Sihe Steel
Sihe Steel
Explore our premium range of precision-manufactured coiled tubes, heat exchanger pipes, and sheets conforming strictly to international standards.
Understanding the microstructural phase balance and element composition that make 2205 the gold standard for corrosive industrial applications.
Duplex 2205 (UNS S31803 / S32205) represents a highly engineered phase-balanced stainless steel alloy consisting of approximately 50% ferrite and 50% austenite phases. This dual-microstructure provides a synergistic combination of the high strength and stress corrosion cracking resistance characteristic of ferritic alloys, combined with the excellent general corrosion resistance and ease of fabrication inherent to austenitic stainless steels.
The metallurgical key to Duplex 2205's superior performance in high-chloride, acidic, and subsea environments lies in its specific alloying elements: Chromium (22%), Molybdenum (3%), and Nitrogen (0.18%). This unique chemistry results in a Pitting Resistance Equivalent Number (PREN) of greater than 35, calculated as:
PREN = %Cr + 3.3(%Mo + 0.5%W) + 16%N
A PREN score above 35 demonstrates high resistance to localized pitting and crevice corrosion, vastly outperforming standard austenitic grades such as 304L and 316L.
| Alloy Grade | Cr (Chromium) | Ni (Nickel) | Mo (Molybdenum) | N (Nitrogen) | C (Carbon) | Mn (Manganese) | Fe (Iron) |
|---|---|---|---|---|---|---|---|
| Duplex 2205 (UNS S32205) | 22.0 - 23.0% | 4.5 - 6.5% | 3.0 - 3.5% | 0.14 - 0.20% | ≤ 0.03% | ≤ 2.0% | Balance |
| Austenitic 316L (UNS S31603) | 16.0 - 18.0% | 10.0 - 14.0% | 2.0 - 3.0% | ≤ 0.10% | ≤ 0.03% | ≤ 2.0% | Balance |
| Mechanical Property | Duplex 2205 (UNS S32205) | Austenitic 316L (UNS S31603) | Engineering Significance |
|---|---|---|---|
| Yield Strength (0.2% Offset) | ≥ 450 MPa (65 ksi) | ≥ 290 MPa (42 ksi) | Allows wall-thickness reduction up to 40% under pressure design. |
| Tensile Strength | ≥ 620 MPa (90 ksi) | ≥ 485 MPa (70 ksi) | Ensures structural integrity under extreme structural/burst pressures. |
| Elongation (in 50mm) | ≥ 25% | ≥ 40% | Provides excellent ductility and formability during bending/coiling operations. |
| Hardness (Brinell / Rockwell B) | ≤ 293 HBW / 31 HRC | ≤ 217 HBW / 95 HRB | Superior wear, erosion, and cavitation resistance in high-flow pipelines. |
A Professional Pioneer in Steel Tubes, Sheet and Pipe Developments
Based in China, Liaocheng sihe stainless steel material LTD is a leading expert in the specialized field of stainless steel coiled tubes, stainless steel polishing tubes, and stainless steel seamless coiled tubing. Utilizing six highly automated production lines, we adhere to strict international production standards: GB, ASTM, ASME, JIS, and EN.
Our metallurgical expertise spans a wide range of steel types, including premium austenitic and duplex grades: 304/304L, 316L, 321, 317L, 309S, 310S, INCOLOY 800, Austenitic steel 316L, Duplex 2205, Super Duplex 2507, Incoloy 825, and Inconel 625 series.
Our coiled tubing is available in size ranges starting from outer diameters of 0.125 inch (3.175 millimeters) to 1 inch (25.4 millimeters), with wall thicknesses up to 0.165 inch (3 millimeters). We offer continuous single-coil lengths up to 32,800 feet (10,000 meters), enabling cost-effective control lines and umbilical hose manufacturing. Customized sizes can be produced to satisfy your exact specifications.
How we leverage advanced process controls and world-class annealing technology to secure lead times and ensure material consistency.
As modern energy, chemical, and subsea projects shift to deeper waters and aggressive chemical processes, the structural integrity of control lines and umbilical cables is non-negotiable. Liaocheng Sihe Stainless Steel Material LTD has integrated a Factory 4.0 manufacturing framework, ensuring end-to-end data tracking, strict metallurgy monitoring, and automated drawing techniques.
By introducing world-class online bright annealing technology, we achieve inline thermal processing. The continuous, protective atmosphere (usually high-purity hydrogen) prevents surface oxidation and preserves a bright finish. Crucially, this treatment ensures the optimal 50:50 ratio of ferrite and austenite phases, avoiding embrittlement or the formation of detrimental sigma phases.
Our integrated quality system features 100% inline eddy current testing, along with a comprehensive suite of mechanical property assessments including compression, flaring, bending, 100% hardness, tensile strength, and air tightness testing. This guarantees that every meter of our stainless steel coiled tubing is defect-free and ready for deployment in critical oil, gas, and aerospace systems.
Every batch undergoes destructive and non-destructive testing: ultrasonic, eddy current, hydrostatic, and structural flaring tests to prevent downhole failure.
Using online protective atmosphere bright annealing, we eliminate carbon contamination, relieve drawing stresses, and maintain superior surface finish properties.
All raw materials are selected from premium tier-one smelters, with full Mill Test Certificates (MTC) according to EN 10204 3.1 or 3.2.
Deploying Duplex 2205 and high-nickel alloys across hazardous marine, chemical, and industrial processing operations.
Liaocheng Sihe is not just a tube supplier; we provide custom fabrication and processing to match the layout of your heat exchangers, manifolds, and control lines.
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Innovating next-generation manufacturing to push the boundaries of length, pressure thresholds, and corrosion resistance.
The steel processing industry faces new demands as oil and gas operators target ultra-deepwater reserves (exceeding 3,000 meters) and high-temperature geothermal wells. In response, Liaocheng Sihe is refining its manufacturing capabilities, focusing on three strategic key areas:
1. Ultra-Long Orbital Welding and Weld-Free Coiled Pipes: We are refining our continuous cold-drawing setups to produce longer seamless lengths. Minimizing intermediate orbital welds lowers stress-concentration zones, ensuring higher reliability in control lines.
2. Clean Interior Surfaces (Electropolishing for Semiconductor and Biotech Projects): High-purity process lines require smooth interior walls to prevent fluid contamination. We are scaling up our interior electropolishing (EP) processes to consistently achieve a surface roughness (Ra) under 0.25 μm.
3. Development of Super-Duplex 2507 and Hyper-Duplex Tubing: For highly aggressive chloride environments, we are scaling production of Super-Duplex 2507 (PREN ≥ 40) and studying Hyper-Duplex alloys to protect against localized pitting and stress corrosion.
Strict adherence to international testing, inspection standards, and third-party quality approvals.
We operate under a complete quality management system certified to global standards. Our metallurgical testing laboratory is fully equipped to perform chemical analysis, mechanical property testing, microscopic grain structure evaluation, and corrosion resistance testing.
Clear logistics pipelines, payment schedules, warranty policies, and customizable lead times.
Our prices vary based on raw material costs and market trends. We require an ongoing minimum order quantity for international shipments. Contact our sales department to receive an updated price list.
We provide complete documentation for compliance, including Certificates of Analysis, Certificates of Conformance, Marine Classification approvals, origin certificates, and standard export documentation.
Standard samples are prepared in approximately 7 days. Mass production runs typically take 20 to 30 days from deposit receipt and final specifications approval. We adjust production runs to meet tight deadlines when possible.
Payments are processed via bank wire transfer, Western Union, or PayPal. Our standard terms require a 30% deposit in advance, with the remaining 70% balance paid against the copy of the Bill of Lading (B/L).
We fully stand behind the quality of our materials and workmanship. In the event of any product quality issues, we resolve them quickly through repair, exchange, or credit adjustments.
We use high-quality packaging for sea, air, and land transport. Specialized heavy-duty crating is used for temperature-sensitive materials, thin-walled capillary tubes, and continuous coiled tubing.
Get answers to common technical, logistics, and engineering questions regarding Duplex 2205 and high-nickel alloys.
High-grade stainless steel pipes, sheets, and capillary tubes manufactured for heavy duty, corrosion-prone industrial applications.
