ASTM A335 P21 Alloy Steel Seamless Pipes (UNS K31545)
Introduction
ASTM A335 P21 (UNS K31545) is a Chromium-Molybdenum alloy steel grade designed for seamless ferritic alloy steel pipes suitable for high-temperature services such as boilers, heat exchangers, and superheater systems. These pipes deliver excellent strength, resistance to creep, superior oxidation resistance, and enhanced toughness under elevated temperatures, making them a preferred choice for power generation and petrochemical industries.
Key Features
- High thermal stability for elevated temperature operations
- Exceptional creep and stress-rupture strength
- Good corrosion and oxidation resistance
- Superior hardenability and long service life
- Suitable for high-pressure and high-temperature environments
- Manufactured as seamless pipes ensuring uniformity and structural integrity
Equivalent Grade
| Standard | Grade |
|---|---|
| ASTM | A335 P21 |
| ASME | SA335 P21 |
| UNS | K31545 |
| EN | 10CrMo5-5 |
| DIN | 13CrMo4-5 |
Sizes
- Outside Diameter (OD): 1/2” to 36”
- Nominal Bore (NB): DN15 to DN900
- Wall Thickness: SCH 20 to XXS
ASTM A335 P21 Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.05 – 0.15 |
| Manganese (Mn) | 0.30 – 0.60 |
| Phosphorus (P) | ≤ 0.025 |
| Sulfur (S) | ≤ 0.025 |
| Silicon (Si) | 0.50 – 1.00 |
| Chromium (Cr) | 1.90 – 2.60 |
| Molybdenum (Mo) | 0.87 – 1.13 |
Gr P21 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 415 MPa |
| Yield Strength | ≥ 205 MPa |
| Elongation | ≥ 30% |
| Hardness | 163 HB Max |
Gr P21 Physical Properties
| Property | Value |
|---|---|
| Density | 7.8 g/cm³ |
| Melting Point | 1425 – 1510°C |
| Thermal Conductivity | 33 W/m·K |
| Modulus of Elasticity | 205 GPa |
Types of ASTM A335 P21 Pipes
- Seamless Pipes
- Hot-Finished Pipes
- Cold-Drawn Pipes
- Boiler Pipes
- Superheater Pipes
- Heat Exchanger Pipes
Application
- Power Generation Plants
- Petrochemical Industry
- Oil & Gas Refineries
- Boiler Manufacturing
- Heat Exchangers
- Superheaters and Reheaters
- Steam Lines
- Chemical Processing Plants
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