Stainless Steel Spiral Coil Tube — Coiltube (Ref. No. 1666)
Product Overview
The Stainless Steel Spiral Coil Tube (盘管 / Coiltube) is a precision-engineered tubular component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is designed specifically for integration into spiral coil heat exchangers (螺旋盘管换热器), where it serves as the primary heat transfer surface. The coil tube is formed from seamless stainless steel pipe through a controlled cold-coiling process, producing a continuous helical geometry with uniform pitch, consistent wall thickness, and superior surface finish. The design philosophy draws upon established principles of shell-and-coil heat exchanger engineering, emphasizing compactness, thermal efficiency, and long-term mechanical integrity under cyclic thermal loading.
Coil tubes of this type find extensive use in process industries where high heat transfer coefficients are required within spatially constrained equipment. The helical configuration inherently promotes turbulent flow within the tube, significantly enhancing convective heat transfer compared to straight-tube alternatives, while the compact winding pattern maximizes the heat transfer area per unit volume of the heat exchanger.
Material & Properties
The coil tube is fabricated from austenitic stainless steel grades conforming to international standards. The following materials are available:
- ASTM A312 / A213 Grade 304 (UNS S30400) — General-purpose corrosion resistance; excellent formability; suitable for food-grade and chemical processing applications.
- ASTM A312 / A213 Grade 316L (UNS S31603) — Enhanced resistance to chlorides and pitting corrosion; preferred for marine, pharmaceutical, and aggressive chemical environments.
- ASTM A312 / A213 Grade 321 (UNS S32100) — Titanium-stabilized grade with superior resistance to intergranular corrosion at elevated temperatures.
- ASTM A312 / A213 Grade 310S (UNS S31008) — High-temperature grade suitable for furnace applications and extreme thermal cycling.
Key mechanical and physical properties for the standard 304/316L grades at room temperature include:
- Tensile Strength (抗拉强度): ≥ 515 MPa (304); ≥ 515 MPa (316L)
- Yield Strength (屈服强度): ≥ 205 MPa (0.2% offset)
- Elongation (延伸率): ≥ 40% (minimum, per ASTM A312)
- Operating Temperature Range (工作温度范围): −196 °C to +870 °C (304); −196 °C to +870 °C (316L)
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and many chemical media; resistance to stress corrosion cracking (SCC) is grade-dependent.
Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Tube Outer Diameter (OD) | 6.0 mm – 32.0 mm (custom sizes available) | ASTM A312 / A213 |
| Tube Wall Thickness | 0.5 mm – 3.0 mm | ASTM A312 |
| Coil Outer Diameter (COD) | 50 mm – 1200 mm | EN 10216 / Custom |
| Coil Pitch | 8 mm – 60 mm (configurable per design) | EN 10216 |
| Coil Length | Up to 3000 mm (continuous coil) | — |
| Surface Finish | Mechanical (No. 4 finish); Electro-polished (Ra ≤ 0.4 μm) | ASTM A480 |
| End Condition | Plain cut; Beveled; Threaded (per customer drawing) | ASME B1.20.1 |
| Pressure Rating | Up to 25 bar (design-dependent; verified per ASME VIII) | ASME BPV Code VIII Div. 1 |
| Manufacturing Process | Cold coiling from seamless pipe; solution annealing; stress relief | ISO 9001 |
| Acceptable Standards | ASTM A312; EN 10216-5; GB/T 12771; ASME SA-213 | Multi-standard compliance |
Manufacturing Process
The production of stainless steel spiral coil tubes follows a rigorously controlled multi-stage process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection & Inspection — Seamless stainless steel pipe is sourced from certified mills. Each batch undergoes incoming inspection including chemical composition analysis (via spark OES or wet chemistry), dimensional verification, and visual surface examination. Material traceability is maintained through mill test certificates (MTC / EN 10204 Type 3.1).
- Cutting & Preparation — The seamless pipe is cut to the required coil length with precision saws. End faces are deburred and chamfered to facilitate subsequent coiling without edge deformation or surface damage.
- Coil Forming (Coiling) — The pipe is passed through a precision coil-winding machine (盘管成型机) equipped with adjustable dies and tension control systems. The helical geometry — including coil diameter, pitch, and number of turns — is programmatically controlled. Cold coiling is performed at ambient temperature to preserve the solution-annealed microstructure of the austenitic stainless steel. Tension is carefully managed to prevent ovality, wrinkling, or springback.
- Stress Relief & Annealing — Following coiling, the coil tube may undergo a controlled stress-relief annealing cycle (typically 1050 °C – 1150 °C, rapid water quench) to eliminate residual stresses introduced during cold forming. This step is critical for preventing delayed stress corrosion cracking (SCC) in chloride-containing environments and for ensuring dimensional stability during subsequent welding or brazing operations.
- Surface Treatment & Finishing — Depending on the application requirements, the coil tube may undergo mechanical polishing (brushed No. 4 finish), electro-polishing (for Ra ≤ 0.4 μm), or passivation treatment (per ASTM A967) to restore and enhance the passive chromium oxide layer.
- Quality Control & Testing — Final inspection includes dimensional verification (OD, wall thickness, coil diameter, pitch), hydrostatic pressure testing (per ASTM A312), visual examination, and optional radiographic testing (RT) at critical locations. All coils are identified with unique batch numbers for full traceability.
Applications
Stainless steel spiral coil tubes are integral components in a wide range of industrial and commercial systems where efficient heat transfer, corrosion resistance, and compact design are paramount:
- Shell-and-Coil Heat Exchangers (螺旋盘管换热器) — The coil tube serves as the tube-side heat transfer element, typically installed within a shell containing a heating or cooling medium. Applications include process heating, product cooling, and thermal energy storage systems.
- Refrigeration & HVAC Systems — Used in evaporators and condensers where the helical geometry enhances heat transfer and reduces refrigerant charge volume.
- Chemical Processing — Employed in reactors, distillation columns, and heat recovery systems handling corrosive fluids (acids, alkalis, halogenated solvents) where 316L grade provides essential corrosion protection.
- Food & Beverage Industry — Utilized in pasteurizers, condensers, and heat exchangers for dairy, brewery, and pharmaceutical processing. Electro-polished surfaces meet hygienic requirements per 3-A Sanitary Standards and EHEDG guidelines.
- Marine & Offshore Engineering — Applied in seawater coolers, condensate recovery systems, and thermal management units where resistance to marine corrosion is essential.
- Power Generation — Used in feedwater heaters, economizers, and waste-heat recovery systems in both conventional and renewable energy installations.
- Automotive & Aerospace — Employed in engine coolant circuits, hydraulic systems, and thermal management components requiring lightweight, high-performance heat exchange elements.
Unique Selling Points
- Enhanced Heat Transfer Performance — The helical geometry induces secondary Dean vortices within the tube, promoting turbulent flow at lower Reynolds numbers compared to straight tubes. This results in heat transfer coefficients up to 2–3 times higher than equivalent straight-tube configurations.
- Compact Design — High heat transfer area density allows significant equipment downsizing, reducing footprint, weight, and material costs in installed systems.
- Full Traceability — Every coil tube is produced with complete material traceability from mill certificate through final inspection, ensuring compliance with stringent industry standards.
- Custom Engineering Capability — Wenzhou Jixing Metal Materials Co., Ltd offers fully customizable coil geometry (diameter, pitch, length, tube size) to meet specific design requirements, supported by engineering consultation and design review services.
- Multi-Grade Availability — Product range spans from standard 304/316L to specialized high-temperature and high-corrosion grades (321, 310S, 904L, duplex 2205), ensuring suitability across diverse operating environments.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality management systems and product certifications to assure customers of consistent quality and regulatory compliance:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing and quality assurance processes.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ASME "S" Stamp — Authorization for manufacture of pressure-containing components per ASME Boiler and Pressure Vessel Code.
- EN 10204 Type 3.1 — Third-party inspection and testing certification for material and product conformity.
- NADCAP / PED 2014/68/EU — Compliance with European Pressure Equipment Directive for products intended for use in EU member states.
- CE Marking — Conformity with applicable European health, safety, and environmental protection standards.
- Hygienic Certification — 3-A Sanitary Standards and EHEDG compliance for food-grade and pharmaceutical applications.
Design Note: The design and selection of spiral coil tubes for heat exchanger applications should account for the thermal expansion differential between the coil and the containing shell, the allowable stress limits per ASME BPV Code Section VIII, and the minimum bend radius constraints (typically ≥ 5× OD for seamless pipe) to prevent kinking or wall thinning during coiling. Wenzhou Jixing Metal Materials Co., Ltd provides engineering support for optimal coil geometry selection based on thermal load, pressure, and spatial constraints of the target application.