Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Product No. 1642) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. in accordance with international quality standards. Coil tubes are formed by bending straight stainless steel pipe into a continuous helical or serpentine configuration, offering superior heat transfer efficiency, compact footprint, and exceptional resistance to corrosion. These products are widely employed in thermal management systems, chemical processing, food and pharmaceutical industries, and automotive applications where both fluid conveyance and heat exchange are critical.
The coil tube design maximizes the surface-area-to-volume ratio, making it an optimal choice for compact heat exchangers, evaporators, condensers, and radiator assemblies. The continuous coil geometry also eliminates the need for extensive welding at installation, reducing potential failure points and lowering manufacturing costs.
2. Material & Properties
2.1 Base Materials
Coil tubes are fabricated from high-grade austenitic and duplex stainless steels, selected based on the intended service environment:
- SAE 304 / AISI 304 (UNS S30400) — General-purpose austenitic stainless steel with excellent corrosion resistance in oxidizing environments. Chromium content: 18–20%, Nickel content: 8–10.5%.
- SAE 316 / AISI 316 (UNS S31600) — Enhanced molybdenum-bearing austenitic grade offering superior resistance to pitting and crevice corrosion in chloride-containing environments. Molybdenum content: 2–3%.
- SAE 321 / AISI 321 (UNS S32100) — Titanium-stabilized austenitic grade suitable for elevated-temperature applications up to 870°C.
- SAE 316L / AISI 316L (UNS S31603) — Low-carbon variant of 316, preferred for welded assemblies requiring resistance to intergranular corrosion.
- SAE 304L / AISI 304L (UNS S30403) — Low-carbon variant of 304, suitable for welding and cryogenic applications.
2.2 Mechanical Properties (Annealed Condition)
| Property | SAE 304 / 304L | SAE 316 / 316L | SAE 321 |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 515 | ≥ 515 |
| Yield Strength (0.2% offset, MPa) | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 |
| Density (g/cm³) | 7.93 | 8.00 | 7.90 |
| Thermal Conductivity at 100°C (W/m·K) | 16.3 | 14.6 | 16.3 |
| Maximum Service Temperature (°C) | 870 | 870 | 900 |
2.3 Corrosion Resistance
All grades exhibit excellent resistance to atmospheric corrosion, dilute acids, and alkaline solutions. The addition of molybdenum in 316-series grades provides enhanced resistance to marine environments, sulfuric acid solutions, and halide-containing media. The passive chromium oxide layer (Cr₂O₃) self-heals in the presence of oxygen, providing long-term protection against corrosion.
3. Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 1.0 mm – 50.8 mm (custom sizes available) |
| Wall Thickness | 0.15 mm – 3.0 mm |
| Coil Diameter | 50 mm – 500 mm (configurable) |
| Coil Length | 1 m – 100 m (continuous or custom-cut) |
| Surface Finish | Bright Annealed (BA), Pickled & Passivated, Polished (2B, No. 4, Mirror) |
| Coil Pitch | 3 mm – 20 mm (adjustable per application) |
| Manufacturing Tolerance (OD) | ±0.05 mm (precision grade); ±0.10 mm (standard grade) |
| Manufacturing Tolerance (Wall) | ±0.03 mm (precision grade); ±0.08 mm (standard grade) |
| Applicable Standards | ASTM A269, ASTM A270, EN 10217-7, GB/T 12771, JIS G3459 |
| End Condition | Plain, Beveled, Flanged, Threaded, or Fitted |
| Coating / Treatment | Passivation (citric acid or nitric acid), Optional PTFE lining |
| Packaging | Wooden crate, export-grade pallet, moisture-proof wrapping |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Procurement: Selection of certified stainless steel seamless or welded pipe stock from approved suppliers, with full chemical and mechanical property verification.
- Material Inspection: Incoming inspection including spectroscopic analysis (OES), dimensional verification, and surface quality assessment.
- Heat Treatment (if required): Solution annealing at 1050–1150°C followed by rapid quenching to achieve the desired microstructure and mechanical properties.
- Coil Forming: Precision cold-bending using CNC-controlled forming machines with hydraulic tensioning systems to achieve uniform coil geometry without material deformation or work-hardening.
- Surface Treatment: Pickling (to remove oxide scale), passivation (to restore protective chromium oxide layer), and polishing (if specified finish is required).
- Quality Control: Dimensional inspection (laser measurement), hydrostatic pressure testing (typically 2–3× working pressure), and visual surface inspection.
- End Processing: Cutting, beveling, threading, or fitting attachment as per customer specifications.
- Final Inspection & Packaging: Comprehensive quality documentation, protective packaging, and labeling for shipment.
4.2 Key Process Parameters
- Minimum Bending Radius: 3× OD (cold forming); 2× OD (hot forming)
- Forming Temperature: Room temperature (cold) or 600–800°C (hot, for larger diameters)
- Hydrostatic Test Pressure: 25 MPa (standard); up to 63 MPa (high-pressure applications)
5. Applications
5.1 Primary Industries
- Heat Exchangers & Radiators: Coil tubes are integral components in automotive radiators, air conditioning condensers, refrigeration evaporators, and industrial heat exchangers where compact design and high thermal efficiency are paramount.
- Chemical Processing: Used for fluid transport, reactor internals, and heat exchange in aggressive chemical environments (acids, alkalis, chlorides).
- Food & Pharmaceutical: Compliant with sanitary standards for dairy processing, beverage production, and pharmaceutical fluid handling due to non-reactive, easy-to-clean surfaces.
- Oil & Gas: Downhole tools, subsea pipelines, and wellhead equipment in corrosive offshore environments.
- Aerospace: Hydraulic lines, fuel systems, and thermal management in aircraft and satellite systems.
- Power Generation: Boiler tubes, superheater coils, and condenser tubes in thermal and nuclear power plants.
- Automotive: Exhaust systems, turbocharger intercoolers, and fuel delivery lines.
5.2 Unique Selling Points
- Superior Heat Transfer Performance: The helical geometry increases turbulence and heat transfer coefficient by up to 30% compared to straight tubes.
- Corrosion Resistance: Long service life in aggressive environments without degradation of mechanical properties.
- Compact Design: Space-efficient packaging of large heat exchange surface areas.
- Weld-Free Installation: Continuous coil design minimizes joints and potential leak points.
- Customizability: Full range of material grades, dimensions, and surface finishes tailored to specific application requirements.
- Low Maintenance: Self-passivating surface reduces cleaning frequency and operational downtime.
6. Quality Certifications & Compliance
6.1 International Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health and Safety Management
- EN 10204 3.1 — Material Test Certificates
- PED 2014/68/EU — Pressure Equipment Directive compliance (where applicable)
- ASME Section IX — Welding qualification (for welded coil tube assemblies)
6.2 Testing & Inspection
- Chemical composition verification (OES / XRF)
- Mechanical property testing (tensile, hardness, impact)
- Hydrostatic pressure testing (100% inspection)
- Dimensional inspection (CMM, laser gauging)
- Surface finish measurement (Ra ≤ 0.8 μm for polished grades)
- Non-destructive testing: Eddy current (ECT), ultrasonic testing (UT), dye penetrant (PT)
- Corrosion testing: Salt spray (ASTM B117), intergranular corrosion (ASTM A262 Practice E)
6.3 Traceability
Every coil tube lot is accompanied by a full traceability package including mill test certificates, heat number documentation, dimensional reports, and non-destructive testing records. This ensures complete supply chain transparency and facilitates regulatory compliance in regulated industries such as pharmaceutical, aerospace, and food processing.
7. Conclusion
The Stainless Steel Coil Tube (Product No. 1642) from Wenzhou Jixing Metal Materials Co., Ltd. represents a premium-grade engineered product combining metallurgical excellence with precision manufacturing. Its versatility across industries, proven corrosion resistance, and compliance with global quality standards make it an indispensable component in modern thermal management and fluid handling systems. Custom engineering support and technical consultation are available for specialized application requirements.