**1. Difference between P11 and P22:**
P11 and P22 are grades of chromium-molybdenum (Cr-Mo) alloy steel pipes under ASTM A335. The key differences lie in their chemical composition and applications:
- **P11**: Contains ~1.25% chromium and ~0.5% molybdenum. Used for moderate high-temperature service (up to ~550°C).
- **P22**: Contains ~2.25% chromium and ~1% molybdenum. Offers better high-temperature strength (up to ~580°C) and oxidation resistance than P11.
**2. Tensile Strength of P11:**
The tensile strength of ASTM A335 P11 material typically ranges between **415 MPa (60 ksi) and 585 MPa (85 ksi)**. Exact values depend on heat treatment and manufacturing standards.
**3. ASTM A335 P11 Material:**
ASTM A335 P11 is a seamless ferritic alloy-steel pipe designed for high-temperature service. It is composed primarily of iron, with **1.25% Cr, 0.5% Mo**, and small amounts of carbon, manganese, and silicon. It is used in power plants, refineries, and pipelines for steam, oil, or gas.
**4. Electrode for Welding P11:**
For welding ASTM A335 P11, **E8018-B2** (AWS classification) or equivalent electrodes are commonly used. Preheating (150–200°C) and post-weld heat treatment (PWHT) at ~650–750°C are critical to avoid cracking and ensure proper microstructure.
**5. Hardness of P11 Material:**
The typical hardness of ASTM A335 P11 ranges between **140–170 HB (Brinell Hardness)**. Hardness values may vary slightly based on heat treatment and manufacturing processes.
