DIN 17100 ST44-2 Double-Sided Submerged Arc Welding (DSAW) Steel Pipe
Basic Overview
DIN 17100 ST44-2 DSAW (Double-Sided Submerged Arc Welded) steel pipe is a large-diameter welded pipe manufactured from non-alloy structural steel conforming to the withdrawn German standard DIN 17100. The "ST44-2" designation indicates a minimum yield strength of 275 MPa (40 ksi) for thicknesses ≤ 16mm, positioning it between ST37-2 (235 MPa) and ST52-3 (355 MPa) [citation:1, citation:2, citation:3].
Important Note: DIN 17100 has been withdrawn since 2004 and replaced by the European standard EN 10025-2. The direct modern equivalent of ST44-2 is S275JR (Material Number 1.0044) . For new projects, it is strongly recommended to specify S275JR instead [citation:2, citation:3].
Name Explanation
| Part | Meaning |
|---|---|
| DIN | Deutsches Institut für Normung (German Institute for Standardization) |
| 17100 | Standard specification for hot-rolled products in non-alloy steels (withdrawn 2004) |
| ST44-2 | Steel grade: "ST" = Stahl (steel), "44" = tensile strength class (approx. 440 MPa), "-2" = quality grade with impact requirements |
| DSAW | Double-Sided Submerged Arc Welding – both inside and outside welds are applied; the welding arc is submerged in granular flux during welding |
| Also Known As | LSAW (Longitudinal Submerged Arc Welded) – when the weld seam runs longitudinally along the pipe [citation:2, citation:3] |
Key Specifications
| Attribute | Description |
|---|---|
| Material Standard | DIN 17100 (withdrawn; replaced by EN 10025-2) |
| Steel Grade | ST44-2 – Minimum yield strength 275 MPa (for thickness ≤ 16mm) [citation:1, citation:2] |
| Modern Equivalent | S275JR (1.0044) per EN 10025-2:2004 |
| Material Type | Non-alloy structural steel with good weldability |
| Manufacturing Process | DSAW (Double-Sided Submerged Arc Welding) / LSAW (Longitudinal Submerged Arc Welding) [citation:2, citation:3] |
| Forming Methods | JCOE (progressive J-C-O forming) or UOE (U-ing, O-ing, Expanding) [citation:2, citation:3] |
| Size Range | 406 mm to 1626 mm (16" to 64") OD – typical for DSAW |
| Wall Thickness | 6.0 mm to 75 mm (depending on diameter and grade) |
| Length | 3 m to 18 m standard; up to 32 m available |
| End Finishes | Plain ends, beveled ends (30° bevel angle) |
Chemical Composition (DIN 17100 ST44-2)
Based on manufacturer data for thickness ≤ 16mm [citation:1, citation:2]:
| Element | Maximum % | Notes |
|---|---|---|
| Carbon (C) | 0.21% | Low carbon for good weldability |
| Phosphorus (P) | 0.050% | Controlled for weldability |
| Sulfur (S) | 0.050% | Controlled for toughness |
| Nitrogen (N) | 0.090% | Controlled |
Note: For thickness > 30mm, carbon content may increase to 0.22% max .
Mechanical Properties (DIN 17100 ST44-2)
Yield Strength (min)
| Thickness (mm) | Yield Strength (MPa) |
|---|---|
| ≤ 16 | 275 |
| 16 < t ≤ 40 | 265 |
| 40 < t ≤ 63 | 255 |
| 63 < t ≤ 80 | 245 |
| 80 < t ≤ 100 | 235 |
Tensile Strength
| Thickness (mm) | Tensile Strength (MPa) |
|---|---|
| ≤ 3 | 430-580 |
| 3 < t ≤ 100 | 410-540 |
Other Properties [citation:1, citation:2]
| Property | Value |
|---|---|
| Elongation | Varies by thickness (typically 18-22%) |
| Charpy Impact | 27 J at 0°C (typical for -2 quality grade) |
ST44-2 vs. Modern Equivalents
| Historical Grade | Modern Equivalent | Standard | Key Difference |
|---|---|---|---|
| ST44-2 | S275JR (1.0044) | EN 10025-2:2004 | S275JR has tighter P/S limits (0.035% vs. 0.050%) |
| ST44-2 | S275J2 | EN 10025-2 | For -20°C impact requirements |
| ST44-2 | Q275B | GB/T 700 | Chinese equivalent |
| ST44-2 | A36 | ASTM | US equivalent (slightly lower strength) |
*Note: ST44-2 is similar to S275JR, but S275JR has stricter controls on phosphorus and sulfur (0.035% vs. 0.050%).*
Dimensional Specifications
| Parameter | Range / Tolerance |
|---|---|
| Outside Diameter | 406 mm to 1626 mm (16" to 64") – typical DSAW range |
| Wall Thickness | 6.0 mm to 75 mm (depending on diameter) |
| Diameter Tolerance | ±0.75% of specified OD (typical) |
| Wall Thickness Tolerance | +15% / -12.5% of nominal (typical) |
| Length | 3 m to 18 m standard; up to 32 m available |
Typical Size Availability (ST44-2):
| 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 |
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 [citation:2, citation:3].
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 [citation:2, citation:3]
| 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 DIN 17100 ST44-2 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
Ultrasonic Testing – 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 DIN 17100 |
| 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 | When specified | For low-temperature applications |
| 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 standard tolerances |
| Mill Test Certificate | EN 10204 Type 3.1B | Provided with full test results |
Common Applications
| Application | Description |
|---|---|
| Structural Engineering | Building frames, columns, trusses for industrial plants, warehouses [citation:1, citation:3] |
| Bridge Construction | Structural members, supports for bridges |
| Piling Foundations | Pipe piles for building foundations and underground engineering [citation:1, citation:3] |
| Low-Pressure Fluid Transmission | Water, gas, and oil pipelines (non-critical) |
| Shipbuilding | Engineering structures in ships |
| Construction Applications | General structural purposes where medium strength is required |
| Offshore Projects | Marine structures, port facilities |
International Approximations
| Standard | Equivalent Grade | Notes |
|---|---|---|
| EN 10025-2 | S275JR (1.0044) | Direct modern equivalent |
| GB/T 700 | Q275B | Chinese equivalent |
| ASTM | A36 | Similar yield strength (250 MPa vs. 275 MPa) |
| JIS G3101 | SS400 | Japanese equivalent |
| BS 4360 | Grade 43 | Historical British equivalent (withdrawn) |
| DIN | St44-2 | Original designation |
Key Advantages
| Advantage | Description |
|---|---|
| Good Weldability | Low carbon content (≤0.21%) ensures excellent weldability |
| Higher Strength than ST37-2 | 275 MPa yield – approximately 17% higher than ST37-2 (235 MPa) |
| Economical | Cost-effective choice for medium-strength structural applications |
| Large Diameter Capability | DSAW produces pipes from 16" to 64" OD – ideal for large-diameter applications |
| High Weld Integrity | Double-sided welding creates a single high-quality weld nugget with 100% UT inspection [citation:2, citation:3] |
| Good Formability | Suitable for cold bending, flanging, and shaping without cracking |
| Widely Available | Commonly stocked by Chinese and European manufacturers [citation:1, citation:2] |
| Proven Performance | Decades of successful use in structural applications |
Important Considerations
1. Standard Status
DIN 17100 has been withdrawn since 2004 and replaced by EN 10025-2 . For new projects, specify S275JR instead.
2. Modern Equivalent
The direct modern equivalent of ST44-2 is S275JR (1.0044) under EN 10025-2:2004 .
3. Strength Comparison
ST44-2 offers approximately 17% higher yield strength than ST37-2 (275 MPa vs. 235 MPa) , making it suitable for applications requiring medium strength.
4. Impact Properties
The "-2" quality grade typically guarantees Charpy impact toughness of 27 J at 0°C. For applications requiring -20°C impact toughness, specify S275J2 instead.
5. Complete Specification Required
A complete order must specify:
Material Standard: DIN 17100 ST44-2 (or modern equivalent EN 10025-2 S275JR)
Manufacturing Process: DSAW / LSAW
Dimensions: OD x WT, Length
End Finish: Plain or beveled
Coating: As required
6. Size Limitations
DSAW manufacturing for ST44-2 is typically available from 16" to 64" OD
Smaller diameters (under 16") are typically produced by ERW or seamless methods
7. Coating Options
DSAW pipe can be supplied with various coatings for corrosion protection:
3LPE (3-layer polyethylene) – for buried pipelines
FBE (Fusion Bonded Epoxy) – for oil & gas pipelines
Varnish / Anti-rust oil – temporary protection
Bitumen Coating – for buried service
Black Oil Coating – standard mill finish
8. Third-Party Inspection
Available inspection services include SGS, BV, Lloyds, TUV
9. Weldability
Low carbon content (≤0.21%) ensures excellent weldability
Suitable for all standard welding methods (SMAW, GTAW, GMAW, SAW)
No post-weld heat treatment required for most thicknesses
10. Minimum Order Quantity
Typical MOQ: 3-5 tons
Larger orders available from manufacturers
11. Delivery Time
Stock items: 7-15 days after payment
Custom sizes: 20-30 days after order confirmation
Summary
DIN 17100 ST44-2 Double-Sided Submerged Arc Welded (DSAW) steel pipe is a standard product for large-diameter structural and medium-strength applications under the now-withdrawn German standard. With minimum yield strength of 275 MPa (40 ksi) – approximately 17% higher than ST37-2 – and tensile strength of 410-580 MPa, this material offers a cost-effective solution for general structural engineering where medium strength is required .
Key features:
Material standard: DIN 17100 ST44-2 (withdrawn; replaced by EN 10025-2 S275JR)
Modern equivalent: S275JR (1.0044)
Low carbon content (≤0.21%) ensures excellent weldability
DSAW manufacturing produces pipes from 16" to 64" OD with wall thickness up to 75 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
Economical choice for medium-strength structural applications
Common applications include:
Structural engineering (building frames, columns, trusses)
Bridge construction and piling foundations
Low-pressure fluid transmission (water, gas, oil)
Shipbuilding and offshore projects
Infrastructure projects
When ordering, specify: DIN 17100 ST44-2 (or EN 10025-2 S275JR for new projects), 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 .
Important Note: For new projects, it is strongly recommended to specify the modern equivalent EN 10025-2 S275JR instead of the withdrawn DIN 17100 ST44-2 .
