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Girgaon, Mumbai - 400004
Duplex Steel Seamless Tubes Manufacturer & Stockist in India
Trusted Global Manufacturer & Stockist of Duplex Steel Seamless Tubes
Kamal Steels, established in 1984, is a trusted Duplex Steel Seamless Tube Manufacturer and Stockist in India. We supply seamless tubes in Duplex 2205 (UNS S31803/UNS S32205) and Super Duplex 2507 (UNS S32750) manufactured in accordance with ASTM A789 and ASME SA789 specifications for demanding industrial applications.
Available in a wide range of sizes and wall thicknesses, our tubes are widely used in heat exchangers, condensers, instrumentation systems, hydraulic lines, chemical processing plants, offshore platforms, marine engineering, and power generation. With ready stock, competitive pricing, and prompt worldwide delivery, Kamal Steels serves customers across India and international markets.
Need a Quote for Duplex Steel Seamless Tubes?
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Certifications & Compliance
- ISO 9001:2015 Certified
- ISO 14001 Certified
- ISO 45001 Certified
- PED Approved Materials
- MSME Registered Company
- IEC Export Certification
- GST Registered Business
Duplex Steel Seamless Tube Specifications
| Product Name | Duplex Steel Seamless Tubes |
|---|---|
| Brand | Kamal Steels |
| Material | Duplex Steel |
| Type | Seamless Tube |
| Grades | UNS S31803, S32205, S32750, S32760 |
| Outer Diameter | 6 mm to 219 mm |
| Wall Thickness | 0.5 mm to 20 mm |
| Length | Single Random, Double Random, Cut Length |
| Tube End | Plain End, Beveled End |
| Surface Finish | Annealed, Pickled, Polished, Bright Annealed |
| Standards | ASTM A789, ASTM A790, ASME SA789 |
| Tube Thickness | 0.5 mm to 20 mm |
Duplex Steel Seamless Tubes Size Chart & Dimensions
Available Grades of Duplex Steel Seamless Tubes
Kamal Steels manufactures the following grades of duplex steel seamless tube:
Duplex vs Stainless Steel Comparison
Duplex Steel and conventional Stainless Steel are widely used in industrial applications, but Duplex Steel offers higher strength and improved resistance to corrosion in aggressive environments. The following comparison highlights the key differences between Duplex Steel and standard Stainless Steel grades such as 304 and 316.
| Property | Duplex Steel | Stainless Steel (304/316) |
|---|---|---|
| Microstructure | Combination of Austenitic and Ferritic Structure | Mainly Austenitic Structure |
| Strength | Approximately Twice the Yield Strength of Stainless Steel | Moderate Strength |
| Corrosion Resistance | Excellent Resistance to Pitting and Crevice Corrosion | Good Corrosion Resistance |
| Chloride Stress Corrosion Cracking | Excellent Resistance | Lower Resistance |
| Pressure Handling Capability | Higher Pressure Capacity | Moderate Pressure Capacity |
| Seawater Applications | Highly Suitable | Limited Suitability |
| Service Life | Longer Service Life in Corrosive Environments | Good Service Life |
| Maintenance Requirements | Lower Maintenance | Moderate Maintenance |
| Cost | Higher Initial Cost but Better Long-Term Value | Lower Initial Cost |
| Common Applications | Oil & Gas, Offshore, Marine, Chemical Processing, Desalination | Food Processing, Pharmaceutical, General Industrial Applications |
Due to their superior mechanical strength and corrosion resistance, Duplex Steel Seamless Tubes are often selected for critical applications where conventional stainless steel may not provide adequate performance. Industries such as offshore, petrochemical, marine and desalination commonly prefer Duplex Steel for enhanced reliability and longer service life.
Why Choose Seamless Tubes Instead of Welded Tubes?
| Feature | Duplex Steel Seamless Tubes | Duplex Steel Welded Tubes |
|---|---|---|
| Manufacturing Method | Produced from solid billets without any weld seam | Manufactured by welding formed steel strips or plates |
| Structural Integrity | Uniform structure throughout the tube | Contains a welded joint |
| Pressure Resistance | Excellent for high-pressure applications | Suitable for moderate pressure applications |
| Corrosion Resistance | Consistent corrosion resistance across the entire tube | Weld area may require additional inspection |
| Mechanical Strength | Higher overall strength and durability | Good strength for general applications |
| Leakage Risk | Very low due to absence of weld seam | Slightly higher at the weld area |
| Service Life | Long service life in demanding environments | Good service life in standard conditions |
| Best Applications | Oil & Gas, Offshore, Marine, Petrochemical, Heat Exchangers | Water Systems, Structural Applications, General Industrial Use |
| Cost | Higher initial cost | More economical option |
Duplex Steel Seamless Tubes are commonly selected for critical applications where high pressure, corrosive media and long-term reliability are important. Their seamless construction eliminates weld-related concerns and provides superior performance in offshore, chemical processing, marine and petrochemical industries.
Duplex Steel Seamless Tube Manufacturing Process
Understanding the Duplex Steel Seamless Tube Manufacturing Process
Duplex steel seamless tubes are manufactured using premium quality duplex stainless steel billets through a hot extrusion and rotary piercing process. Since seamless tubes are produced without any welded joint, they offer excellent strength, superior corrosion resistance, high pressure handling capability and long service life for critical industrial applications.
| Step 1 |
Raw Material Selection High quality duplex steel billets such as UNS S31803, S32205 and S32750 are selected according to ASTM standards and application requirements. |
|---|---|
| Step 2 |
Billet Heating The duplex steel billet is heated uniformly in a rotary hearth or walking beam furnace to achieve the required forming temperature. |
| Step 3 |
Piercing Process The heated billet is pierced using a rotary piercing mill and mandrel to create a hollow shell. |
| Step 4 |
Elongation & Rolling The hollow shell is elongated and rolled through mandrel mills to obtain the required tube diameter and wall thickness. |
| Step 5 |
Sizing Process The tube passes through sizing mills for accurate outside diameter, wall thickness and dimensional consistency. |
| Step 6 |
Heat Treatment Tubes undergo solution annealing and rapid water quenching to improve mechanical strength, toughness and corrosion resistance. |
| Step 7 |
Pickling & Straightening Tubes are pickled to remove oxide scale and then straightened using precision equipment for smooth finish and dimensional accuracy. |
| Step 8 |
Cutting Process The seamless tubes are cut into required lengths as per customer specifications and industry standards. |
| Step 9 |
Testing & Inspection Tubes are tested through hydrostatic testing, ultrasonic testing, PMI testing, eddy current testing and visual inspection to ensure quality compliance. |
| Step 10 |
Marking & Packaging Finished duplex steel seamless tubes are marked with grade, size and heat number, then packed securely in bundles or wooden boxes for safe dispatch. |
Chemical Composition of Duplex Steel Seamless Tubes
The chemical composition of Duplex Steel Seamless Tubes plays an important role in corrosion resistance, mechanical strength and long-term industrial performance. Duplex and Super Duplex grades are widely used for highly corrosive and high-pressure applications.
| Grade | Cr % | Ni % | Mo % | N % |
|---|---|---|---|---|
| UNS S31803 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | 0.08–0.20 |
| UNS S32205 | 22.0–23.0 | 4.5–6.5 | 3.0–3.5 | 0.14–0.20 |
| UNS S32750 | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | 0.24–0.32 |
| UNS S32760 | 24.0–26.0 | 6.0–8.0 | 3.0–4.0 | 0.20–0.30 |
Duplex Steel Seamless Tube Standards
| ASTM Standards | ASME Standards |
|---|---|
| ASTM A789 | ASME SA789 |
| ASTM A790 | ASME SA790 |
| ASTM A928 | ASME SA928 |
Mechanical Properties of Duplex Steel Seamless Tubes
Tensile Strength
Tensile strength indicates how much stress the Duplex Steel Seamless Tube can withstand before breaking. Duplex Steel Seamless Tubes provide reliable tensile performance for industrial and heat exchanger applications.
Yield Strength
Yield strength shows the stress level at which the tube starts permanent deformation. Good yield strength ensures safe performance in pressure and load-bearing applications.
Elongation
Elongation reflects the ductility and forming capability of Duplex Steel Seamless Tubes. Higher elongation allows easier fabrication, bending and installation.
| Grade | Tensile Strength (MPa, min) | Yield Strength (MPa, min) | Elongation (%) |
|---|---|---|---|
| UNS S31803 | 620 | 450 | 25% |
| UNS S32205 | 655 | 450 | 25% |
| UNS S32750 | 800 | 550 | 15% |
| UNS S32760 | 750 | 550 | 25% |
Features of Duplex Steel Seamless Tubes
- Excellent Corrosion Resistance: Duplex Steel Seamless Tubes offer excellent resistance against pitting, crevice corrosion and chloride stress corrosion cracking in aggressive industrial environments.
- High Mechanical Strength: These tubes provide higher tensile and yield strength compared to standard stainless steel grades for demanding applications.
- Superior Durability: Manufactured without welding joints, Duplex Steel Seamless Tubes offer superior durability and long service life.
- Leak-Proof Construction: The seamless manufacturing process minimizes leakage risks and improves reliability in critical service applications.
- Smooth Surface Finish: Smooth internal and external tube surfaces improve flow efficiency and reduce contamination during service.
- High Pressure Handling Capability: Duplex Steel Seamless Tubes are suitable for high-pressure and heavy-duty industrial operations.
- Accurate Dimensions: Precision manufacturing ensures consistent wall thickness and dimensional accuracy for reliable installation.
- Excellent Heat Resistance: Duplex tubes maintain good mechanical properties under elevated temperature operating conditions.
- Long Service Life: Duplex Steel Seamless Tubes provide dependable long-term performance in offshore and corrosive environments.
- Low Maintenance Requirements: Due to their corrosion resistance and strength, these tubes require minimal maintenance during operation.
Applications of Duplex Steel Seamless Tubes
Duplex Steel Seamless Tubes are widely used in industrial applications where high strength, corrosion resistance and pressure handling capability are required.
Oil & Gas Industry
Used for transporting oil, gas and high-pressure fluids in offshore and onshore operations with reliable performance.
Petrochemical Industry
Widely used in petrochemical plants for handling corrosive chemicals and high-temperature processing systems.
Chemical Processing Plants
Suitable for chemical processing applications requiring excellent corrosion resistance and durability.
Power Generation Plants
Used in thermal and power generation systems for steam handling and heat transfer applications.
Heat Exchangers
Preferred for heat exchanger systems because of their corrosion resistance and high strength properties.
Desalination Plants
Suitable for seawater desalination systems because of excellent chloride corrosion resistance.
Water Treatment Plants
Used in water treatment systems where corrosion-resistant and hygienic tubing solutions are required.
Pharmaceutical Industry
Ideal for pharmaceutical applications requiring clean, durable and contamination-free tubing systems.
Food Processing Industry
Widely used in food and beverage industries due to hygienic surface finish and corrosion resistance.
Marine Industry
Marine environments require corrosion-resistant tubing systems capable of handling seawater exposure.
Construction Industry
Used in industrial and structural construction projects because of their strength and long service life.
Industries We Serve
Kamal Steels supplies Duplex Steel Seamless Tubes to various industries worldwide for corrosion-resistant and high-pressure applications.
Refineries
Our Duplex Steel Seamless Tubes are widely used in refinery applications for handling corrosive fluids and high-pressure operations.
Fertilizer Plants
Fertilizer industries require corrosion-resistant tubing systems for chemical processing and industrial operations.
Cement Plants
These seamless tubes are suitable for demanding cement manufacturing and industrial handling systems.
Engineering Industry
Engineering sectors use Duplex Steel Seamless Tubes for fabrication and industrial tubing systems.
Offshore Industry
Offshore applications require durable and corrosion-resistant tubing solutions for marine environments.
Automobile Industry
Automobile industries use seamless tubes in fluid transportation and industrial engineering applications.
Packaging, Testing & Inspection
Packaging
- Wooden Boxes: Duplex Steel Seamless Tubes are packed securely in wooden boxes to prevent damage during transportation and export handling.
- Bundles Packing: Tubes are bundled properly for easy loading, unloading and safe storage during shipment.
- Plastic End Caps: Plastic caps are provided on tube ends to protect against dust, moisture and external damage.
- Export Standard Packaging: All products are packed according to international export standards for safe worldwide delivery.
- Bubble Wrap Protection: Bubble wrapping provides additional surface protection during transportation and handling.
Testing & Inspection
- Hydrostatic Testing: Ensures the tube can withstand high internal pressure without leakage or failure.
- Ultrasonic Testing: Detects internal defects and confirms structural integrity of Duplex Steel Seamless Tubes.
- PMI Testing: Positive Material Identification verifies the chemical composition and material grade accuracy.
- Flattening Test: Checks tube flexibility and resistance to cracking under deformation conditions.
- Flaring Test: Evaluates tube expansion capability and forming performance for fabrication applications.
- Intergranular Corrosion Test: Confirms corrosion resistance performance in aggressive industrial environments.
- Third Party Inspection: Independent inspection agencies verify quality, dimensions and testing compliance.
Frequently Asked Questions
A Duplex Steel Seamless Tube is a high-strength stainless steel tube manufactured without a welded seam. It combines the properties of austenitic and ferritic stainless steels, offering excellent corrosion resistance, superior mechanical strength and outstanding resistance to chloride stress corrosion cracking.
Duplex Steel Seamless Tubes such as UNS S31803 and UNS S32205 provide excellent strength and corrosion resistance, while Super Duplex grades such as UNS S32750 and UNS S32760 offer even higher resistance to pitting, crevice corrosion and seawater environments.
Duplex Steel Seamless Tubes are manufactured without a weld seam, which improves structural integrity and pressure-handling capability. The seamless construction reduces the risk of weld-related defects and corrosion.
Common grades include UNS S31803, UNS S32205, UNS S32750 and UNS S32760. These grades provide different levels of corrosion resistance and mechanical performance for various industrial applications.
Duplex Steel Seamless Tubes are widely used in oil and gas, petrochemical, chemical processing, offshore, marine, desalination, power generation and heat exchanger applications.
Yes, Duplex Steel Seamless Tubes offer excellent resistance to chloride-induced corrosion and are commonly used in seawater, marine and desalination environments. Super Duplex grades are especially suitable for these applications.
Duplex Steel Seamless Tubes are typically manufactured according to ASTM A789, ASME SA789 and other applicable international standards to ensure quality and performance.
Testing may include hydrostatic testing, ultrasonic testing, PMI testing, eddy current testing, flattening tests, flaring tests and visual inspections to verify product quality.
Duplex Steel Seamless Tubes provide higher strength and better resistance to pitting, crevice corrosion and stress corrosion cracking than 316 stainless steel tubes, making them suitable for more demanding environments.
You can request a quote by sharing your required grade, size, wall thickness, quantity and application details. Kamal Steels offers competitive pricing, ready stock availability and worldwide delivery support.