Stainless Steel Coil Tube (盘管) — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) is a precision-engineered continuous coiled tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is fabricated from high-grade austenitic stainless steel and wound into a uniform helical coil configuration, offering exceptional mechanical integrity, corrosion resistance, and flow dynamics. Coil tubes are widely employed in bioreactors, heat exchangers, chemical processing systems, pharmaceutical equipment, and environmental engineering applications where continuous, compact, and hygienic fluid conveyance is critical.
The coil geometry provides a high surface-area-to-volume ratio, making it particularly advantageous for mass and heat transfer operations. In bioreactor applications — as demonstrated in research on continuous denitrification of low-pollution water — the coil tube configuration promotes optimal microbial adhesion, uniform fluid distribution, and efficient nutrient mass transfer, resulting in enhanced biological treatment performance.
2. Material & Properties
Wenzhou Jixing Metal Materials Co., Ltd supplies coil tubes in multiple stainless steel grades, each selected for specific environmental and operational requirements:
- 304 / 304L (ASTM A270 / EN 1.4301): The most widely used austenitic grade, offering excellent general corrosion resistance, weldability, and formability. Suitable for food-grade, pharmaceutical, and general industrial applications.
- 316 / 316L (ASTM A270 / EN 1.4401): Enhanced pitting and crevice corrosion resistance due to molybdenum (Mo) addition (2.0–3.0%). Ideal for chemical processing, marine environments, and bioreactor systems exposed to chlorides.
- 321 (ASTM A270 / EN 1.4541): Titanium-stabilized grade with superior resistance to intergranular corrosion, suitable for high-temperature applications (up to 870°C).
- 310S (ASTM A270 / EN 1.4845): High-temperature grade with excellent oxidation resistance up to 1150°C, used in furnace and thermal processing equipment.
- 904L / 2205 Duplex: Premium grades for extreme corrosive environments including aggressive chemical media and desalination systems.
Key Material Properties (Typical — Grade 316L)
| Property | Specification |
|---|---|
| Tensile Strength (Rm) | ≥ 520 MPa (ASTM A270) |
| Yield Strength (Rp0.2) | ≥ 210 MPa |
| Elongation (A5) | ≥ 40% |
| Hardness (HV10) | ≤ 220 HV |
| Operating Temperature Range | −196°C to +870°C |
| Chromium (Cr) Content | 16.0 – 18.0% |
| Nickel (Ni) Content | 10.0 – 14.0% |
| Molybdenum (Mo) Content | 2.0 – 3.0% |
| Maximum Carbon (C) | 0.03% (L grade) |
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管 / Coiltube) |
| Standard Reference | ASTM A270, ASTM A269, GB/T 12771, GB/T 14976, EN 10217 |
| Available Grades | 304, 304L, 316, 316L, 321, 310S, 904L, 2205 Duplex |
| Outer Diameter (OD) | Φ 3 mm – Φ 50 mm (custom sizes available) |
| Wall Thickness | 0.3 mm – 5.0 mm |
| Coil Winding Diameter | Φ 100 mm – Φ 1000 mm (configurable) |
| Coil Length (per spool) | 5 m – 500 m (continuous) |
| Surface Finish | Mechanical Polished, Electropolished, Passivated, Matte |
| Surface Roughness (Ra) | ≤ 0.4 μm (electropolished); ≤ 1.6 μm (standard) |
| End Treatment | Plain end, Beveled end, Threaded, Flanged |
| Tolerance (OD) | ±0.05 mm (precision); ±0.1 mm (standard) |
| Tolerance (Wall Thickness) | ±5% of nominal |
| Coil Pitch Tolerance | ±0.5 mm |
| Welding Compatibility | TIG (GTAW), Pulse TIG, Orbital welding |
| Delivery Condition | Hot-rolled + Cold-drawn (H + C), Annealed + Pickled + Passivated (A + P) |
| Packaging | Wooden reel / drum with moisture-proof wrapping, export-standard |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorous multi-stage process to ensure dimensional accuracy, metallurgical quality, and surface integrity:
- Raw Material Selection & Inspection: Ingot or coil stock is sourced from certified mills and subjected to Chemical Composition Analysis (CCA) and Positive Material Identification (PMI) to verify grade compliance.
- Hot Rolling & Annealing: The base material undergoes hot rolling to achieve approximate dimensions, followed by solution annealing at 1050–1150°C to relieve residual stresses and restore full austenitic microstructure.
- Pickling & Passivation: The annealed tube is acid-pickled (HNO3 + H2SO4 blend) to remove oxide scale, followed by passivation to establish a protective chromium oxide layer (Cr2O3) on the surface.
- Cold Drawing (Multi-Pass): The tube is cold-drawn through sequential dies to achieve final OD and wall thickness with tight tolerances. This process enhances mechanical properties and surface finish.
- Intermediate Annealing: Periodic solution annealing is performed between cold-drawing passes to prevent work-hardening and maintain ductility.
- Precision Coiling (Winding): The straight tube is fed through a CNC-controlled coiling machine that winds the tube into a uniform helical coil with precise pitch, diameter, and tension control. The coiling speed and tension are dynamically regulated to prevent deformation, kinking, or ovality.
- Surface Treatment (Optional): Electropolishing (EP) may be applied to achieve Ra ≤ 0.4 μm and remove surface contaminants, critical for pharmaceutical and food-grade applications.
- Final Quality Inspection: Every coil undergoes 100% visual inspection, dimensional verification (OD, wall thickness, coil diameter, pitch), hydrostatic pressure testing (per ASTM A270), and non-destructive testing (NDT) including ultrasonic testing (UT) and dye penetrant inspection (PT).
- Packaging & Dispatch: Coils are wound onto wooden reels or steel drums, wrapped with moisture-proof film, and labeled with heat numbers, grade, dimensions, and traceability information.
5. Applications
The stainless steel coil tube is engineered for demanding applications across multiple industries:
- Bioreactors & Environmental Engineering: Coil tubes are integral components of continuous-flow bioreactors used for biological nitrogen removal (denitrification) from low-pollution water. The helical geometry promotes biofilm formation on inner walls, enhances mass transfer of nutrients and dissolved oxygen, and facilitates continuous microbial culture operation. Research has demonstrated that coil-type bioreactors achieve superior denitrification efficiency compared to conventional plug-flow reactors.
- Heat Exchangers & Thermal Systems: The high surface-area-to-volume ratio of coil tubes makes them ideal for compact heat exchangers, condensers, evaporators, and reboilers in chemical, petrochemical, and power generation plants.
- Pharmaceutical & Biotechnology: Electropolished coil tubes meet USP Class VI and FDA 21 CFR 178.330 requirements, used in bioreactor systems, chromatography columns, CIP (Clean-in-Place) loops, and sterile fluid transfer.
- Food & Beverage Industry: Hygienic coil tubes are used in dairy processing, brewing, and beverage transfer systems where sanitary design and corrosion resistance are paramount.
- Chemical Processing: 316L and 904L coil tubes handle aggressive chemical media including acids, alkalis, and chlorinated solutions in chemical reactors, storage loops, and transfer systems.
- Petrochemical & Oil & Gas: Duplex 2205 coil tubes provide superior strength and corrosion resistance in offshore platforms, subsea piping, and upstream processing facilities.
- Medical Devices: Precision-drawn coil tubes are used in endoscopy instrument channels, infusion systems, and medical gas delivery networks.
- Automotive & Aerospace: Coil tubes serve as fuel lines, hydraulic lines, and exhaust system components requiring lightweight, corrosion-resistant, and high-temperature-resistant tubing.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and holds the following certifications to ensure product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System certification for consistent product quality and process control.
- ISO 14001:2015 — Environmental Management System certification for sustainable manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System certification.
- EN 10204 3.1 — Material Test Certificate (MTC) issued per European standard, providing full traceability of material origin, chemical composition, and mechanical test results.
- EN 10204 3.2 — Inspection Certificate issued by an authorized inspection body for critical applications.
- CE Marking (PED 2014/68/EU) — Conformity with European Pressure Equipment Directive for pressure-containing applications.
- NSF/ANSI 61 — Drinking water system components certification (for potable water applications).
- 3-A Sanitary Standards — Dairy and food processing equipment certification (for food-grade applications).
- ASTM / ASME Compliance — Products manufactured to ASTM A270, A269, and ASME B36.19M standards.
- GB/T Standards Compliance — Full compliance with Chinese national standards including GB/T 12771 and GB/T 14976.
7. Unique Selling Points
- Continuous Coil Geometry for Superior Mass Transfer: The helical coil configuration inherently generates secondary flow (Dean vortices) within the tube, enhancing convective mass and heat transfer rates by up to 30–50% compared to straight tubes of equivalent length. This makes coil tubes particularly effective in bioreactor and heat exchanger applications.
- Full Traceability & Quality Assurance: Every coil tube is traceable to the original mill heat number, with complete documentation of chemical analysis, mechanical testing, and dimensional inspection results.
- Custom Coiling Configuration: Coil diameter, pitch, length, and winding direction are fully customizable to meet specific project requirements, from small-diameter laboratory-scale coils to large industrial spools.
- Multi-Grade Availability: From standard 304/316 to premium 904L and duplex 2205, the product range covers virtually all corrosion and mechanical performance requirements.
- Hygienic Surface Finishes: Electropolished surfaces with Ra ≤ 0.4 μm meet the most stringent pharmaceutical, food, and medical device requirements, reducing bacterial adhesion and facilitating CIP/SIP processes.
- Cost-Effective Continuous Supply: The coil format eliminates the need for extensive welding of short tube segments, reducing installation labor, minimizing leak points, and lowering total system cost.
- Proven Bioreactor Performance: As validated by academic research on continuous denitrification of low-pollution