Duplex Steel Pipes Manufacturer & Supplier
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Midland Alloys is a trusted duplex stainless steel pipe manufacturer in India, known for high quality and consistent supply worldwide. Our duplex steel stainless pipes are made of Fe-Ni-Cr alloy with a ferritic-austenitic structure, which provides strength and corrosion resistance for demanding applications. Lower nickel content makes these pipes a cost-effective choice. Seamless pipes range in size from 4 mm to 219 mm, while duplex steel welded pipes range in size from 5 mm to 1219.2 mm. These pipes work well in high-pressure, high-temperature systems such as oil and gas, petrochemicals, and power generation. We offer duplex stainless steel pipe grades UNS S31803 and UNS S32205, which are designed for long-term performance. This page covers specifications, composition, mechanical data, coatings, sizes, price details, certifications, and our export services.
Key Benefits of Duplex Steel Pipes
- High strength-to-weight ratio lowers material costs and handling effort.
- Excellent fatigue resistance makes Duplex Pipe suitable for systems with pressure fluctuations.
- Superior resistance to stress corrosion cracking even in chloride-rich environments.
- Good weldability ensures secure joints without preheating, saving time and effort.
- Better thermal conductivity and low thermal expansion enhance efficiency in heat exchangers.
- Long service life reduces downtime and maintenance costs.
- ASTM A789 Steel Pipe maintain mechanical properties in acid and alkaline environments at temperatures up to 250–300°C
Duplex Stainless Steel vs 316 Pipe
When looking at duplex stainless steel vs 316 pipe, the main difference lies in their structure and strength. Duplex Steel Pipes have a dual-phase mix of ferritic and austenitic grains, which gives them high strength and better resistance to stress corrosion cracking. They can handle harsh conditions, especially in chloride-rich environments, where 316 stainless steel may fail. Duplex also uses less nickel and molybdenum, making it more affordable and ensures durability. 316 stainless steel is fully austenitic, known for good corrosion resistance and easier welding. It works well in mild to moderate environments but has lower yield strength than duplex.
Technical Specifications of Duplex Steel Pipes
Seamless Pipe OD : ½″ NB – 16″ NB
Welded Pipe OD : ½″ NB – 24″ NB
EFW Pipe Size : 6″ NB – 24″ NB
ASTM A790 ASME SA790
Seamless, ERW, Welded, Fabricated
Round, Square, Rectangular, Hydraulic Etc
Single Random, Double Random & Cut Length.
Plain End, Beveled End, Treaded
SCH5, SCH10, SCH20, SCH30, SCH40, STD, SCH80, SCH 80S, SCH60, SCH80, SCH120, SCH140, SCH160, SCH XXS, SCH XS
No. 2B – Mill finish / Matte finish, No. 4 – Brushed finish, No. 8 – Mirror finish, Bright Annealed – Smooth / Slightly reflective, Polished – Smooth / Enhanced corrosion resistance,Mirror – Highly reflective,
Types of Duplex Steel Pipes
Manufacturing Types
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Seamless PipeWeld-free, perfect for even strength and sizing precision.
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Welded PipeWelded from flat-rolled steel, widely used where economy and large sizes are required.
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ERW PipeElectric Resistance Welded (ERW) pipes provide neat, high quality weld seams and are ideal for medium-pressure applications.
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EFW PipeElectric Fusion Welded (EFW) pipes are welded by fusion welding, usually applied in larger diameters and high-demand processes.
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LSAWLongitudinal Submerged Arc Welded (LSAW) pipes provide straight seam welding which is favored for thick-wall pieces and structural requirements.
Pipe Forms
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Round PipeThe most common shape for fluid and gas transport.
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Square PipeUsed in architectural and structural applications requiring angular profiles.
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Rectangular PipeProvides greater strength in load-bearing regions and flat structures.
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Hydraulic PipeDesigned to provide precise dimensional control for fluid systems under pressure.
Contact us today to discuss how Duplex Steel Pipes can benefit your application. Whether you need guidance in selecting the right pipes or have specific requirements, our team of experts is here to help you find the optimal solution.
Duplex & Super Duplex Steel Pipes Grades We Offer
Duplex Steel Pipe Schedule
| Nominal Pipe Size | Available Schedules | Nominal Pipe Size | Available Schedules |
| 1/8″ IPS (0.405″ O.D.) | Seamless Pipes, SCH 40, 80 | 3-1/2″ IPS (4.000″ O.D.) | Pipes, SCH 10, 40, 80, 160, XXH |
| 1/4″ IPS (0.540″ O.D.) | Pipes, SCH 10, 40, 80 | 4″ IPS (4.500″ O.D.) | Seamless Pipes, SCH 10, 40, 80, 160, XXH |
| 3/8″ IPS (0.675″ O.D.) | Seamless Pipes, SCH 10, 40, 80 | 5″ IPS (5.563″ O.D.) | Pipes, SCH 10, 40, 80, 160, XXH |
| 1/2″ IPS (0.840″ O.D.) | Seamless Pipes, SCH 5, 10, 40, 80, 160, XXH | 6″ IPS (6.625″ O.D.) | Seamless Pipes, SCH 5, 10, 40, 80, 120, 160, XXH |
| 3/4″ IPS (1.050″ O.D.) | Pipes, SCH 10, 40, 80, 160, XXH | 8″ IPS (8.625″ O.D.) | Stainless Pipes, SCH 5, 10, 40, 80, 120, 160, XXH |
| 1″ IPS (1.315″ O.D.) | Seamless Pipes, SCH 5, 10, 40, 80, 160, XXH | 10″ IPS (10.750″ O.D.) | Pipes, SCH 10, 20, 40, 80 (.500), TRUE 80 (.500) |
| 1-1/4″ IPS (1.660″ O.D.) | Seamless Pipes, SCH 10, 40, 80, 160, XXH | 12″ IPS (12.750″ O.D.) | Pipes, SCH 10, 20, 40 (.375), TRUE 40 (.406), SCH 80 (.500) |
| 1-1/2″ IPS (1.900″ O.D.) | Seamless Pipes, SCH 10, 40, 80, 160, XXH | 14″ IPS (14.000″ O.D.) | Pipes, SCH 10 (.188), SCH 40 (.375) |
| 2″ IPS (2.375″ O.D.) | Seamless Pipes, SCH 10, 40, 80, 160, XXH | 16″ IPS (16.000″ O.D.) | Pipes, SCH 10 (.188), SCH 40 (.375) |
| 2-1/2″ IPS (2.875″ O.D.) | Seamless Pipes, SCH 10, 40, 80, 160, XXH | 18″ IPS (18.000″ O.D.) | Pipes, SCH 40 (.375) |
| 3″ IPS (3.500″ O.D.) | Seamless Pipes, SCH 5, 10, 40, 80, 160, XXH | — | — |
Duplex Steel Pipe Weight Chart
| Outside Dia (mm) |
Wall Thk (mm) |
in. | Schedule | Kg/m |
|---|---|---|---|---|
| 13.72 | 1.65 | 1/4 | 10S | 0.50 |
| 13.72 | 2.24 | 1/4 | 40S | 0.64 |
| 13.72 | 3.02 | 1/4 | 80S | 0.81 |
| 17.15 | 1.65 | 3/8 | 10S | 0.64 |
| 17.15 | 2.31 | 3/8 | 40S | 0.86 |
| 17.15 | 3.20 | 3/8 | 80S | 1.12 |
| 21.34 | 2.11 | 1/2 | 10S | 1.02 |
| 21.34 | 2.77 | 1/2 | 40S | 1.29 |
| 21.34 | 3.73 | 1/2 | 80S | 1.65 |
| 26.67 | 2.11 | 3/4 | 10S | 1.30 |
| 26.67 | 2.87 | 3/4 | 40S | 1.71 |
| 26.67 | 3.91 | 3/4 | 80S | 2.23 |
| 33.40 | 2.77 | 1 | 10S | 2.13 |
| 33.40 | 3.38 | 1 | 40S | 2.54 |
| 33.40 | 4.55 | 1 | 80S | 3.29 |
| 33.40 | 6.35 | 1 | 160 | 4.30 |
| 42.16 | 2.77 | 1¼ | 10S | 2.73 |
| 42.16 | 3.56 | 1¼ | 40S | 3.44 |
| 42.16 | 4.85 | 1¼ | 80S | 4.53 |
| 42.16 | 6.35 | 1¼ | 160 | 5.69 |
| 48.26 | 2.77 | 1½ | 10S | 3.16 |
| 48.26 | 3.68 | 1½ | 40S | 4.11 |
| 48.26 | 5.08 | 1½ | 80S | 5.49 |
| 60.33 | 2.77 | 2 | 10S | 3.99 |
| 60.33 | 3.91 | 2 | 40S | 5.52 |
| 60.33 | 5.54 | 2 | 80S | 7.60 |
| 60.33 | 8.74 | 2 | 160 | 11.29 |
| 73.03 | 3.05 | 2½ | 10S | 5.35 |
| 73.03 | 5.16 | 2½ | 40S | 8.77 |
| 73.03 | 7.01 | 2½ | 80S | 11.59 |
| 88.90 | 3.05 | 3 | 10S | 6.56 |
| 88.90 | 5.49 | 3 | 40S | 11.47 |
| 88.90 | 7.62 | 3 | 80S | 15.51 |
| 88.90 | 11.13 | 3 | 160 | 21.67 |
| 101.60 | 3.05 | 3½ | 10S | 7.53 |
| 101.60 | 5.74 | 3½ | 40S | 13.78 |
| 101.60 | 8.08 | 3½ | 80S | 18.92 |
| 114.30 | 3.05 | 4 | 10S | 8.50 |
| 114.30 | 6.02 | 4 | 40S | 16.32 |
| 114.30 | 8.56 | 4 | 80S | 22.67 |
| 114.30 | 13.49 | 4 | 160 | 34.05 |
| 141.30 | 6.55 | 5 | 40S | 22.10 |
| 141.30 | 9.53 | 5 | 80S | 31.44 |
| 141.30 | 15.88 | 5 | 160 | 49.87 |
| 168.28 | 3.40 | 6 | 10S | 14.04 |
| 168.28 | 7.11 | 6 | 40S | 28.69 |
| 168.28 | 10.97 | 6 | 80S | 43.21 |
| 168.28 | 14.27 | 6 | 120 | 54.75 |
| 168.28 | 18.26 | 6 | 160 | 68.59 |
| 219.08 | 8.18 | 8 | 40S | 43.20 |
| 219.08 | 12.70 | 8 | 80S | 65.63 |
| 219.08 | 18.23 | 8 | 120 | 91.30 |
| 219.08 | 23.01 | 8 | 160 | 112.97 |
How Duplex Steel Pipes Are Manufactured
Round Bar
Analytic
Cut to Length
Centering
Heating
Perforation
Inspection of Size
Pickling
Inspection of Surface
Lubricating
Cold Drawing (Cold Rolling)
Degreasing
Annealing
Straightening
Cut
Pickling / Passivating
Inspection
Analytic
Marking
Packing & Shipping
Applications of Duplex Pipes
Duplex Steel Pipes are used in industries where fluid handling and structural performance are essential. In chemical processing plants, they move aggressive acids, solvents, and brines without contamination. Offshore and subsea oil rigs use them for risers, flowlines, and pipelines that face seawater exposure. Construction projects use duplex stainless steel pipe in bridges, high-rise supports, and desalination systems where strength and long service life matter. Pulp and paper mills use them in bleach plants and digester systems that handle harsh pulping chemicals. They are also used in power plants for condenser tubing and in fire-fighting networks where safety under pressure is critical.
Why Choose Midland Alloys Inc. for Duplex Pipes
Frequently Asked Questions About Duplex Steel Pipes
A duplex steel pipe is a stainless steel pipe with a dual-phase microstructure of ferritic and austenitic grains, offering high strength and corrosion resistance.
Duplex SS has higher strength and better resistance to stress corrosion cracking than SS 304. SS 304 is fully austenitic and has less strength.
Yes, duplex steel is stronger and more corrosion-resistant than standard austenitic stainless steels, especially in chloride-rich environments.
The duplex stainless steel pipe price varies by size, grade, and order quantity. Request a quote for accurate pricing.
Common codes are ASTM A789 for seamless and welded pipes and ASTM A790 / ASME SA790 for heavier-duty duplex steel pipes.
