JIS G3106 SM400C SSAW Pipe
JIS G3106 SM400C SSAW Pipe: Structural Carbon Steel for Welded Applications
Detailed material data for SM400C steel used in spiral submerged arc welded (SSAW) pipes, covering chemical composition, mechanical properties, thermal properties, international equivalents and application guidance.
Hot rolling, spiral forming, submerged arc welding (SAW)
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JIS G3106 SM400C SSAW Pipe Introduction
SM400C is a carbon steel grade specified in JIS G3106 for rolled steels for welded structures. It is extensively employed in the production of SSAW (Spiral Submerged Arc Welded) pipes because of its outstanding weldability, moderate strength and guaranteed Charpy impact toughness at 0°C. The steel provides a minimum yield strength of 245 MPa for thicknesses up to 16 mm and a tensile strength of 400–510 MPa.
- Key Features: Reliable weldability, defined low‑temperature toughness, uniform mechanical properties across thickness ranges.
- Delivery Condition: Typically as‑rolled or normalized; SSAW pipes are formed and submerged‑arc welded from hot‑rolled plates/coils.
JIS G3106 SM400C SSAW Pipe Chemical Composition
The chemical composition of SM400C is strictly controlled to ensure weldability and notch toughness. Typical values for product thickness ≤50 mm are shown. For thickness >50–100 mm the maximum carbon is 0.20 % and the manganese range may extend to 0.60–1.50 %.
| Element | Standard Value | Notes |
|---|---|---|
| C | ≤0.18 | Thickness ≤50 mm |
| Si | ≤0.35 | |
| Mn | 0.60–1.40 | Thickness ≤50 mm |
| P | ≤0.035 | |
| S | ≤0.035 |
JIS G3106 SM400C SSAW Pipe Thermal and Electrical Physical Properties
The following physical properties are typical for carbon steels of this type and are not part of the material specification. They support engineering calculations for thermal expansion, heat transfer and electrical behaviour.
| Property | Typical Value | Unit | Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | at 20°C |
| Elastic Modulus (E) | 205 | GPa | at 20°C |
| Shear Modulus (G) | 80 | GPa | at 20°C |
| Poisson's Ratio (ν) | 0.3 | – | at 20°C |
| Thermal Expansion Coefficient (α) | 11.7 × 10⁻⁶ | 1/K | 20–100°C |
| Thermal Conductivity (λ) | 52 | W/(m·K) | at 20°C |
| Specific Heat Capacity (c) | 490 | J/(kg·K) | at 20°C |
| Electrical Resistivity (ρₑ) | 0.16 | µΩ·m | at 20°C |
JIS G3106 SM400C SSAW Pipe Mechanical Properties
Mechanical properties are verified on test pieces taken parallel to the rolling direction. The tensile test and Charpy V‑notch impact test at 0 °C are mandatory for SM400C. Yield strength decreases with increasing thickness while tensile strength remains 400–510 MPa. Elongation is reported for different thickness ranges and test piece types.
| Property | Standard Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥245 | MPa | Thickness ≤16 mm |
| Yield Strength (ReH) | ≥235 | MPa | Thickness 16–40 mm |
| Yield Strength (ReH) | ≥215 | MPa | Thickness 40–100 mm |
| Tensile Strength (Rm) | 400–510 | MPa | All thicknesses |
| Elongation (A) | ≥23 | % | Thickness ≤5 mm, No.5 test piece (gauge length 25 mm) |
| Elongation (A) | ≥18 | % | Thickness >5–16 mm, No.1A test piece (gauge length 50 mm) |
| Elongation (A) | ≥22 | % | Thickness >16–50 mm, No.1A test piece |
| Elongation (A) | ≥24 | % | Thickness >40–100 mm, No.10 test piece (gauge length 50 mm) |
| Charpy Impact Energy (KV₂, 0°C) | ≥27 | J | Average of 3 specimens, thickness >12 mm, V‑notch, longitudinal |
JIS G3106 SM400C SSAW Pipe Exact Equivalent Standards and Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM400C | Original specification |
| Korea | KS D 3515 | SM400C | Identical adoption of JIS standard |
| ISO | ISO 630 | Fe 430C | Approximate equivalent; tensile range 410–560 MPa slightly higher |
| China | GB/T 700 | Q235C | Similar yield and 0°C impact, tensile 375–500 MPa, close substitution |
| USA | ASTM A36/A36M | – | Comparable strength (400–550 MPa) but no guaranteed impact toughness; use with caution |
JIS G3106 SM400C SSAW Pipe Application Introduction
SM400C SSAW pipes are produced by spirally winding hot‑rolled SM400C plate/coil and joining the seam with submerged arc welding. The process yields cost‑effective, large‑diameter pipes combining high structural integrity with reliable toughness. Typical applications include:
- Water and low‑pressure gas transmission pipelines
- Structural columns and trusses in buildings and industrial plants
- Steel pipe piles for deep foundations and retaining walls
- Bridge support members and offshore structural elements
- Penstock pipes in hydropower projects
Product Applications: SSAW steel pipes (spiral‑welded pipes), Spiral‑welded water transmission mains, Structural columns and trusses, Steel pipe piles for foundations, Bridge support beams and bracing, Penstock pipes for hydroelectric power
Processed into products: Pipe sections for pipelines, Pile casings for driven or bored piles, Structural pipe legs for platforms, Cross‑bracing and strut members, Penstock segments and bends, Welded tubular connectors and reducers
Application industries: Water Supply and Drainage, Oil & Gas (low‑pressure gathering lines), Construction and Civil Engineering, Piling and Foundation Engineering, Bridge and Infrastructure, Mechanical and Structural Fabrication
JIS G3106 SM400C SSAW Pipe Similar Materials and Performance‑Close Alternatives
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025‑2 | S235J0 | Yield ~235 MPa, tensile 360–510 MPa, 0°C impact 27J; lower yield |
| Europe | EN 10025‑2 | S275JR | Yield ~275 MPa, tensile 410–560 MPa; no impact requirement; higher strength |
| USA | ASTM A283/A283M | Grade C | Yield 205 MPa, tensile 380–515 MPa, no impact; lower strength |
| China | GB/T 1591 | Q345C | Higher strength 345 MPa yield, 0°C impact; suitable for heavier structures |
| Japan | JIS G3101 | SS400 | Similar strength but no impact requirement; general structural use |
Notes:
Ordering and Fabrication Notes: When procuring SSAW pipes to SM400C, additional requirements such as hydrostatic test, ultrasonic (UT) or radiographic (RT) inspection, and external/internal coatings (e.g., 3LPE, FBE) may be specified. The mandatory Charpy impact test applies for wall thicknesses >12 mm; for thinner pipes, impact properties must be agreed. For welded structures, proper preheating (typically 50–150°C) and low‑hydrogen welding consumables are recommended to avoid hydrogen‑induced cracking. Post‑weld heat treatment is generally not required for thicknesses up to 50 mm, but may be applied based on service conditions.
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