BS EN 10217-2 Spiral Submerged Arc Welded Steel Pipe (SSAW)
Basic Overview
BS EN 10217-2 SSAW (Spiral Submerged Arc Welded) steel pipe is a welded carbon/alloy steel tube manufactured to the European standard for pressure purposes with specified elevated temperature properties . This standard is specifically designed for welded tubes used in pressure applications at elevated temperatures, such as in boilers, heat exchangers, superheaters, and high-temperature pipelines .
The SSAW process-also known as helical submerged arc welding (SAWH)-is a high-integrity welding method where both inside and outside welds are applied, forming a single high-quality weld nugget. This process is particularly suited for large-diameter, thick-wall pipes used in demanding high-temperature pressure applications .
Name Explanation
| Part | Meaning |
|---|---|
| BS EN | British Standard adopted from European Norm |
| 10217-2 | European standard for welded steel tubes for pressure purposes – Part 2: Electric welded non-alloy and alloy steel tubes with specified elevated temperature properties |
| SSAW | Spiral Submerged Arc Welding – pipe formed from steel coil with the weld seam running continuously in a spiral; also known as SAWH (helical seam) |
| GH Grades | "GH" suffix indicates suitability for elevated temperature service (Gases, High temperature) |
Key Specifications
| Attribute | Description |
|---|---|
| Standard | BS EN 10217-2:2019 – "Welded steel tubes for pressure purposes - Technical delivery conditions - Part 2: Electric welded non-alloy and alloy steel tubes with specified elevated temperature properties" |
| Primary Application | Elevated temperature pressure service – boilers, heat exchangers, superheaters, steam lines |
| Pipe Types Covered | Electric welded tubes – including longitudinal (SAWL) and helical (SAWH/SSAW) seam welding |
| Steel Grades (GH series) | P235GH (most common), P265GH, 16Mo3 (alloy), P195GH |
| Temperature Range | Designed for elevated temperature service up to 400°C for GH grades |
| Size Range (SSAW) | 219 mm to 4064 mm (approx. 8" to 160") OD |
| Wall Thickness | 5 mm to 40 mm (up to 60 mm for special applications) |
| Length | 6 m to 12 m standard; up to 18 m available |
Steel Grades for EN 10217-2 SSAW
| Grade | Min Yield Strength (t ≤ 16mm) | Tensile Strength | Charpy Impact (0°C) | Typical Application |
|---|---|---|---|---|
| P195GH | 195 MPa | 320-440 MPa | 40 J | Low-pressure boilers, heat exchangers |
| P235GH | 235 MPa | 360-500 MPa | 40 J | General boiler applications, power plant piping |
| P265GH | 265 MPa | 410-570 MPa | 40 J | High-pressure boiler tubes, superheaters |
| 16Mo3 | 280 MPa | 450-600 MPa | 40 J (20°C) | High-temperature service up to 500°C |
Note: GH grades require mandatory Charpy impact testing at 0°C (40J min longitudinal) .
Chemical Composition (P235GH - Typical)
| Element | Maximum % | Notes |
|---|---|---|
| Carbon (C) | 0.16% | Low carbon for good weldability |
| Silicon (Si) | 0.35% | Deoxidizer |
| Manganese (Mn) | 1.20% | Provides strength |
| Phosphorus (P) | 0.025% | Controlled for weldability |
| Sulfur (S) | 0.020% | Controlled for toughness |
| Aluminum (Al) | ≥0.020% | Fully killed steel, fine grain |
| Copper (Cu) | 0.30% | Residual |
Note: P235GH is the most common grade for general elevated temperature pressure applications .
Mechanical Properties (P235GH)
| Property | Value at Room Temperature |
|---|---|
| Yield Strength (t ≤ 16mm) | 235 MPa min |
| Yield Strength (16 < t ≤ 40mm) | 225 MPa min |
| Tensile Strength | 360-500 MPa |
| Elongation (longitudinal) | ≥ 25% |
| Charpy Impact (0°C) | ≥ 40 J (longitudinal) |
Elevated Temperature Yield Strength (P235GH)
| Temperature | Min Yield Strength (Rp0.2) |
|---|---|
| 100°C | 198 MPa |
| 150°C | 187 MPa |
| 200°C | 170 MPa |
| 250°C | 150 MPa |
| 300°C | 132 MPa |
| 350°C | 120 MPa |
| 400°C | 112 MPa |
SSAW Manufacturing Process for EN 10217-2
Spiral submerged arc welded pipes are produced using the following process :
| Step | Description |
|---|---|
| 1. Coil Selection | Hot-rolled steel coils meeting P235GH/P265GH chemistry requirements (fully killed, fine grain steel with Al ≥ 0.020%) |
| 2. Edge Preparation | Strip edges are milled for proper welding |
| 3. Spiral Forming | Steel strip is continuously formed into a cylindrical shape at a specific helix angle at room temperature |
| 4. Submerged Arc Welding | Double-sided automatic submerged arc welding (inside and outside) creates the spiral seam with full penetration |
| 5. Heat Treatment | Weld seam may be normalized to refine grain structure |
| 6. NDT Inspection | 100% ultrasonic (UT) or radiographic (RT) inspection of the entire weld seam – mandatory for EN 10217-2 |
| 7. Hydrostatic Testing | Each pipe individually tested (≥1.5 × design pressure, ≥10 seconds) |
| 8. Finishing | End processing (plain or beveled), coating, and marking |
Testing & Inspection Requirements (EN 10217-2)
| Test Type | Requirement | Notes |
|---|---|---|
| Chemical Analysis | Per heat lot | Verifies composition limits per EN 10217-2 |
| Tensile Test | Per lot | At room temperature (and elevated when specified) |
| Impact Test | Mandatory for GH grades | Charpy V-notch at 0°C (40J min longitudinal) |
| Flattening Test | Required | Checks ductility |
| Bend Test | Required | Verifies weld integrity |
| Hydrostatic Test | Each pipe | ≥1.5 × design pressure, ≥10 seconds |
| Ultrasonic Inspection (UT) | 100% of weld seam | Mandatory – detects weld defects |
| Radiographic Inspection (RT) | For critical applications | Available upon request |
| Dimensional Inspection | 100% | Per EN 10217-2 tolerances |
| Mill Test Certificate | EN 10204 Type 3.1B | Provided with full test results |
PED Compliance
EN 10217-2 is harmonized with the EU Pressure Equipment Directive (PED) 2014/68/EU. Pipes manufactured to this standard are suitable for CE-marked pressure equipment in Europe .
PED Categories: Suitable for equipment in categories I, II, III, or IV
AD2000 Compliance: Aligned with AD2000 Merkblatt W4
Dimensional Tolerances
| Parameter | Tolerance |
|---|---|
| Outside Diameter (D ≤ 219.1mm) | ±1% or ±0.5mm (whichever is greater) |
| Outside Diameter (D > 219.1mm) | ±0.75% or ±6mm (whichever is greater) |
| Wall Thickness (t ≤ 5mm) | ±10% or ±0.3mm (whichever is greater) |
| Wall Thickness (t > 5mm) | ±8% |
| Straightness | ≤ 0.15% of total length (max 3mm/m) |
| Length (L ≤ 6000mm) | 0 – +10 mm (D < 406.4mm); 0 – +25 mm (D ≥ 406.4mm) |
| Length (6000 < L ≤ 12000mm) | 0 – +15 mm (D < 406.4mm); 0 – +50 mm (D ≥ 406.4mm) |
Common Applications
| Application | Temperature Range | Typical Grade |
|---|---|---|
| Boiler Tubes | Up to 400°C | P235GH, P265GH |
| Heat Exchangers | Up to 400°C | P235GH, P265GH |
| Superheater Tubes | Up to 400°C | P265GH |
| Steam Piping | Up to 400°C | P235GH |
| Power Plant Piping | Up to 400°C | P235GH, 16Mo3 |
| Feedwater Lines | Up to 300°C | P235GH |
| District Heating | Up to 150°C | P235GH |
| Industrial Process Piping | Up to 400°C | P235GH, P265GH |
Comparison with Related Standards
| Standard | Application | Key Difference |
|---|---|---|
| EN 10217-1 | Room temperature pressure purposes | No elevated temperature properties (TR grades) |
| EN 10217-2 | Elevated temperature pressure purposes (GH grades) | Specifies elevated temperature properties |
| EN 10217-5 | Submerged arc welded tubes with elevated temperature properties | Also covers SAW; Part 5 is for SAW specifically |
| EN 10219 | Structural hollow sections | Not for pressure applications |
| API 5L | Oil and gas transmission | Different grade designation system |
| ASTM A106 | Seamless carbon steel pipe for high-temperature service | US standard equivalent |
Key Advantages of EN 10217-2 SSAW Pipe
| Advantage | Description |
|---|---|
| Elevated Temperature Performance | Specifically designed for high-temperature service up to 400°C |
| Guaranteed Toughness | Mandatory Charpy impact testing at 0°C (40J min) ensures low-temperature performance |
| Large Diameter Capability | SSAW produces pipes from 8" to 160" OD – ideal for large-diameter high-temperature applications |
| High Weld Integrity | Double-sided welding creates a single high-quality weld nugget with 100% UT inspection |
| PED Compliance | Harmonized with Pressure Equipment Directive 2014/68/EU for CE marking |
| Full Traceability | Mill certificates to EN 10204 Type 3.1 with full test results |
| Cost-Effective | SSAW process provides economical production for large diameters |
Important Considerations
1. Part 2 vs. Part 5
EN 10217-2: Covers electric welded tubes (including SAWH) – generally the same requirements apply to SAWH
EN 10217-5: Specifically covers submerged arc welded tubes (SAWL and SAWH) – both are applicable to SSAW pipes
2. GH Grade Requirements
GH grades require mandatory Charpy impact testing at 0°C (40J min longitudinal)
Elevated temperature properties are specified and must be documented
Fully killed, fine-grain steel with minimum aluminum content (≥0.020%)
3. Impact Testing Temperature
Standard: 27J at 0°C for GH grades
For lower temperatures (arctic, offshore), specify Option 5 for testing at -10°C or -20°C
4. SSAW Size Limitations
SSAW manufacturing for EN 10217-2 is typically available from 8" to 160" OD
Smaller diameters (under 8") are typically produced by ERW or seamless methods
5. Test Categories
TC1: Standard test category for non-alloy steel tubes
TC2: Enhanced test category with additional NDT of the pipe body; mandatory for alloy steel tubes
6. Weldability
Low carbon content (≤0.16%) ensures excellent weldability
Suitable for all standard welding methods
Preheat may be required for thicker sections (100-150°C)
7. International Approximations
| US Standard | European Equivalent |
|---|---|
| ASTM A106 Gr B | P235GH (similar strength) |
| ASTM A106 Gr C | P265GH (similar strength) |
| ASME SA-106 | P235GH, P265GH |
Summary
BS EN 10217-2 Spiral Submerged Arc Welded (SSAW) steel pipe is the European standard for large-diameter welded tubes used in elevated temperature pressure applications. With grades P235GH (most common) and P265GH, these pipes offer guaranteed high-temperature strength up to 400°C and mandatory Charpy impact toughness at 0°C.
Key features:
Material standard: EN 10217-2 – welded tubes for pressure purposes with elevated temperature properties
Grades: P195GH, P235GH (most common), P265GH, 16Mo3
GH suffix indicates suitability for elevated temperature service
Mandatory impact testing at 0°C (40J min)
Elevated temperature properties specified and guaranteed
SSAW manufacturing produces pipes from 8" to 160" OD with wall thickness up to 40 mm
Double-sided welding creates a single high-quality weld nugget
100% ultrasonic inspection of weld seam mandatory
PED 2014/68/EU compliant for CE-marked pressure equipment
Mill certificates to EN 10204 Type 3.1B
Common applications include:
Boiler tubes and superheaters
Heat exchangers
Steam piping in power plants
Feedwater lines
District heating systems
Industrial process piping at elevated temperatures
When ordering, specify: BS EN 10217-2, Grade P235GH (or P265GH), SAWH (spiral welded), Test Category (TC1/TC2), Size (OD x WT), Length, End Finish (plain/beveled), Coating Requirements, and Mill Test Certificate to EN 10204 Type 3.1B. For CE-marked pressure equipment, specify PED compliance .
