1. **What is ASTM A335 material?**
ASTM A335 is a specification for **seamless ferritic alloy-steel pipe** intended for **high-temperature service**. It covers pipes made primarily from chromium-molybdenum (Cr-Mo) alloy steels.
2. **What is the ASTM equivalent of A335?**
ASTM A335 is the primary specification for the *material* requirements of seamless alloy-steel pipes for high-temperature service. Its **dimensional and mechanical testing requirements counterpart** is **ASTM A999/A999M** (Standard Specification for General Requirements for Alloy and Stainless Steel Pipe). You specify both A335 and the grade (e.g., P5, P11, P22, P91) along with A999 for the dimensional requirements.
3. **What is the specification of A335 P5 pipe?**
ASTM A335 Grade P5 pipe has the following key specifications:
* **Composition:**
* Carbon (C): 0.15% max
* Manganese (Mn): 0.30-0.60%
* Phosphorus (P): 0.025% max
* Sulfur (S): 0.025% max
* Silicon (Si): 0.50% max
* Chromium (Cr): 4.00-6.00%
* Molybdenum (Mo): 0.45-0.65%
* **Tensile Strength:** 415 MPa (60 ksi) min
* **Yield Strength:** 205 MPa (30 ksi) min
* **Heat Treatment:** Full Anneal, Isothermal Anneal, or Normalize and Temper
* **Common Applications:** High-temperature piping in power plants, refineries, and petrochemical plants (e.g., boiler tubes, superheaters, headers) where service temperatures typically range up to about 650°C (1200°F).
4. **What is the hardness of ASTM A335?**
ASTM A335 **does not specify a single hardness value**. The allowable hardness **depends on the specific grade and heat treatment condition**. Typical hardness ranges for normalized and tempered pipes are often:
* **Brinell Hardness (HBW):** Approximately 140-210 HBW for common grades like P11, P22.
* **Maximum Hardness:** Some applications or supplementary requirements (like S1 - Hardness Requirement) might impose maximum limits (e.g., 250 HBW, 22 HRC, or 265 HV) to ensure weldability or resistance to hydrogen-induced cracking (HIC), especially for higher strength grades like P91. Hardness is primarily controlled by the strength requirements and heat treatment.
5. **Is A335 stainless steel?**
**No, ASTM A335 pipe is not stainless steel.** It is classified as **ferritic alloy steel** (specifically chromium-molybdenum alloy steel). While some grades (like P5, P9) have significant chromium content (up to 9%), they do not meet the minimum 10.5% chromium required to form the passive oxide layer that defines stainless steel. A335 steels rely on their Cr-Mo content primarily for high-temperature strength and oxidation resistance, not general corrosion resistance like stainless steels.
