The maximum operating temperature of Duplex seamless tubes is 300°C (572°F) in continuous service.
Duplex Steel Seamless Tube Manufacturer in China
We are Zhejiang Xintongda Special Steel (XTD), a reputable Duplex seamless steel tube manufacturer and a renowned supplier. This Duplex SMLS tube is a high-strength tube consisting of chromium (21–23%), nickel (4.5–6.5%), molybdenum (2.5–3.5%), and nitrogen (0.08–0.20%). With 4 decades of experience, we strictly manufacture this tube in compliance with the ASTM A789 standard. It offers an optimal balance between durability and corrosion resistance. This tube has exceptional resistance to stress corrosion cracking. This makes it the preferred choice over standard austenitic grades. The seamless construction provides structural integrity required for heavy-duty service. Duplex seamless tubing is important in major industrial applications, including chemical processing, oil and gas extraction, and marine engineering, where reliability is non-negotiable. We hold multiple international certifications and have an annual supply capacity of 25000 tons. We supply the duplex seamless tube within a week for stock orders, and production orders can take 15-60 days.
We produce tubes that meet the following specifications:
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OD Range 6-720mm -
Thickness 1-65 mm -
Length ≤ 22 m
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Production Process of Seamless Duplex Steel Tube
The manufacturing process of the seamless Duplex tube starts by heating a solid round billet and piercing it to form a hollow shell. To achieve the precise dimensions, these seamless tubes are cold-drawn or cold-rolled. We manufacture without any welded seams for strength, so the tube can handle high mechanical stress. Check this page to learn about our detailed manufacturing process of seamless tubes.
What is a Duplex Seamless Tube?
A Duplex stainless steel seamless tube is defined by its unique dual-phase microstructure that consists of approximately equal parts ferrite and austenite. This seamless tube is made for mechanical and thermal uses that need high precision. It has a smooth inside surface that helps fluids flow smoothly and lowers pressure drop. The main advantage of this tubing is its high tensile strength and durability. This makes the walls thinner and the weight lighter without compromising on safety. It is designed for high-pressure applications and is rated for continuous service up to approximately 300°C (572°F). Above this temperature, prolonged exposure risks 475°C embrittlement of the ferrite phase. The tube is very resistant to crevice corrosion and stress corrosion cracking in harsh chemical environments. This makes it suitable for pressure vessels and heat exchangers.
Seamless Duplex Steel Tube Supplied in Various Grades
We provide the following Duplex steel grades at XTD:
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UNS S31803 Seamless Tube
This is the most common duplex grade. It offers high general corrosion resistance and excellent mechanical strength. It is used in chemical tankers and pulp and paper infrastructure.
02
UNS S32205 Seamless Tube
This grade is a nitrogen-enhanced version of S31803. It provides even better protection against pitting and crevice corrosion. It is the standard choice for aggressive chloride environments and marine applications.
100% Certified Testing & Documentation
- Raw Materials Certificate
- 100% Positive Material Identification (PMI)
- Heat Treatment Charts
- Third-Party Inspection Report
- Surface roughness and size measurement
- Manufacturer Test Certificate (Impact Testing, Flattening, Flare, Bend, Hardness, Intergranular Corrosion, Pitting Corrosion, Grain size, Eddy Current (ET), Ultrasonic Testing (UT), Hydrostatic Testing (HT), etc.)
- Laboratory Test Certificate from Govt. Approved Lab
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Frequently Asked Questions
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What is the maximum operating temperature of Duplex Seamless Tubes?
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Why choose a duplex seamless tube instead of a welded tube?You should choose a duplex seamless tube instead of a welded tube, as seamless tubes offer superior strength, no weld seams for better corrosion resistance and higher pressure ratings. Welded tubes risk defects at seams in harsh conditions.
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What industries commonly use Seamless Duplex Steel Tubes?Oil and gas, chemical processing, marine, power generation, and desalination plants commonly use seamless Duplex steel tubes for corrosion resistance and strength.
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Can duplex seamless tubes be used in heat exchangers?Yes, duplex seamless tubes can be used in heat exchangers due to their improved thermal conductivity and pitting resistance in corrosive fluids.
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Are duplex seamless tubes available in custom sizes?Yes, at XTD, duplex seamless tubes are available in custom diameters, wall thicknesses, and lengths.