Oil and gas, chemical processing, offshore platforms, desalination plants, and marine industries use Super duplex steel seamless pipes for corrosion resistance in harsh environments.
Super Duplex Steel Seamless Pipes Manufacturer in China
We are Zhejiang Xintongda Special Steel (XTD), a leading China-based manufacturer and global supplier of super duplex steel seamless pipe. Super duplex steel seamless pipe is a high-strength, corrosion-resistant pipe produced without a longitudinal weld, formed from a solid stainless steel billet by hot piercing and cold finishing. The dual-phase microstructure of roughly 50% ferrite and 50% austenite, combined with a chemistry of about 25% chromium, 4% molybdenum, and 0.28% nitrogen, gives the top super duplex grades a PREN above 40. That translates to near-nickel-alloy chloride pitting resistance and about three times the minimum yield strength of 316L stainless. We manufacture seamless super duplex pipe to ASTM A790 (equivalent ASME SA-790) in the grades: UNS S32750 (SAF 2507), UNS S32760 (Zeron 100), and UNS S32550 (Ferralium 255). The following are the common industries where super duplex pipes are preferred: offshore oil and gas, subsea flowlines and risers, seawater cooling in tropical fields, and aggressive chemical processing, wherever 304, 316L, or standard duplex would pit or fail. We hold multiple international certifications, listed on our Certificate page, and we run an annual supply capacity of 25,000 tons with over four decades of manufacturing experience.
We manufacture pipes that meet the following specifications:
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OD Range
6-720 mm
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Thickness
1-65 mm
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Length
≤ 18 m
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What is a Super Duplex Steel Seamless Pipe?
A Super duplex steel seamless pipe is a high-strength, corrosion-resistant, and high-performance tubular product. It is made from a 50% ferrite and 50% austenite structure. The seamless construction means it is made from a single piece of solid steel that creates a consistent metallurgical structure across the entire circumference. It is designed for harsh environments and consists of high levels of chromium and molybdenum, with balanced nickel. We supply the following three super duplex grades as seamless pipe: UNS S32750, UNS S32760, and UNS S32550.
Manufacturing Process of Super Duplex Seamless Pipe
The production process of SDSS seamless pipes begins by heating a solid steel billet and piercing it to create a hollow shell. After that, the shell is cold worked and heated to the right temperature to get the right mechanical properties. This process ensures that the finished pipe has a smooth surface and a fine internal grain structure. For details on our manufacturing process, refer to our production page.
Super Duplex Grades Commonly Delivered as Seamless Pipes
We offer the following 3 Super duplex grades, like UNS S32750, UNS S32550, and UNS S32760 as seamless pipes at XTD:
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UNS S32750 Seamless Pipe
UNS S32750 Pipe consists of 24–26% chromium, 6–8% nickel, 3–5% molybdenum, and 0.24–0.32% nitrogen. It has a PREN value of ≥ 41. It is the most common super duplex variety, known for its high alloy content and exceptional strength. It provides excellent resistance to chloride stress corrosion cracking in seawater applications.
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UNS S32550 Seamless Pipe
UNS S32550 pipe consists of 24-27% chromium, 4.5-6.5% nickel, 3-4% molybdenum, and 1.5-2.5% of copper. The high copper content significantly improves its resistance to sulfuric acid. It has a PREN value of ≥ 38. It is frequently selected for its durability in rugged chemical processing and marine engineering environments.
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UNS S32760 Seamless Pipe
UNS S32760 pipe has 24-26% chromium, 6-8% nickel, 3-4% molybdenum, and equal additions of tungsten and copper (0.5-1%) to enhance performance in sour gas environments. It has a PREN of ≥ 41. It is a reliable choice for deep-sea oil and gas exploration where stability is vital.
100% Certified Testing & Documentation
- Surface roughness and size measurement
- Laboratory Test Certificate from the Government-Approved Lab
- Raw Materials Certificate
- 100% PMI
- Heat Treatment Charts
- EN 10204 3.1 and EN 10204 3.2 Material Test Certificates (MTC)
- Third-Party Inspection Report
- Manufacturer Test Certificate (Impact Testing, Flattening, Flare, Bend, Hardness, Intergranular, Pitting Corrosion, Grain size, ET, UT, HT...)
Frequently Asked Questions
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Which industries use Super Duplex Steel Seamless Pipes?
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What are the available OD, wall thickness (schedule), and standard lengths?At XTD we provide Super duplex steel pipes in OD ranges from 6 mm to 720 mm. Thickness ranges between 1 mm and 65 mm and standard lengths are up to 18 m.
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Which product standards do you manufacture to?We manufacture this pipe to the ASTM A790 standard at XTD.
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What are the main benefits of Super Duplex Steel SMLS Pipes?The main benefits of Super duplex steel SMLS pipes are high strength, excellent pitting/crevice corrosion resistance, superior stress corrosion cracking resistance, and durability in chloride/acid environments.
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What is the current stock availability versus lead time for made-to-order production?Check our live stock page to learn about our current stock availability. The lead time for our made-to-order production is 15 to 60 days.
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Why choose Seamless Super Duplex Steel Pipe over welded Pipes?The reason you should choose seamless Super duplex steel pipe over welded pipes is that seamless pipe offers higher pressure ratings, no weld seams for better corrosion resistance, and superior strength uniformity.
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Which Super duplex grades do you supply?We supply Super duplex grades UNS S32750, UNS S32550, and UNS S32760 at XTD.