Duplex Steel Welded Pipes Manufacturer in India
Duplex Steel Welded Pipes Manufacturer in India
Stainless Steel Pipe Manufacturers is a leading Duplex Steel Welded Pipes Manufacturer in India, supplying welded pipes for industrial applications that require high strength and excellent corrosion resistance. We have been manufacturing and supplying pipes and tubes in India since 2005, with a facility near Mumbai and an export office in Mumbai. Our duplex steel welded pipes are available in different grades, sizes, wall thicknesses and specifications to suit project and piping requirements. Popular sizes can be supplied from ready stock, subject to availability.
Our duplex welded pipes are used in oil and gas, petrochemical, chemical processing, marine, desalination, power and other corrosion-resistant applications. We provide EN 10204 3.1 certification with every order, while 3.2 certification and third-party inspection are available on request. With ISO 9001:2015, ISO 14001:2015, ISO 45001:2018, PED 2014/68/EU and TUV approvals, we support domestic and export orders. Our products are shipped to 85+ countries, with export packing and documentation arranged according to the requirements of each order.
What Are Duplex Steel Welded Pipes?
Duplex Steel Welded Pipes are stainless steel pipes made by rolling duplex plate or strip into a round shape and joining the edges with a longitudinal weld. Duplex steel has a mixed structure of about half austenite and half ferrite. That mix gives high strength and strong resistance to chloride pitting and stress corrosion cracking.
Welded construction lets makers build pipes in sizes and wall thicknesses that seamless mills cannot match. After welding, the pipe is heat treated as the standard requires, so the weld and the parent metal share the same two-phase balance. A properly made seam resists corrosion as well as the rest of the pipe.
Duplex Steel Welded Pipes
High-quality Duplex Steel Welded Pipes manufactured for demanding applications across chemical, petrochemical, oil & gas, power generation, marine, construction and engineering industries. Available in UNS S31803 and S32205 grades, multiple sizes, wall thicknesses and ASTM A928 / ASME specifications.
Types of Duplex Steel Welded Pipes
As a Duplex Steel Welded Pipes Manufacturer, we supply welded pipes in different grades, weld configurations, sizes and surface finishes to suit various industrial requirements.
- Lean Duplex Welded Pipes (S32101, S32304): Suitable for moderate corrosion service where good strength and controlled material cost are required.
- Standard Duplex Welded Pipes (S31803, S32205): Duplex 2205 grades widely used in process piping, marine systems, chemical plants and seawater applications.
- Super Duplex Welded Pipes (S32750, S32760): Designed for demanding chloride environments, offshore service, seawater systems and suitable sour-service applications.
- Single-Welded Pipes: Manufactured with a longitudinal weld for applications where the required size and service conditions permit this construction.
- Double-Welded Pipes: Welded from both sides where the required diameter and wall thickness call for a larger or more robust welded construction.
- Radiographed Welded Pipes: Weld seams can undergo full or spot radiographic examination when required by the applicable specification or project.
- Large-Diameter Duplex Welded Pipes: Welded construction is suitable for larger outside diameters where seamless pipe may not be the preferred option.
- Pickled and Passivated Welded Pipes: Chemically treated to remove surface contamination and restore a clean passive surface.
- Plain-End and Bevelled-End Pipes: Supplied with plain ends or bevelled ends for welding and installation requirements. Bevel geometry is selected according to the applicable standard and project specification.
S31803, S32205, S32750, S32760 and S32304 Duplex Steel Welded Pipes Manufacturers and Suppliers in India
Duplex Steel Welded Pipes are supplied in different grades to meet varying strength and corrosion-resistance requirements. We manufacture and supply UNS S31803, S32205, S32750, S32760 and S32304 grades for industrial piping, process systems and corrosion-resistant applications.
- UNS S31803 Duplex Steel Welded Pipes: Duplex 2205 grade with good strength and corrosion resistance for chemical processing, oil and gas, marine and process piping.
- UNS S32205 Duplex Steel Welded Pipes: Duplex 2205 grade with controlled chemistry and strong resistance to general and chloride corrosion. Used in petrochemical, marine and process applications.
- UNS S32750 Duplex Steel Welded Pipes: Super Duplex 2507 grade with high strength and excellent resistance to chloride-containing environments. Suitable for offshore, seawater, desalination and chemical applications.
- UNS S32760 Duplex Steel Welded Pipes: Super Duplex grade containing chromium, molybdenum, tungsten and copper. Used for demanding marine, seawater, oil and gas and chemical-processing service.
- UNS S32304 Duplex Steel Welded Pipes: Lean Duplex 2304 grade offering good mechanical strength and corrosion resistance. Suitable for moderate-duty process, structural and corrosion-resistant applications.
Types of Pipes & Tubes
Explore our range of industrial pipes and tubes, manufactured for different applications, materials, specifications and engineering requirements.
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Carbon Steel Seamless Pipes
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Carbon Steel Pipe
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Stainless Steel Pipe
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Alloy Steel Pipe
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Duplex Steel Pipe
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Super Duplex Steel Pipe
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Nickel Alloy Pipe
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Copper Nickel Alloy Pipe
→Get Certified Duplex Steel Welded Pipes at Competitive Factory Prices
Duplex Steel Welded Pipes Specification
The table below shows the working specification of our Duplex Steel Welded Pipes.
| Item | Detail |
|---|---|
| Product | Duplex Steel Welded Pipes |
| Process | Formed from plate or strip, longitudinal arc weld, with filler metal where the class requires |
| Grades | S31803, S32205, S32750, S32760, S32304, S32101 |
| Pipe standards | ASTM A790 / ASME SA790, ASTM A928 / ASME SA928 |
| General requirements | ASTM A999 (for A790) |
| Dimensions | ASME B36.19M (Sch 10S, 40S, 80S), ASME B36.10M for other walls |
| Size reference | NPS 6 to 48 in the weight chart, other sizes on request |
| Weld classes | Single or double welded, with or without radiography, per ASTM A928 |
| Length | Single random, double random or cut length |
| Ends | Plain or bevelled (ASME B16.25) |
| Heat treatment | Solution annealed and quenched, as the standard requires |
| Surface | Pickled and passivated |
| Tests | Chemical analysis, weld and parent tensile, hardness, flattening or bend, hydrostatic or non-destructive test, radiography per class, ASTM A923 on request |
| Certificate | EN 10204 3.1 with every order, 3.2 on request |
| Inspection | Third-party inspection on request |
Duplex Steel Welded Pipes Standards and Specifications
Welded duplex pipe is bought to a pipe standard, a weld class standard and, for harsh service, a corrosion or sour-service standard. The table sets out each.
| Standard | Scope | Where it applies |
|---|---|---|
| ASTM A790 / ASME SA790 | Seamless and welded ferritic/austenitic stainless pipe | Main duplex pipe standard |
| ASTM A928 / ASME SA928 | Electric fusion welded ferritic/austenitic stainless pipe, made with filler metal | Weld classes and radiography |
| ASTM A999 | General requirements for alloy and stainless pipe | Tolerances and test rules |
| ASTM A240 | Plate, sheet and strip for pressure vessels | Duplex plate behind welded pipe |
| ASTM A923 | Test methods for detrimental intermetallic phases | Structure check |
| ASTM G48 | Pitting and crevice corrosion test | Corrosion check |
| NACE MR0175 / ISO 15156 | Materials for sour service | Oil and gas projects |
| ASME B36.19M and B36.10M | Pipe dimensions and weights | Wall and OD reference |
| ASME B31.3 | Process piping design code | Weld joint factors, your engineer applies |
| EN 10204 | Types of inspection documents | 3.1 and 3.2 certificates |
Duplex Steel Welded Pipes Material and Grades
The grade decides corrosion resistance, strength and filler choice. PREN, the pitting resistance equivalent number, is a rough pitting index: Cr + 3.3 × Mo + 16 × N. A higher PREN means better resistance.
| Grade | Common name | EN number | PREN (about) | Matching filler (AWS A5.9) | Typical use |
|---|---|---|---|---|---|
| S32101 | Lean duplex 2101 | 1.4162 | 26 | ER2209 | Tanks and structures |
| S32304 | Lean duplex 2304 | 1.4362 | 25 | ER2209 | Water and mild process lines |
| S31803 | Duplex 2205 | 1.4462 | 34+ | ER2209 | General process, seawater cooling |
| S32205 | Duplex 2205 | 1.4462 | 35 | ER2209 | General process, higher spec than S31803 |
| S32750 | Super duplex 2507 | 1.4410 | 40+ | ER2594 | Subsea, brine, sour service |
| S32760 | Super duplex | 1.4501 | 40+ | ER2594 | Seawater and aggressive chloride duty |
What Is the Difference Between Duplex Steel Welded Pipes and Duplex Steel Seamless Pipes?
The short answer: welded pipe is rolled from plate or strip and has one weld seam, while seamless pipe is pierced from a solid billet and has none. Welded duplex pipe reaches larger diameters, costs less and ships faster. Seamless pipe is the pick for small bores and for the most severe pressure duty.
| Point | Duplex Steel Welded Pipes | Duplex Steel Seamless Pipes |
|---|---|---|
| Starting material | Plate or strip | Solid billet |
| Seam | One longitudinal weld | None |
| Largest sizes | Very large bore | Limited by mill size |
| Thin walls | Easy to make | Harder at large diameters |
| Design weld factor | Set by weld class and radiography | Not applied |
| Cost per metre | Lower, especially in large sizes | Higher |
| Lead time | Usually shorter | Usually longer |
| Best fit | Large headers, seawater and brine lines | Small bore, high-pressure lines |
Duplex Steel Welded Pipes Chemical Composition
Chemistry controls the phase balance and the corrosion resistance. The table gives ASTM A790 limits, laid out by element. Values are percentage by weight, maximum unless shown as a range.
| Element | S31803 | S32205 | S32750 | S32304 |
|---|---|---|---|---|
| Carbon (C) | 0.030 | 0.030 | 0.030 | 0.030 |
| Manganese (Mn) | 2.00 | 2.00 | 1.20 | 2.50 |
| Silicon (Si) | 1.00 | 1.00 | 0.80 | 1.00 |
| Phosphorus (P) | 0.030 | 0.030 | 0.035 | 0.040 |
| Sulphur (S) | 0.020 | 0.020 | 0.020 | 0.040 |
| Chromium (Cr) | 21.0–23.0 | 22.0–23.0 | 24.0–26.0 | 21.5–24.5 |
| Nickel (Ni) | 4.5–6.5 | 4.5–6.5 | 6.0–8.0 | 3.0–5.5 |
| Molybdenum (Mo) | 2.5–3.5 | 3.0–3.5 | 3.0–5.0 | 0.05–0.60 |
| Nitrogen (N) | 0.08–0.20 | 0.14–0.20 | 0.24–0.32 | 0.05–0.20 |
| Copper (Cu) | — | — | 0.50 max | 0.05–0.60 |
For S32760, chromium is 24.0–26.0, nickel 6.0–8.0, molybdenum 3.0–4.0, nitrogen 0.20–0.30, copper 0.50–1.00 and tungsten 0.50–1.00. The weld uses an over-alloyed filler, so nickel in the seam is higher than in the plate. This keeps the phase balance right after welding.
Weld Filler Composition
| Filler | C max | Cr | Ni | Mo | N |
|---|---|---|---|---|---|
| ER2209 | 0.03 | 21.5–23.5 | 7.5–9.5 | 2.5–3.5 | 0.08–0.20 |
| ER2594 | 0.03 | 24.0–27.0 | 8.0–10.5 | 3.5–4.5 | 0.20–0.30 |
Duplex Steel Welded Pipes Mechanical Properties
Mechanical properties show why duplex allows thinner walls. The table gives minimum parent-metal values under ASTM A790.
| Grade | Yield min (MPa) | Tensile min (MPa) | Elongation min (%) | Hardness max |
|---|---|---|---|---|
| S31803 | 450 | 620 | 25 | 290 HBW |
| S32205 | 450 | 655 | 25 | 290 HBW |
| S32750 | 550 | 795 | 15 | 310 HBW |
| S32760 | 550 | 750 | 25 | — |
| S32304 | 400 | 600 | 25 | 290 HBW |
| S32101 | 450 | 650 | 30 | 290 HBW |
Welded pipe also takes weld tests, such as a transverse tension test and a bend test across the seam. The weld must meet the minimum tensile strength of the grade.
Duplex Steel Welded Pipes Size and Weight Chart
Weight depends on OD and wall thickness. Duplex steel has a density of about 7.80 g/cm³, so we use this formula:
OD and wall are in mm. Example: NPS 20 with a 9.53 mm wall weighs (508.0 − 9.53) × 9.53 × 0.02450 = 116.39 kg/m. The chart uses 6.35, 9.53 and 12.7 mm walls (¼, ⅜ and ½ inch).
| NPS | OD (mm) | 6.35 mm wall (kg/m) | 9.53 mm wall (kg/m) | 12.7 mm wall (kg/m) |
|---|---|---|---|---|
| 6" | 168.3 | 25.20 | 37.07 | 48.41 |
| 8" | 219.1 | 33.10 | 48.93 | 64.22 |
| 10" | 273.1 | 41.50 | 61.54 | 81.02 |
| 12" | 323.9 | 49.40 | 73.40 | 96.83 |
| 14" | 355.6 | 54.33 | 80.80 | 106.69 |
| 16" | 406.4 | 62.24 | 92.66 | 122.50 |
| 18" | 457.2 | 70.14 | 104.52 | 138.31 |
| 20" | 508.0 | 78.04 | 116.39 | 154.11 |
| 24" | 609.6 | 93.85 | 140.11 | 185.73 |
| 30" | 762.0 | 117.56 | 175.69 | 233.14 |
| 36" | 914.4 | 141.27 | 211.27 | 280.56 |
| 42" | 1066.8 | 164.98 | 246.86 | 327.98 |
| 48" | 1219.2 | 188.69 | 282.44 | 375.40 |
Available Sizes, Dimensions and Schedules
Duplex Steel Welded Pipes are made in the sizes shown above, and other sizes and walls can be quoted on request. Small and mid sizes follow the stainless schedules of ASME B36.19M. Larger sizes are usually ordered by wall thickness in millimetres. Many designs use a lighter wall than 316L would need, because duplex is stronger. Your engineer should confirm wall thickness against the design code.
| NPS | OD (mm) | Sch 10S wall (mm) | Sch 40S wall (mm) |
|---|---|---|---|
| 2" | 60.3 | 2.77 | 3.91 |
| 4" | 114.3 | 3.05 | 6.02 |
| 6" | 168.3 | 3.40 | 7.11 |
| 8" | 219.1 | 3.76 | 8.18 |
| 10" | 273.1 | 4.19 | 9.27 |
| 12" | 323.9 | 4.57 | 9.53 |
For NPS 14 to 24, ASME B36.10M gives a Sch 10 wall of 6.35 mm and a standard wall of 9.53 mm. Tolerances follow ASTM A999, and wall may run up to 12.5% under nominal.
Common Materials in Duplex Steel Welded Pipes
These are the commonly requested materials from Duplex Steel Welded Pipes Suppliers for process, marine, oil and gas, chemical and other corrosion-resistant applications.
UNS S31803 / S32205 (1.4462): Duplex 2205 grades with around 22% chromium and 3% molybdenum. They offer a good balance of strength and corrosion resistance for general duplex service.
UNS S32750 (1.4410): Super Duplex 2507 with around 25% chromium and 4% molybdenum. It is selected for severe chloride environments, seawater systems, offshore applications and demanding process service.
UNS S32760 (1.4501): Super Duplex grade containing chromium, molybdenum, tungsten and copper. It is suitable for aggressive seawater, marine, chemical and oil and gas applications.
UNS S32304 (1.4362): Lean Duplex 2304 with good strength and corrosion resistance. It is used for moderate-duty applications where a leaner alloy is suitable.
UNS S32101 (1.4162): Lean Duplex 2101 with lower nickel and additions of manganese and nitrogen. It provides good strength and corrosion resistance for selected structural and process applications.
Duplex Steel Welded Pipes We Manufacture and Supply
We make Duplex Steel Welded Pipes for the services below. The grade and the weld class follow the duty.
| Service | Grades | Weld class guide |
|---|---|---|
| Seawater intake and cooling headers | S31803, S32205, S32750 | Double welded, radiographed where required |
| Desalination brine lines | S32205, S32750 | Double welded, radiographed |
| Chemical and process piping | S31803, S32205, S32304 | As the process code requires |
| Offshore topside piping | S32205, S32750, S32760 | Double welded, radiographed |
| Pulp and paper and FGD ducts | S32101, S32304, S32205 | Single or double welded |
Applications of Duplex Steel Welded Pipes
- Desalination plants: Seawater intake, brine heater and high-pressure reverse-osmosis lines.
- Oil and gas: Topside process piping, produced-water lines and manifolds.
- Offshore and marine: Firewater, ballast and seawater cooling systems.
- Chemical and petrochemical plants: Lines carrying chlorides, acids and caustic liquids.
- Pulp and paper mills: Digester feed, bleach plant and liquor lines.
- Power generation: Flue gas desulphurisation and cooling water headers.
- Pharmaceutical plants: Utility lines and water systems where chloride resistance is needed.
- Construction and infrastructure: Large-diameter structural and water-transfer pipework.
Why Choose Us as Your Duplex Steel Welded Pipes Manufacturer in India?
With experience in manufacturing and supplying pipes and tubes since 2005, we understand the requirements of customers looking for a dependable Duplex Steel Welded Pipes Supplier in India. We manufacture and supply UNS S31803, S32205, S32750, S32760 and S32304 grades in different sizes, wall thicknesses and specifications. Popular sizes can be available from ready stock, subject to availability, while our regular supply capability can reach 100 tons per month, depending on the grade, size and order requirements. Our experience helps us manage domestic and international orders with the required material grade, dimensions and project specifications.
Every order is supplied with an EN 10204 3.1 certificate, while EN 10204 3.2 certification and third-party inspection can be arranged on request. Our quality systems include ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018, along with PED 2014/68/EU and TUV approvals. We also handle export requirements for customers in 85+ countries, including packing, documentation and shipment coordination based on the order.
Countries We Export Duplex Steel Welded Pipes To
As a reliable Duplex Steel Welded Pipes Supplier, we export welded pipes from India to customers in 85+ countries. Our export support covers material grades, sizes, wall thicknesses, inspection requirements, certificates, packing and shipping documentation. We work with buyers across major industrial markets, including:
Middle East: UAE, Saudi Arabia, Qatar, Oman, Kuwait and Bahrain
Europe: Germany, Italy, United Kingdom, Netherlands, France, Norway and Spain
Asia-Pacific: Singapore, Malaysia, Indonesia, Thailand, Vietnam and Australia
North and South America: USA, Canada, Mexico and Brazil
Africa: South Africa, Nigeria, Egypt and Kenya
For international orders, we provide EN 10204 3.1 certification with every order, while 3.2 certification and third-party inspection are available on request. Export packing and documentation can be arranged according to destination and project requirements, helping customers source duplex steel welded pipes from India for industrial projects worldwide.
Duplex Steel Welded Pipes FAQs
Common questions about duplex welded pipe grades, weld classes, seawater service, dimensions, and supply.
Which duplex grade should I choose for a seawater header?
S32205 suits many seawater lines. For warm, stagnant or high-chloride seawater, step up to super duplex S32750 or S32760 for higher pitting resistance.
How do I choose between single-welded and double-welded pipe?
Double welding gives a fuller weld section and suits harsher or higher-pressure duty. Single welding costs less and suits lighter service. Your design code and weld class decide.
Which ASTM A928 weld class should I order?
The class sets how the pipe is welded and how much of the seam is radiographed. Choose it from your piping code and the weld joint factor your design needs, and state it on the order.
Is the weld as corrosion resistant as the pipe?
Yes, when the pipe is welded with a correct duplex filler and heat treated as the standard requires. The filler is over-alloyed in nickel so the seam keeps the right balance of phases.
Which filler metal is used for welded duplex pipe?
ER2209 is the usual match for 2205 and lean grades, and ER2594 for super duplex. The filler is chosen to keep the weld metal in the duplex range.
Can duplex welded pipe be used in sour service?
Yes, within the limits of NACE MR0175 / ISO 15156, which set hardness, temperature and H2S limits. State the sour-service requirement when you enquire.
What is the maximum service temperature?
Keep duplex below about 300°C. Long exposure at higher temperatures can make it brittle. Your engineer should check the limit for the grade and code.
What tolerances apply to OD and wall?
ASTM A999 sets them. Wall may run up to 12.5% under nominal, and OD limits depend on the pipe size.
What sizes can I order?
The chart above covers NPS 6 to 48 in 6.35, 9.53 and 12.7 mm walls, and the schedule table covers common stainless walls. Other sizes and walls can be quoted on request.
How do I calculate the weight of an order?
Use Weight (kg/m) = (OD − Wall) × Wall × 0.02450, with OD and wall in mm. Multiply by length and quantity. Real weight varies slightly with wall tolerance.
What affects the price of Duplex Steel Welded Pipes?
Grade is the main factor, because nickel, molybdenum and nitrogen content move the cost. Size, wall, weld class, radiography, testing, inspection, quantity and freight also count.
Which certificates come with the pipes?
Each order carries an EN 10204 3.1 certificate showing chemistry and mechanical results. A 3.2 certificate and third-party inspection are available on request.
Are you a manufacturer or a supplier of Duplex Steel Welded Pipes?
We are both. We manufacture near Mumbai and supply ready stock of popular sizes from the same location, subject to availability.
Do you export Duplex Steel Welded Pipes, and how are they packed?
Yes. We ship to 85+ countries from our Mumbai export office, and we pack the pipes to suit sea or air freight and your project needs.