1. **What is A335 P9 material?**
ASTM A335 P9 is a specific grade of seamless ferritic alloy-steel pipe designed for high-temperature service. It falls under the ASTM A335 standard, which covers seamless pipes intended for use in pressure systems and high-temperature applications, such as power plant boilers, refineries, and petrochemical plants. P9 pipe is made from a chromium-molybdenum alloy steel known for its good high-temperature strength and oxidation resistance.
2. **What is the composition of SA335 P9?**
The chemical composition of ASTM A335 P9 alloy steel pipe typically includes: Carbon (C) up to 0.15%, Manganese (Mn) between 0.30% and 0.60%, Phosphorus (P) up to 0.025%, Sulfur (S) up to 0.025%, Silicon (Si) between 0.25% and 1.00%, Chromium (Cr) between 8.00% and 10.00%, and Molybdenum (Mo) between 0.90% and 1.10%.
3. **What is the difference between A335 P9 and P91?**
The primary differences between A335 P9 and P91 lie in their chemical composition and resulting mechanical properties. P91 contains significantly more chromium (8.00-9.50%) than P9 (8.00-10.00%), but crucially, P91 has additions of Vanadium (V) (0.18-0.25%), Niobium (Nb) (0.06-0.10%), and Nitrogen (N) (0.03-0.07%), along with tighter control of other elements like Carbon and Molybdenum. These additions give P91 much higher strength, particularly creep strength at elevated temperatures, allowing for thinner pipe walls at the same pressure/temperature conditions. P91 also requires specific controlled heating and cooling during heat treatment and welding (post weld heat treatment).
4. **What is the hardness of ASTM A335 P9?**
The typical hardness range for ASTM A335 P9 material in the normalized and tempered condition is approximately 160 to 190 Brinell Hardness (HBW). The ASTM A335 standard itself specifies a maximum hardness limit of 197 HBW for P9 material.
5. **What material is equivalent to A335 P91?**
ASTM A335 P91 has several common international equivalents. Key equivalents include: European Norm (EN) 10216-2 material designation X10CrMoVNb9-1 (1.4903), Japanese Industrial Standard (JIS) G3458 material STPA 28, Chinese Standard (GB) 5310 material 10Cr9Mo1VNb, and the Unified Numbering System (UNS) designation K91560. It's important to consult the specific standards for exact requirements as equivalence depends on the context (chemical, mechanical, application).
