Stainless Steel Coil Tube — Direct Flame Deodorization Series
1. Product Overview
The Stainless Steel Coil Tube (盘管) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1588). This coil tube is specifically designed and optimized for use in Direct Flame Deodorization Devices (直焰式除臭装置), where it serves as the core heat-exchange and gas-conduction component. The product combines the superior corrosion resistance and mechanical integrity of austenitic stainless steel with a continuous coil winding geometry, enabling efficient thermal transfer and durable performance under repeated high-temperature cycling conditions.
Unlike conventional straight-length pipes, coil tubes offer a significantly increased surface-area-to-volume ratio, making them ideal for applications requiring rapid heat dissipation, compact installation footprints, and resistance to thermal fatigue. The direct flame deodorization application subjects the coil tube to localized high-temperature zones and aggressive chemical environments, demanding materials and manufacturing processes that exceed standard industrial pipe specifications.
2. Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, high-temperature strength, and weldability. The primary grades utilized include:
- SUS304 (UNS S30408 / 1.4301) — General-purpose austenitic grade offering excellent resistance to atmospheric, aqueous, and mild chemical corrosion. Chromium content of 18–20% and nickel content of 8–10.5% provide a robust passive oxide film.
- SUS316 (UNS S31608 / 1.4401) — Enhanced grade with 2–3% molybdenum addition, providing superior resistance to pitting and crevice corrosion, particularly in chloride-containing environments encountered during deodorization processes.
- SUS321 (UNS S32168 / 1.4541) — Titanium-stabilized grade offering excellent resistance to intergranular corrosion at elevated temperatures (450–850°C), making it suitable for sustained high-temperature flame exposure.
Key Mechanical Properties
| Property | SUS304 | SUS316 | SUS321 | Test Standard |
|---|---|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 515 | ≥ 515 | ASTM A213 / GB/T 12771 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 205 | ASTM A213 / GB/T 12771 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 | ASTM A213 / GB/T 12771 |
| Maximum Service Temperature (°C) | 870 | 870 | 925 | Material Data Sheet |
| Corrosion Resistance (Pitting) | Good | Excellent | Good | ASTM G48 |
| Thermal Conductivity (W/m·K at 100°C) | 16.3 | 14.6 | 14.6 | ASTM E1461 |
Chemical Composition (Typical, wt%)
| Grade | C | Si | Mn | P | S | Cr | Ni | Mo | Ti |
|---|---|---|---|---|---|---|---|---|---|
| SUS304 | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | 18.0–20.0 | 8.0–10.5 | — | — |
| SUS316 | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — |
| SUS321 | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | 17.0–19.0 | 9.0–12.0 | — | 5×C–0.40 |
3. Specifications
| Parameter | Specification | Tolerance | Standard Reference |
|---|---|---|---|
| Product Designation | Stainless Steel Coil Tube (盘管) | — | Product No. 1588 |
| Outer Diameter (OD) | 6 mm – 51 mm | ±0.1 mm | ASTM A213 / GB/T 12771 |
| Wall Thickness | 0.5 mm – 3.0 mm | ±10% of nominal | ASTM A213 / GB/T 12771 |
| Coil Diameter | 100 mm – 600 mm | ±2% | Manufacturer Specification |
| Coil Length per Spool | 5 m – 500 m (configurable) | ±5% | Manufacturer Specification |
| Surface Finish | Mill Finish / Polished / Electropolished | Ra ≤ 0.8 μm (polished) | ASTM A270 |
| Form | Seamless or Welded (per customer requirement) | — | ASTM A213 / ASTM A269 |
| Heat Treatment | Solution Annealed (1050–1150°C) + Water Quenched | — | ASTM A213 |
| End Treatment | Cut Square / Beveled / Threaded | — | Customer Specification |
| Packaging | Wooden Spool / Pallet with VCI (Vapor Corrosion Inhibitor) Wrap | — | ISO 4180 |
4. Manufacturing Process
The production of stainless steel coil tubes for direct flame deodorization applications follows a rigorous multi-stage manufacturing protocol designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
-
Raw Material Selection & Inspection
Ingot or strip material is sourced from certified mills and subjected to spectroscopic analysis (Optical Emission Spectrometry, OES) to verify chemical composition compliance with the specified grade. Each heat lot is traceable to its mill test certificate (MTC). -
Pipe Forming
For seamless coil tubes, hot-rolled or cold-rolled stainless steel strip is wound around a mandrel and welded longitudinally via Automatic Transverse Argon (ATA) or Laser Welding (LTW) processes. For seamless variants, hot piercing and cold drawing are employed. The forming process is controlled to minimize residual stress and maintain uniform wall thickness. -
Coil Winding
The formed tube is wound onto a precision coil-winding machine using computer-controlled tension systems to produce consistent coil diameters and pitch. The winding process employs variable-speed motors to prevent tube distortion, kinking, or ovality exceeding ±1% of nominal OD. -
Solution Annealing
The coil tube is heated to 1050–1150°C in a protective atmosphere (hydrogen or argon) to dissolve carbide precipitates, followed by rapid water quenching. This restores full austenitic microstructure, eliminates cold-work hardening, and maximizes corrosion resistance. -
Pickling & Passivation
Post-annealing, the surface is pickled using a mixed acid bath (nitric acid + hydrofluoric acid) to remove oxide scale, followed by passivation with 20–30% nitric acid solution. This establishes a stable chromium oxide passive film critical for long-term corrosion resistance. -
Surface Finishing
Depending on the application requirement, the coil tube may undergo mechanical polishing (Ra ≤ 1.6 μm) or electropolishing (Ra ≤ 0.4 μm). Electropolishing simultaneously removes surface contamination, refines grain structure at the surface, and enhances the passive film. -
Non-Destructive Testing (NDT)
Each coil tube undergoes comprehensive quality inspection including:- Eddy Current Testing (ECT) — Detection of surface and near-surface defects (ASTM E309)
- Hydrostatic Pressure Testing — Verification of weld integrity and pressure resistance (ASTM A213)
- Dimensional Inspection — OD, wall thickness, and coil diameter verification via ultrasonic gauging
- Intergranular Corrosion Testing — ASTM A262 Practice E for stabilized grades
-
Packaging & Shipping
Finished coil tubes are wound onto hardwood spools, wrapped with VCI (Vapor Corrosion Inhibitor) film, and secured with steel strapping. Each shipment is accompanied by a full documentation package including MTC, NDT reports, and dimensional certificates.
5. Applications
The primary application domain for this stainless steel coil tube is the Direct Flame Deodorization Device (盘管直焰式除臭装置), a specialized environmental treatment system used for odor control and air purification. Key application areas include:
- Environmental Deodorization Systems — The coil tube functions as the heat-exchange conduit and gas channel in direct flame deodorization units, where combustion gases pass through the coil to achieve thermal decomposition of odor-causing compounds (volatile organic compounds, VOCs). The stainless steel construction withstands temperatures up to 870°C while resisting sulfuric acid and nitrogen oxide corrosion.
- Industrial Waste Gas Treatment — Municipal waste treatment plants, sewage treatment facilities, and landfill gas systems utilize these coil tubes in flue gas treatment and catalytic oxidation (Catalytic Oxidation, CO) units.
- Food Processing & Pharmaceutical Cleanrooms — Odor control in food processing plants, dairy facilities, and pharmaceutical manufacturing environments where hygienic-grade stainless steel surfaces are mandated.
- Heat Exchanger Coils — The coil geometry is also applicable in air-to-air and air-to-water heat exchangers, refrigeration systems, and HVAC (Heating, Ventilation, and Air Conditioning) applications where compact, high-efficiency thermal exchange is required.
- Process Piping in Chemical Industries — Continuous coil lengths eliminate the need for numerous weld joints, reducing leak points in chemical processing, petrochemical, and semiconductor manufacturing applications.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring full traceability and compliance with international standards:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System — Ensures consistent product quality and customer satisfaction through documented processes and continuous improvement. |
| ISO 14001:2015 | Environmental Management System — Demonstrates commitment to environmentally responsible manufacturing practices. |
| ASTM A213 / A26 |