EN 10217 S355 Electric Resistance Welded (ERW) Pipe
Basic Overview
A European standard specification for electric resistance welded steel tubes made from high-strength S355 carbon steel, designed for pressure purposes. S355 represents the high-strength tier of non-alloy structural steels used in pressure applications, offering significantly higher yield strength than S235 or S275 grades.
Name Explanation
| Part | Meaning |
|---|---|
| EN | European Norm (standard) |
| 10217 | Standard for welded steel tubes for pressure purposes |
| S355 | Steel grade designation – S = structural steel, 355 = minimum yield strength (MPa) |
| Electric Resistance Welded | Manufacturing process – pipe formed from strip and welded longitudinally without filler metal |
Important Clarification: S355 in EN 10217
Note: EN 10217 (pressure tubes) officially uses P-prefix grades (e.g., P235, P265, P355) for pressure applications . The structural grade S355 is commonly used in practice for EN 10217 pipes, but the technically correct designation for pressure purposes is:
| Intended S355 | Correct EN 10217 Grade | Standard Part |
|---|---|---|
| S355 (structural grade) | P355 (pressure grade) | EN 10217-3 (fine grain steels) |
| S355J2H (structural hollow section) | P355NH (pressure fine grain) | EN 10217-3 |
Key Features of EN 10217 S355/P355 ERW Pipe
| Feature | Description |
|---|---|
| Material Type | Fine-grain, fully-killed carbon-manganese steel |
| Manufacturing | Electric Resistance Welded (ERW) or High Frequency Welded (HFW) – longitudinal weld seam fully normalized |
| Yield Strength | 355 MPa minimum (~51,500 psi) |
| Tensile Strength | 490-650 MPa |
| Elongation | 22% minimum (longitudinal) |
| Key Advantages | High strength-to-weight ratio, excellent weldability, fine-grain structure |
| Temperature Range | -20°C to +400°C for pressure applications |
| Certification | EN 10204 3.1 inspection certificate standard |
Chemical Composition (P355NH per EN 10217-3)
| Element | Content (%) | Notes |
|---|---|---|
| Carbon (C) | 0.20 max | Low carbon for weldability |
| Silicon (Si) | 0.10-0.50 | |
| Manganese (Mn) | 0.90-1.65 | Provides strength |
| Phosphorus (P) | 0.025 max | Tight control |
| Sulfur (S) | 0.020 max | Tight control |
| Aluminum (Al) | 0.02 min | Grain refinement |
| Niobium (Nb) | 0.05 max | Micro-alloying |
| Vanadium (V) | 0.10 max | Micro-alloying |
| Titanium (Ti) | 0.04 max | Micro-alloying |
| Chromium (Cr) | 0.30 max | Residual |
| Molybdenum (Mo) | 0.08 max | Residual |
| Nickel (Ni) | 0.30 max | Residual |
| Copper (Cu) | 0.30 max | Residual |
| Nitrogen (N) | 0.02 max |
Source:
Mechanical Properties Comparison
| Grade | Yield Strength (MPa) min | Tensile Strength (MPa) | Elongation % | Impact Energy (J) |
|---|---|---|---|---|
| S235 | 235 | 360-510 | 24 | 27 @ 20°C |
| S275 | 275 | 430-580 | 20 | 27 @ 20°C |
| S355 | 355 | 490-650 | 22 | 27 @ 0°C or -20°C (depending on suffix) |
Source:
Quality Grades & Impact Testing
| Designation | Impact Test Temperature | Min. Impact Energy |
|---|---|---|
| S355J0 | 0°C | 27J |
| S355J2 | -20°C | 27J |
| S355K2 | -20°C | 40J |
| P355NH | -20°C | 27J (transverse) |
Source:
EN 10217 Parts for S355/P355 Materials
| Part | Title | Applicable Grades | Key Application |
|---|---|---|---|
| Part 1 | Non-alloy tubes with room temp properties | P235, P265, P355 | General pressure (room temp) |
| Part 3 | Alloy fine grain tubes | P355N, P355NH, P355NL1, P460N | High-strength pressure applications, elevated temp |
| Part 5 | SAW tubes of alloy steel with elevated temp properties | P355GH, P355N | Large-diameter high-pressure lines |
Key Manufacturer Examples
Tata Steel Inflow™ Plus 355
Primary standard: EN 10217-3 Grade P355NH
Multi-certified: Also meets EN 10219 S355J2H (for sizes ≥219.1mm OD)
Delivery conditions: Hot-finished (OD 17.2-193.7mm) or Weld Line Annealed (OD 219.1-508mm)
Temperature range: -20°C to +400°C
Certification: EN 10204 3.1 inspection certificate
PED compliance: Suitable for PED categories I, II, III, IV
Tata Steel Inline™ Plus 360
Primary grade: EN 10217-3 P355N/NH/TC1
Also certified: API 5L X52N, EN 10219 S355J2H
Temperature range: -20°C to +400°C
Pressure ratings: Available with detailed pressure tables for various sizes
Size Availability
| Parameter | Typical Range |
|---|---|
| Outside Diameter | 17.2mm to 610mm (1/2" to 24") |
| Wall Thickness | 2.0mm to 25.0mm |
| Length | 3-18m (random or cut lengths) |
| End Finish | Plain, beveled, threaded |
Test Categories: TC1 vs. TC2
| Category | Description | Typical Application |
|---|---|---|
| TC1 | Standard quality, without mandatory ultrasonic testing of weld seam | General pressure applications |
| TC2 | Enhanced quality, with mandatory ultrasonic testing of weld seam | Critical service, higher integrity requirements |
Testing & Inspection Requirements
| Test Type | Purpose |
|---|---|
| Chemical Analysis | Verify composition per specifications |
| Tensile Test | Confirm yield and tensile strength |
| Flattening Test | Verify ductility across weld seam |
| Bend Test | Check weld integrity and formability |
| Impact Test | Charpy V-notch at specified temperature (J0/J2/K2) |
| Hydrostatic Test | Proof of leak-tightness (min 20MPa, ≥15s hold) |
| NDT of Weld Seam | Eddy current (EN ISO 10893-2) or ultrasonic (EN ISO 10893-10) examination |
| UT Testing | 100% weld + 10mm base metal on both sides, sensitivity Φ3.2mm FBH |
| Visual & Dimensional | Per EN 10246 series |
Heat Treatment Requirements (P355NH)
| Process | Parameters | Purpose |
|---|---|---|
| Normalizing (N) | 910±10°C × 1.5min/mm, air cooling | Refine grains to ASTM 6-8 grade |
| Weld Line Annealing (WLA) | Induction heating to 550-600°C, slow cooling | Normalize weld zone structure |
| Stress Relief Annealing (SR) | 580-620°C × 2min/mm, furnace cooling ≤200°C/h | Eliminate welding residual stress |
Common Applications
| Industry | Applications |
|---|---|
| Oil & Gas | Onshore gas pipelines, process plant piping |
| Petrochemical | Industrial conveyance, process plant equipment |
| Power Generation | Steam services, elevated temperature lines |
| Industrial | Compressed air systems, hydraulic lines, HVAC |
| Fire Protection | Fire sprinkler systems |
| Structural | High-strength pressure-containing structural elements |
| Water | High-pressure water conveyance |
Surface Finish & Protection Options
| Coating Type | Application |
|---|---|
| Black (bare) | Standard mill finish, indoor use |
| Varnish coating | Short-term corrosion protection |
| Primer-painted | Basic corrosion protection |
| 3LPE / FBE | Buried pipelines, harsh environments |
| Galvanized | Outdoor exposed applications |
| Epoxy coating | Enhanced corrosion protection |
Pressure Ratings
For EN 10217-3 P355NH materials, pressure ratings depend on size and wall thickness. Example from Tata Steel Inline™ Plus 360 (similar strength level) :
| OD (mm) | Thickness (mm) | Schedule | Max Operating Pressure (bar) @ Ambient |
|---|---|---|---|
| 219.1 | 8.18 | STD (40) | 128 |
| 219.1 | 12.7 | XS (80) | 198 |
| 323.9 | 9.53 | STD | 101 |
| 323.9 | 12.7 | XS | 134 |
| 406.4 | 9.53 | STD | 80 |
| 508.0 | 12.7 | XS | 86 |
International Equivalents (Approximate)
| Standard | Equivalent Grade |
|---|---|
| ASTM A53 | Gr.B (yield 240 MPa) – lower strength |
| ASTM A106 | Gr.B (yield 240 MPa) – lower strength |
| ASTM A333 | Gr.6 (low temp, yield 240 MPa) – lower strength |
| DIN 1629 | St52.0N |
| DIN 17178 | WSt E 355 |
| DIN 1630 | St52.4 |
| ISO 3183 | L360 |
| API 5L | X52N (PSL1/PSL2) |
| GB/T 3091 | Q355 |
Important Selection Notes
1. Correct Grade Designation
For pressure applications, specify P355 (EN 10217-3) rather than S355
S355J2H is for structural hollow sections (EN 10219), not pressure purposes
Tata Steel's Inflow™ Plus 355 is multi-certified to both standards
2. Temperature Limitations
Standard temperature range: -20°C to +400°C
Lower temperatures possible with special order (LT option)
For temperatures below -50°C, additional agreements required (impact ≥60J)
3. Quality Level Selection
TC1: Standard quality, sufficient for most applications
TC2: Enhanced quality with ultrasonic weld examination – for critical service
4. Certification Requirements
Standard: EN 10204 3.1 (manufacturer's independent testing)
For critical applications: EN 10204 3.2 (third-party witnessed)
Must include: chemical composition, mechanical properties, NDT results, heat treatment curve
5. Advantages of S355/P355 over Lower Grades
Higher strength allows thinner walls for same pressure rating
Weight savings reduce supporting structure requirements
Increased wear resistance provides longer service life
Suitable alternative to seamless tubes
Final Takeaway: EN 10217 S355 ERW Pipe (technically P355 per EN 10217-3) is a high-strength, fine-grain carbon steel welded tube designed for demanding pressure applications. With minimum yield strength of 355 MPa, it offers significant advantages over lower grades (S235, S275) through thinner walls, reduced weight, and enhanced wear resistance. Available in quality grades J0 (0°C impact), J2 (-20°C impact), and K2 (higher energy at -20°C), it is suitable for temperatures from -20°C to +400°C and fully compliant with the Pressure Equipment Directive (PED). For critical applications, specify EN 10217-3 P355NH with TC2 test category and EN 10204 3.1 certification.
