (MTR) typically covers both material and pipe tests per the ASTM product standard. |
| Common SAW Pipe Product Standard | EN 10219 (Structural), EN 10224 (Water) | ASTM A139 (General), ASTM A252 (Piling), ASTM A671/A672 (Pressure) |
Procurement Example
To order a European SAW structural tube:
Structural Hollow Sections to EN 10219-2.
Material: EN 10025-2 S355J2H
Dimensions: 300 mm x 200 mm x 10 mm (Rectangular)
Manufacturing Process: Longitudinal Submerged Arc Welding (SAW) with internal and external welds.
Certification: 3.1 Certificate (Type Inspection) to be supplied.
In summary, "EN 10025 Longitudinally Submerged Arc Welding Pipe" refers to pipe manufactured from hot-rolled steel plate conforming to the European material standard EN 10025. The pipe itself must be specified under a separate European product standard, creating a clear chain of specifications from raw material to finished product.
