**1. What is A335 pipe?**
ASTM A335 is a standard specification for seamless ferritic alloy-steel pipe designed for high-temperature service. It is commonly used in power plants, refineries, and other high-pressure, high-temperature applications.
**2. What is the difference between P22 and P91?**
- **P22 (Grade P22):** A chromium-molybdenum alloy steel (2.25Cr-1Mo) with good strength and oxidation resistance up to about 593°C (1100°F).
- **P91 (Grade P91):** A higher-grade alloy steel (9Cr-1Mo-V) with superior creep resistance and strength at elevated temperatures (up to about 649°C / 1200°F). P91 has better performance than P22 in high-stress applications.
**3. What is the difference between A335 and SA335?**
- **ASTM A335:** The standard set by ASTM International for seamless ferritic alloy-steel pipes.
- **SA335:** The same standard adopted by ASME (American Society of Mechanical Engineers) for use in boiler and pressure vessel codes. Essentially, they are technically identical, but SA335 is used when compliance with ASME codes is required.
**4. Is the ASTM A335 stainless?**
No, ASTM A335 covers **seamless ferritic alloy-steel pipes**, not stainless steel. Stainless steel pipes are typically covered under standards like ASTM A312 or A358.
**5. Is A335 carbon steel?**
No, ASTM A335 is not carbon steel-it is an **alloy steel** containing chromium, molybdenum, and other elements for high-temperature performance. Carbon steel pipes are covered under standards like ASTM A106 or A53.
