Stainless Steel Helical Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Helical Coil Tube is a precisely manufactured continuous tubular product formed by winding stainless steel pipe or tubing into a helical (spiral) configuration. This product is supplied in coil form, enabling efficient storage, transport, and on-site deployment in process engineering systems. The helical geometry is not merely a packaging format — it is a functionally optimized configuration that significantly enhances fluid dynamics performance compared to straight tubular counterparts.
Based on rigorous experimental research into the flow characteristics of helical coil tubes, it has been demonstrated that the helical curvature induces a centrifugal force component on the flowing medium, generating secondary Dean vortices within the tube cross-section. These Dean vortices effectively disrupt the boundary layer, increase turbulence intensity, and substantially improve heat transfer coefficients — typically achieving a 20% to 40% enhancement in heat transfer performance relative to equivalent straight tubes, while simultaneously maintaining a favorable pressure drop profile. This makes helical coil tubes an ideal choice for compact heat exchangers, condensers, evaporators, and high-efficiency process piping systems.
Produced by Wenzhou Jixing Metal Materials Co., Ltd., this product series adheres to international manufacturing standards and is engineered for demanding industrial, chemical, pharmaceutical, food and beverage, and energy applications where corrosion resistance, mechanical integrity, and thermal performance are critical design parameters.
2. Material & Properties
2.1 Available Material Grades
- Austenitic Stainless Steel: SUS304 (ASTM A312 TP304), SUS316 (ASTM A312 TP316), SUS316L (ASTM A312 TP316L), SUS321 (ASTM A312 TP321), SUS347 (ASTM A312 TP347)
- Super-Austenitic Stainless Steel: SUS904L (ASTM A312 TP904L), Duplex 2205 (ASTM A312 TP2205)
- Custom Alloys: Available upon request for specialized corrosion or temperature requirements
2.2 Key Material Properties
| Property | SUS304 | SUS316 | Duplex 2205 |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 520 MPa | ≥ 515 MPa | ≥ 550 MPa |
| Yield Strength (Rp0.2) | ≥ 205 MPa | ≥ 205 MPa | ≥ 450 MPa |
| Elongation (A) | ≥ 40% | ≥ 40% | ≥ 25% |
| Maximum Service Temperature | 870 °C (1600 °F) | 870 °C (1600 °F) | 320 °C (608 °F) |
| Corrosion Resistance (Pitting) | Good | Excellent (Mo-enhanced) | Outstanding |
| Thermal Conductivity (20 °C) | 16.3 W/(m·K) | 14.6 W/(m·K) | 18.0 W/(m·K) |
| Surface Roughness (Ra) | ≤ 0.8 μm (Standard) | ≤ 0.8 μm (Standard) | ≤ 0.8 μm (Standard) |
2.3 Surface Finish Options
- 2B Finish: Standard cold-rolled finish for general industrial applications
- No. 4 Brushed Finish: Aesthetic and functional brushed surface for visible installations
- Mirror Polish (8K): High-gloss finish for food-grade and pharmaceutical applications
- Electropolished: Ultra-clean surface with Ra ≤ 0.25 μm, suitable for sanitary and bioprocessing
- Pickled & Passivated: Chemically cleaned surface restoring full corrosion resistance
3. Specifications
| Parameter | Specification Range | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 159.0 mm (1/4" – 6") | ASTM A312 / ASME SA-312 |
| Wall Thickness | 0.5 mm – 12.0 mm (0.020" – 0.470") | ASTM A312 / ASME SA-312 |
| Coil Diameter (CD) | 300 mm – 2000 mm (12" – 80") | Customer-Specified |
| Helical Pitch | 50 mm – 300 mm (adjustable) | Engineering Design Requirement |
| Length per Coil | 5 m – 200 m (continuous or cut-to-length) | Customer-Specified |
| OD Tolerance | ±0.1 mm (≤ 25 mm OD); ±0.15% (＞ 25 mm OD) | ASTM A312 |
| Wall Thickness Tolerance | ±10% (standard); ±5% (close tolerance on request) | ASTM A312 |
| Hardness (HV) | ≤ 200 HV (annealed); 250–350 HV (work-hardened) | ASTM A312 |
| Operating Pressure (Design) | Up to 64 bar (918 psi) — grade dependent | ASME B31.3 |
| Operating Temperature Range | −196 °C to +870 °C (grade dependent) | ASME B31.3 |
| Winding Accuracy | ±1.5 mm (pitch deviation); ±3 mm (diameter deviation) | ISO 9001 Quality Control |
| Packaging | Wooden crate / export-grade pallet / shrink-wrapped coil | ISO 4180 (Packaging for Transport) |
4. Manufacturing Process
The production of high-quality stainless steel helical coil tubes follows a rigorous multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Procurement & Inspection: Stainless steel coils or bar stock are sourced from certified mills. Incoming material undergoes 100% chemical composition analysis (via optical emission spectroscopy, OES) and mechanical property verification to ensure compliance with the specified ASTM or EN grade.
- Cold Drawing / Seamless Tube Forming: Raw material is processed through cold-drawing or seamless piercing to produce the base tube with precise outer diameter and wall thickness. This step establishes the fundamental geometric accuracy of the product.
- Intermediate Annealing & Pickling: The drawn tube undergoes controlled annealing to relieve cold-work stresses and restore ductility. Subsequent pickling and passivation removes surface oxides, restoring the full corrosion resistance of the chromium-oxide passive layer.
- Helical Winding & Forming: The straight tube is fed through a precision-controlled helical winding machine. CNC-guided rollers impose the specified coil diameter and pitch. The winding parameters are continuously monitored to ensure geometric fidelity. The helical curvature is formed without introducing excessive residual stresses that could compromise fatigue life or cause springback.
- Post-Forming Stress Relief (Optional): For applications requiring dimensional stability after forming, a low-temperature stress-relief anneal (typically 400–550 °C) may be applied to the coiled configuration.
- Surface Treatment & Finishing: Depending on the application, the coil tube may undergo additional surface finishing — including mechanical polishing, electropolishing, or final passivation treatment — to achieve the required surface roughness and cleanliness.
- Quality Inspection & Testing: Each batch undergoes comprehensive quality assurance, including:
- Visual inspection for surface defects, dents, or scratches
- Dimensional verification (OD, wall thickness, coil diameter, pitch) using calibrated gauges and laser measurement systems
- Hydrostatic pressure testing (typically 1.5× design pressure, minimum 2.0 MPa)
- Eddy current testing (ECT) for internal defect detection
- Spectroscopic analysis (PMI — Positive Material Identification) to confirm alloy composition
- Hardness testing per ASTM E18 (Vickers) or E92 (Rockwell)
- Packaging & Dispatch: Finished coil tubes are securely packaged to prevent mechanical damage, moisture exposure, and contamination during transit. Each shipment is accompanied by a Mill Test Certificate (MTC) / Certificate of Conformity (CoC).
5. Applications
The helical coil geometry, combined with the superior properties of stainless steel, renders this product suitable for a broad spectrum of industrial applications:
5.1 Heat Exchanger Systems
- Shell-and-tube heat exchangers utilizing helical coil bundles for enhanced heat transfer
- Plate-fin heat exchangers and air-cooled condensers
- Refrigeration and HVAC (Heating, Ventilation, and Air Conditioning) systems
- Cryogenic heat exchangers for LNG (Liquefied Natural Gas) processing
5.2 Chemical & Petrochemical Processing
- Process piping for corrosive chemical transfer (acids, alkalis, halides)
- Reactor coil internals for jacketed reactors and tubular reactors
- Distillation column condensers and reboilers
- High-pressure process lines in refineries and petrochemical plants
5.3 Food, Beverage & Pharmaceutical
- Sterile fluid transfer and process piping (electropolished finish)
- Steam sterilization (SIP — Sterilization In Place) systems
- Milk pasteurization and UHT (Ultra-High Temperature) processing equipment
- Beverage brewing, fermentation, and carbonation systems
5.4 Power Generation & Energy
- Supercritical and ultra-supercritical boiler economizers
- Solar thermal collector loop tubes
- Geothermal heat extraction systems
- Nuclear-grade heat transfer components (SUS316L, DUPLEX 2205)
5.5 Mechanical & Structural Applications
- Automotive exhaust systems and turbocharger manifolds
- Spring coils and load-bearing helical elements
- Industrial filter housings and filtration system internals
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring full traceability and compliance with international standards:
| Certification / Standard | Scope of Compliance |
|---|---|
| ISO 9001:2015 | Quality Management System — Full manufacturing process |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management System |
| ASTM A312 / ASME SA-312 | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing |
| ASTM A269 / ASME SA-269 | Standard Specification for Welded Austenitic Stainless Steel Tubing |
| EN 10217-7 | European Standard for Heat Exchanger Tubes — Stainless Steel |
| GB/T 12771 | Chinese National Standard for Stainless Steel Tubes for General Fluid Transport |
| ASME B31.3 | Process Piping Design Code Compliance |
| CE Marking (PED 2014/68/EU |