Sihe Steel
Sihe Steel
Explore our high-precision product portfolio engineered to withstand severe operating environments, compliant with GB, ASTM, ASME, JIS, and EN standards.
As a leading Chinese pioneer in the metallurgical field, Liaocheng Sihe Stainless Steel Material LTD operates six state-of-the-art production lines designed to manufacture world-class stainless steel coiled tubes, polishing tubes, and seamless coiled tubing. Our manufacturing framework enforces strict adherence to internationally recognized guidelines including GB, ASTM, ASME, JIS, and EN standards.
Leveraging over a decade of production history, we have optimized our metallurgical methods to process highly resilient steel types, including austenitic grades (304/304L, 316L, 321, 317L, 309S, 310S), Duplex 2205, Super Duplex 2507, Incoloy 825, and Inconel 625. Our commitment to quality control is demonstrated through our integrated testing labs, offering online bright annealing, 100% mechanical tests, flaring, flanging, tensile testing, and non-destructive hydrostatic testing.
Today, our specialized alloy products serve mission-critical operations across 30+ countries, including the United States, Germany, Spain, South America, Southeast Asia, the Middle East, and Eastern Europe. Over 80% of our precision coil exports support global industrial hubs.
A comprehensive breakdown of alloy composition, corrosion resistance indices, and operational parameters for structural designers and engineering procurement professionals.
Austenitic stainless steel grade 316L (UNS S31603) is the low-carbon variant of the standard 316 alloy. By strictly limiting the carbon threshold to a maximum of 0.03%, this material eliminates the risk of chromium carbide precipitation along the grain boundaries during high-temperature thermal exposure (such as welding). This property prevents intergranular corrosion, allowing the material to be used in heavy welded structures without post-weld annealing.
The addition of Molybdenum (2.0% to 3.0%) chemically alters the alloy's passivity. This increases the material's resistance to localized pitting and crevice corrosion, especially in environments rich in chloride ions, such as seawater, salt spray, and chlorinated sanitation systems. The pitting resistance of this alloy is quantified by the Pitting Resistance Equivalent Number (PREN), calculated as:
While standard 304 stainless steel displays a PREN of approximately 18 to 20, 316L regularly achieves a PREN score between 23 and 25, signifying vastly superior endurance in aggressive marine and industrial media.
| Alloy Grade | UNS Designator | Carbon (C) % | Chromium (Cr) % | Nickel (Ni) % | Molybdenum (Mo) % | Nitrogen (N) % | PREN Value Range |
|---|---|---|---|---|---|---|---|
| 304 / 304L | UNS S30403 | ≤ 0.03 | 18.00 - 20.00 | 8.00 - 12.00 | - | ≤ 0.10 | 18.0 - 20.0 |
| 316L | UNS S31603 | ≤ 0.03 | 16.00 - 18.00 | 10.00 - 14.00 | 2.00 - 3.00 | ≤ 0.10 | 23.0 - 25.0 |
| 310S | UNS S31008 | ≤ 0.08 | 24.00 - 26.00 | 19.00 - 22.00 | - | - | 24.0 - 26.0 |
| Duplex 2205 | UNS S32205 | ≤ 0.03 | 22.00 - 23.00 | 4.50 - 6.50 | 3.00 - 3.50 | 0.14 - 0.20 | 34.0 - 36.0 |
| Super Duplex 2507 | UNS S32750 | ≤ 0.03 | 24.00 - 26.00 | 6.00 - 8.00 | 3.00 - 5.00 | 0.24 - 0.32 | 41.0 - 43.0 |
| Alloy 825 | UNS N08825 | ≤ 0.05 | 19.50 - 23.50 | 38.00 - 46.00 | 2.50 - 3.50 | - | 31.0 - 32.0 |
Molybdenum content creates a robust, self-healing oxide barrier that resists chloride-induced pitting, making it suitable for marine coastal infrastructures and wastewater systems.
An ultra-low carbon ceiling prevents carbide precipitation during welding, maintaining tensile strength and corrosion resistance along Heat Affected Zones (HAZ).
The stable fcc austenitic crystal structure maintains high impact toughness and mechanical ductility at temperatures ranging from cryogenic levels up to 800°C.
How Liaocheng Sihe integrates raw material sourcing, automated processing, and logistics to deliver cost-effective global supply security.
The industrial landscape in China provides raw material availability, skilled engineering, and transport infrastructure. Operating out of Liaocheng—a prominent hub for metal manufacturing—Liaocheng Sihe Stainless Steel Material LTD leverages localized manufacturing advantages:
Ensuring compliance with international standards through testing protocols and comprehensive mill documentation.
At Liaocheng Sihe, quality control is central to our manufacturing process. We understand that our tubing and sheets are deployed in critical operations, such as offshore subsea umbilicals, high-pressure heat exchangers, and pharmaceutical fluid loops. Because of this, every manufacturing batch undergoes testing procedures in our certified QA laboratory:
Includes tensile strength and yield stress determination, 100% flaring and flattening testing (to verify weld line integrity), and hardness mapping across cross-sections.
Includes 100% eddy current testing of capillary and heat-exchanger tubing, hydrostatic pressure verification up to specified limits, and ultrasonic wall thickness scans.
Our facility holds certifications verifying compliance with international shipping, quality management, and pressure equipment directives.
Our stainless steel sheets, coiled tubing, and precision capillary systems are utilized in major global industries, withstanding high pressures, corrosive environments, and temperature extremes.
In deepwater oil and gas operations, control fluid lines face challenging offshore environments where high pressures and seawater exposure require robust materials. Our work is to help you use the right corrosion-resistant material for coiled umbilical tubing to support safe and reliable operations. This focus on reliability drives our continuous product improvements. We prioritize our customers' specifications, offering sizing flexibility ranging from outer diameters of 0.125 inch (3.175 mm) to 1 inch (25.4 mm), with wall thicknesses up to 0.165 inch (3 mm), and continuous lengths reaching up to 32,800 feet (10,000 meters).
Tailored fabrication services designed to meet specific engineering layouts, ensuring integration with your manufacturing lines.
Supporting custom diameter configurations (6.35mm to 19mm) and complex geometry bending or spiral forming, optimized for heat exchangers and condensing units.
Laser and mechanical cutting lines ensure clean edge preparation, length accuracy, and deburred pipe openings for welding setups.
Offering mechanical polishing, bright annealing (retaining metallic luster without scale), and chemical passivation to enhance pitting resistance.
Find answers to common questions regarding specifications, lead times, quality assurance, and international shipment protocols.
Select from our range of structural steel sheets, coiled tubing, and heat-exchanger components for industrial and chemical processing systems.
An overview of our production capabilities across standard tubing, capillary profiles, heat exchangers, and flat-rolled sheets.
