Sihe Steel
Sihe Steel
Explore our top-performing precision-engineered stainless steel coil configurations, compliant with international quality baselines.
Operating from our modern manufacturing base in Liaocheng, China, we operate six precision production lines dedicated to fabricating high-quality stainless steel coiled tubes, polished tubes, and seamless coiled tubing. Our operational strategy is built on compliance with global standards, including GB, ASTM, ASME, JIS, and EN standards.
Our material catalog encompasses standard austenitic grades (304/304L, 316L, 321, 317L, 309S, 310S), high-temperature alloys (INCOLOY 800, 825, INCONEL 625), and corrosion-resistant duplex structures (Duplex 2205, Super Duplex 2507). With over 10 years of export experience, 80% of our production volume is delivered to global industrial partners in the United States, Germany, Spain, South America, Southeast Asia, and the Middle Europe.
A comprehensive engineering analysis of grade 304, material characteristics, processing mechanics, and life-cycle performance.
Grade 304 (UNS S30400 / EN 1.4301) is the standard alloy of the austenitic stainless steel class, formulated with a minimum of 18% chromium and 8% nickel. The austenitic microstructure is stabilized by the nickel addition, allowing the material to retain its non-magnetic profile and mechanical properties across a temperature range from cryogenic levels up to 870°C.
Liaocheng Sihe monitors the carbon content within our melt runs. For structural or high-temperature application baselines, we balance the chromium-nickel equivalents to suppress the precipitation of chromium carbides at grain boundaries in the critical heat-affected zone (HAZ) during welding. For applications requiring extensive welding operations, we offer 304L (UNS S30403), limiting carbon to 0.03% to mitigate intergranular corrosion vulnerability.
Our coiled tubes undergo multi-pass cold drawing to achieve dimensional precision and surface characteristics. Cold-working increases the yield and tensile strength of the alloy through work hardening. To restore ductility and corrosion resistance, the tubing is processed through our in-line bright annealing lines.
Bright annealing is conducted in a controlled, oxygen-free hydrogen/nitrogen protective atmosphere at temperatures between 1040°C and 1150°C, followed by rapid cooling. This process dissolves precipitated carbides back into the austenitic matrix and maintains a clean, scale-free, and reflective surface finish, eliminating the need for subsequent acid pickling and passivation for most clean gas or fluid systems.
| Alloy Grade | C (%) | Mn (%) | Si (%) | P (%) | S (%) | Cr (%) | Ni (%) | N (%) |
|---|---|---|---|---|---|---|---|---|
| 304 (UNS S30400) | ≤ 0.08 | ≤ 2.00 | ≤ 0.75 | ≤ 0.045 | ≤ 0.030 | 18.0 - 20.0 | 8.0 - 10.5 | ≤ 0.10 |
| 304L (UNS S30403) | ≤ 0.03 | ≤ 2.00 | ≤ 0.75 | ≤ 0.045 | ≤ 0.030 | 18.0 - 20.0 | 8.0 - 12.0 | ≤ 0.10 |
| 316L (UNS S31603) | ≤ 0.03 | ≤ 2.00 | ≤ 0.75 | ≤ 0.045 | ≤ 0.030 | 16.0 - 18.0 | 10.0 - 14.0 | ≤ 0.10 |
In modern industrial design, weight reduction and material efficiency are driving the adoption of thin-wall coiled tubing with wall thicknesses under 0.8 mm. This transition is supported by advances in grain-size control and micro-alloying, which allow for high pressure-retaining capabilities without increasing material volume.
The industry is also focusing on surface electropolishing (EP) inside the ID (inner diameter) of coiled tubing. This achieves an average surface roughness (Ra) of less than 0.25 µm, which is essential for preventing particulate contamination in pharmaceutical manufacturing and semiconductor gas lines.
Advanced manufacturing infrastructure, real-time quality control protocols, and reliable global distribution frameworks.
Modern industrial sourcing requires stable product quality and delivery timelines. At Liaocheng Sihe, we address this demand through our digital manufacturing environment, integrating raw material batch tracking with downstream cold-working processes.
Our raw materials are sourced from domestic manufacturers (such as Tsingshan and TISCO) and verified through spectral and chemical testing. We operate three specialized coiling lines that can manufacture continuous lengths up to 32,800 feet (10,000 meters) without orbital welds. This reduces potential leak points in deepwater oil exploration umbilicals and chemical plant trace heating loops.
Our quality assurance program is backed by a testing laboratory capable of performing:
• 100% Non-Destructive Eddy Current Testing (ECT)
• In-line Hydrostatic Pressure testing up to 80 MPa
• Pneumatic / Air Tightness testing for control line assemblies
• Microstructural grain size examinations
• Mechanical tests including flaring, flattening, reverse-bending, and hardness testing
Tailored processing services for specific engineering design specifications.
Supports various materials (e.g., 304, 316L, 2205) and specifications (diameter 6.35mm to 19mm) for stainless steel coils.
Includes bending, spiral forming, precision drawing, and other processes tailored for heat exchangers.
Laser cutting, mechanical cutting, or flame cutting for high-precision and efficient material processing.
We devote ourselves to developing new products with state-of-art technologies.
Used in automotive exhaust systems, chemical pipelines, and precision instrument connections.
Our stainless steel coils are deployed in high-performance applications globally.
Browse our catalog of custom processing options, capillary piping, heat exchanger tubes, and special alloy variations.
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Liaocheng Sihe manufactures in strict accordance with international material testing, welding, and quality assurance criteria.
All delivered products can be accompanied by standard Mill Test Certificates (MTC) conforming to EN 10204 3.1. We support customer-appointed third-party inspectors (including SGS, BV, ABS, Lloyd's) for dimensional checks, mechanical testing, and chemical verification prior to dispatch.
Essential pricing, ordering, compliance, and material engineering information for global procurement managers.
Specialty grades, ultra-long heat exchanger pipes, and customized dimensions manufactured to order.
