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Inox Steel India is one of the leading manufacturers and exporters of Alloy Steel Welded Pipes in grades equivalent to ASTM A335 / ASME SA335, manufactured as per the welded standard ASTM A691.
We supply welded Chrome-Moly (Cr-Mo) alloy steel pipes for high-temperature and high-pressure applications such as power plants, boilers, refineries, petrochemical units, HRSG systems, and thermal processing lines.
Our alloy steel welded pipes are produced using rolled plates and multi-pass SAW/GTAW welding, followed by mandatory post-weld heat treatment (PWHT) to restore mechanical strength and creep resistance.
With full documentation, weld qualification, NDT, hydro testing, and TPI approvals (SGS, BV, DNV, TÜV, Lloyd’s), our pipes are used across demanding industries worldwide including the Middle East, Africa, Europe, USA, and Southeast Asia.
We manufacture Chrome-Moly alloy steel welded pipes in grades P11, P22, P5, P9, P91, delivering exceptional performance in steam lines, heaters, high-temperature furnaces, pressure lines, and refinery piping systems.
Alloy Steel Welded Pipes are manufactured by welding alloy steel plates containing chromium (Cr) and molybdenum (Mo), which significantly enhance:
Since seamless A335 pipes cannot always be manufactured in large diameters or heavy thickness, the welded equivalent ASTM A691 is used to fabricate custom OD/WT pipes required in power generation, petrochemicals, and refinery units.
These pipes undergo multi-pass welding (SAW/GTAW/SMAW), followed by PWHT, ensuring the weld seam matches the base metal in performance.
Types of Alloy Steel Welded Pipes We Manufacture
1️⃣ Plate Selection & Inspection
Chrome-Moly alloy steel plates (A387/A335 equivalent) undergo UT, chemical verification & mechanical testing.
2️⃣ Plate Cutting & Edge Preparation
Edges are beveled to ensure deep welding penetration.
3️⃣ Rolling & Forming
Plates are rolled into cylindrical form with precise roundness and dimensional tolerance.
4️⃣ Root Pass Welding (GTAW / TIG)
A controlled GTAW root ensures clean, defect-free fusion.
5️⃣ Fill & Cap Pass (SAW / SMAW)
Multi-pass weld layers are applied to achieve the required thickness and weld strength.
6️⃣ Mandatory Post-Weld Heat Treatment (PWHT)
PWHT restores toughness, reduces residual stresses, and ensures high-temperature creep performance.
7️⃣ Non-Destructive Testing (NDT)
Includes RT, UT, DP, hardness test & visual inspection.
8️⃣ Hydrostatic Testing
Pipes are pressure-tested to ensure safety under operational pressure.
9️⃣ Surface Treatment / Protection
Black coating or high-temperature protective coating applied as per requirement.
🔟 Final Inspection & Marking
Each pipe is marked with grade, heat number, OD, WT, PWHT condition & standard.
Power Plants (Thermal & HRSG)
P11, P22, P91 pipes for high-temperature steam and pressure lines.
Refineries & Petrochemical Units
Furnace coils, heater lines, catalytic units, high-temperature process lines.
Boilers & Heat Exchangers
Chrome-Moly pipes used in boiler tubes, headers & superheater systems.
Oil & Gas Processing
High-pressure & high-temperature refinery piping systems.
Chemical & Fertilizer Plants
Pipes used for high-temperature reactors, reformers & ammonia lines.
Offshore & Marine Industries
Cr-Mo pipes used in high-temperature mechanical systems.
Alloy Steel Welded Pipes are engineered for extreme temperature, pressure, and stress conditions, making them essential for power plants, refineries, boilers, petrochemicals, and thermal processing lines. These pipes are typically produced from Chrome-Moly (Cr-Mo) alloy plates using multi-pass welding techniques, and follow the welded standard ASTM A691, which mirrors the chemistry and mechanical strength of seamless ASTM A335 grades.
Due to their ability to withstand prolonged exposure to 600–650°C, resist oxidation, creep, and high-pressure flow, these pipes are preferred for steam lines, heater tubes, reformer piping, and HRSG units.
Post-Weld Heat Treatment (PWHT) is mandatory for most grades to ensure weld seam stability and durability under thermal cycling.
Inox Steel India manufactures alloy steel welded pipes with strict adherence to A691, A387, A335, and project-specific welding & heat treatment protocols, ensuring consistent high-temperature performance.
| Parameter / Property | A691 Welded Chrome-Moly Pipes (Equivalent to A335) | Chrome-Moly Alloy Steel Welded Pipes (Cr-Mo Grades) | High-Temperature & High-Pressure Welded Pipes |
|---|---|---|---|
| Standard / Specification | ASTM A691 (CM Grades), ASME SA691 | ASTM A387 / A213 / A335 equivalent chemistry | ASME B31.1 / B31.3 & ASME Section VIII |
| Grade Options | 1-1/4Cr-1/2Mo (P11), 2-1/4Cr-1Mo (P22), 5Cr-0.5Mo, 9Cr-1Mo (P91) | A387 Gr 11 / Gr 22 / Gr 5 / Gr 9 | P11 / P22 / P5 / P9 / P91 |
| Material Type | Chrome-Moly Alloy Steel (Cr-Mo) | High-temperature ferritic alloy steels | Heat-resistant, pressure-rated alloys |
| Manufacturing Process | Plate rolling + multi-pass welding (SAW/GTAW/SMAW) | SAW / GTAW / SMAW / EFW | SAW / Multi-pass GTAW |
| Chemical Composition | Cr: 1–9%, Mo: 0.5–1.2% | Cr-Mo chemistry per grade | High Cr-Mo for creep resistance |
| Mechanical Strength | TS: 415–760 MPa | TS: 450–600 MPa | TS: 550–760 MPa |
| Yield Strength | 205–415 MPa | 275–450 MPa | 415+ MPa |
| Temperature Resistance | Up to 600–650°C | Up to 550°C | Up to 650°C (depending on grade) |
| Corrosion Resistance | Good (oxidation & sulfidation) | Very Good (high temp) | Excellent (creep, oxidation, thermal cycling) |
| Weld Type | Multi-pass SAW / GTAW root | GTAW + SAW | GTAW + SAW, PWHT mandatory |
| Heat Treatment | PWHT mandatory | PWHT / Normalizing | PWHT + stress relief |
| NDT Requirements | UT, RT, DP, Hydro | UT, RT (for critical) | 100% RT + UT + Hydro |
| OD Range | 200 mm – 4000 mm | 100 mm – 3500 mm | 200 mm – 4000 mm |
| Wall Thickness | 6 mm – 80 mm | 5 mm – 60 mm | 10 mm – 80 mm |
| Available Lengths | 6 m – 12 m | 6 m – 12 m | 6 m – 12 m |
| End Finish | Bevelled / Plain / Machined | Bevelled / Plain | Bevelled / Machined Ends |
| Coating Options | Black / Anti-corrosion | Black / Red Oxide | High-temp resistant coating |
| Applications | Boilers, heaters, refinery pipes | Thermal process lines, steam service | HRSG, power plants, refineries |
| Testing Documentation | MTC 3.1/3.2, WPS/PQR, PWHT chart, RT films | MTC + NDT reports | Full pressure + weld qualification |
| HSN Code | 7306.29 | 7306.29 | 7306.29 |
Chrome-Moly (Cr-Mo) Grades (A335 Equivalent Chemistry)
Welded Specification (ASTM A691 / ASME SA691)
Plate Material Base (ASTM A387)
✔ Superheated Steam Lines / Boilers / HRSG Units
Use P22 / P91
Highest creep resistance and temperature strength.
✔ Heater Coils & Refinery Thermal Systems
Use P5 / P9
Excellent oxidation & sulfidation resistance.
✔ General High-Temperature Process Lines (Up to 550°C)
Use P11
Economical & reliable for steam and thermal fluids.
✔ Furnace and Reformer Piping
Use P22 / P9
Superior thermal cycling capability.
✔ Large Diameter High-Temperature Piping
Use A691 multi-pass SAW welded pipes
Ideal when seamless pipes are not available.
| Application | Recommended Grade | Reason |
|---|---|---|
| Steam & superheater lines | P22 / P91 | High creep + temperature resistance |
| Refinery heater outlet | P5 / P9 | Oxidation & hot corrosion resistance |
| HRSG piping systems | P91 | High strength at elevated temperatures |
| Thermal fluid piping | P11 | Cost-effective + good high-temp properties |
| Boiler tubes & headers | P22 | Strength + weldability |
| Petrochemical reactors | P9 | Suitable for cracking & reforming units |
| Power plant high-pressure lines | P91 | Most advanced creep-resistant alloy |
| Parameter | Capability |
|---|---|
| Outside Diameter (OD) | 200 mm – 4000 mm |
| Wall Thickness | 6 mm – 80 mm |
| Length | 6 m – 12 m |
| Weld Type | GTAW root + SAW multi-pass |
| Heat Treatment | PWHT / Normalizing / Stress Relieving |
| Ends | Bevelled / Plain |
| Coating Options | Black, Red Oxide, High-Temp Protective Paint |
| Grade / Type | Price (INR/kg) | Price (USD/kg) |
|---|---|---|
| P11 / A691 Grade 11 | ₹ 180 – ₹ 260 | $ 2.8 – $ 3.8 |
| P22 / A691 Grade 22 | ₹ 200 – ₹ 320 | $ 3.2 – $ 4.2 |
| P5 / P9 | ₹ 300 – ₹ 480 | $ 4.5 – $ 6.8 |
| P91 | ₹ 460 – ₹ 700 | $ 6.5 – $ 9.2 |
| Heavy Wall (PWHT Included) | ₹ 350 – ₹ 600 | $ 5.0 – $ 8.5 |
Prices vary based on OD, thickness, welding procedure, PWHT requirement, documentation, and third-party inspection.
7306.29 — Alloy Steel Welded Pipes
All Alloy Steel Welded Pipes undergo:
✔ Non-Destructive Testing (NDT)
✔ Mechanical Tests
✔ Mandatory PWHT
Performed as per A691 grade & project PQR.
✔ Hydrostatic Testing
Ensures leakproof performance under high pressure.
✔ PMI Testing
Ensures correct Chrome-Moly composition before welding & dispatch.
✔ Documentation & Certification
✔ Third-Party Inspection
Available from SGS, BV, DNV, TÜV, Lloyd’s.
We export alloy steel welded pipes to:
Middle East:
Africa:
Europe:
Americas:
Asia Pacific:
Used in power plants, boilers, HRSG units, refineries, chemical reactors & thermal piping systems worldwide.
Alloy Steel Welded Pipes, especially Chrome-Moly grades like P11, P22, P5, P9, P91, require precise welding procedures, controlled heat treatment, and stringent testing to withstand extreme high-temperature and high-pressure operating conditions.
Inox Steel India is preferred globally because:
Our pipes are trusted for critical services where failure is not an option.
Power Plants (Coal, Gas, HRSG Units)
P11, P22, P91 pipes for high-pressure steam, boiler headers, superheater coils, and thermal lines.
Refineries & Petrochemical Plants
Cr-Mo pipes used for heater lines, reformer tubes, furnace manifolds, and high-temperature reactors.
Boilers & Heat Exchangers
High-temperature alloy welded pipes used in steam generation systems.
Chemical & Fertilizer Units
Pipes for reactors, ammonia processing, cracking units, and high-heat transfer systems.
Oil, Gas & Thermal Piping
High-pressure service lines requiring oxidation, sulfidation, and creep resistance.
Offshore & Marine
High-strength alloy pipes used in extreme thermal cycles & corrosive environments.
To ensure safe delivery of chrome-moly alloy welded pipes, we follow strict export packaging standards.
✔ Standard Export Packing Includes:
✔ Coated Pipes (If Required):
✔ Ports of Dispatch:
JNPT, Mundra, Hazira, Chennai
✔ Export Destinations:
GCC, Africa, Europe, USA, Latin America, Southeast Asia
Looking for Alloy Steel Welded Pipes in grades P11, P22, P5, P9, P91 for power plants, refineries, boilers, HRSG units, or high-temperature systems?
52-A, Mulji Thackersi Bldg, Islampura Street, Shop No. 10, Near Alankar Cinema, Mumbai – 400 004
alloy@inoxsteelindia.in
+91 9930796690
Inox Steel India
Email
Phone
PWHT restores toughness, reduces weld stress, and provides creep resistance for high-temperature service.
200 mm to 4000 mm OD and 6 mm to 80 mm wall thickness.
Yes — complete documentation including RT films, PWHT charts, WPS, PQR & WPQ.
Yes — SGS, BV, DNV, TÜV, Lloyd’s are available on request.
Yes — all global project documentation & certifications provided.
We provide complete technical support, NDT documentation, PWHT charts, and global export solutions.