JIS G3461 STB410 Carbon Steel Boiler Tube
JIS G3461 STB410 Boiler Steel Pipe – Carbon Steel Tube for Heat Exchanger & Boiler Service
STB410 is a carbon steel boiler and heat exchanger tube specified in JIS G3461, offering minimum tensile strength 410 MPa and yield strength 255 MPa at room temperature. It is widely used for water tubes, smoke tubes, superheater tubes, and air preheater tubes in boilers and heat exchangers.
Hot rolling or cold drawing; suitable for subsequent cold bending, flaring, flanging, and welding
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JIS G3461 STB410 Carbon Steel Boiler Tube Introduction
JIS G3461 STB410 is a Japanese industrial standard carbon steel tube intended for boiler and heat exchanger applications. It is manufactured by hot rolling or cold drawing, and normally supplied in the as-manufactured condition. The grade provides a good balance of strength and formability, with minimum specified tensile strength of 410 MPa and yield strength 255 MPa. The material offers reliable weldability and can be bent or expanded for tube-to-tubesheet joining.
Typical delivery forms include straight lengths and U‑bend tubes. This grade is commonly selected for water tubes, smoke tubes, economizer tubes, and air preheater tubes, where moderate pressure and temperature conditions apply. Its chemical composition is controlled to ensure adequate ductility and resistance to cracking during fabrication and service. STB410 is also recognized internationally with comparable grades, facilitating global sourcing and replacement.
JIS G3461 STB410 Carbon Steel Boiler Tube Chemical Composition
The chemical composition of STB410 is defined by JIS G3461. The standard specifies limits for carbon, silicon, manganese, phosphorus and sulfur. Other residual elements like copper, nickel and chromium are not specified but are usually limited by the steelmaking practice to ensure proper weldability and ductility. Any additional alloying elements beyond those listed are subject to agreement between purchaser and manufacturer.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| C (Carbon) | ≤ 0.32 | Max |
| Si (Silicon) | ≤ 0.35 | Max |
| Mn (Manganese) | 0.30 – 0.80 | Range |
| P (Phosphorus) | ≤ 0.035 | Max |
| S (Sulfur) | ≤ 0.035 | Max |
JIS G3461 STB410 Carbon Steel Boiler Tube Physical, Thermal and Electrical Properties
The following property data are representative of plain carbon steel with similar composition; they are not mandatory values in JIS G3461. Actual values may vary slightly depending on the exact chemistry and manufacturing route. These values are useful for engineering design, heat transfer calculations and electrical resistance estimates.
| Property | Typical Value | Unit | Test Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Modulus of Elasticity (E) | 200 – 207 | GPa | 20°C |
| Shear Modulus (G) | 80 – 81 | GPa | 20°C |
| Poisson's Ratio (ν) | 0.29 – 0.30 | – | 20°C |
| Thermal Expansion Coefficient (α) | 11.5 – 12.0 | 10⁻⁶/K | 20°C to 100°C |
| Thermal Conductivity (λ) | 51 – 54 | W/(m·K) | 20°C – 100°C |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | 20°C – 100°C |
| Electrical Resistivity (ρ_e) | 0.14 – 0.18 | μΩ·m | 20°C |
JIS G3461 STB410 Carbon Steel Boiler Tube Mechanical Properties
Mechanical properties are specified by JIS G3461 for STB410. Tensile strength, yield strength, and elongation are mandatory; bending test is required for tubes with wall thickness up to 20 mm. Impact test is not a standard requirement but may be specified by supplementary agreement. The elongation values depend on wall thickness, following the test piece dimensions prescribed in the standard.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 410 | MPa | Room temperature, all thicknesses |
| Yield Strength (ReH) | ≥ 255 | MPa | Room temperature; wall thickness ≤ 20 mm |
| Elongation (A) – longitudinal | ≥ 20 | % | Wall thickness < 8 mm (Gauge length: 5.65√S0) |
| Elongation (A) – longitudinal | ≥ 25 | % | Wall thickness ≥ 8 mm (Gauge length: 50 mm) |
| Bend Test (180°) | No cracks | – | Bend diameter = 4 × wall thickness; wall thickness ≤ 20 mm |
JIS G3461 STB410 Carbon Steel Boiler Tube Fully Equivalent Materials – Standards and Replacement Grades
The grades listed below are recognized as direct or very close equivalents to JIS STB410. Minor differences in permissible ranges of chemical elements or mechanical requirements may exist. These alternatives are commonly used for boiler and heat exchanger seamless tubes and can be substituted with due consideration of the specific design code and service conditions.
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10216-2 | P265GH | Tensile strength 410–570 MPa, yield strength ≥265 MPa; similar service temperature range; minor differences in Mn and Si limits |
| United States | ASTM A106 | Grade B | Tensile strength ≥415 MPa, yield strength ≥240 MPa; carbon max 0.30%; widely used for high-temperature piping |
| China | GB/T 5310 | 20G | Tensile strength 410–550 MPa, yield strength ≥245 MPa; seamless boiler tubes; chemical composition closely matches STB410 |
| International | ISO 2604-2 | TW2 | Carbon steel tube for pressure purposes; tensile strength ≥410 MPa, yield strength ≥255 MPa (depending on wall thickness) |
| Japan | JIS G3456 | STPT410 | Piping steel tubes for higher temperature service; strength level equivalent; used for structures and piping, not primarily boiler tubes |
JIS G3461 STB410 Carbon Steel Boiler Tube Application Introduction
JIS G3461 STB410 is a workhorse grade for the boiler and heat exchanger industry. It is selected when moderate strength, good weldability, and reliable bending/expanding properties are needed. The tube can be formed into U‑bends, coiled, or joined to tubesheets by rolling or expansion. Typical service temperatures up to approximately 400–450°C are permissible depending on design codes. It is also commonly used as pressure parts in shell-and-tube heat exchangers, evaporators, and preheaters.
Product Applications: Water tube boilers, Smoke tube / fire tube boilers, Economizers and superheaters, Shell-and-tube heat exchangers, Air preheaters, Condensers and evaporators
Processed into products: Boiler water wall tubes and riser tubes, Smoke tube bundles, Economizer coils and headers, Superheater and reheater tubes, Tube-to-tubesheet joints (expanded and/or welded), U‑bend heat exchanger tubes, Air preheater tubes, Downcomer and feeder pipes
Application industries: Power generation (including fossil-fuel and biomass-fired boilers), Petrochemical and chemical processing, Oil & gas (heat recovery steam generators), Refrigeration and air conditioning (large chillers), Shipbuilding (auxiliary boilers, exhaust gas economizers), Industrial boiler manufacturing
JIS G3461 STB410 Carbon Steel Boiler Tube Similar Substitute Materials with Comparable Performance
These materials are not full equivalents but can often be considered for replacement in less demanding conditions or after engineering assessment. Differences in strength level, hardness or weldability should be verified against the project requirements.
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| United States | ASTM A192 | – | Seamless carbon steel boiler tubes for high-pressure service; tensile strength ≥325 MPa, lower strength but often used for water wall panels where strength is secondary |
| United States | ASTM A179 | – | Seamless cold-drawn low-carbon steel heat exchanger and condenser tubes; tensile strength ≥325 MPa, good formability |
| European Union | EN 10216-2 | P235GH | Tensile strength 360–500 MPa, yield strength ≥235 MPa; lower strength grade but acceptable for some low- to medium-pressure boiler applications |
| China | GB/T 3087 | 20 | Seamless steel tubes for low and medium pressure boilers; tensile strength 410–550 MPa, yield strength ≥245 MPa; similar chemistry, different production standard |
Notes:
- Welding consumables should be matched to the steel composition; ER70S-6 or ER80S-D2 for TIG/MIG and E7018 for SMAW are commonly used.
- Post-weld heat treatment (PWHT) is generally not mandatory for thin-walled tubes, but may be required by design codes for thick sections or certain service conditions.
- Coating or painting is often applied for corrosion protection in non-boiler applications (e.g., air heaters).
- When used in sour service, compliance with NACE MR0175/ISO 15156 must be evaluated (hardness control).
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