Sihe Steel
Sihe Steel
Precision-engineered solutions conforming strictly to GB, ASTM, ASME, JIS, and EN standards.
Grade 304 (UNS S30400 / EN 1.4301) is the gold standard of austenitic stainless steels. Engineered with 18% chromium and 8% nickel, it forms a self-healing passive chromium oxide layer that delivers exceptional resistance to corrosion, high temperatures, and stress-cracking. For high-reliability environments such as oil and gas umbilical systems and subsea applications, choosing our premium raw materials ensures optimal structural integrity under extreme marine pressure.
The difference between 304 and 304L is the carbon content: 304L is restricted to a maximum of 0.03%, preventing chromium carbide precipitation during welding. This mitigates intergranular corrosion at heat-affected zones. In critical capillary lines, semiconductor manufacturing, and aerospace operations, this low-carbon profile eliminates the need for post-weld annealing, ensuring long-term mechanical reliability.
With an yield strength of ≥205 MPa and tensile strength of ≥515 MPa, 304 stainless steel tubing maintains robust mechanical properties at cryogenic temperatures down to -196°C and structural strength at elevated temperatures up to 800°C. This makes it a preferred choice for automotive exhaust systems, steam condenser loops, and complex heat-transfer circuits where reliability cannot be compromised.
A premium Chinese manufacturer with 10 years of experience, operating 6 state-of-the-art production lines for continuous coiled tubing and precision instruments.
We are a leading expert in the production of stainless steel coiled tubing, seamless coiled tubes, and precision polishing tubes. Our continuous line drawings allow us to supply ultra-long lengths up to 32,800 feet (10,000 meters) without orbital welds. This decreases installation costs, eliminates potential leak paths, and improves safety margins in deepwater offshore oil and gas developments.
To guarantee maximum corrosion resistance and scale-free interior surfaces, we utilize online bright annealing technology. Processing steel in a protective atmosphere of hydrogen and nitrogen prevents oxidation. This produces a smooth, clean surface with a mirror-like finish, which is critical for semiconductor transport lines, biotechnology instruments, and capillary tubes.
In addition to Grade 304 and 304L, we manufacture products using a wide range of high-performance alloys and super duplex steels to suit different environments:
Size Envelope: Outer diameters ranging from 0.125 inch (3.175 mm) to 1 inch (25.4 mm). Wall thickness up to 0.165 inch (3 mm).
A comparison of chemical composition and physical properties for engineers and procurement specialists.
| Alloy Grade | C (%) | Mn (%) | Si (%) | P (%) | S (%) | Cr (%) | Ni (%) | Tensile Strength (MPa) | Yield Strength (MPa) |
|---|---|---|---|---|---|---|---|---|---|
| 304 (UNS S30400) | ≤ 0.08 | ≤ 2.00 | ≤ 0.75 | ≤ 0.045 | ≤ 0.030 | 18.0 - 20.0 | 8.0 - 10.5 | ≥ 515 | ≥ 205 |
| 304L (UNS S30403) | ≤ 0.03 | ≤ 2.00 | ≤ 0.75 | ≤ 0.045 | ≤ 0.030 | 18.0 - 20.0 | 8.0 - 12.0 | ≥ 485 | ≥ 170 |
Providing solutions for modern engineering challenges, supply chain volatility, and rigorous quality standards.
By manufacturing continuous coiled tubing up to 10,000 meters in length, we eliminate the need for orbital structural welds. This reduces weld-inspection overhead (RT/UT tests) and installation time, and mitigates the risk of stress corrosion cracking (SCC) at heat-affected weld zones.
Liaocheng Sihe performs a complete testing process before delivery. Our quality control includes 100% positive material identification (PMI), hydrostatic pressure testing, ultrasonic inspection, eddy current examination, mechanical flattening, flaring testing, and Rockwell hardness verification.
Liaocheng Sihe exports 80% of its coiled tubing production to more than 30 countries across the US, Germany, Spain, South America, Southeast Asia, and the Middle East. We provide full traceability with Mill Test Certificates (MTC) conforming to EN 10204 3.1.
Providing tailored processing solutions to meet specific dimensional and mechanical design requirements.
We provide precision spiral coiling and structural bending of 304, 316L, and Duplex 2205 tubes (with outer diameters ranging from 6.35 mm to 19 mm) to fit compact heat exchanger housings, condenser coils, and geothermal loops.
We utilize advanced laser cutting and high-speed mechanical straightening machines to deliver clean, burr-free tube ends. This is ideal for precision capillary tubing and automotive assembly lines.
We offer high-tolerance flanging, expansion, and end-reduction processing. These services are designed for secure mechanical jointing in chemical processing lines and automotive exhaust systems.
Providing high-reliability tubing solutions across critical engineering sectors.
Browse our categories, including capillary tubes, heat exchangers, coiled tubes, and sheets.
Duplex 2205 and 304/304L stainless steels containing austenitic and ferritic microstructures for high pressure pipelines.
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Premium 1/2" coiled tubing for oilfield injections, control systems, and chemical delivery networks.
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High-temperature oxidation-resistant 310/310S tubing for furnace treatment lines and thermal processing plants.
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Specialized capillary and coiled tube designs matching international industrial criteria.
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Ultra-fine high precision steel tubes tailored for chromatography and sensor instrumentation.
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Optimized thin-walled seamless tubes designed for boilers, condenser loops, and energy plants.
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Cold-rolled structural sheets available in various thicknesses and surface finishes.
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Standard compliance range covering ASTM A269, A213, A312, and A789 for duplex steels.
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Delivering dimensional tolerances and smooth interior surfaces for high-purity processes.
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Engineered for offshore energy extraction environments where reliability is paramount.
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Sized for pressure sensors, temperature measuring devices, and medical instrumentation.
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Includes Incoloy 825, Inconel 625, and Duplex 2205 for acidic and saline applications.
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Internally and externally polished tubes designed for sanitary, food, and beverage processes.
VIEW MORE PRODUCTExplore our advanced drawing, bright annealing, and processing workshop.
Liaocheng Sihe is fully audited and certified under international quality assurance standards.
Addressing key technical and commercial considerations for global industrial buyers.
High-performance stainless steel control tubes, capillary lines, and high-pressure coils.
