What Are Alloy Pipes?
Per ASTM A335 and ASME SA335, alloy steel pipes are chrome-molybdenum (Cr-Mo) seamless pipes engineered for 400–600 °C service and pressures exceeding 100 bar. Chromium provides oxidation resistance; molybdenum enhances creep strength under sustained high-temperature load per ASME Section II Part D. They are the critical piping material in refinery heater circuits, power-plant main steam lines, and petrochemical reactors. We supply ASTM A335 grades (P11, P22, P91) with MTC and IBR certification.
- P11 (1¼Cr-½Mo): Standard grade for moderate-temperature service up to 540°C
- P22 (2¼Cr-1Mo): Higher creep strength for main steam and hot reheat lines up to 565°C
- P91 (9Cr-1Mo-V-Nb): Advanced grade for ultra-supercritical power plants up to 600°C
- All grades: Seamless, normalized and tempered, with MTC and IBR certification
Specifications We Stock
| Type | Seamless — hot-finished and cold-drawn |
|---|---|
| Size Range | NPS 1/2" to 24" in Schedules 40, 80, 120, 160, XXS |
| Grades | ASTM A335 P11, P22, P5, P9, P91, P92 |
| Temperature Rating | P11 up to 540°C, P22 up to 565°C, P91 up to 600°C |
| Certification | MTC 3.1/3.2, IBR Form III-C, NACE MR0175 (on request) |
Common Applications
- Power Generation: Main steam lines, hot reheat piping, boiler headers, economizer tubes.
- Refineries: Catalytic cracker piping, hydroprocessing units, heater tubes, furnace piping.
- Petrochemical: Reactor piping, reformer tubes, high-temperature process lines.
- Fertiliser Plants: Ammonia converter piping, synthesis gas lines.
Source Mills We Work With
We procure materials exclusively from highly reputed Indian and global steel mills, including:
ISMT LimitedMaharashtra Seamless Limited (MSL)Jindal SAWChandra Metal Enterprises
Applicable Standards & Specifications
How To Order
- Specify ASTM A335 grade (P11/P22/P91), NPS, schedule, and length.
- Indicate certification requirements — MTC 3.1/3.2, IBR Form III-C, NACE.
- Provide quantity and delivery location for freight calculation.
- Approve quotation and PO — we dispatch from Kanpur stockyard.
Frequently Asked Questions
What is the difference between P11, P22, and P91?
P11 (1¼Cr-½Mo) is used up to 540°C and is the standard choice for moderate-temperature refinery piping. P22 (2¼Cr-1Mo) handles up to 565°C and is used for main steam and hot reheat lines in power plants. P91 (9Cr-1Mo-V-Nb) is the advanced grade for ultra-supercritical power plants, offering the highest creep strength up to 600°C with significantly thinner walls (weight and cost savings of 30-40% vs P22 for the same duty).
Are alloy steel pipes available with IBR certification?
Yes, we supply ASTM A335 (SA335) alloy pipes with IBR Form III-C certification for boiler and pressure vessel service regulated by the Indian Boiler Regulations. IBR certification requires third-party inspection at the mill and specific documentation including stage-wise inspection reports.
How do alloy pipes differ from carbon steel seamless pipes?
Alloy steel pipes contain intentional additions of chromium (0.5% to 9%) and molybdenum (0.5% to 1%) that provide oxidation resistance and creep strength at high temperatures. Carbon steel pipes (ASTM A106) are limited to approximately 425°C before creep becomes a concern. For any piping service above 425°C, alloy steel grades are mandatory.
Related
- Calculate the weight of Alloy Steel Pipes for your BOQ — size, wall, and length to MT before requesting a quote.
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