BS EN 10025 S355JR Double-Sided Submerged Arc Welding (DSAW) Steel Pipe
Basic Overview
BS EN 10025 S355JR DSAW (Double-Sided Submerged Arc Welded) steel pipe is a large-diameter welded pipe manufactured from steel plate conforming to the European material standard EN 10025-2. The "S355JR" designation indicates a minimum yield strength of 355 MPa (51 ksi) and guaranteed Charpy impact toughness of 27 J at room temperature (+20°C) .
A critical distinction: EN 10025 is a material standard for hot-rolled structural steel plate, not a pipe standard . The finished DSAW pipe must be specified under a separate European product standard (typically EN 10219 for structural applications) .
Name Explanation
| Part | Meaning |
|---|---|
| BS EN | British Standard adopted from European Norm |
| 10025-2 | European standard for hot-rolled structural steel products (plates, sheets, strips) |
| S355 | Structural steel with minimum yield strength of 355 MPa |
| JR | Impact test requirement: 27 J at room temperature (+20°C) |
| DSAW | Double-Sided Submerged Arc Welding – both inside and outside welds are applied; the welding arc is submerged in granular flux during welding |
European Standards Framework
A key conceptual difference exists between European (EN) and American (ASTM) standards:
| Aspect | European System (EN) | American System (ASTM) |
|---|---|---|
| Philosophy | Modular – Material standards separate from product standards | Integrated – Most pipe standards combine material and product requirements |
| Material Standard | EN 10025 (defines steel plate properties) | Within the product standard |
| Product Standard | EN 10219 (pipe geometry, tolerances, weld quality) | Within the same standard |
| Designation | Based on yield strength and toughness (e.g., S355JR) | Based on grade letter or tensile strength |
Therefore, a complete specification requires two standards:
Material Standard: EN 10025-2 S355JR (for the steel plate)
Product Standard: EN 10219-1/-2 (cold-formed welded structural hollow sections)
Key Specifications
| Attribute | Description |
|---|---|
| Material Standard | EN 10025-2 – Hot-rolled products of structural steels |
| Product Standard | EN 10219 (cold-formed structural hollow sections) |
| Steel Grade | S355JR – Minimum yield strength 355 MPa, 27J impact at +20°C |
| Manufacturing Process | DSAW (Double-Sided Submerged Arc Welding) / LSAW (Longitudinal Submerged Arc Welding) |
| Forming Methods | JCOE (progressive J-C-O forming) or UOE (U-ing, O-ing, Expanding) |
| Size Range | 219 mm to 1829 mm (8" to 72") OD – typical for DSAW |
| Wall Thickness | 5 mm to 50 mm (up to 60 mm for piling applications) |
| Length | 6 m to 12.3 m standard; up to 18 m available |
Chemical Composition (EN 10025-2 S355JR)
| Element | Maximum % | Notes |
|---|---|---|
| Carbon (C) | 0.20-0.24% | Low carbon for excellent weldability |
| Silicon (Si) | 0.55% | Deoxidizer |
| Manganese (Mn) | 1.60% | Provides strength |
| Phosphorus (P) | 0.035% | Controlled for weldability |
| Sulfur (S) | 0.035% | Controlled for toughness |
| Nitrogen (N) | 0.012% | Controlled; fully killed steel required |
Note: CEV (Carbon Equivalent Value) limits also apply for weldability.
Mechanical Properties (EN 10025-2 S355JR)
| Property | Value | Condition |
|---|---|---|
| Yield Strength (min) | 355 MPa | Thickness ≤ 16mm |
| 345 MPa | 16mm < t ≤ 40mm | |
| 335 MPa | 40mm < t ≤ 63mm | |
| 325 MPa | 63mm < t ≤ 80mm | |
| Tensile Strength | 470-630 MPa | Thickness 3-16mm |
| 510-680 MPa | Thickness ≤ 3mm | |
| Elongation (min) | 20-22% | Varies by thickness |
| Charpy Impact (JR) | 27 J at +20°C | Mandatory for JR suffix |
S355 Grade Suffixes: Impact Properties
| Designation | Impact Test Temperature | Minimum Impact Energy | Typical Application |
|---|---|---|---|
| S355JR | +20°C (room temperature) | 27 J | Indoor or warm climate applications |
| S355J0 | 0°C | 27 J | Temperate climate outdoor structures |
| S355J2 | -20°C | 27 J | Cold climates, demanding applications |
| S355K2 | -20°C | 40 J | Critical applications requiring higher toughness |
*Note: For EN 10219, the correct designation for hollow sections includes the "H" suffix: S355J0H (0°C), S355J2H (-20°C), or S355K2H (40J at -20°C) .*
Dimensional Specifications
| Parameter | Range / Tolerance |
|---|---|
| Outside Diameter | 219 mm to 1829 mm (8" to 72") – typical DSAW range |
| Wall Thickness | 5 mm to 50 mm (up to 60 mm for piling) |
| Diameter Tolerance | ±0.75% of specified OD (typical) |
| Wall Thickness Tolerance | +15% / -12.5% of nominal (typical) |
| Length | 6 m to 12.3 m standard; up to 18 m available |
| Out-of-Roundness | ≤ 1% of specified OD |
Wall Thickness Availability by Diameter (S355JR):
| OD (inch) | OD (mm) | Wall Thickness Range (mm) |
|---|---|---|
| 16" | 406 | 6.0 - 14.0 |
| 20" | 508 | 6.0 - 16.0 |
| 24" | 610 | 6.0 - 18.0 |
| 30" | 762 | 7.0 - 21.0 |
| 36" | 914 | 8.0 - 24.0 |
| 40" | 1016 | 8.0 - 26.0 |
| 48" | 1219 | 9.0 - 28.0 |
| 56" | 1422 | 10.0 - 29.0 |
| 60" | 1524 | 10.0 - 29.0 |
| 64" | 1626 | 10.0 - 30.0 |
| 72" | 1829 | 10.0 - 30.0 |
DSAW/LSAW Manufacturing Process
Double-Sided Submerged Arc Welding (DSAW), also known as Longitudinal Submerged Arc Welding (LSAW), is a high-efficiency process used primarily for large-diameter steel pipes :
Process Description
Welding arc is submerged in granular flux during welding, protecting the weld from atmospheric contamination
Both inside and outside welds are required, usually accomplished in separate processes
The separate welds consume a portion of the other, resulting in a single high-quality weld nugget
Forming Methods
| Method | Description | Typical Diameters |
|---|---|---|
| JCOE | Progressive J-C-O forming steps (J-shape → C-shape → O-shape), expanded after welding | 406-1626 mm (16"-64") |
| UOE | Plate pressed into U-shape, then O-shape, expanded after welding | 508-1118 mm (20"-44") |
Process Steps
Plate Selection – Steel plates meeting EN 10025-2 S355JR requirements
Edge Preparation – Edges are beveled to create a V-shaped groove
Forming – Steel plates are formed into cylindrical shapes using JCOE or UOE presses
Tack Welding – Formed plates are tack-welded to maintain shape
Double Submerged Arc Welding – Pipe seam welded on both interior and exterior surfaces
Cold Expansion – Pipe may be expanded up to 1.5% to achieve final OD dimension; this process can increase yield strength
Ultrasonic Inspection – Seam inspected by continuous ultrasonic automatic flaw detection
Hydrostatic Pressure Test – Each pipe undergoes hydrostatic pressure testing
Finishing – End processing, beveling, coating, and marking according to specifications
Testing & Inspection Requirements
| Test Type | Requirement | Notes |
|---|---|---|
| Chemical Analysis | Per heat lot | Verifies composition limits per EN 10025-2 |
| Tensile Test | Per lot | Verifies yield and tensile strength |
| Flattening Test | Required | Checks ductility and weld integrity |
| Bend Test | Required | Verifies weld integrity |
| Charpy Impact Test | Mandatory for JR | 27 J at +20°C – the defining test for JR suffix |
| Hydrostatic Test | Each pipe | Pressure integrity verification |
| Ultrasonic Inspection | 100% of weld seam | Continuous automatic flaw detection |
| X-ray Inspection | For "T" joints | Where strip butt welds intersect spiral seams |
| Dimensional Inspection | 100% | Per product standard tolerances |
| Mill Test Certificate | EN 10204 Type 3.1B | Provided with full test results |
Product Standards for Finished DSAW Pipe
Since EN 10025 is only a material standard, the finished pipe must conform to a separate product standard :
| Product Standard | Application | Common Grade Designation |
|---|---|---|
| EN 10219-1/-2 | Cold-formed welded structural hollow sections | S355JRH / S355J0H / S355J2H |
| EN 10217 | Welded steel tubes for pressure purposes | P355GH |
| Project Specification | Large-diameter custom pipes (penstocks, piles) | Directly calls for EN 10025 S355JR plate |
For DSAW pipe under EN 10219, the correct designation for hollow sections includes the "H" suffix: S355J0H (0°C impact) or S355J2H (-20°C impact) .
Common Applications
| Application | Description |
|---|---|
| High-Rise Building Construction | Support columns, steel structure frames for skyscrapers and tall buildings |
| Bridge Engineering | Main beams, structural members, major bridge components |
| Offshore Platforms | Marine structures, oil/gas platforms requiring high strength |
| Wind Turbine Towers | Large-diameter support structures for wind energy projects |
| Piling Foundations | Load-bearing piles for heavy structures |
| Pressure Vessels | Tanks and vessels for non-corrosive fluids (with appropriate product standard) |
| Low-Pressure Fluid Transmission | Water, gas, and oil pipelines |
| Industrial Process Piping | Chemical plants, power generation, steel mills |
| Infrastructure Projects | Tunnels, retaining walls, highway structures |
| Heavy Machinery | Crane booms, excavator components, agricultural equipment |
International Approximations
| Standard | Equivalent Grade | Notes |
|---|---|---|
| ASTM | A572 Grade 50 | Similar yield strength, different impact temperature requirements |
| GB/T 1591 | Q355B / Q355C | Chinese equivalent (Q355 replaced Q345) |
| DIN | St52-3 | Historical German equivalent |
| BS 4360 | Grade 50 | Historical British standard (withdrawn) |
| JIS G3106 | SM490 | Japanese standard |
Key Advantages
| Advantage | Description |
|---|---|
| High Strength | 355 MPa yield – approximately 50% higher than S235 and 30% higher than S275 |
| Excellent Weldability | Low carbon content ensures good field weldability |
| Guaranteed Toughness | 27 J at +20°C ensures reliable performance at room temperature |
| Large Diameter Capability | DSAW produces pipes from 8" to 72" OD – ideal for large-diameter applications |
| High Weld Integrity | Double-sided welding creates a single high-quality weld nugget with 100% UT inspection |
| Long Service Life | With proper corrosion control, service life can reach 80 to 100 years |
| CE/UKCA Marking | Available for construction products under EU/UK regulations |
| Versatile Applications | Suitable for structural, piling, pressure, and low-pressure fluid applications |
Coating Options
BS EN 10025 S355JR DSAW pipe can be supplied with various coatings for corrosion protection :
| Coating Type | Best For | Key Features |
|---|---|---|
| 3LPE (3-layer polyethylene) | Buried pipelines | Most common; excellent corrosion protection, high impact resistance |
| FBE (Fusion Bonded Epoxy) | Oil & gas pipelines | Strong adhesion, chemical resistance |
| Coal Tar Epoxy | Marine environments | Heavy-duty protection |
| Varnish / Anti-rust oil | Temporary protection | Short-term corrosion protection during transport |
| Bitumen Coating | Buried service | Cost-effective protection |
| Black Oil Coating | Standard mill finish | Temporary protection |
End Finishes
Available end treatments include:
Plain ends (PE) – standard for most applications
Beveled ends (BE) – for field welding (30° bevel angle)
Threaded ends – for mechanical connections
Important Considerations
1. EN 10025 is NOT a Pipe Standard
EN 10025 defines the steel plate properties only. The finished pipe must be specified under a separate product standard .
2. Complete Specification Required
A complete order must specify:
Material Standard: EN 10025-2 S355JR
Product Standard: EN 10219-1 (structural) or EN 10217 (pressure)
Dimensions: OD x WT, Length
Manufacturing Process: DSAW / LSAW
End Finish: Plain or beveled
Coating: As required
3. Impact Testing Temperature
S355JR – 27 J at +20°C (room temperature) – suitable for indoor or warm climate applications
For 0°C impact requirements, specify S355J0
For -20°C impact requirements, specify S355J2
For 40 J at -20°C, specify S355K2
4. Product Standard Designation
For EN 10219, the correct designation for hollow sections includes the "H" suffix: S355J0H (0°C) or S355J2H (-20°C) .
5. Pressure Applications
For pressure purposes, EN 10217 applies. The pressure vessel grade equivalent is P355GH under EN 10217 .
6. Size Limitations
DSAW manufacturing for S355JR is typically available from 8" to 72" OD
Smaller diameters (under 8") are typically produced by ERW or seamless methods
7. Cold-Formed vs. Hot-Finished
EN 10219 specifically covers cold-formed hollow sections
Hot-finished structural hollow sections are covered by EN 10210
8. Weld Quality
DSAW produces a single high-quality weld nugget from the combination of inside and outside welds
100% ultrasonic inspection of the weld seam is standard practice
9. Third-Party Inspection
Available inspection services include SGS, BV, Lloyds
10. Mill Test Certificate
Typically provided as EN 10204 Type 3.1B with full test results
Third-party inspection available upon request
Summary
BS EN 10025 S355JR Double-Sided Submerged Arc Welded (DSAW) steel pipe is a premium high-strength product for large-diameter structural applications under the European framework. With minimum yield strength of 355 MPa (51 ksi) – approximately 50% higher than S235 and 30% higher than S275 – and guaranteed Charpy impact toughness of 27 J at room temperature (+20°C), this material offers an excellent balance of strength, weldability, and cost-effectiveness for a wide range of demanding applications .
Key features:
Material standard: EN 10025-2 S355JR
Product standard: EN 10219-1/-2 (structural) or EN 10217 (pressure)
DSAW manufacturing produces pipes from 8" to 72" OD with wall thickness up to 50 mm
Double-sided welding creates a single high-quality weld nugget
JCOE or UOE forming methods ensure precise dimensional accuracy
100% ultrasonic inspection of weld seam ensures quality
"JR" suffix guarantees room temperature impact toughness (27 J at +20°C)
Excellent weldability and good formability
Equivalent to Q355 in Chinese standard and Grade 50 in BS 4360
Common applications include:
High-rise building construction (support columns, steel frames)
Bridge engineering (main beams, structural members)
Offshore platforms and marine structures
Wind turbine towers and piling foundations
Pressure vessels and industrial process piping
Low-pressure fluid transmission (water, gas, oil)
When ordering, specify: EN 10219-1, Grade S355J0H (for 0°C impact) or S355J2H (for -20°C impact), DSAW (Double-Sided Submerged Arc Welded), Size (OD x WT), Length, End Finish (plain/beveled), Coating Requirements, and Mill Test Certificate to EN 10204 Type 3.1B . For applications requiring only room temperature impact, specify the material plate standard EN 10025-2 S355JR with appropriate product standard.
