Sihe Steel
Sihe Steel
Liaocheng Sihe Stainless Steel Material LTD is a premier enterprise based in China, boasting over 10 years of expertise in manufacturing premium-grade stainless steel coiled tubes, capillary tubes, and heat exchanger pipes. We have expanded our operations to six state-of-the-art production lines, integrating global technological innovations like advanced online bright annealing to supply ultra-long, high-integrity tubing products.
We manufacture strictly according to rigorous global production standards, including GB, ASTM, ASME, JIS, and EN. Our material expertise extends across high-performance steel grades: 304/304L, 316L, 321, 317L, 309S, 310S, and INCOLOY 800, along with high-performance alloys and duplex steels such as Duplex 2205, Super Duplex 2507, Incoloy 825, and Inconel 625.
Our high-integrity coiled tubing is available in outer diameters ranging from 0.125 inch (3.175 mm) to 1 inch (25.4 mm), with wall thicknesses up to 0.165 inch (3 mm), and continuous splice-free lengths up to 32,800 feet (10,000 meters). This makes our products a preferred choice for marine control line umbilicals, deep-water oil and gas systems, and petrochemical processing plants worldwide.
Choosing the correct grade of stainless steel is critical to the longevity, safety, and reliability of your system. AISI 316L (UNS S31603) is an extra-low carbon version of the AISI 316 molybdenum-bearing austenitic stainless steel. The addition of molybdenum (2.0% to 3.0%) significantly improves the material's resistance to pitting and crevice corrosion in chloride-containing environments, compared to standard 304 or 304L alloys.
The "L" in 316L stands for "Low Carbon" (max 0.03% carbon content compared to 0.08% in standard 316). This low carbon level minimizes the harmful carbide precipitation (sensitization) during welding, ensuring optimal corrosion resistance at weld joints. This is a critical factor for heavy-gauge welded components in petrochemical, oil and gas, and pharmaceutical applications.
| Steel Grade | Carbon (C) Max % | Chromium (Cr) % | Nickel (Ni) % | Molybdenum (Mo) % | PREN (Pitting Resistance Equivalent) |
|---|---|---|---|---|---|
| 304 / 304L | 0.03 / 0.08 | 18.0 - 20.0 | 8.0 - 10.5 | - | ~ 18.0 - 20.0 |
| 316 / 316L | 0.03 / 0.08 | 16.0 - 18.0 | 10.0 - 14.0 | 2.0 - 3.0 | ~ 23.0 - 25.0 |
| Duplex 2205 | 0.03 | 21.0 - 23.0 | 4.5 - 6.5 | 2.5 - 3.5 | ~ 34.0 - 36.0 |
| Super Duplex 2507 | 0.03 | 24.0 - 26.0 | 6.0 - 8.0 | 3.0 - 5.0 | ~ 40.0 - 43.0 |
For applications exposing the system to harsh marine environments, high saline fluids, or acidic chemicals, 316L offers a higher Pitting Resistance Equivalent Number (PREN) compared to 304. Calculated via the formula PREN = %Cr + 3.3%Mo + 16%N, 316L exhibits values between 23 and 25, indicating high suitability for coastal structures, marine instrumentation tubing, and heat exchangers handling brackish water.
Sourcing your 316L and duplex stainless steel tubes directly from a Chinese manufacturer like Liaocheng Sihe provides significant strategic, logistical, and financial benefits for global operations:
1. Vertically Integrated Steel Ecosystem: China's industrial clusters in Shandong and adjacent provinces host the world's most robust stainless steel supply chains, ensuring stable raw material sourcing and competitive pricing even during global market shifts.
2. Advanced Online Bright Annealing: Our facility is equipped with state-of-the-art inline hydrogen bright annealing technology. This process soft-anneals the tubes under a controlled protective atmosphere, leaving a clean, oxide-free, mirror-like inner and outer surface. It eliminates the need for acid pickling, improving both safety and structural integrity.
3. Unmatched Scale & Customization: With six automated lines, we easily accommodate high-volume requirements. We customize tube dimensions from capillary sizes to large-diameter coils, providing continuous lengths up to 10,000 meters to minimize fitting costs and leak paths in your installations.
We support various materials (including 304, 316L, 2205, and super alloys) and specific dimensional drawings from outer diameters of 6.35 mm to 19 mm, tailored to custom wall thicknesses.
Our facility offers precision tube bending, spiral coiling, ultra-precision drawing, and high-tolerance shaping designed for tight assemblies, high-performance heat exchangers, and cooling lines.
Leveraging high-precision laser cutting, mechanical abrasive saw cutting, and automatic straightening machines, we ensure burr-free ends, excellent straightness tolerances, and exact cut lengths.
We provide multiple finish options to meet various clean-room requirements, including bright annealing, electro-polishing (EP), mechanical polishing, and acid pickling treatments.
Our flanging and end-forming services prepare pipes for quick-connect joints, vital for automotive exhaust manifolds, chemical transport lines, and high-vibration aerospace assemblies.
From subsea oil wells to advanced aerospace fluid systems, our high-precision 316L and alloy tubes perform reliably in critical environments.
High thermal efficiency coiled tubes designed for power generation and chemical cooling.
Seamless copper-replacement tubes with high pressure ratings for eco-friendly refrigerants.
Chloride pitting resistant 316L and 2205 piping systems for volatile chemical transport.
Ultra-smooth inner diameters preventing bacterial accumulation, meeting FDA standards.
Electropolished capillary tubes engineered for sterile fluid transport and instrumentation.
Superheater and steam piping designed to withstand prolonged cyclic thermal stress.
High-strength alloy systems built to handle sour gas environments and high pressures.
Lightweight, high-precision capillary and hydraulic lines meeting tight aerospace tolerances.
For operations in hazardous offshore environments or precision pharmaceutical plants, compromising on material quality is not an option. Liaocheng Sihe implements a comprehensive zero-defect testing protocol for all batches of stainless steel coiled tubing and sheets. Our inline testing setup includes:
100% Eddy Current Testing (ECT): Every millimetre of our tubing is evaluated using electromagnetic induction to detect surface and sub-surface imperfections, cracks, or voids without damaging the pipe.
Pneumatic & Hydrostatic Testing: All coils undergo high-pressure air-tightness testing at our factory to ensure 100% leak-proof reliability under elevated pressures.
Mechanical Verification: Destructive tests, including flaring, flattening, reverse-bending, and tensile tests, are routinely performed in our laboratories to confirm ductility, elongation, and ultimate yield strength.
Hardness & Microstructure Auditing: Rockwell and Vickers hardness testing, alongside metallographic analysis, ensures correct grain size and eliminates residual stress from drawing.
Our mill maintains full compliance with major classification societies and quality control certifications to facilitate smooth customs clearance and import approval processes globally.
Importing high-precision industrial metals from China requires navigating quality standards, anti-dumping policies, and transit logistics. Implementing a structured procurement strategy ensures competitive pricing and project compliance:
1. Verify Material Test Reports (MTR): Always request detailed EN 10204 3.1 or 3.2 mill test certificates. These documents verify the exact chemical composition (Cr, Ni, Mo levels) and mechanical properties, confirming the authenticity of 316L and duplex materials.
2. Understand Anti-Dumping & Tariff Coding: Depending on the destination port (EU, North America, India), specific steel products may face anti-dumping tariffs. Working with a supplier like Liaocheng Sihe, who can optimize HS codes and provide certificates of origin, can significantly lower import duties.
3. Insist on Sea-Worthy Protective Packaging: Coiled tubes and precision capillary pipes are susceptible to transit damage. We protect our international shipments with reinforced steel-framed wooden crates, custom core supports, and moisture-proof plastic wrapping to prevent saltwater corrosion during ocean transport.
