EN S275 Double-Sided Submerged Arc Welding (DSAW) Steel Pipe

Basic Overview

EN S275 DSAW (Double-Sided Submerged Arc Welding) steel pipe is a high-strength structural steel product manufactured to European standards for large-diameter applications. The "S275" designation indicates a minimum yield strength of 275 MPa (40 ksi) , positioning it between S235 (235 MPa) and S355 (355 MPa) in the European structural steel hierarchy .

DSAW is a specific manufacturing process where the welding arc is submerged in granular flux, and both inside and outside welds are applied-usually in separate processes-with these welds consuming a portion of each other to form a single, high-quality weld nugget. This process is particularly well-suited for large-diameter, thick-wall pipes required for demanding structural and piling applications .

Name Explanation

Key Specifications

Chemical Composition (EN 10219-1)

*Note: Fully killed steel (FF) containing nitrogen-binding elements (e.g., min. 0.020% total Al) is required .*

Mechanical Properties (EN 10219-1)

S275 Grade Suffixes: Impact Properties

*The "H" suffix indicates Hollow Section, conforming to EN 10219 for cold-formed welded structural hollow sections .*

Dimensional Specifications

Wall Thickness Availability by Diameter (S275):

DSAW Manufacturing Process

Double-Sided Submerged Arc Welding 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

Process Steps

Plate Selection – High-quality steel plates chosen according to EN 10219 requirements

Edge Preparation – Edges of the steel plates are beveled to create a V-shaped groove

Forming – Steel plates are formed into cylindrical shapes using press or roll bending machines (JCOE or UOE)

Tack Welding – Formed plates are tack-welded to maintain the 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

Common Applications

Comparison: S275 vs. Other Structural Grades

S275 offers approximately 17% higher yield strength than S235 .

Product Standard vs. Material Standard

It is important to distinguish between the material standard and the product standard:

For DSAW pipe, the correct product standard is EN 10219-1 (cold-formed welded structural hollow sections) . Some manufacturers also produce to EN 10217 (pressure purposes) depending on the application .

International Equivalents

Coating Options

S275 DSAW pipe can be supplied with various coatings for corrosion 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

Third-Party Inspection

Available inspection services include:

SGS, BV, Lloyds, TUV

Important Considerations

1. Product Standard Selection

EN 10219 – Structural hollow sections (most common for DSAW)

EN 10217 – Pressure purposes (when hydrostatic testing and pressure ratings are required)

2. Impact Testing Temperature

S275JRH – 27 J at +20°C (indoor or warm climate)

S275J0H – 27 J at 0°C (temperate outdoor climate)

S275J2H – 27 J at -20°C (cold climate, offshore)

3. Size Limitations

DSAW manufacturing for S275 is typically available from 16" to 72" OD

Smaller diameters (under 16") are typically produced by ERW or seamless methods

4. Cold-Formed vs. Hot-Finished

EN 10219 specifically covers cold-formed hollow sections (produced by cold forming without subsequent heat treatment)

Hot-finished structural hollow sections are covered by EN 10210

5. 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

6. Mill Test Certificate

Typically provided as EN 10204 Type 3.1B with full test results

Third-party inspection available upon request

Summary

EN S275 Double-Sided Submerged Arc Welded (DSAW) steel pipe is a standard product for large-diameter structural and engineering applications under European standards. With minimum yield strength of 275 MPa (40 ksi) – approximately 17% higher than S235 – this material offers an excellent balance of strength, weldability, and cost-effectiveness for a wide range of applications .

Key features:

Available in impact grades S275JRH (+20°C), S275J0H (0°C), and S275J2H (-20°C) for varying service temperatures

DSAW manufacturing produces pipes from 16" 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

CE/UKCA marking available for construction products under EU regulations

Common applications include:

Structural engineering (building frames, columns, trusses)

Piling foundations and bridge construction

Offshore projects and marine structures

Infrastructure projects (tunnels, retaining walls)

Low-pressure fluid transmission

When ordering, specify: EN 10219-1, Grade S275J0H or S275J2H (as required), 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 3.1 .