Sihe Steel
Sihe Steel
Elevated temperature service with superior creep strength and stabilization against carbide precipitation.
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Ultra-low carbon molybdenum alloy for high corrosion environments, available in extra-long continuous coils.
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High-precision micro-bore tubing designed for HPLC, gas chromatography, and hydraulic instruments.
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Reliable and cost-effective grade for general heat transfer applications in light-medium industrial conditions.
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Dual certified premium standard coiled tubes with excellent formability and welding characteristics.
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Engineered for fluid transport, heating/cooling systems, and mechanical instrumentation setups.
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Precision calibrated 3.5mm OD by 0.5mm WT micro-bore capillary tubing for precision sensors.
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Bright finish sheets processed to rigorous tolerances for cladding, structures, and industrial parts.
View DetailsDuplex 2205 stainless steel (UNS S31803 and UNS S32205) represents a technological paradigm shift in critical fluid handling systems. With a dual-phase microstructure comprising roughly equal parts of austenite and ferrite, this alloy combines the best mechanical and corrosion-resistant properties of both phases. Standard austenitic grades like 304 and 316L, while highly ductile, often fall short under high tensile loads, extreme chloride concentrations, or environments prone to Stress Corrosion Cracking (SCC).
Alloy 2205 possesses nearly double the yield strength of conventional austenitic steels, with mechanical properties meeting ASTM A789 and ASME SA789 specifications. Consequently, designers can specify thinner-walled tubes for high-pressure installations. This translates directly to significant weight reduction, improved flow characteristics, and optimized thermal transfer. The high nitrogen, chromium, and molybdenum content provides a Pitting Resistance Equivalent Number (PREN) exceeding 34, rendering Duplex 2205 capillary tubing highly resilient to sour gas wells, deep-sea exploration, and acidic chemical environments.
| Alloy Grade | Yield Strength (MPa Min) | Tensile Strength (MPa Min) | PREN Value | SCC Resistance | Chloride Concentration Suitability |
|---|---|---|---|---|---|
| Austenitic 304/304L | 205 | 515 | 18 - 20 | Low | Poor (< 200 ppm) |
| Austenitic 316/316L | 220 | 520 | 23 - 25 | Moderate | Fair (< 1,000 ppm) |
| Duplex 2205 (S32205) | 450 | 655 | 34 - 36 | Outstanding | Excellent (> 10,000 ppm) |
| Super Duplex 2507 | 550 | 800 | > 40 | Extreme | Severe Marine Conditions |
As an industry-leading expert, Liaocheng Sihe Stainless Steel Material LTD leverages advanced drawing techniques to produce precision capillary tubes with outer diameters from 0.125 inches (3.175 mm) to 1 inch (25.4 mm) and wall thicknesses up to 0.165 inches (3.0 mm). Our drawing process is strictly monitored to prevent microscopic surface inclusions or wall-thickness variations that could act as stress concentrators.
Our manufacturing infrastructure utilizes inline bright annealing technology. Bright annealing occurs in a controlled hydrogen atmosphere, ensuring that the inner and outer surfaces of the capillary tube remain free of oxide scale, clean, and mechanically optimized. This eliminates the need for acid pickling, resulting in a mirror-like finish that is critical for chromatographic applications, sensor lines, and subsea hydraulic assemblies where boundary-layer friction must be minimized.
Furthermore, continuous coiled tubing lengths up to 10,000 meters (32,800 feet) allow for seamless installations in umbilicals without the need for orbital butt-welds. This is key for oil and gas extraction in deeper, harsher waters, where welding joints represent potential points of mechanical fatigue and localized crevice corrosion.
"By controlling the ferrite-austenite balance within a strict 45% to 55% window, our Duplex 2205 capillary tubes achieve the perfect structural synergy, combining superior ductility with high mechanical limits."
In global infrastructure projects, compliance is non-negotiable. Liaocheng Sihe is certified to produce tubing according to GB, ASTM, ASME, JIS, and EN standards. Every batch of 2205 capillary tubing is accompanied by Mill Test Certificates (MTC) in accordance with EN 10204 3.1, detailing chemical composition, tensile testing, yield limits, elongation, and hydrostatic test pressures.
We provide localized engineering support across North America, Germany, Spain, South America, Southeast Asia, the Middle East, and Eastern Europe. Whether navigating the Pressure Equipment Directive (PED) in Europe or meeting specific API requirements for offshore platforms in the Gulf of Mexico, our team ensures that all document clearances, insurance, and origin certifications are prepared for seamless customs clearance and quality auditing.
Large-scale EPC (Engineering, Procurement, and Construction) companies require raw material suppliers that offer price stability, flexible MOQ (Minimum Order Quantity), and short lead times. Working directly with a Chinese factory offers specific advantages:
Direct sourcing of premium duplex billets combined with in-house hot rolling and cold drawing ensures complete quality control and competitive pricing.
Six specialized production lines provide the capacity to run high-volume industrial orders while simultaneously processing custom, short-run dimensions.
Strategically situated near key logistics ports, ensuring fast shipping coordinates via air freight for critical prototypes or maritime containers for massive project sites.
From OD 0.125 inch up to 1 inch, with wall thickness variations up to 0.165 inch. Customized coiling lengths up to 10,000 meters for umbilical manufacturing.
100% tensile, hardness, flaring, compression, and air tightness tests. Advanced eddy current inspection ensures zero pinhole defects.
Online bright annealing soft treatment at high temperatures in a hydrogen shielding environment ensures clean, scale-free inner and outer surfaces.
Tailored post-drawing services including laser cutting, mechanical straightening, flanging, and custom spiral bending for heat exchangers and hydraulic manifolds.
Due to its specific combination of mechanical strength and corrosion resistance, Duplex 2205 capillary and coiled tubing is utilized across highly specialized industries:
Established with a vision to redefine high-precision tube drawing, Liaocheng Sihe Stainless Steel Material LTD is a leading enterprise in the manufacturing of stainless steel coiled tubing, precision capillary lines, and high-performance heat exchanger pipes. Based in China, we manage six automated, high-precision production lines, operating under strict alignment with ISO 9001 and international quality frameworks.
With over 10 years of manufacturing history, our facility exports 80% of our products worldwide. Through our advanced online bright annealing technology, we continuously deliver tubing with a bright finish and reliable mechanical properties. Our technicians carry out testing protocols including hardness, flaring, compression, and air tightness testing to ensure each delivery operates safely in high-stakes fields like aerospace, subsea engineering, and medical diagnostic instruments.
Deepwater offshore exploration requires reliable control umbilicals. Our continuous long coiled tubing (up to 10,000 meters) helps prevent typical weld-joint degradation when exposed to deep sea pressure and corrosive brine. We offer options in chemical injection lines, hydraulic control lines, and subsea downhole safety valve lines, manufactured in Duplex 2205, Austenitic 316L, and Super Alloys like Inconel 625 or Incoloy 825.
Duplex 2205 containing austenitic and ferritic structures, offering dual phase corrosion benefits.
1/2 inch coiled tubes for rapid field deployments, fluid routing, and high pressure connections.
High chromium-nickel steel coil designed for elevated temperature scaling resistance.
The exploration of subsea energy reserves has shifted into ultra-deep waters where conventional platforms face higher temperatures, greater hydrostatic pressures, and sour environments. Under these conditions, the failure of a subsea umbilical or chemical injection line results in significant downtime, repair costs, and environmental risk. This risk profile driving the industry-wide transition from traditional 316L stainless steel to Duplex 2205 and Super Duplex 2507 capillary tubes.
Furthermore, the emerging green hydrogen economy relies heavily on high-pressure transport pipelines. The resistance of Duplex 2205 to hydrogen embrittlement makes it a strong candidate for fuel cell supply circuits and gas transportation infrastructure. The increased yield strength allows operators to use thinner walls, minimizing system weight on offshore tension-leg platforms and floating production storage and offloading (FPSO) units.
Our continuous improvement strategy centers on drawing technology and advanced non-destructive testing (NDT). We integrate online high-speed eddy current scanning with ultrasonic wall-thickness mapping to detect wall concentricity deviations down to the micron level. This ensures that Liaocheng Sihe capillary tubing performs reliably in automated chemical injection systems.
Duplex 2205 (UNS S31803/S32205) features higher concentrations of chromium (21–23%) and molybdenum (2.5–3.5%), along with an addition of nitrogen (0.14–0.20%), compared to standard 316L. This composition creates a dual-phase structure of austenite and ferrite. Consequently, Duplex 2205 offers twice the yield strength and significantly higher resistance to localized pitting and stress corrosion cracking in chloride environments compared to 316L.
To ensure production line efficiency and maintain competitive pricing, we require all international orders to meet a minimum order quantity depending on the size and grade of the material. If your project requires smaller trial runs or prototype samples, please contact our sales team to discuss inventory availability or coordinate production scheduling.
Yes, we provide comprehensive documentation with every shipment, including Mill Test Certificates (MTC) conforming to EN 10204 3.1, raw material chemical analyses, mechanical properties test reports, non-destructive testing (NDT) results, and certificates of origin. Custom export documentation and insurance paperwork can also be provided upon request.
For standardized sample sizes, the lead time is approximately 7 days. For large-scale mass production orders, the standard lead time is 20 to 30 days following deposit verification and dimensional approval. We coordinate with clients to align production schedules with project deadlines, and can accelerate manufacturing for urgent operations when needed.
We accept wire transfers (T/T), L/C, Western Union, and PayPal. Our typical payment terms require a 30% deposit in advance to initiate production, with the remaining 70% balance due against the copy of the Bill of Lading (B/L). Alternate payment arrangements can be reviewed for long-term contract partners.
We warrant both our materials and workmanship. In the event of material deviations from standard specifications, our technical team works to resolve the issue to your satisfaction. We offer material replacements or compensation options as part of our commitment to quality assurance.
We use high-grade export packaging. Long coiled tubing is wound onto steel or wooden reels, wrapped in protective plastic, and secured in heavy-duty wooden crates. This packaging is designed to prevent mechanical damage, humidity exposure, and surface scratching during international maritime transit.
Shipping fees depend on the selected shipping method (express courier, air freight, or sea freight), package weight, volume, and destination port. We provide freight rate quotes based on the specific volume of your order, allowing you to choose the most cost-effective shipping method.
High-durability transfer coils engineered for industrial thermal systems and fluid distribution lines.
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Seamless drawn 304 alloy coiled tubing offering structural uniformity for high pressure systems.
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Precision-drawn 9.52mm OD by 1.24mm WT tubing for downhole control lines and chemical injection systems.
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Polymer-encapsulated stainless steel tubing for extreme environmental protection in marine applications.
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Optimized for spiral heat exchangers, offering flexible structural geometry and efficient thermal conductivity.
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Micro-bore duplex capillary tubing engineered for subsea hydraulic lines and high-pressure sensor lines.
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Precision-toleranced 202 grade tubing suited for general mechanical structures and light duty configurations.
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High-alloy austenitic stainless steel designed for applications handling severe sulfuric and phosphoric acids.
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