Sihe Steel
Sihe Steel
Explore our foundational range of precision-drawn seamless tubes, capillary products, and specialized heat exchanger lines direct from our manufacturing center.
As a prominent authority in metallurgical precision, Liaocheng sihe stainless steel material LTD stands as a premier manufacturer specializing in high-performance stainless steel coiled tubing, precision polished tubes, and ultra-long seamless solutions. Drawing on more than a decade of industrial experience, our factory is equipped with six state-of-the-art production lines designed to support critical hydraulic, thermal, and subsea infrastructures.
We enforce strict adherence to standard protocols including GB, ASTM, ASME, JIS, and EN. Our material capabilities span a broad selection of demanding steel grades: 304/304L, 316L, 321, 317L, 309S, 310S, and Incoloy 800, alongside advanced alloys like Duplex 2205, Super Duplex 2507, Incoloy 825, and Inconel 625.
Our infrastructure features advanced bright annealing lines that execute in-line atmospheric thermal processing. This achieves complete recrystallization and uniform grain structure without surface oxidation, delivering tubes with superior flexibility, micro-smooth internal surfaces, and enhanced corrosion resistance. To verify absolute reliability, our quality assurance protocols include 100% pneumatic testing, mechanical flaring and flattening diagnostics, hydrostatic tests, and micro-hardness surveys.
Austenitic stainless steel grade 316L (UNS S31603 / 1.4404) represents the benchmark for applications demanding high corrosion resistance and structural stability under extreme environments. The "L" suffix denotes a low carbon composition limit of ≤ 0.030%. This restriction prevents carbide precipitation along grain boundaries during thermal exposure and welding operations, mitigating the risk of intergranular corrosion (sensitization).
The addition of 2.0% to 3.0% Molybdenum (Mo) significantly improves resistance to localized halide attack (pitting and crevice corrosion) compared to basic chromium-nickel alloys like 304. Below is a comparative overview of key chemical compositions:
| Element | 304L (UNS S30403) | 316L (UNS S31603) | Duplex 2205 (UNS S32205) | Incoloy 825 (UNS N08825) |
|---|---|---|---|---|
| Carbon (C) max | 0.030% | 0.030% | 0.030% | 0.05% |
| Chromium (Cr) | 18.0 - 20.0% | 16.0 - 18.0% | 22.0 - 23.0% | 19.5 - 23.5% |
| Nickel (Ni) | 8.0 - 12.0% | 10.0 - 14.0% | 4.5 - 6.5% | 38.0 - 46.0% |
| Molybdenum (Mo) | - | 2.0 - 3.0% | 3.0 - 3.5% | 2.5 - 3.5% |
| Nitrogen (N) | 0.10% max | 0.10% max | 0.14 - 0.20% | - |
For applications in subsea umbilicals, deepwater petroleum extraction, and chemical processing, selecting the proper alloy is vital to ensuring safe operation. 316L provides an optimal balance of cost-efficiency and mechanical reliability, maintaining ductile properties from cryogenic ranges up to elevated process temperatures.
Modern engineering demands higher pressure ratings, extreme temperature thresholds, and cleaner fluid delivery systems. The transition toward high-pressure hydrogen infrastructure presents challenges like hydrogen embrittlement. In response, our technical roadmap focuses on optimization of the nickel equivalent within the 316L spectrum, targeting levels > 12.5% to stabilize the austenitic phase and minimize microstructural transformation under mechanical strain.
Simultaneously, the semiconductor and pharmaceutical industries require minimized internal surface roughness to prevent particle accumulation and bacterial colonization. We continue to refine our cold-drawing techniques and gas-purged bright annealing methods to reliably deliver internal surface roughness levels of Ra ≤ 0.25 μm, reducing the need for extensive post-draw electropolishing processes.
Our manufacturing complex in Liaocheng combines raw material sourcing with advanced quality control systems. We produce seamless coiled tubing in continuous, orbitally welded-free lengths up to 32,800 feet (10,000 meters). Eliminating intermediate mechanical joints reduces leak paths and flow resistance, which is critical for subsea control lines and downhole chemical injection systems.
This efficiency is supported by a comprehensive suite of in-house material testing capabilities:
Liaocheng Sihe Stainless Steel Material LTD maintains a robust quality management framework certified to meet strict global specifications. Our products are exported to over 30 countries across North America, Europe, Southeast Asia, and the Middle East. We provide Mill Test Certificates (MTC) in accordance with EN 10204 3.1, confirming traceability from the melt batch to the finished product.
We provide advanced structural fabrication and finishing services for custom engineering specifications.
We support various materials (including 304, 316L, 2205) and custom specifications with outer diameters ranging from 6.35mm to 19mm for stainless steel coils.
We offer high-precision bending, tight spiral forming, and precision drawing, producing custom configurations tailored for heat exchangers.
We utilize laser cutting, mechanical abrasive saw cutting, and high-speed precision straightening to prepare raw material sections to exact tolerances.
We apply advanced polishing methodologies, bright hydrogen atmospheres, and controlled passivation chemistry to develop clean internal and external surface finishes.
We provide structural flared connections for automotive exhaust assemblies, chemical transport systems, and critical analytical instrumentation.
Our core manufacturing capabilities are organized into structural product divisions, ensuring targeted solutions for specific industrial challenges.
2205 duplex and 316L stainless steel coiled tubing options, offering continuous runs without mechanical joints.
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High-precision straight and coiled tubing options with outer diameters from 0.125 inch (3.175 mm) to 1 inch (25.4 mm).
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Specifically formulated 310S and Incoloy grades, engineered for chemical process furnaces and high-heat environments.
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Our stainless steel tubes are engineered for demanding performance criteria across diverse industrial sectors.
Comprehensive technical and commercial insights for engineers, procurement managers, and logistics coordinators.
Explore our complete product catalog, featuring additional specifications, alloys, and coiled configurations designed for diverse operational requirements.
