FH40 SSAW Pipe Material
FH40 SSAW Pipe: High-Strength Shipbuilding Steel for Low-Temperature Applications
Comprehensive data sheet for FH40 steel, a high strength hull structural steel used in spiral submerged arc welded (SSAW) pipes for marine and offshore applications. Includes chemical composition, mechanical and thermal properties, equivalent grades, and application guide.
Welding, hot rolling, cold forming, cutting, machining
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FH40 SSAW Pipe Introduction
FH40 is a high-strength hull structural steel grade designed for ship and offshore structures operating at low temperatures. With a minimum yield strength of 390 MPa, it offers excellent weldability and impact toughness at -40 °C. FH40 SSAW (Spiral Submerged Arc Welded) pipes are manufactured from hot-rolled steel coils or plates and are widely used in marine risers, offshore platforms, and structural components. The steel is typically supplied in normalized or thermomechanically rolled condition, meeting classification society rules such as ABS, DNV, LR, and GB/T 712.
FH40 SSAW Pipe Chemical Composition
The chemical composition of FH40 steel as per GB/T 712-2011. Microalloying elements such as Nb, V, Ti are often added to ensure fine grain size and strength. Residual elements are tightly controlled for weldability and toughness.
| Element | Typical Value (≤) | Remarks |
|---|---|---|
| Carbon (C) | 0.16 | Ladle analysis |
| Silicon (Si) | 0.50 | Max |
| Manganese (Mn) | 0.90 - 1.60 | Depending on thickness |
| Phosphorus (P) | 0.020 | Max |
| Sulfur (S) | 0.020 | Max |
| Aluminum (Al, total) | ≥ 0.015 | For grain refinement |
| Niobium (Nb)ᵅ | 0.02 - 0.05 | Optional, microalloying |
| Vanadium (V)ᵅ | 0.05 - 0.10 | Optional, microalloying |
| Titanium (Ti)ᵅ | 0.007 - 0.05 | Optional, microalloying |
| Nitrogen (N) | 0.009 | Max, for normalized steel |
| Copper (Cu)ᵇ | 0.35 | Residual element |
| Chromium (Cr)ᵇ | 0.20 | Residual element |
| Nickel (Ni)ᵇ | 0.40 | Residual element |
| Molybdenum (Mo)ᵇ | 0.08 | Residual element |
| Carbon Equivalent (CEV) | 0.40 (typical) | For weldability assessment |
FH40 SSAW Pipe Thermal and Electrical Physical Properties
Typical physical properties of FH40 steel at room temperature unless otherwise noted. These values are representative for low-alloy structural steels.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Elastic Modulus (E) | 206 | GPa | 20 °C |
| Shear Modulus (G) | 80 | GPa | 20 °C |
| Poisson's Ratio (ν) | 0.3 | - | 20 °C |
| Thermal Expansion Coefficient (α) | 12.0 | 10⁻⁶/K | 20 - 100 °C |
| Thermal Expansion Coefficient (α) | 12.8 | 10⁻⁶/K | 20 - 200 °C |
| Thermal Expansion Coefficient (α) | 13.5 | 10⁻⁶/K | 20 - 400 °C |
| Thermal Conductivity (λ) | 48 | W/(m·K) | 20 °C |
| Thermal Conductivity (λ) | 45 | W/(m·K) | 100 °C |
| Thermal Conductivity (λ) | 40 | W/(m·K) | 200 °C |
| Specific Heat Capacity (c) | 480 | J/(kg·K) | 20 °C |
| Electrical Resistivity (ρ_e) | 0.25 | μΩ·m | 20 °C |
FH40 SSAW Pipe Mechanical Properties
Mechanical properties of FH40 steel at ambient temperature according to GB/T 712-2011. Values depend on thickness. Impact test temperature is -40 °C.
| Property | Standard Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 390 | MPa | Thickness ≤ 50 mm |
| Yield Strength (ReH) | ≥ 370 | MPa | Thickness > 50 - 70 mm |
| Yield Strength (ReH) | ≥ 350 | MPa | Thickness > 70 - 100 mm |
| Tensile Strength (Rm) | 510 - 660 | MPa | Thickness ≤ 100 mm |
| Elongation (A) | ≥ 20 | % | Thickness ≤ 50 mm, gauge length 5.65√So |
| Elongation (A) | ≥ 19 | % | Thickness > 50 - 70 mm |
| Elongation (A) | ≥ 18 | % | Thickness > 70 - 100 mm |
| Charpy Impact (KV2) | ≥ 41 (longitudinal) | J | -40 °C, min average for set of 3 |
| Charpy Impact (KV2) | ≥ 28 (transverse) | J | -40 °C, min average for set of 3 |
| Bend Test (D = bend diameter, a = thickness) | D = 3a, 180° no cracks | - | Thickness ≤ 25 mm |
FH40 SSAW Pipe Fully Equivalent Material Standards and Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | ASTM A131 / A131M | FH40 | Marine steel |
| Norway/Germany | DNV GL Rules | FH40 | Ship classification |
| United Kingdom | LR Rules | FH40 | Lloyd's Register |
| USA | ABS Rules | FH40 | American Bureau of Shipping |
| France | BV Rules | FH40 | Bureau Veritas |
| Japan | NK Rules (ClassNK) | FH40 | Nippon Kaiji Kyokai |
| South Korea | KR Rules | FH40 | Korean Register |
FH40 SSAW Pipe Application Introduction
FH40 SSAW pipes are designed for demanding structural applications requiring high strength and excellent low-temperature toughness. The spiral welded manufacturing allows cost-effective large-diameter pipes. Suitable for marine and offshore structures operating in cold climate regions.
Product Applications: Hull structures, Deck girders, Container ship frames, Offshore platform legs and braces, Marine risers and conductor pipes, Piling pipes, Wind turbine tower monopiles, Caissons, Port and dock structures
Processed into products: Welded tubular joints, Transition pieces, Jacket legs, Mud mats, Anchor piles, Shear keys, Pipe spools, Welded beams, Stiffeners
Application industries: Shipbuilding, Offshore Oil & Gas, Marine & Port Engineering, Bridge Construction, Wind Energy (Offshore Towers)
FH40 SSAW Pipe Similar/Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China/International | GB/T 712 / ASTM A131 | EH40 | Impact test at -20 °C, otherwise similar strength |
| China/International | GB/T 712 / ASTM A131 | DH40 | Impact test at -20 °C, less stringent |
| China/International | GB/T 712 / ASTM A131 | FH36 | Lower yield strength (355 MPa), same -40 °C toughness |
| Europe | EN 10025-4 | S420ML | Fine grain structural steel, similar strength, impact -50 °C option |
| Europe | EN 10025-3 | S420N/NL | Normalized fine grain steel, comparable yield |
| USA | ASTM A572 | Grade 60 | Similar strength, not specifically for marine, lower Ceq |
Notes:
For SSAW (Spiral Submerged Arc Welded) pipes, the base material shall comply with FH40 requirements, and the weld metal shall match the base material strength and toughness. Welding procedure qualification is necessary. Post-weld heat treatment may be required for thick sections. The steel can be supplied with various impact test options and through-thickness property requirements (Z-direction) per agreed specification. All values are for reference only and specific test certificates from the manufacturer must be followed.
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