Duplex Steel Tubing

Duplex steel tubing is a dual-phase alloy tube with a ferritic-austenitic microstructure, comprising approximately 50% ferrite and 50% austenite. Standard grades include UNS S31803 and S32205, with a chemical composition of 21–23% chromium, 4.5–6.5% nickel, and 2.5–3.5% molybdenum. The three key properties that define its value are tensile strength of at least 620 MPa, a PREN (Pitting Resistance Equivalent Number) above 34, and corrosion resistance that outperforms standard 304 and 316 austenitic grades in chloride-rich environments. Duplex stainless steel tubing is specified for oil and gas pipelines, chemical processing plants, desalination systems, marine heat exchangers, and power generation equipment.

Duplex Steel Tubing Prices

Duplex steel tubing costs in India depend on the grade, wall schedule, and order quantity. Understanding each cost factor helps you plan your procurement budget more accurately.

Approximate Price Range (Rs.)

The price typically ranges from Rs 480 to 720 per kg for standard grades. The final cost may vary depending on the grade, outer diameter (OD), pipe schedule, and order quantity.

Factors Affecting Price

Grade and alloy content, wall thickness and schedule, manufacturing method (seamless vs. welded), and market fluctuations in nickel and molybdenum.

• Grade and alloy content

Higher-alloyed grades such as 2507 (UNS S32750) carry more chromium and molybdenum than standard 2205. Raw material cost rises accordingly.

• Wall thickness and schedule

Heavier schedules, such as Sch 80S and Sch 160S, consume more alloy per unit length. Cost per kg increases with wall thickness.

• Manufacturing method

Seamless duplex steel tubes cost more than welded variants. Production volumes are lower, and tooling requirements are tighter for seamless output.

• Market fluctuations

Nickel and molybdenum spot prices on the LME directly affect raw material costs. Confirm current pricing before placing bulk orders.

Duplex Steel Tubing Grades

Duplex stainless steel tube manufacturers produce tubing in multiple grades, each optimised for a specific combination of strength, corrosion resistance, and service temperature. Common grades available are:

• Duplex Steel S31803 Tubing
• Duplex Steel 2205 Tubing
• Duplex Steel S32205 Tubing

Types Of Duplex Steel Tubing

Duplex steel tube is available in 3 primary product forms, selected based on pressure rating, service environment, and fabrication requirements.

• Seamless Duplex Steel Tubing
• Welded/ERW Duplex Steel Tubing
• Redrawn Tubing Duplex Steel Tubing

Duplex Steel Tubing Specifications

The table below lists the governing standards, dimensional range, mechanical properties, and delivery conditions for selecting and procuring duplex stainless steel tubes.

Duplex Steel Tubing Size Chart

Duplex steel tubing sizes run from NPS 1/8" through NPS 4", with outside diameters from 6.35 mm to 101.6 mm. Use this chart to confirm the OD and wall range for your layout.

Schedule Chart Of Duplex Steel Tubing

Wall thickness increases with schedule number. A higher schedule delivers a thicker wall and a higher pressure rating. Use this chart to confirm the correct wall specification for your operating pressure and temperature.

Key Features Of Duplex Steel Tubing

Duplex steel tubing is specified for 8 performance characteristics that standard austenitic grades cannot consistently match under load or corrosive exposure.

• High Strength
• Exceptional Corrosion Resistance
• Enhanced Fatigue Resistance
• Good Weldability
• Thermal Stability
• Reduced Maintenance
• Sustainable Performance
• Versatility

Applications Of Duplex Steel Tubing

Duplex stainless steel tubing serves 6 major industries where high pressure, elevated pressure, or saline conditions rule out conventional piping materials.

• Oil and Gas Industry
• Chemical Processing
• Marine Engineering
• Power Generation
• Water Treatment
• Petrochemical Industry

How To Choose The Right Duplex Steel Tubing Supplier And Manufacturer?

Choosing the right duplex stainless steel tube manufacturers directly affects tubing integrity, project timelines, and total procurement cost. Evaluate these 4 areas before finalising a vendor.

Selecting The Right Supplier And Manufacturer

Confirm that the manufacturer produces duplex steel tubing with the exact grade and NPS required. Not all facilities handle duplex alloys. Before filing an RFQ, verify the production capabilities of UNS S31803 and S32205.

Technical Considerations

Match the grade to the service environment, whether chloride exposure, acidic media, or elevated pressure is the primary concern. Request a Material Test Certificate (MTC) confirming chemical composition and mechanical properties. Confirm compliance with ASTM A789 for seamless and ASTM A789 for welded tubing. Custom wall schedules carry 8–12 week lead times; check stock availability early.

Evaluating Supplier Credibility

A reliable duplex steel tube provider must be ISO 9001 certified. Every tube batch must have a heat number that can be traced back to the originating mill. This is required for both project documentation and quality inspections.

Procurement Strategy

Send a clear RFQ that includes grade (UNS number), NPS, schedule, finish, governing standard, and quantity. Make sure to compare at least 3 supplier proposals based on pricing, lead time, MTC availability, and order quantities. For bulk orders, schedule a pre-dispatch inspection (PDI) or third-party inspection (TPI) at the manufacturer's facility.