GB/T 5310 20G Boiler Steel Pipe
GB/T 5310 20G Boiler Steel Pipe: Properties, Equivalents and Applications
Discover the complete data sheet of GB/T 5310 20G boiler steel pipe, including chemical composition, mechanical and physical properties, international equivalents, similar grades, and typical applications in power plants and petrochemical industry.
Hot rolling, cold drawing, heat treatment (normalizing, or normalizing plus tempering)
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GB/T 5310 20G Boiler Steel Pipe Introduction
20G is a high-quality carbon steel grade specified in GB/T 5310 for seamless steel tubes used in high-pressure boiler applications. It is widely applied in China for manufacturing boiler components such as superheaters, reheaters, water wall panels, and steam pipelines. Key features include:
- Excellent weldability and formability
- Stable high-temperature strength up to 450°C
- Good resistance to steam oxidation
- Reliable impact toughness at room temperature
Delivered in normalized condition, 20G tubes meet strict requirements for non-destructive testing. The grade is recognized as a workhorse material for power generation and industrial boiler systems, equivalent to ASTM A106 Grade B and DIN 17175 St45.8.
GB/T 5310 20G Boiler Steel Pipe Chemical Composition
Chemical composition according to GB/T 5310-2017. All values are ladle analysis. The sum of residual elements (Cr+Ni+Cu+Mo+V) shall not exceed 0.70%. Note: For product analysis, permissible deviations from the specified limits apply per the standard.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon, C | 0.17 – 0.23 | |
| Silicon, Si | 0.17 – 0.37 | |
| Manganese, Mn | 0.35 – 0.65 | |
| Phosphorus, P | ≤ 0.025 | Max |
| Sulfur, S | ≤ 0.015 | Max |
| Chromium, Cr | ≤ 0.25 | Maximum residual content |
| Nickel, Ni | ≤ 0.25 | Maximum residual content |
| Copper, Cu | ≤ 0.20 | Maximum residual content |
| Molybdenum, Mo | ≤ 0.15 | Maximum residual content |
| Vanadium, V | ≤ 0.08 | Maximum residual content |
| Total other residuals | ≤ 0.70 | Sum of Cr+Ni+Cu+Mo+V |
GB/T 5310 20G Boiler Steel Pipe Thermal and Electrical Physical Properties
These values are typical for carbon steel 20G / A106 Gr.B in the normalized condition; they are not mandatory in GB/T 5310 but represent frequently used engineering data. Density is at 20°C. Elastic properties, thermal expansion, conductivity, specific heat, and electrical resistivity are averages over the indicated temperature ranges.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density, ρ | 7.85 | g/cm³ | 20°C |
| Modulus of elasticity, E | 206 | GPa | 20°C |
| Shear modulus, G | 79.4 | GPa | 20°C |
| Poisson's ratio, ν | 0.30 | – | 20°C |
| Thermal expansion coefficient, α | 11.8 × 10<sup>-6</sup> | K<sup>-1</sup> | 20–100°C |
| Thermal expansion coefficient, α | 12.2 × 10<sup>-6</sup> | K<sup>-1</sup> | 20–200°C |
| Thermal expansion coefficient, α | 12.8 × 10<sup>-6</sup> | K<sup>-1</sup> | 20–300°C |
| Thermal conductivity, λ | 50.7 | W/(m·K) | 20°C |
| Thermal conductivity, λ | 48.6 | W/(m·K) | 200°C |
| Thermal conductivity, λ | 46.2 | W/(m·K) | 300°C |
| Specific heat capacity, cp | 460 | J/(kg·K) | 20–100°C |
| Specific heat capacity, cp | 490 | J/(kg·K) | 100–200°C |
| Specific heat capacity, cp | 520 | J/(kg·K) | 200–300°C |
| Electrical resistivity, ρe | 0.19 | Ω·mm²/m | 20°C |
GB/T 5310 20G Boiler Steel Pipe Mechanical Properties
Room-temperature tensile and impact properties per GB/T 5310-2017 for normalized 20G tubes. Test orientation: longitudinal (L) and transverse (T). Specimen geometry: full section or strip for wall thickness ≤ 30 mm, round bar for wall thickness > 30 mm. Impact test: Charpy V-notch, 20°C. Hardness may be agreed upon; typical values are given for reference.
| Property | Standard Required Value | Unit | Test Condition/Range |
|---|---|---|---|
| Tensile strength, Rm | 410 – 550 | MPa | Room temperature, longitudinal specimen |
| Yield strength, ReL (min) | 245 | MPa | Wall thickness ≤ 16 mm |
| Yield strength, ReL (min) | 235 | MPa | Wall thickness > 16 mm to ≤ 40 mm |
| Yield strength, ReL (min) | 225 | MPa | Wall thickness > 40 mm |
| Elongation, A (min) | 24 | % | Longitudinal, gauge length 5.65√S0 |
| Elongation, A (min) | 22 | % | Transverse, gauge length 5.65√S0 |
| Impact absorbed energy, KV2 (min) | 40 | J | Longitudinal, 20°C, Charpy V-notch |
| Impact absorbed energy, KV2 (min) | 27 | J | Transverse, 20°C, Charpy V-notch |
| Bending test | No cracking or disbands | – | Mandrel diameter according to standard; not mandatory unless specified |
| Hardness (reference) | ≤ 85 HRB or ≤ 170 HBW | HRB/HBW | For information, not required unless agreed |
GB/T 5310 20G Boiler Steel Pipe Fully Equivalent Material Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 5310 | 20G | Original designation |
| USA | ASTM A106/A106M | Grade B | Seamless carbon steel pipe for high-temperature service; similar composition and tensile requirements |
| USA | ASTM A210/A210M | Grade A-1 | Seamless medium-carbon steel boiler tubes; closely matches 20G |
| Germany | DIN 17175 | St45.8 | Heat-resistant seamless steel tubes; directly comparable carbon steel boiler grade |
| Japan | JIS G3456 | STPT410 | Carbon steel pipes for high temperature service; equivalent strength level |
| UK | BS 3059-2:1990 | 440 | Carbon steel boiler and superheater tubes with specified elevated temperature properties |
| International | ISO 9329-2 | PH 26 | Seamless steel tubes for pressure purposes; carbon steel grade PH 26 aligns with 20G |
GB/T 5310 20G Boiler Steel Pipe Application Introduction
20G seamless steel tubes are primarily intended for pressure parts in boilers and heat exchangers operating at temperatures up to about 450°C. The material's reliable weldability and toughness make it suitable for complex fabrication and site welding. Typical usage environments:
- Steam-water circuits in fossil fuel power plants
- Combined cycle heat recovery steam generators
- Industrial process heaters and waste-heat boilers
- High-pressure piping systems in petrochemical plants
The normalized microstructure ensures consistent mechanical properties and good resistance to thermal fatigue.
Product Applications: Superheater and reheater tube panels, Water wall tubes (membrane wall panels), Economizer tubes, Steam headers and main steam pipelines, Downcomers and risers, Boiler drums (as part of shell connections), Heat exchanger tube bundles
Processed into products: Cold- and hot-formed pipe bends and elbows, U-bend tubes for heat exchangers, Reducer and tee fittings, Boiler tube stubs and stubs with welded attachments, Collector headers with multiple branch connections, Steam and water separator body connections, Pressure vessel nozzles and manways
Application industries: Thermal power generation (coal, gas, oil), Nuclear power (secondary circuit piping, non-nuclear safety), Petrochemical and refinery, Industrial boiler manufacturing, Waste incineration energy recovery, Combined heat and power (CHP) plants
GB/T 5310 20G Boiler Steel Pipe Similar/Comparable Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 5310 | 20MnG | Higher manganese content (0.70–1.00% Mn) for slightly improved strength; otherwise similar to 20G |
| China | GB/T 5310 | 25MnG | Higher carbon and manganese for greater strength; suitable where higher design stress is allowed |
| USA | ASTM A210/A210M | Grade C | Higher tensile strength (min 485 MPa) than 20G; can be considered if higher load capacity is required |
| Germany | DIN 17175 | 17Mn4 | Alloy (Mo-containing) boiler tube; use where elevated temperature strength and creep resistance are needed beyond 20G capabilities |
| Germany | DIN 17175 | 15Mo3 | 0.3% Mo carbon steel; offers improved high-temperature properties; alternative for slightly higher service temperatures |
Notes:
Non-destructive testing: According to GB/T 5310, tubes shall be subjected to ultrasonic or eddy current testing; specific acceptance levels are agreed upon. Hydrostatic test: Each tube is hydraulically pressure-tested at 1.5 times the design pressure unless waived by agreement. Surface condition: Free from cracks, laps, scabs, and harmful scale. Marking: Permanently marked with manufacturer's name, standard, grade, dimension, heat number. Heat treatment: Normalizing treatment is mandatory; the structure should be ferrite + pearlite without detrimental phases. Weldability: Excellent, with preheat generally recommended for wall thickness above 25 mm; post-weld heat treatment (PWHT) is necessary for thick sections and boiler code requirements.
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