**1. What is A335?**
ASTM A335 is a standard specification for seamless ferritic alloy-steel pipe designed for high-temperature service. It covers pipes made from various grades of alloy steel, primarily chromium-molybdenum (Cr-Mo) compositions, used in power plants, refineries, and similar environments where elevated temperatures and pressures are involved.
**2. What is A335 P22 material?**
A335 Grade P22 is a specific chromium-molybdenum alloy steel under the ASTM A335 standard. It contains approximately 2.25% chromium and 1% molybdenum. P22 is widely used in high-temperature/pressure applications like boilers, superheaters, and heat exchangers due to its strength, creep resistance, and weldability at temperatures up to about 593°C (1,100°F).
**3. What is the ASTM A335 grade P11 equivalent to?**
ASTM A335 Grade P11 is closely equivalent to:
- **EN (European)**: 13CrMo4-5 (1.7335)
- **ISO**: 13CrMo4-5
- **JIS (Japanese)**: STPA 23
- **UNS**: K11597
Note: While chemical compositions and mechanical properties are similar, exact equivalence depends on specific application requirements and regional standards. Always verify with design specifications.
**4. Is the ASTM A335 stainless?**
No, ASTM A335 is **not stainless steel**. It covers **ferritic alloy steels** (primarily chromium-molybdenum grades). Stainless steels (e.g., Austenitic Cr-Ni alloys) fall under separate ASTM standards like A312/A213. A335 pipes are magnetic and have lower corrosion resistance compared to stainless steels.
**5. What is the specification of ASTM A335?**
Key requirements of ASTM A335 include:
- **Material**: Seamless ferritic alloy-steel pipe.
- **Grades**: P1, P2, P5, P5c, P9, P11, P12, P15, P21, P22, P23, P24, P36, P91, P92, P911 (varying Cr-Mo compositions).
- **Manufacturing**: Pipes are made by hot-working, optionally followed by cold-working and heat treatment (normalizing, tempering, or annealing).
- **Dimensions**: Conform to ASME B36.10M (standard sizes) or specified tolerances.
- **Testing**: Mandatory hydrostatic testing, plus nondestructive electric tests.
- **Chemical Analysis**: Verified for each heat of steel.
- **Mechanical Properties**: Tensile strength, yield strength, and hardness per grade-specific requirements.
- **Marking**: Grade (e.g., "P22"), size, heat number, manufacturer, and standard designation.
For full details, refer to the latest ASTM A335 standard document.
