DIN 17100 ST37-2 Double-Sided Submerged Arc Welding (DSAW) Steel Pipe
Basic Overview
DIN 17100 ST37-2 DSAW (Double-Sided Submerged Arc Welded) steel pipe is a large-diameter welded pipe manufactured from low carbon structural steel conforming to the withdrawn German standard DIN 17100. The "ST37-2" designation indicates a minimum yield strength of 235 MPa (34,000 psi) for thicknesses ≤ 16mm, making it suitable for general structural and low-pressure applications where high strength is not required [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Important Note: DIN 17100 has been withdrawn since 2004 and replaced by the European standard EN 10025-2.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 ST37-2 is S235JR (Material Number 1.0038) . For new projects, it is recommended to specify S235JR instead.
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| 17100 | Standard specification for hot-rolled products in non-alloy steels (withdrawn 2004) |
| ST37-2 | Steel grade: "ST" = Stahl (steel), "37" = tensile strength class (approx. 370 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:4, citation:5] |
Key Specifications
| Attribute | Description |
|---|---|
| Material Standard | DIN 17100 (withdrawn; replaced by EN 10025-2) |
| Steel Grade | ST37-2 – Minimum yield strength 235 MPa (for thickness ≤ 16mm) [citation:1, citation:2] |
| Modern Equivalent | S235JR (1.0038) per EN 10025-2:2004 |
| Material Type | Low carbon non-alloy structural steel |
| Manufacturing Process | DSAW (Double-Sided Submerged Arc Welding) / LSAW (Longitudinal Submerged Arc Welding) [citation:4, citation:5] |
| Forming Methods | JCOE (progressive J-C-O forming) or UOE (U-ing, O-ing, Expanding) |
| Size Range | 219 mm to 1625 mm (approx. 8" to 64") OD – typical for DSAW [citation:1, citation:3, citation:5] |
| Wall Thickness | 6.35 mm to 60 mm (up to 75 mm for special applications) [citation:3, citation:5] |
| Length | 2 m to 18 m standard; up to 32 m available [citation:3, citation:5] |
| End Finishes | Plain ends, beveled ends (30° bevel angle) |
Chemical Composition (DIN 17100 ST37-2)
| Element | Maximum % (for thickness) | Notes |
|---|---|---|
| Carbon (C) | ≤0.17% (t ≤ 16mm); ≤0.20% (t > 16mm) | Low carbon for good weldability [citation:1, citation:2, citation:3] |
| Phosphorus (P) | 0.050% | Controlled for weldability [citation:1, citation:2, citation:3] |
| Sulfur (S) | 0.050% | Controlled for toughness [citation:1, citation:2, citation:3] |
| Nitrogen (N) | 0.090% | Controlled [citation:1, citation:2, citation:3] |
Mechanical Properties (DIN 17100 ST37-2)
Yield Strength (min) [citation:1, citation:2, citation:3]
| Thickness (mm) | Yield Strength (MPa) |
|---|---|
| ≤ 16 | 235 |
| 16 < t ≤ 40 | 225 |
| 40 < t ≤ 63 | 215 |
| 63 < t ≤ 80 | 205 |
| 80 < t ≤ 100 | 195 |
| ≥ 100 | 185 |
Tensile Strength [citation:1, citation:2, citation:3]
| Thickness (mm) | Tensile Strength (MPa) |
|---|---|
| ≤ 3 | 360-510 |
| 3 < t ≤ 100 | 340-470 |
Other Properties
| Property | Value |
|---|---|
| Elongation | Varies by thickness (typically 18-22%) |
| Charpy Impact | 27 J at 0°C (typical for -2 quality grade) |
ST37-2 vs. Modern Equivalents
| Historical Grade | Modern Equivalent | Standard | Key Difference |
|---|---|---|---|
| ST37-2 | S235JR (1.0038) | EN 10025-2:2004 | S235JR has tighter P/S limits |
| ST37-2 | Q235B | GB/T 700 | Chinese equivalent |
| ST37-2 | A36 | ASTM | US equivalent (slightly higher strength) |
*Note: ST37-2 is similar to S235JR, but S235JR has stricter controls on phosphorus and sulfur (0.035% vs. 0.050%).*
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:4, citation:5].
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 DIN 17100 ST37-2 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
Dimensional Specifications
| Parameter | Range / Tolerance |
|---|---|
| Outside Diameter | 219 mm to 1625 mm (8" to 64") – typical DSAW range [citation:3, citation:5] |
| Wall Thickness | 6.35 mm to 60 mm (up to 75 mm for special applications) [citation:3, citation:5] |
| Diameter Tolerance | ±0.75% of specified OD (typical) |
| Wall Thickness Tolerance | +15% / -12.5% of nominal (typical) |
| Length | 2 m to 18 m standard; up to 32 m available [citation:3, citation:5] |
Typical Size Availability:
| 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 |
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:2] |
| Piling Foundations | Pipe piles for building foundations and underground engineering |
| Low-Pressure Fluid Transmission | Water, gas, and oil pipelines (non-critical) |
| Construction Applications | General structural purposes where high strength is not required |
| Vehicle and Shipbuilding | Engineering structures in vehicles and ships [citation:1, citation:2] |
| Pressure Vessels | Low-pressure vessels (with appropriate design) |
| Infrastructure Projects | Tunnel supports, retaining walls, highway structures |
International Approximations
| Standard | Equivalent Grade | Notes |
|---|---|---|
| EN 10025-2 | S235JR (1.0038) | Direct modern equivalent |
| GB/T 700 | Q235B | Chinese equivalent |
| ASTM | A36 | Similar yield strength (250 MPa) |
| JIS G3101 | SS400 | Japanese equivalent |
| BS 4360 | Grade 43 | Historical British equivalent |
Key Advantages
| Advantage | Description |
|---|---|
| Good Weldability | Low carbon content (≤0.20%) ensures excellent weldability |
| Economical | Cost-effective choice for general structural applications |
| Large Diameter Capability | DSAW produces pipes from 8" 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 |
| Good Formability | Suitable for cold bending, flanging, and shaping without cracking |
| Widely Available | Commonly stocked by Chinese and European manufacturers [citation:1, citation:2, citation:3] |
| 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 S235JR instead.
2. Modern Equivalent
The direct modern equivalent of ST37-2 is S235JR (1.0038) under EN 10025-2:2004 .
3. Strength Comparison
ST37-2 is not as strong as typical ASTM A36, but it is widely used in everyday applications where high strength requirements are not necessary .
4. Complete Specification Required
A complete order must specify:
Material Standard: DIN 17100 ST37-2 (or modern equivalent EN 10025-2 S235JR)
Manufacturing Process: DSAW / LSAW
Dimensions: OD x WT, Length
End Finish: Plain or beveled
Coating: As required
5. Size Limitations
DSAW manufacturing for ST37-2 is typically available from 8" to 64" OD [citation:3, citation:5]
Smaller diameters (under 8") are typically produced by ERW or seamless methods
6. 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
7. Third-Party Inspection
Available inspection services include SGS, BV, Lloyds, TUV
8. Weldability
Low carbon content (≤0.20%) ensures excellent weldability
Suitable for all standard welding methods (SMAW, GTAW, GMAW, SAW)
No post-weld heat treatment required for most thicknesses
9. Minimum Order Quantity
Typical MOQ: 3 tons
Larger orders available from manufacturers
10. Delivery Time
Stock items: 3-7 days after payment
Custom sizes: 20-30 days after order confirmation
Summary
DIN 17100 ST37-2 Double-Sided Submerged Arc Welded (DSAW) steel pipe is a standard product for large-diameter structural and low-pressure applications under the now-withdrawn German standard. With minimum yield strength of 235 MPa (34,000 psi) and tensile strength of 340-510 MPa, this material offers a cost-effective solution for general structural engineering where high strength is not required.
Key features:
Material standard: DIN 17100 ST37-2 (withdrawn; replaced by EN 10025-2 S235JR)
Modern equivalent: S235JR (1.0038)
Low carbon content (≤0.20%) ensures excellent weldability
DSAW manufacturing produces pipes from 8" to 64" OD with wall thickness up to 60 mm [citation:3, citation:5]
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 general structural applications
Common applications include:
General structural engineering (building frames, columns, trusses)
Piling foundations for buildings
Low-pressure fluid transmission (water, gas, oil)
Vehicle and shipbuilding
Infrastructure projects
When ordering, specify: DIN 17100 ST37-2 (or EN 10025-2 S235JR 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 S235JR instead of the withdrawn DIN 17100 ST37-2 .
