EN 10219 S355NH SHS/RSH Pipe
EN 10219 S355NH SHS/RHS Pipe – Normalized Fine‑Grain Structural Hollow Sections
Comprehensive data for S355NH hollow sections according to EN 10219: cold‑formed welded square and rectangular pipes with minimum yield strength 355 MPa, excellent notch toughness at -20 °C.
Cold forming, welding, normalizing (optional), straightening
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EN 10219 S355NH SHS/RSH Pipe Introduction
S355NH is a normalized fine‑grain structural steel hollow section defined in EN 10219‑1. It is produced by cold forming and welding flat‑rolled products made from steel conforming to EN 10025‑3 grade S355N. The grade guarantees a minimum yield strength of 355 MPa for thicknesses up to 16 mm and reliable impact toughness of 40 J at −20 °C (longitudinal). It is widely used in welded structures, buildings, bridges and offshore applications where both high strength and good weldability are required. S355NH is available in square (SHS), rectangular (RHS) and circular hollow sections and can be delivered in various conditions including normalized or normalized rolled.
EN 10219 S355NH SHS/RSH Pipe Chemical Composition
The chemical composition of S355NH corresponds to that of S355N in EN 10025‑3. Maximum limits apply unless a range is indicated. The steel is fully killed and contains fine‑grain forming elements (Al, Nb, V, Ti). The carbon equivalent value (CEV) is restricted to ensure good weldability.
| Element | Value (max, %) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.20 | CEV ≤0.43 for t≤40 mm; CEV ≤0.45 for 40 |
| Silicon (Si) | ≤0.60 | — |
| Manganese (Mn) | 0.90–1.65 | — |
| Phosphorus (P) | ≤0.025 | — |
| Sulfur (S) | ≤0.020 | — |
| Aluminium (Altotal) | ≥0.020 | minimum content for fine‑grain practice |
| Chromium (Cr) | ≤0.30 | — |
| Nickel (Ni) | ≤0.50 | — |
| Molybdenum (Mo) | ≤0.10 | — |
| Copper (Cu) | ≤0.55 | — |
| Niobium (Nb) | ≤0.050 | if not combined with V; otherwise Nb+V ≤0.12% |
| Vanadium (V) | ≤0.12 | — |
| Titanium (Ti) | ≤0.050 | — |
| Nitrogen (N) | ≤0.015 | — |
| CEV | ≤0.43/0.45 | depending on thickness, calculated as C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15 |
EN 10219 S355NH SHS/RSH Pipe Physical Properties
The following physical properties are typical for normalized fine‑grain structural steel and are not specified in the delivery standard. They may vary slightly with composition and microstructure. Values are valid at room temperature unless otherwise noted.
| Property | Typical value | Unit | Test condition / Remark |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | — |
| Modulus of elasticity (E) | 210 | GPa | — |
| Shear modulus (G) | ≈81 | GPa | calculated from E and ν |
| Poisson's ratio (ν) | 0.3 | — | elastic range |
| Thermal expansion coefficient (α) | 12 | 10⁻⁶/K | 20–100 °C |
| Thermal expansion coefficient (α) | 13 | 10⁻⁶/K | 20–200 °C |
| Thermal conductivity (λ) | ≈50 | W/(m·K) | at 20 °C |
| Specific heat capacity | ≈460 | J/(kg·K) | at 20 °C |
| Electrical resistivity (ρe) | ≈0.23 | μΩ·m | at 20 °C |
EN 10219 S355NH SHS/RSH Pipe Mechanical Properties
Mechanical properties of S355NH hollow sections at ambient temperature, tested in the longitudinal direction according to EN 10219‑1. Values apply to the finished product after cold forming. For bend test, no cracks shall occur when bent around a mandrel of specified diameter through 180° (W = wall thickness).
| Property | Required value | Unit | Test condition |
|---|---|---|---|
| Upper yield strength (ReH) | ≥355 | MPa | Wall thickness t ≤16 mm |
| Upper yield strength (ReH) | ≥345 | MPa | 16 < t ≤ 40 mm |
| Upper yield strength (ReH) | ≥335 | MPa | 40 < t ≤ 63 mm |
| Upper yield strength (ReH) | ≥325 | MPa | 63 < t ≤ 80 mm |
| Upper yield strength (ReH) | ≥315 | MPa | 80 < t ≤ 100 mm |
| Tensile strength (Rm) | 470–630 | MPa | t ≤ 100 mm |
| Elongation (A) | ≥22 | % | t ≤ 40 mm, L0=5.65√S0 |
| Elongation (A) | ≥21 | % | 40 < t ≤ 63 mm |
| Elongation (A) | ≥20 | % | 63 < t ≤ 100 mm |
| Bend test (mandrel diameter) | 3 × t | — | t ≤ 16 mm, 180° bend |
| Bend test (mandrel diameter) | 4 × t | — | 16 < t ≤ 40 mm |
| Charpy V‑notch impact (KV2) | ≥40 | J | −20 °C, longitudinal, t ≤ 60 mm |
| Charpy V‑notch impact (KV2) | ≥27 | J | −20 °C, longitudinal, 60 < t ≤ 100 mm |
EN 10219 S355NH SHS/RSH Pipe Identical Grade Designations and Direct Substitutes
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10219-1 | S355NH | Cold‑formed welded structural hollow sections of normalized fine‑grain steels |
| European Union | EN 10025-3 | S355N | Hot‑rolled normalized fine‑grain structural steel; used as parent material for hollow sections |
| International (ISO) | ISO 630-3 | S355NL | Normalized fine‑grain structural steels; similar mechanical properties but with a guaranteed lower impact temperature (−50 °C) |
EN 10219 S355NH SHS/RSH Pipe Application Introduction
S355NH hollow sections combine high strength, guaranteed toughness at sub‑zero temperatures and excellent weldability. Their closed section shape provides high torsion stiffness and a highly efficient strength‑to‑weight ratio. These properties make them ideal for load‑bearing and dynamically stressed structures.
Product Applications: Multi‑storey building frames and trusses, Pedestrian and road bridges, Offshore platform substructures and decks, Lattice masts and telecommunications towers, Crane booms and jibs, Steel columns and scaffoldings, Agricultural machinery frames, Railway and road sign gantries
Processed into products: Columns and beams in steel structures, Truss chords and bracing members, Bridge box girders and cross‑beams, Welded pipe racks and support frames, Boom segments and leg sections of mobile cranes, Tower sections for wind turbines, Machine bases and press frames
Application industries: Building and civil engineering, Bridge construction, Offshore and marine engineering, Crane and heavy machinery manufacturing, Renewable energy structures (wind turbine towers), Agricultural equipment, Transportation (truck frames, trailers)
EN 10219 S355NH SHS/RSH Pipe Near‑Equivalent / Similar Grades for Reference
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10025-4 | S355M / S355ML | Thermomechanical rolled fine‑grain steel; similar strength and toughness, but different delivery condition |
| USA | ASTM A500 / A501 | Grade C | Cold‑formed welded carbon steel structural tubing; comparable yield strength (345 MPa) but less stringent notch toughness |
| USA | ASTM A572 | Grade 50 | High‑strength low‑alloy structural steel; yield 345 MPa, often used in similar applications, but not a hollow section standard |
| Japan | JIS G 3466 | STKR490 | Carbon steel square/rectangular tubes; yield 325 MPa, lower toughness requirements |
| China | GB/T 1591 | Q355D | High‑strength low‑alloy structural steel; yield 355 MPa, impact tested at −20 °C, widely used for welded structures |
| Russia | GOST 19281 | C345 / 09G2S | Structural low‑alloy steel; typical yield 345 MPa, used in welded metal structures |
Notes:
- Weldability: S355NH is readily weldable by all common processes, provided the maximum carbon equivalent value and the recommendations of EN 1011‑2 are followed. Preheating may be required for thicker sections or under low ambient temperatures.
- Notch toughness: The NLH variant (S355NLH) guarantees 40 J at −50 °C and can be selected for more severe conditions.
- Corrosion protection: The steel is not intrinsically corrosion resistant; suitable surface protection (painting, hot‑dip galvanizing) should be applied for outdoor or aggressive environments.
- Tolerances: Dimensions and shape tolerances comply with EN 10219‑2; tighter tolerances can be agreed upon.
- Inspection and testing: Mandatory specific inspection and testing acc. to EN 10219‑1, Section 8. Option 14 (Charpy tests) is mandatory for the S355NH grade.
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