ASME SA335 P22 Alloy Steel Boiler Pipe
ASME SA335 P22 Alloy Steel Boiler Pipe: Composition, Properties, Equivalents & Applications
Complete material data for ASME SA335 Grade P22 seamless ferritic alloy steel pipe: chemical composition, mechanical and thermal properties, international equivalents (10CrMo9-10, 12Cr2MoG), and industrial applications.
Hot rolling, cold drawing, normalizing and tempering, annealing, quenching and tempering (optional)
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ASME SA335 P22 Alloy Steel Boiler Pipe Introduction
ASME SA335 P22 is a seamless ferritic alloy steel pipe designed for high-temperature service in boilers, superheaters, and heat exchangers. It contains approximately 2.25% chromium and 1.0% molybdenum, offering outstanding creep strength, oxidation resistance, and thermal stability up to 600°C (1112°F).
- Standard: ASME SA335/SA335M
- Grade: P22
- Material type: Cr-Mo alloy steel
- Form: seamless pipe
- Delivery condition: normalized and tempered (NT) or full annealed
This alloy provides good weldability and resistance to hydrogen attack and graphitization, making it a key material in power generation, petrochemical, and refining industries.
ASME SA335 P22 Alloy Steel Boiler Pipe Chemical Composition
The chemical composition of ASME SA335 P22 as specified in ASME SA335/SA335M. The alloying elements chromium and molybdenum enhance high-temperature strength and corrosion resistance. Impurity limits ensure good ductility and weldability.
| Element | Standard Value (%) | Remarks |
|---|---|---|
| Carbon (C) | 0.05 – 0.15 | Required |
| Manganese (Mn) | 0.30 – 0.60 | Required |
| Phosphorus (P) | ≤ 0.025 | Max |
| Sulfur (S) | ≤ 0.025 | Max |
| Silicon (Si) | ≤ 0.50 | Max |
| Chromium (Cr) | 1.90 – 2.60 | Key alloying element |
| Molybdenum (Mo) | 0.87 – 1.13 | Key alloying element |
ASME SA335 P22 Alloy Steel Boiler Pipe Thermal and Electrical Physical Properties
These physical properties are not directly specified in SA335 but are representative for 2.25Cr-1Mo steel based on ASME B&PV Code Section II Part D and other reliable sources for design calculations.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Modulus of Elasticity (E) | 210 | GPa | 20°C |
| Shear Modulus (G) | 80 | GPa | 20°C (typical) |
| Poisson's Ratio (ν) | 0.3 | – | 20°C |
| Thermal Expansion (α) | 10.5 | 10⁻⁶/K | 20–100°C |
| Thermal Expansion (α) | 12.5 | 10⁻⁶/K | 20–300°C |
| Thermal Expansion (α) | 13.0 | 10⁻⁶/K | 20–500°C |
| Thermal Conductivity (λ) | 42 | W/(m·K) | 100°C |
| Specific Heat Capacity (c) | 500 | J/(kg·K) | 20°C |
| Electrical Resistivity (ρₑ) | 0.24 | µΩ·m | 20°C |
ASME SA335 P22 Alloy Steel Boiler Pipe Mechanical Properties
Mechanical properties are per ASME SA335/SA335M. Values are based on the material in the normalized and tempered condition. Elongation requirements depend on wall thickness and specimen orientation. Hardness testing is mandatory.
| Property | Standard Requirement | Unit | Test Condition / Remarks |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 415 | MPa | Room temperature |
| Yield Strength (Rp0.2) | ≥ 205 | MPa | Room temperature |
| Elongation (A, longitudinal) | ≥ 30 | % | For wall thickness ≥ 7.94 mm (5/16 in.), 50 mm (2 in.) gauge length |
| Elongation (A, transverse) | ≥ 20 | % | For wall thickness ≥ 7.94 mm (5/16 in.), 50 mm (2 in.) gauge length |
| Brinell Hardness (HBW) | ≤ 179 | - | Room temperature, 3000 kgf / 10 mm ball |
| Rockwell Hardness (HRB) | ≤ 90 | - | Alternative to Brinell |
ASME SA335 P22 Alloy Steel Boiler Pipe Complete Equivalent Material Standards and Grades
| Country/Region | Standard | Grade / Designation | Remarks |
|---|---|---|---|
| USA | ASME SA335/SA335M | P22 (Grade P22) | Original specification |
| Germany | DIN 17175 | 10CrMo9-10 (1.7380) | Seamless steel tubes for elevated temperatures |
| European Union | EN 10216-2 | 10CrMo9-10 (1.7380) | Seamless steel tubes for pressure purposes |
| China | GB/T 5310 | 12Cr2MoG | Seamless steel tubes for high-pressure boiler |
| Japan | JIS G3458 | STPA 24 | Alloy steel pipes for high temperature service |
| International | ISO 9329-2 | 10CrMo9-10 | Seamless steel tubes for pressure purposes |
| Russia | GOST 550-75 | 15ХМ (or 12Х1МФ) | Close grade; 15ХМ is 1Cr-Mo, 12Х1МФ also used |
ASME SA335 P22 Alloy Steel Boiler Pipe Application Introduction
ASME SA335 P22 is the backbone material for high-temperature steam piping and boiler components. Its microstructure and stability under long-term creep conditions make it suitable for a wide range of industrial applications where strength, oxidation resistance, and reliability at elevated temperatures are essential. The material is typically formed into seamless tubes and pipes, which are then assembled by welding.
Product Applications: Superheater and reheater tube bundles, Main steam lines and hot reheat piping, Boiler waterwall tubes, Economizer and furnace tubes, High-pressure steam headers, Heat exchanger tubes and U-bends
Processed into products: Superheater tube panels, Reheater tube assemblies, Steam outlet pipes and connections, High-temperature flanges and fittings, Desuperheater tubes, Pressure vessel internal attachments, Welded pipe spools for high-energy piping
Application industries: Power Generation (fossil-fuel, nuclear, combined cycle), Petrochemical and Refinery, Oil & Gas (onshore/offshore piping), Chemical Processing, Heat Recovery Steam Generators (HRSG)
ASME SA335 P22 Alloy Steel Boiler Pipe Similar/Alternative Material Recommendations
| Country/Region | Standard | Grade | Remarks (Differences / Applications) |
|---|---|---|---|
| USA | ASTM A335/A335M | P12 (1Cr-0.5Mo) | Lower creep strength but better weldability; used up to ~540°C |
| USA | ASTM A335/A335M | P5 (5Cr-0.5Mo) | Higher oxidation resistance, lower ductility; service up to ~600°C |
| USA | ASTM A335/A335M | P9 (9Cr-1Mo) | Improved high-temperature strength and oxidation resistance; up to ~650°C |
| USA | ASTM A335/A335M | P91 (9Cr-1Mo-V) | Significantly higher creep strength than P22; modern replacement |
| China | GB/T 5310 | 15CrMoG (1Cr-0.5Mo) | Lower Cr content; used in lower-temperature sections |
| EU | EN 10216-2 | 13CrMo4-5 (1.7335) | 1Cr-0.5Mo type; good alternative for less demanding conditions |
Notes:
- ASME SA335 P22 is often subject to supplementary requirements such as restricted chemistry (e.g., lower P/S, controlled hardenability), special heat treatment, and non-destructive testing.
- Welding must be performed with matching filler metals (e.g., E9018-B3 electrodes, ER90S-B3 wire) and preheat/postweld heat treatment to avoid cracking.
- For long-term service above 500°C, creep data from ASME BPVC Section II Part D should be consulted for design.
- Material can be supplied with IBR (Indian Boiler Regulations) or other international certifications depending on project requirements.
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