P22 Alloy Steel Pipe Supplier — ASTM A335 P22 (2.25Cr-1Mo)

ASTM A335 P22 is a 2.25% chromium, 1% molybdenum alloy steel seamless pipe designed for high-temperature, high-pressure service in power plants and refineries. Primary applications include main steam piping in subcritical boilers (up to 565°C/103 bar), hot reheat lines, HRSG superheater and evaporator headers, high-pressure boiler headers, and hydrogen service piping in refineries. P22 is the workhorse grade for Indian thermal power plants operating at subcritical parameters, widely used by BHEL, L&T and Thermax in 210MW and 500MW units.

ASTM A335 P22 pipe has ASME allowable stress values up to 600°C (1112°F) per ASME B31.1 Power Piping code, though the practical design limit is typically 565°C where the allowable stress is approximately 47 MPa. For subcritical power plants (168 kg/cm² main steam pressure), P22 is used for main steam lines up to 565°C. Above this temperature, the allowable stress drops significantly and P91 (9Cr-1Mo-V-Nb) becomes the preferred choice. For HRSG applications, P22 headers typically operate at 540°C and 100-140 bar.

P22 (2.25Cr-1Mo) is used for subcritical main steam (≤565°C, ≤170 bar) while P91 (9Cr-1Mo-V-Nb) is required for supercritical and ultra-supercritical parameters (580-620°C, 250+ bar). At 565°C, P91 has approximately 2.5 times higher allowable stress than P22, enabling much thinner pipe walls. This reduces weight, thermal stresses during startup, and fabrication costs. However, P91 requires strict heat treatment control and experienced welders. For subcritical 500MW units in India, P22 remains the standard choice for main steam piping.

Yes, Creative Metal Industries maintains dedicated IBR-certified stock of ASTM A335 P22 seamless pipe for boiler and power plant applications. We supply P22 with IBR Form III-C from approved mills including Sumitomo (Japan), Vallourec (France), ISMT (India) and Maharashtra Seamless. Our IBR stock covers 1/2 inch to 24 inches in schedules up to XXS. Heavy-wall P22 (SCH 120-XXS) for main steam headers is a speciality. All pipes individually marked with IBR stamp, heat number and full traceability documentation for boiler inspector approval.

P22 (2.25Cr-1Mo) requires preheat of 200-250°C minimum before welding. Interpass temperature maintained at 200-300°C. Filler metals: ER90S-B3 (GTAW) and E9018-B3 (SMAW). Post-weld heat treatment is mandatory at 690-730°C for minimum 1 hour per 25mm wall thickness, with heating/cooling rates not exceeding 200°C/hour above 300°C. Maximum hardness after PWHT is 241 HBW (225 HBW for sour service). Hydrogen bake-out at 300-350°C for 2 hours is recommended for thick sections before final PWHT.

We maintain heavy-wall stock of ASTM A335 P22 seamless pipe specifically for main steam and high-pressure header applications. Stock includes sizes from 1/2 inch (15NB) to 24 inches (600NB) in SCH 40, 60, 80, 100, 120, 140, 160 and XXS. For 500MW main steam lines, we stock P22 in 14"-18" x SCH 120-160. For headers, 6"-12 inch x SCH XXS. Standard lengths 5-7 metres random. Fixed-length cutting available. All heavy-wall P22 stock maintained with IBR Form III-C for immediate deployment to power plant sites.