ASTM A335 Alloy Steel Pipe
ASTM A335 Alloy Steel Pipe
ASTM A335 (also known as ASME SA335) is a specification for seamless ferritic alloy-steel pipe for high-temperature service. This specification covers several grades of ferritic steel, each suitable for fusion welding, bending, flanging (vanstoning), and similar forming operations.
Key Features
- High-Temperature Service: Designed to withstand high-temperature environments, making it ideal for power plants, refineries, petrochemical plants, and other industries requiring high-temperature and high-pressure service.
- Seamless Construction: Ensures high strength and durability, suitable for critical applications.
- Alloy Composition: Contains various alloying elements like chromium, molybdenum, and sometimes vanadium, which enhance its mechanical properties and resistance to heat and corrosion.
Common Grades
Each grade within the ASTM A335 specification has distinct chemical compositions and properties. Here are some of the most commonly used grades:
- P1
- P2
- P5
- P9
- P11
- P22
- P91
- P92
Chemical Composition
The exact chemical composition varies by grade, but generally, these alloys include:
- Chromium (Cr): Enhances hardness, strength, and corrosion resistance.
- Molybdenum (Mo): Increases strength at high temperatures.
- Carbon (C): Provides hardness and strength.
- Silicon (Si), Manganese (Mn), Phosphorus (P), Sulfur (S): Present in varying amounts to improve various properties.
Chemical Composition
The chemical composition of ASTM A335 pipes varies by grade. Here are the typical compositions for some common grades:
| Element | P1 | P2 | P5 | P9 | P11 | P22 | P91 | P92 |
|---|---|---|---|---|---|---|---|---|
| Carbon (C) | 0.10-0.20 | 0.05-0.15 | 0.15 max | 0.15 max | 0.05-0.15 | 0.05-0.15 | 0.08-0.12 | 0.07-0.13 |
| Manganese (Mn) | 0.30-0.80 | 0.30-0.61 | 0.30-0.60 | 0.30-0.60 | 0.30-0.60 | 0.30-0.60 | 0.30-0.60 | 0.30-0.60 |
| Phosphorus (P) | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.020 max | 0.020 max |
| Sulfur (S) | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.010 max | 0.010 max |
| Silicon (Si) | 0.50 max | 0.50 max | 0.50 max | 0.25-1.00 | 0.50-1.00 | 0.50 max | 0.20-0.50 | 0.50 max |
| Chromium (Cr) | 0.50-0.80 | 0.50-0.81 | 4.00-6.00 | 4.00-6.00 | 1.00-1.50 | 1.90-2.60 | 8.00-9.50 | 8.50-9.50 |
| Molybdenum (Mo) | 0.44-0.65 | 0.44-0.65 | 0.45-0.65 | 0.90-1.10 | 0.44-0.65 | 0.85-1.05 | 0.85-1.05 | 0.30-0.60 |
| Vanadium (V) | – | – | – | – | – | – | 0.18-0.25 | 0.15-0.25 |
| Nitrogen (N) | – | – | – | – | – | – | 0.03-0.07 | 0.03-0.07 |
Mechanical Properties
These properties also vary by grade but typically include:
- Tensile Strength: Minimum 415 MPa (60,000 psi)
- Yield Strength: Minimum 205-275 MPa (30,000-40,000 psi), depending on the grade
- Elongation: Varies by grade and specific dimensions
The mechanical properties of ASTM A335 pipes also vary by grade. Here are the typical mechanical properties for some common grades:
| Property | P1 | P2 | P5 | P9 | P11 | P22 | P91 | P92 |
|---|---|---|---|---|---|---|---|---|
| Tensile Strength, min (MPa) | 380 (55,000) | 415 (60,000) | 415 (60,000) | 415 (60,000) | 415 (60,000) | 415 (60,000) | 585 (85,000) | 620 (90,000) |
| Yield Strength, min (MPa) | 205 (30,000) | 205 (30,000) | 205 (30,000) | 205 (30,000) | 205 (30 |
Applications
ASTM A335 pipes are commonly used in:
- Power Generation:
- Superheater and reheater tubes
- Steam lines
- Petrochemical and Refinery:
- Process piping
- Heat exchangers
- Industrial Boilers:
- Boiler tubes
- High-pressure steam boilers
- Oil and Gas:
- Transmission of fluids and gases under high pressure and temperature
Manufacturing Process
The manufacturing process of ASTM A335 pipes involves:
- Seamless Construction: Ensures no welded seams, which enhances the pipe’s ability to withstand high pressure and temperature.
- Heat Treatment: Normalizing, tempering, or other heat treatments to achieve the desired mechanical properties.
- Testing: Includes various mechanical and chemical tests to ensure compliance with the standards, such as tensile tests, hardness tests, and hydrostatic tests.
Standards and Specifications
- ASTM A335/A335M: Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service.
- ASME SA335: Equivalent ASME standard.
Summary
ASTM A335 Alloy Steel Pipe is a critical material for high-temperature and high-pressure applications across various industries, particularly in power generation and petrochemicals. Its seamless construction and alloy composition provide excellent strength, durability, and resistance to heat and corrosion.
