Quick Answer
Quick Answer
EN 10219 specifies requirements for cold formed welded structural hollow sections (CHS, RHS, SHS) in non-alloy and fine grain steels. Part 1 covers technical delivery conditions; Part 2 covers tolerances, dimensions, and sectional properties. Cold forming at ambient temperature produces higher corner yield strength than the parent strip but different ductility compared to hot-finished EN 10210 sections.
EN 10219 is the European standard for cold formed welded structural hollow sections — the most widely used hollow section product in European steel construction. Unlike hot-finished sections governed by EN 10210, these sections are shaped at room temperature from strip or plate, then welded longitudinally to form circular (CHS), rectangular (RHS), and square (SHS) profiles. The two-part structure mirrors EN 10210: Part 1 defines grades, chemical composition, mechanical properties, and delivery conditions; Part 2 defines dimensional tolerances and sectional properties.
Scope and Applicability
EN 10219 applies to cold formed welded circular (CHS), rectangular (RHS), and square (SHS) hollow sections for structural purposes. The sections are produced by cold-forming of strip or plate and welding, without subsequent heat treatment (except for stress relieving if agreed). Wall thicknesses are typically 2–25 mm. The standard is harmonized under the EU Construction Products Regulation.
Grade Coverage
| Grade | Base Material Standard | Sub-grade | Notes |
|---|---|---|---|
| S235H | EN 10025-2 | — | Non-alloy |
| S275H | EN 10025-2 | — | Non-alloy |
| S355H | EN 10025-2 | — | Non-alloy (most common) |
| S275NH | EN 10025-3 | — | Normalized fine grain |
| S275NLH | EN 10025-3 | — | NL = −50°C impact |
| S355NH | EN 10025-3 | — | Normalized fine grain |
| S355NLH | EN 10025-3 | — | NL = −50°C impact |
| S460NH | EN 10025-3 | — | High strength fine grain |
| S460NLH | EN 10025-3 | — | High strength, −50°C impact |
Note: EN 10219 does not include S420NH/NLH or thermo-mechanical (M/ML) grades, which are available in EN 10210.
Chemical Composition Requirements
Heat (ladle) analysis. All values wt% maximum unless a range is stated.
Non-Alloy Grades
| Grade | C max | Mn max | Si max | P max | S max | N max |
|---|---|---|---|---|---|---|
| S235H | 0.17 | 1.40 | — | 0.035 | 0.035 | 0.012 |
| S275H | 0.21 | 1.50 | — | 0.035 | 0.035 | 0.012 |
| S355H | 0.22 | 1.60 | 0.55 | 0.035 | 0.035 | 0.012 |
Al ≥ 0.020% where N is not controlled by other alloying elements.
Fine Grain Grades
| Grade | C max | Si max | Mn max | P max | S max | Al min | Nb max | V max | Ti max | N max | CEV max | |---|---|---|---|---|---|---|---|---|---|---|---|---| | S275NH | 0.18 | 0.50 | 1.50 | 0.030 | 0.025 | 0.020 | 0.05 | 0.12 | 0.05 | 0.015 | 0.40 | | S275NLH | 0.18 | 0.50 | 1.50 | 0.025 | 0.020 | 0.020 | 0.05 | 0.12 | 0.05 | 0.015 | 0.40 | | S355NH | 0.20 | 0.50 | 1.65 | 0.030 | 0.025 | 0.020 | 0.05 | 0.12 | 0.05 | 0.015 | 0.43 | | S355NLH | 0.20 | 0.50 | 1.65 | 0.025 | 0.020 | 0.020 | 0.05 | 0.12 | 0.05 | 0.015 | 0.43 | | S460NH | 0.20 | 0.60 | 1.70 | 0.030 | 0.025 | 0.020 | 0.05 | 0.12 | 0.05 | 0.025 | 0.47 | | S460NLH | 0.20 | 0.60 | 1.70 | 0.025 | 0.020 | 0.020 | 0.05 | 0.12 | 0.05 | 0.025 | 0.47 |
Mechanical Properties
Properties apply to the flat face of the section. Corner properties differ — see Additional Tests section.
Non-Alloy Grades
| Grade | t ≤ 16mm ReH (MPa) | t 16–40mm ReH (MPa) | t 40–65mm ReH (MPa) | Rm (MPa) | A min % |
|---|---|---|---|---|---|
| S235H | 235 | 225 | 215 | 360–510 | 26 |
| S275H | 275 | 265 | 255 | 430–580 | 23 |
| S355H | 355 | 345 | 335 | 510–680 | 22 |
Fine Grain Grades
| Grade | t ≤ 16mm ReH (MPa) | t 16–40mm ReH (MPa) | t 40–65mm ReH (MPa) | Rm (≤16mm, MPa) | A min % |
|---|---|---|---|---|---|
| S275NH/NLH | 275 | 265 | 255 | 370–530 | 24 |
| S355NH/NLH | 355 | 345 | 335 | 470–630 | 22 |
| S460NH/NLH | 460 | 440 | 430 | 540–720 | 17 |
Impact Test Requirements
Charpy V-notch per EN ISO 148-1, flat face specimens.
| Grade sub-designation | Test Temperature | Minimum Energy |
|---|---|---|
| S235H, S275H, S355H | 0°C | 27 J |
| S275NH, S355NH, S460NH | −20°C | 27 J |
| S275NLH, S355NLH, S460NLH | −50°C | 27 J |
Test on parent material (flat face), not on the weld seam unless separately agreed.
Corner Properties
Cold forming work-hardens the corner regions, raising yield strength but reducing ductility and elongation. EN 10219 addresses this by:
- Permitting the purchaser to specify additional Charpy testing at corners
- Providing guidance that corner zones should be avoided for welded connections in fatigue-critical structures
- Requiring the manufacturer to declare the corner radius (outer radius ≤ 3t for RHS/SHS)
Corner yield strength enhancement: The yield strength at corners of cold-formed sections can be 20–40% higher than the flat face due to work hardening. EN 1993-1-3 (Eurocode 3, Part 1-3) provides design rules exploiting this enhanced strength for thin-walled sections.
Residual stresses: Cold forming introduces tensile residual stresses at the outer surface of corners and compressive stresses inside. These affect column buckling behaviour, which is why EN 1993-1-1 uses different buckling curves for hot-finished and cold-formed hollow sections.
Dimensional Tolerances
Per EN 10219-2.
Circular Hollow Sections (CHS)
| Dimension | Tolerance |
|---|---|
| Outside diameter D ≤ 406.4 mm | ±1.0% of D, min ±0.5 mm |
| Outside diameter D > 406.4 mm | ±0.75% of D |
| Wall thickness | ±10% of nominal t, min ±0.5 mm |
| Straightness | 0.2% of total length |
| Length (exact length ordered) | +10 mm / −0 mm |
| End squareness | ≤1% of D |
Rectangular and Square Hollow Sections (RHS/SHS)
| Dimension | Tolerance |
|---|---|
| External width/height b or h ≤ 100 mm | ±1.0 mm |
| External width/height b or h > 100 mm | ±1.0% |
| Wall thickness t | ±10% of nominal, min ±0.5 mm |
| Corner radius (outer) | ≤3t (max) |
| Side squareness | ≤2 mm per 100 mm |
| Straightness | 0.2% of total length |
| Twist | ≤2 mm per metre |
Note: EN 10219-2 tolerances are generally slightly wider than EN 10210-2 in some dimensions. Verify when critical fits are required.
Additional Tests and Requirements
- Delivery condition: Cold-formed, as-welded. No re-heating unless stress relieving is agreed and stated on the MTC.
- Weld seam: The longitudinal ERW or HF weld seam shall be of the same quality as the parent material. Non-destructive testing of the weld may be specified.
- Surface condition: Free from injurious defects. Scale, light rust, and forming marks consistent with the cold-forming process are acceptable unless a special surface class is specified.
- Test unit: Products of the same cast, same production lot, and same nominal dimensions.
- Inspection documents: EN 10204 Type 3.1 standard; Type 3.2 by agreement.
- CE marking: Harmonized under CPR for structural hollow sections; DoP required.
Cross-Standard Equivalents
| EN 10219 Grade | EN 10210 Equivalent | ASTM Equivalent | IS Equivalent | Notes |
|---|---|---|---|---|
| S235H | S235H (hot-finished) | ASTM A500 Grade A | IS 4923 YST 210 | Same designation, different process |
| S275H | S275H (hot-finished) | ASTM A500 Grade B | IS 4923 YST 240 | Cold-formed |
| S355H | S355H (hot-finished) | ASTM A500 Grade C | IS 4923 YST 310 | Most used grade |
| S355NH | S355NH (hot-finished) | ASTM A500 Grade C (notch tough) | — | Impact tested |
| S460NH | S460NH (hot-finished) | ASTM A500 Grade D | — | High strength |
ASTM A500 covers cold-formed structural tubing and is the closest North American equivalent. IS 4923 covers hot-formed and cold-formed hollow steel sections for structural use in India.
MTC Verification Checklist
When verifying an EN 10219 Mill Test Certificate, confirm:
- Standard cited as EN 10219-1 and grade (e.g., S355NH) matches the purchase order
- Product form (CHS/RHS/SHS) and nominal dimensions match order
- Heat number traceable to product markings
- Chemical analysis (ladle) within limits for the specified grade, including CEV for NH/NLH grades
- Yield strength (ReH), tensile strength (Rm), and elongation (A) meet minima for the declared wall thickness range
- Charpy impact results (KV in J) at the correct temperature for the sub-grade suffix
- Delivery condition stated as cold-formed (no re-heating unless agreed)
- Corner radius stated (≤3t for RHS/SHS)
- EN 10204 certificate type, signatory, and date
Frequently Asked Questions
What is the key structural difference between EN 10219 and EN 10210 sections?
The critical difference is the manufacturing process. EN 10210 sections are hot-finished — formed and reheated above the recrystallization temperature — giving uniform microstructure and residual stresses throughout, including at corners. EN 10219 sections are cold-formed at ambient temperature, resulting in work-hardened corners with higher yield but lower ductility than the flat faces. Eurocode 3 (EN 1993-1-1) assigns different buckling curves to each: curve 'a' for hot-finished and curve 'c' for cold-formed, making hot-finished sections more efficient in column design.
Can I use EN 10219 cold-formed sections in a fatigue-critical application?
Cold-formed hollow sections can be used in fatigue applications but require more careful detailing. EN 1993-1-9 (Eurocode 3 fatigue) differentiates between welds at the flat face and welds near the cold-formed corners; joints at corners attract lower fatigue categories. Avoid welded connections in the corner zone of cold-formed sections unless fatigue assessment confirms acceptability. Hot-finished EN 10210 sections have better fatigue performance at corner welds.
Why is S420NH not in EN 10219?
EN 10219 does not include S420NH/NLH grades. The standard covers non-alloy grades S235H/S275H/S355H and fine grain grades up to S460NH/NLH, but S420NH is absent. For S420-class hollow sections, specify EN 10210 hot-finished sections, which include S420NH and S420NLH.
How should I verify the weld seam quality on EN 10219 hollow sections?
EN 10219-1 requires that the longitudinal weld meets the same quality requirements as the parent material. Standard delivery does not mandate NDT of the weld unless specified on the purchase order. If weld quality is critical (e.g., pressure applications, fatigue), specify weld seam NDT (ultrasonic or electromagnetic) as a supplementary requirement on the order. The MTC should state that NDT was performed if required.
Is the yield strength at corners of an EN 10219 section higher than the specified minimum?
Yes. Cold forming work-hardens the corners, typically raising yield strength 20–40% above the flat-face minimum. For example, S355H corners may exhibit ReH of 430–480 MPa versus the specified 355 MPa minimum on the flat face. EN 1993-1-3 includes design rules that allow engineers to exploit this enhanced corner strength for thin-walled section design, provided the manufacturer can demonstrate the enhanced properties through testing.
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