Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product supplied in continuous coil form. Designed for high-volume downstream processing, this coil tube combines the inherent corrosion resistance and mechanical integrity of austenitic stainless steel with the logistical and operational advantages of coil configuration. The product is intended for secondary fabrication processes including straightening, cutting, forming, and welding into finished pipe assemblies or structural components.
Coil tube represents a critical intermediate form in the stainless steel supply chain, bridging the gap between mill-produced seamless or welded tubes and end-use applications. Its continuous coil geometry enables automated feeding into high-speed processing lines, significantly reducing material waste and labor costs compared to individual bar-length supply.
2. Material & Properties
2.1 Base Alloy Composition
The coil tube is fabricated from austenitic stainless steel conforming to recognized international standards. The primary grade options include:
- 304 (UNS S30400 / AISI 304) — The most widely used general-purpose austenitic stainless steel, offering excellent corrosion resistance, formability, and weldability.
- 316 (UNS S31600 / AISI 316) — Enhanced corrosion resistance due to the addition of molybdenum (Mo), suitable for aggressive chemical and marine environments.
- 316L (UNS S31603 / AISI 316L) — Low-carbon variant of 316, optimized for welding applications requiring reduced sensitization risk.
- 321 (UNS S32100 / AISI 321) — Titanium-stabilized grade offering superior resistance to intergranular corrosion at elevated temperatures.
2.2 Mechanical Properties
- Tensile Strength (Ultimate Tensile Strength, UTS): 515–730 MPa (depending on grade and temper condition)
- Yield Strength (0.2% offset): 205–310 MPa
- Elongation at Break: ≥ 40% (minimum)
- Hardness (Rockwell B): 80–100 HRB
- Thermal Conductivity: 14–16 W/(m·K) at 20°C
2.3 Chemical Composition (Typical — Grade 304)
| Element | Specification (%) |
|---|---|
| C (Carbon) | ≤ 0.08 |
| Mn (Manganese) | ≤ 2.00 |
| P (Phosphorus) | ≤ 0.045 |
| S (Sulfur) | ≤ 0.030 |
| Si (Silicon) | ≤ 1.00 |
| Cr (Chromium) | 18.00 – 20.00 |
| Ni (Nickel) | 8.00 – 10.50 |
| N (Nitrogen) | ≤ 0.10 |
2.4 Physical Properties
- Density: 8.0 g/cm³
- Melting Range: 1400–1450°C (2552–2642°F)
- Specific Heat: 0.50 J/(g·K) at 100°C
- Modulus of Elasticity: 193 GPa (28 × 10⁶ psi)
- Surface Finish: 2B (cold-rolled, annealed, and bright-passed) or No. 4 brushed finish available upon request
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Catalog No. | 840 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Outer Diameter (OD) | 3.00 mm – 32.00 mm (custom sizes available) |
| Wall Thickness | 0.20 mm – 3.00 mm |
| Coil Inner Diameter (ID) | 150 mm / 200 mm / 300 mm (standard options) |
| Coil Weight | 500 kg – 1,500 kg per coil (typical) |
| Length per Coil | 100 m – 500 m (variable based on OD and wall thickness) |
| Applicable Standards | ASTM A213, ASTM A269, EN 10216-5, GB/T 12771 |
| Manufacturing Method | ERW (Electric Resistance Welding) or seamless (upon request) |
| Surface Treatment | 2B finish (standard); pickled & passivated (P&P) available |
| Heat Treatment | Annealed and pickled (solution annealed at 1040–1120°C) |
| Packaging | Export-standard wooden pallet with moisture-proof wrapping; coil cores protected |
| Moisture Proof | VCI (Vapor Corrosion Inhibitor) paper wrapping for long-term storage |
4. Manufacturing Process
4.1 Raw Material Procurement & Inspection
High-purity stainless steel strip or coil is sourced from certified mill suppliers. Incoming material undergoes rigorous inspection including chemical composition verification (via optical emission spectrometry, OES), mechanical property testing, and surface quality examination to ensure conformity with specified grades and standards.
4.2 Coil Winding & Forming
The stainless steel strip is fed into a precision roll-forming line where it is shaped into a circular cross-section. The forming process is carefully calibrated to maintain dimensional accuracy and avoid work hardening or surface defects.
4.3 Welding (ERW Process)
For welded coil tube, the formed strip passes through an Electric Resistance Welding (ERW) station. High-frequency current is applied to the edges of the strip, heating them to the welding temperature, after which they are pressed together to form a tight, metallurgically sound weld seam. The weld zone is subsequently trimmed and inspected.
4.4 Heat Treatment
Following welding, the coil tube undergoes solution annealing at temperatures between 1040°C and 1120°C, followed by rapid cooling (air or water quench). This process dissolves carbides, restores the austenitic microstructure, and imparts optimal corrosion resistance and ductility.
4.5 Pickling & Passivation
The annealed coil is subjected to a pickling process using a controlled acid bath (typically a mixture of hydrofluoric and nitric acid) to remove the oxide scale formed during annealing. This is followed by passivation, which establishes a protective chromium oxide film on the surface, enhancing corrosion resistance.
4.6 Final Coiling & Packaging
The finished coil tube is wound onto a core with controlled tension to prevent deformation. Each coil is wrapped with protective VCI paper and secured for export-standard shipping on wooden pallets.
5. Applications
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. finds extensive application across multiple industrial sectors:
5.1 HVAC & Building Services
- Chiller and condenser tube bundles
- Fan coil unit heat exchangers (variable air volume systems)
- Air conditioning condensate drainage lines
- Underfloor heating distribution piping
5.2 Food & Beverage Processing
- Sanitary process piping for dairy, brewing, and pharmaceutical production
- Heat exchangers and pasteurization systems
- Conveyance lines requiring CIP (Clean-In-Place) compatibility
5.3 Chemical & Petrochemical Industry
- Corrosive fluid transfer lines
- Reactor internals and heat exchanger tubes
- Marine and offshore platform piping systems
5.4 Automotive & Mechanical Engineering
- Exhaust system components
- Fluid lines and hydraulic components
- Structural tubing for precision machinery
5.5 Medical & Laboratory Equipment
- Instrumentation tubing for analytical equipment
- Medical device housings and fluidic components
- Gas delivery lines in hospital infrastructure
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring product conformity and traceability:
- ISO 9001:2015 — Quality Management System certification for consistent manufacturing practices
- ISO 14001:2015 — Environmental Management System compliance
- CE Marking — Conformity with European health, safety, and environmental protection standards (EU Pressure Equipment Directive 2014/68/EU where applicable)
- EN 10204 3.1 Certificate — Third-party test certification available for each batch
- Mill Test Certificate (MTC) — Full chemical and mechanical analysis documentation provided with every shipment
- ASTM / EN Standard Compliance — Product manufactured and tested to applicable ASTM and European Norm specifications
7. Unique Selling Points
Dimensional Precision: Tolerances controlled to ±0.05 mm on wall thickness and ±0.10 mm on outer diameter, ensuring reliable fit-up in automated processing lines.
Superior Surface Quality: 2B finish with Ra ≤ 0.4 μm surface roughness, minimizing friction in fluid-carrying applications and reducing biofilm formation in sanitary environments.
Consistent Chemical Composition: Each production batch is verified by independent laboratory analysis, ensuring uniform corrosion resistance and mechanical properties throughout the coil length.
Logistical Efficiency: Coil configuration enables continuous automated feeding, reducing downstream processing time by up to 40% compared to bar-length supply.
Customization Capability: Non-standard dimensions, surface finishes, and packaging configurations are available through the engineering support team to meet specific project requirements.
8. Technical Support & Documentation
Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical documentation including material certifications, dimensional drawings, and application engineering guidance. The technical team is available to assist with material selection, specification compliance verification, and integration into downstream processing workflows.