Duplex seamless pipes are commonly used in oil and gas, chemical processing, marine engineering, heat exchangers, and offshore platforms.
Duplex Steel Seamless Pipe Manufacturer
We provide high-performance Duplex steel seamless pipe at Zhejiang Xintongda Special Steel (XTD). Duplex seamless piping is a high-strength, corrosion-resistant pipe that is constructed without a weld seam. This ensures the seamless (SMLS) pipe remains structurally uniform and pressure-resilient across its entire length. As a Duplex seamless pipe manufacturer, we produce pipes that comply with the ASTM A790 standard. The seamless construction makes Duplex SMLS pipe a preferred choice for high-pressure environments where leakage or mechanical failure is not an option. We hold multiple international certifications and maintain an impressive annual supply capacity of 25,000 tons. Our logistics efficiency allows us to dispatch stock orders for Duplex seamless pipes within just one week, while customised production orders are typically fulfilled within 15 to 60 days.
As a reputable Duplex seamless steel pipe supplier, we provide pipes that meet the following specifications:
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OD Range
6-720mm
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Thickness
1-65 mm
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Length
≤ 18 m
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What is a Duplex Seamless Pipe?
Seamless duplex steel pipe is a specialised piping product made from duplex stainless steel. It features a unique dual-phase microstructure consisting of approximately equal parts austenite and ferrite. This alloy contains chromium (21–23%), molybdenum (2.5–3.5%), nickel (4.5–6.5%), and nitrogen (0.08–0.20%) to enhance its corrosion resistance. The low carbon content in the alloy helps reduce sensitisation and prevents intergranular corrosion during service. This pipe is manufactured as one continuous hollow section without any weld seams or joints. We offer these products in standard grades like S32205 and S31803.
Manufacturing Process of Duplex Seamless Pipe
The duplex seamless pipe making process begins by heating a solid round steel billet until it is malleable. This hot billet is pierced to create a hollow shell and then rolled or drawn to achieve the required diameter and wall thickness. Finally, the pipe undergoes solution annealing and water quenching to ensure the correct microstructure and strength. Refer to this page to learn about our detailed seamless pipe manufacturing process.
Available Duplex SMLS Pipe Grades
We provide the following duplex steel grades at XTD:
01
UNS S31803 Seamless Pipe
This is the original duplex grade, offering a balanced mix of high mechanical strength and excellent resistance to localised corrosion. It provides a cost-effective solution for high-pressure applications where standard stainless steels might fail.
02
UNS S32205 Seamless Pipe
This grade is a refined-composition variant of S31803 with tighter minimum ranges for chromium (22–23%), molybdenum (3.0–3.5%), and nitrogen (0.14–0.20%). This ensures more consistent corrosion resistance.
Both grades are commercially known as Duplex 2205 (Werkstoff Nr. 1.4462). Most S31803 production today also meets S32205 composition — contact us for dual-certified pipe availability.
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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Where are duplex seamless pipes commonly used?
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Which international standards do duplex seamless pipes comply with?Our duplex seamless pipes comply with ASTM A790/ASME SA-790 (seamless and welded pipe), with EN 10216-5 (European seamless tubes for pressure purposes) also available on request. The equivalent ASME Boiler & Pressure Vessel Code designation is SA-790.
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What is the lead time for bulk duplex seamless pipe export orders?The lead time for bulk duplex seamless pipe export orders at XTD is typically 15-60 days.
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Why are duplex seamless pipes preferred for critical industrial applications?Duplex seamless pipes are preferred for critical industrial applications because of their high strength, excellent corrosion resistance, and resistance to stress cracking in harsh environments.