### 1. What is the yield strength of P22 pipe?
The yield strength (Rp0.2) of P22 pipe typically ranges between **≥205 MPa** and **≥280 MPa**, depending on the applicable standard and material condition:
- ASTM A335/A335M specifies a **minimum yield strength of 205 MPa** (30 ksi).
- Some suppliers report higher values, such as **≥280 MPa**, particularly for pipes adhering to GB 5310 (equivalent to 12Cr2MoG steel). This variation arises from differences in national standards, heat treatment (e.g., normalizing + tempering), and wall thickness.
### 2. What is the temperature range of ASTM A335 P22?
ASTM A335 P22 operates effectively in high-temperature environments, with a recommended service range of **540°C to 750°C**. Key performance benchmarks include:
- **Oxidation resistance** up to 600°C (oxidation rate ≤0.1 mm/year).
- **Creep resistance**: Sustains 550°C/50 MPa for ≥100,000 hours without rupture.
- Real-world applications: Steam pipelines at 515°C–553°C (design limits).
### 3. What is the hardness of P22 material?
P22 material hardness varies by measurement scale and processing:
- **Brinell hardness (HBW)**: Typically **≤163 HB** per ASTM A335, though some data report **144 HB** in annealed conditions.
- After heat treatment (normalizing + tempering), hardness is controlled to **<22 HRC** (≈220 HB) to enhance weldability and avoid cold cracking.
### 4. What is the yield strength of A335?
Yield strength for ASTM A335 pipes **depends on the specific grade**:
- **P22**: **≥205 MPa**.
- **P11/P12**: **≥205–220 MPa**.
- **High-grade alloys (e.g., P91/P92)**: **≥415–440 MPa**.
*Note:* A335 covers multiple grades; values are minimums per ASTM standards.
### 5. What is the hardness of ASTM A335?
Hardness limits for ASTM A335 are **grade-specific and capped to ensure material integrity**:
- **P22, P11, P12**: **≤163 HB**.
- **P5**: **≤187 HB**.
- **P91/P92**: **≤250 HB**.
Hardness is tested via Brinell (HB) or Rockwell (HRC) methods post-heat treatment.
### Key Notes on Variability
- Values may differ slightly across standards (e.g., ASME vs. GB).
- Heat treatment (e.g., quenching, tempering) critically influences strength and hardness.
- For rigorous applications (e.g., power plants), verify properties against the latest material certifications.
