P5 Alloy Steel Pipe Supplier — ASTM A335 P5 (5Cr-0.5Mo)

ASTM A335 P5 is a 5% chromium, 0.5% molybdenum alloy steel seamless pipe specifically designed for high-temperature service in petroleum refineries. The 5Cr-0.5Mo composition provides excellent resistance to oxidation and sulfidation at temperatures up to 593°C (1100°F). Primary applications include crude distillation column piping, vacuum distillation transfer lines, fired heater coils and convection section piping, catalytic reformer piping, and hydrodesulfurization unit piping where resistance to hydrogen attack and sulfur corrosion is critical.

ASTM A335 P5 pipe is rated for continuous service up to 593°C (1100°F) per ASME B31.3 allowable stress tables. At this temperature, the 5% chromium content provides adequate oxidation resistance while the 0.5% molybdenum contributes to creep strength. For cyclic service or where frequent thermal transients occur, a derating to 565°C is commonly applied. Above 593°C, higher chromium grades such as P9 (9Cr-1Mo) or P91 (9Cr-1Mo-V-Nb) should be considered for adequate long-term creep life.

All three grades share the 5Cr-0.5Mo base composition but have important variations. P5 is the standard grade for general refinery piping. P5b adds silicon (1.0-2.0% Si) which improves resistance to high-temperature oxidation and is preferred for furnace outlet piping. P5c adds titanium (0.50% min Ti) as a stabilising element which prevents sensitisation during welding and is preferred for piping exposed to polythionic acid stress corrosion cracking during shutdowns. Selection depends on the specific corrosion mechanism in your service environment.

Yes, Creative Metal Industries supplies ASTM A335 P5 pipe with IBR Form III-C certification for boiler and pressure vessel applications regulated under Indian Boiler Regulations. Our IBR-certified P5 stock is sourced from approved mills including ISMT India, Sumitomo Metal Industries Japan, and Maharashtra Seamless Limited. Each pipe is marked with heat number, IBR stamp, grade designation and manufacturer identification. IBR Form III-C documentation includes complete chemical analysis, mechanical test results, heat treatment parameters and NDE results.

We maintain ready stock of ASTM A335 P5 seamless pipe from 1/2 inch (15NB) through 24 inches (600NB) in schedules SCH 40, SCH 60, SCH 80, SCH 120, SCH 160 and XXS (extra extra strong). Standard lengths are 5.0 to 7.0 metres random. Fixed-length and cut-to-length orders are available with 2-3 day lead time. For heavy-wall requirements above SCH 120, we maintain dedicated stock up to 24 inches specifically for refinery heater piping and critical process lines.

P5 (5Cr-0.5Mo) requires preheat of 200-300°C before welding to prevent hydrogen-induced cracking in the heat-affected zone. Interpass temperature should be maintained between 200-350°C. Post-weld heat treatment (PWHT) is mandatory at 690-750°C for a minimum of 1 hour per 25mm wall thickness. Filler metals should be ER505 (GTAW) or E502-15/16 (SMAW) matching the 5Cr-0.5Mo composition. Hardness after PWHT must not exceed 241 HBW per NACE MR0175 if the pipe will be in sour service.