Sihe Steel
Sihe Steel
Grade 321 Stainless Steel (UNS S32100 / EN 1.4541) is an austenitic alloy stabilized with titanium, specifically engineered to operate in thermal environments that promote intergranular chromium carbide precipitation. In standard unstabilized austenitic steels such as Grade 304, exposure to temperatures between 800°F (427°C) and 1500°F (816°C) triggers chromium depletion at the grain boundaries, causing intergranular corrosion (IGC) sensitization.
By integrating titanium at a minimum ratio of 5 times the carbon content plus nitrogen ($Ti \ge 5 \times (C+N)$), Grade 321 selectively forms titanium carbides (TiC) instead of chromium carbides. This stabilization preserves the chromium matrix, securing maximum corrosion resistance, superior creep rupture properties, and high-temperature integrity.
| Chemical Elements & Properties | 321 (UNS S32100) | 304L (UNS S30403) | 316L (UNS S31603) |
|---|---|---|---|
| Titanium (Ti) % | $5 \times (C+N)$ to 0.70% max | N/A | N/A |
| Chromium (Cr) % | 17.0 - 19.0% | 18.0 - 20.0% | 16.0 - 18.0% |
| Nickel (Ni) % | 9.0 - 12.0% | 8.0 - 12.0% | 10.0 - 14.0% |
| Molybdenum (Mo) % | N/A | N/A | 2.0 - 3.0% |
| Yield Strength ($0.2\%$ Offset, MPa) | $\ge 205$ | $\ge 170$ | $\ge 170$ |
| Maximum Service Temp (Continuous) | 815°C (1500°F) | 425°C (800°F) | 450°C (840°F) |
As a leading high-precision steel mill from China, Liaocheng sihe stainless steel material LTD has driven development in the manufacture of stainless steel coiled tubes, capillary lines, and seamless instrumentation pipes. Operating six state-of-the-art production lines, we support international standards including GB, ASTM, ASME, JIS, and EN.
Equipped with high-precision cold rolling and cold drawing mills. Our facilities are designed for strict dimensional tolerance controls and continuous spooling protocols.
Integration of inline eddy current testing and high-efficiency hydrostatic testing allows for verification of pressure integrity across long coiled spool lines.
Bespoke steel framing and multi-layered packaging protection guarantee that long spools arrive safe and untangled for orbital subsea deployment.
Our facility utilizes world-class online bright annealing technology. This process performs heat treatment in a protective hydrogen environment to keep the surface mirror-clean, removing the need for acid pickling and guaranteeing structural ductility. We support steel grades ranging from standard austenitic alloys (304/304L, 316L, 321, 317L, 309S, 310S) to high-performance nickel superalloys and duplex steels (Duplex 2205, Super Duplex 2507, INCOLOY 800, Incoloy 825, Inconel 625).
Industrial buyers face challenges when sourcing 321 stainless steel coiled tubing, including maintaining tight wall thickness tolerances for high-pressure gas connections, avoiding pitting in marine salt spray environments, and preventing carbide precipitation during thermal cycling.
Withstanding thermal cycling from 400°C to 800°C. Coil structures eliminate potential leakage points by minimizing mid-run orbital welds.
Continuous length spools prevent refrigerant fluid loss and allow for complex space-saving bends within commercial chiller units.
Resistant to organic and inorganic acids at elevated temperatures. Often applied in refinery pipelines and organic synthesis loops.
Smooth, bright-annealed internal diameter (ID) prevents bacterial growth and is easy to clean, meeting international hygiene guidelines.
Ultra-clean capillary tubes and process tubing ensure zero product contamination during fluid transfer and reaction stages.
Superheater and reheater tubes require the titanium stabilization of 321 to prevent stress corrosion cracking in high-temperature steam lines.
Long, continuous coiled lines are essential for deep subsea chemical injection and hydraulic control systems, eliminating the need for joint couplings.
Aircraft exhaust manifolds, engine stack rings, and vehicle exhaust system bellows utilize Grade 321's high fatigue limits and scaling resistance up to 800°C.
To provide complete ready-to-install solutions, we deliver a range of precision processing services to match your design specifications.
We support various custom specifications for stainless steel coils (outside diameters ranging from 0.125 inches up to 1 inch, wall thicknesses up to 3 millimeters). Customized spooled configurations are processed to customer requirements.
Bending, spiral forming, coiling, and precision cold drawing processes are executed on specialized tooling to avoid internal deformation or micro-cracks in critical heat exchanger loops.
Using industrial laser cutting and mechanical saws, we supply precise cut-to-length solutions, keeping the cut ends clean and free of burrs for subsequent orbital welding.
Our mechanical and electrochemical polishing lines provide custom interior and exterior surface finishes, designed for chemical and pharmaceutical applications.
Specialized flanged tube ends are produced for connection joints in automotive exhaust setups, chemical lines, and precision instruments, ensuring gas-tight sealing.
Sihe Steel maintains compliance with structural certifications to meet global standards. We provide Mill Test Certificates (MTC) conforming to EN 10204 3.1, showing complete chemical tracking, heat numbers, and mechanical verification.
Global industrial processes are moving toward higher operation temperatures and pressures. Energy exploration in deeper offshore fields demands long, continuous lines to limit leak risks.
Additionally, green hydrogen production, carbon capture plants, and aerospace injection systems require titanium-stabilized steels (Grade 321) and super-duplex alloys. This helps limit stress corrosion cracking and reduces plant down-time.
Our quality management is audited against ISO standards. We test 100% of outgoing coiled tubing shipments using hydrostatic, eddy current, tensile, hardness, flare, and bend testing.
Seamless coiled tubing manufactured with duplex and austenitic alloys (such as 2205, 316L, and 321) for fluid transmission lines.
Industry-standard 1/2 inch coiled configurations, optimized for hydraulic control and analytical instrument lines.
High-temperature oxidation-resistant 310/310S grade coils, suited for combustion chambers and kiln piping.
Pricing for 321 stainless steel seamless coiled tubing is dynamic and depends on the price of base metals (Nickel, Chromium, and Titanium surcharges) as well as the dimensional specifications.
| Outer Diameter (OD) | Wall Thickness (WT) | Typical Price Range (FOB China / Ton) | Minimum Order Quantity (MOQ) | Key Testing Standard |
|---|---|---|---|---|
| 1/8" (3.175 mm) | 0.020" to 0.035" | $4,800 - $6,200 | 500 kg | ASTM A269 / Hydrostatic |
| 1/4" (6.35 mm) | 0.035" to 0.049" | $4,500 - $5,800 | 500 kg | ASTM A269 / Eddy Current |
| 3/8" (9.52 mm) | 0.035" to 0.065" | $4,300 - $5,500 | 500 kg | ASTM A269 / Bright Annealed |
| 1/2" (12.7 mm) | 0.049" to 0.083" | $4,200 - $5,300 | 1,000 kg | ASTM A269 / EN 10216-5 |
| 3/4" (19.05 mm) | 0.065" to 0.109" | $4,100 - $5,200 | 1,000 kg | ASTM A312 / Industrial Use |
| 1" (25.4 mm) | 0.083" to 0.120" | $4,050 - $5,100 | 1,000 kg | ASTM A312 / Pressure Code |
Please Note: The prices listed above are reference ranges for standard specifications. For exact, real-time quotes including delivery options and volume discounts, please contact our export sales department directly with your technical specification sheet.
