Sihe Steel
Sihe Steel
Explore our industrial grade seamless coiled and straight tubes engineered to withstand extreme pressures and corrosive environments.
Understanding the microstructural performance, mechanics under load, and chemical characteristics of standard-setting austenitic alloys.
AISI 304 is a classic Austenitic Stainless Steel containing 18% Chromium and 8% Nickel. This specific chemistry generates a stable austenitic crystal structure (FCC) at room temperature, assuring complete lack of magnetism when solution annealed. Low-carbon variants (304L) limit carbon to ≤0.03% to prevent chromium carbide precipitation at grain boundaries during welding processes.
Our seamless tubing features a minimum tensile strength of 515 MPa and a yield strength of 205 MPa, coupled with excellent elongation (>40%). These metrics translate to outstanding energy absorption and ductility, ideal for critical high-pressure oil/gas conduits and hydraulic manifolds requiring intensive cold forming, flanging, or bending.
The passive chromium oxide (Cr2O3) layer formed on the outer and inner tube surfaces provides superior self-healing properties in oxygenated environments. However, in aggressive chloride media, local breakdown of the passive layer can lead to pitting. To counter this, our manufacturing emphasizes a strict control of Pitting Resistance Equivalent Number (PREN) to ensure chemical durability.
Choosing the correct alloy requires careful examination of operating environments. While AISI 304 provides an exceptionally economical answer for general fluid systems, high-humidity environments, and food processing, marine and heavy chemical applications utilize molybdenum-bearing 316L or super duplex 2205. Review the technical distinctions below:
| Steel Grade | Cr (%) | Ni (%) | Mo (%) | PREN Value | Optimal Operating Environments |
|---|---|---|---|---|---|
| AISI 304 | 18.0 - 20.0 | 8.0 - 10.5 | - | ~18-20 | Food processing, beverage, HVAC, clean structural applications. |
| AISI 316L | 16.0 - 18.0 | 10.0 - 14.0 | 2.0 - 3.0 | ~23-25 | Marine, pharmaceutical bio-tech, severe chemical processing. |
| Duplex 2205 | 21.0 - 23.0 | 4.5 - 6.5 | 2.5 - 3.5 | ~34-36 | Offshore subsea umbilicals, high-chloride environments. |
Behind the superior surface finish and physical durability of Liaocheng Sihe's stainless steel pipes lies advanced manufacturing methodology.
Traditional heat treatment leads to oxidation layers that require acidic pickling, which can introduce micro-cracks and rough surface topologies. At Liaocheng Sihe, we utilize online hydrogen-atmosphere bright annealing.
By heating the tube to 1040°C - 1150°C in a completely sealed, oxygen-free hydrogen-nitrogen environment and quickly cooling it, we prevent chrome depletion along the grain boundaries. This technique preserves the metallic sheen of the tube, eliminates internal stresses, and prevents microscopic intergranular corrosion.
Available Sizes: Outer diameter (OD) sizes range from 0.125 inch (3.175 mm) to 1 inch (25.4 mm). Wall thickness is customizable up to 0.165 inch (3 mm). Lengths up to 32,800 feet (10,000 meters) are available for continuous, weld-free umbilical and subsea systems, maximizing structural reliability.
Premium hot-rolled billets are precisely cold drawn or cold rolled (pilgered) through custom dies. This optimizes grain orientation, refines inner/outer surface roughness (Ra ≤ 0.4 μm), and establishes tight dimensional tolerances.
Tubes enter our advanced inline softening furnaces to re-establish the homogeneous austenitic phase, ensuring zero stress retention and high structural stability.
Every single batch undergoes hydrostatic testing, electromagnetic eddy current verification, pneumatic air-tightness testing, micro-hardness verification (100%), and mechanical flaring/tensile testing.
A powerhouse of high-output stainless steel tubing manufacturing serving 30+ countries globally.
From metallurgical verification of raw coil inputs to state-of-the-art winding systems, our facility in Liaocheng features 6 dedicated production lines, operating 24/7 to fulfill high-volume international orders without bottlenecks.
We comply fully with international standards including ASTM A269, ASTM A213, JIS G3459, and EN 10216-5. Testing is performed in-house and documented via full MTRs (Material Test Reports) and Certificates of Conformance.
Our partnerships with global freight carriers enable cost-effective ocean transit to the US, Germany, Spain, and beyond. Specialized seaworthy packaging guarantees zero damage and humidity control during shipping.
Delivering high-reliability tubing designed to withstand challenging environments across multiple industries.
Our coiled tubes optimize heat transfer efficiency and pressure retention in steam lines and chemical thermal cyclers.
Seamless design guarantees zero refrigerant leakage under high pressure cycles in commercial chilling plants.
Resistant to nitric acid and localized weathering, supporting stable transport of reagents through production plants.
Ultra-clean inner diameters ensure hygienic conditions and prevent bacteria growth in beer cooling coils and milk processing lines.
High-grade polished surfaces prevent product adherence and resist chemical degradation during CIP (Clean-in-Place) procedures.
Used for critical steam distribution, control loop instrumentation, and cooling systems in traditional and nuclear plants.
Provides critical reliability in high-temperature crude processing lines and hydrocarbon recovery operations.
Superior strength-to-weight ratio for hydraulic pressure lines, aircraft fuel routing, and engine instrumentation.
Beyond producing raw tubes, we offer fabrication capabilities tailored to your specific application requirements.
We support various materials (including 304, 316L, 2205) and custom specifications, covering diameters from 6.35mm up to 19mm. Tubes can be coiled, wound to customized drums, or cut to custom straight lengths.
We offer specialized coiling, double-wall spiral configuration, and precision cold drawing to match the space envelopes of complex heat exchangers and condensing units.
Our facility utilizes laser and high-speed mechanical cutting tools to produce precise lengths with clean, deburred edges, minimizing fit-up and welding preparation time.
We offer mechanical polishing, electro-polishing, and chemical passivation to achieve surface roughness as low as Ra 0.25 μm, meeting high purity requirements.
We supply pre-fabricated flanged pipes and custom end connections, saving processing time on assembly lines for automotive exhaust and chemical bypass valves.
Tubes are packaged on wooden spools, metal reels, or within custom crates, ensuring product integrity during ocean freight and multi-modal transit.
Our manufacturing facility and products are fully accredited by leading international verification bodies.
Answers to common technical, metallurgical, and logistics questions from procurement managers and engineers.
Prices are primarily based on raw LME Nickel and Chromium market index values. We provide updated price lists based on material size, wall thickness, required tolerances, and order volumes.
To optimize production runs and freight costs, we maintain a minimum order volume for custom factory runs. For stock items or standard sizes, lower quantities can be supported.
We supply comprehensive EN 10204 3.1 Material Test Certificates (MTR), heat code traceability, chemical composition analysis, mechanical test records, and non-destructive test documentation.
Sample manufacturing takes approximately 7 days. Mass production averages 20 to 30 days after drawing approval and deposit receipt. Shipping times vary depending on the destination port.
We accept T/T (30% deposit in advance, 70% balance against copy of the Bill of Lading). Letter of Credit (L/C) and other secure payment methods can be discussed for high-volume contracts.
We guarantee the chemical composition and mechanical properties of our products. Any dimension or structural discrepancies are resolved in cooperation with our quality control department.
Coiled tubing is wrapped on robust spools, packaged with protective film, and crated. This prevents shifting and moisture exposure during maritime transit.
Seamless tubing does not have a welded seam, ensuring uniform pressure containment, higher corrosion resistance, and eliminating potential weld line failures.
Yes, we specialize in high-precision, customized drawing. Our engineers work directly with your specifications to manufacture custom tolerances for critical applications.
Yes. All high-pressure lines undergo hydrostatic testing in accordance with ASTM guidelines, certifying them for use in critical control systems.
Explore our wider range of high-alloy capillary, welded, and heat exchanger piping options.
We operate modern production lines, manufacturing sheet and pipe developments to international standards (GB, ASTM, ASME, JIS, EN). Our material range includes 304/304L, 316L, 321, 317L, 309S, 310S, and Incoloy 800.
Specialized testing, including compression, flaring, bending, and hardness verification, is performed to ensure quality standards are met prior to shipment.
Explore the dimensions and configurations of our steel coils and structural sheets.
