Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered, continuous-length tubular product supplied in coiled form to facilitate downstream processing, storage, and installation. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd, this product series is designed for demanding applications requiring superior corrosion resistance, thermal conductivity, mechanical integrity, and dimensional accuracy. The coiled configuration eliminates the need for butt-welding during fabrication, thereby reducing joint-related failure points and improving overall system reliability.
The product line has been extensively studied in the context of heat exchanger performance, particularly under water film cooling conditions, where the coil geometry demonstrates enhanced convective heat transfer coefficients compared to conventional straight-tube arrangements.
Material & Properties
The stainless steel coil tube is fabricated from austenitic and duplex stainless steel grades conforming to international standards. Key material grades include:
- 304 (UNS S30400) — General-purpose corrosion resistance with excellent formability; 18% Cr, 8% Ni
- 316 (UNS S31600) — Enhanced chloride resistance due to 2–3% Mo addition; suitable for marine and chemical environments
- 316L (UNS S31603) — Low-carbon variant for welding applications; prevents sensitization and intergranular corrosion
- 321 (UNS S32100) — Titanium-stabilized grade for high-temperature service up to 870 °C
- 304L (UNS S30403) — Low-carbon 304 for critical welding and cryogenic applications
- Duplex 2205 (UNS S31803) — High-strength, pitting-resistant grade for aggressive chloride environments
Key Mechanical Properties (Annealed Condition, 304 Grade):
- Tensile Strength: ≥ 515 MPa
- Yield Strength (0.2% offset): ≥ 205 MPa
- Elongation (50 mm gauge): ≥ 40%
- Hardness: ≤ 210 HB
Corrosion Resistance:
- Excellent resistance to atmospheric corrosion, dilute acids, and organic compounds
- Pitting Resistance Equivalent Number (PREN): 19–20 for 316; 34–38 for 2205
- Resistance to stress corrosion cracking (SCC) in chloride environments
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Standard Reference | ASTM A213, ASTM A269, EN 10216-5, GB/T 12771 |
| Outer Diameter (OD) | 6.0 mm – 114.3 mm (1/4" – 4") |
| Wall Thickness | 0.3 mm – 6.0 mm (as required) |
| Coil Length | 50 m – 500 m per coil (customizable) |
| Coil Inner Diameter (ID) | 300 mm – 1,200 mm |
| Surface Finish | No. 1 Annealed, 2B, BA (Bright Annealed), Electropolished (Ra ≤ 0.4 μm) |
| End Condition | Plain cut, Beveled (45°), Threaded, or Custom |
| Delivery Form | Coiled (as-rolled), Straight lengths available upon request |
| Tolerance (OD) | ±0.05 mm (precision); ±0.15 mm (standard) |
| Tolerance (Wall Thickness) | ±10% of nominal (standard); ±5% (precision) |
| Maximum Operating Temperature | 870 °C (304/321); 450 °C (316); 300 °C (2205) |
| Minimum Operating Temperature | −196 °C (304L/316L cryogenic service) |
| Weldability | Excellent — TIG, MIG, Laser, Orbital welding compatible |
| Packaging | Wooden crates, steel banding, VCI corrosion-inhibitive wrapping |
Manufacturing Process
The production of high-quality stainless steel coil tubes follows a rigorous multi-stage process:
- Strip Preparation: Cold-rolled stainless steel strip is supplied from certified mills and inspected for chemical composition, mechanical properties, and surface quality.
- Forming (Seamless or Welded):
- Seamless Process: Hot-rolled blanks are pierced, cold-drawn, and annealed to produce seamless tubing, then coiled.
- Welded Process: Strip is roll-formed into a tube shape and joined via Automatic Transverse Argon (ATA) or High-Frequency Induction (HFI) welding, followed by cold-drawing and annealing.
- Heat Treatment: Solution annealing at 1,010–1,120 °C followed by controlled cooling (air or water quench) to achieve austenitic microstructure and relieve residual stresses.
- Precision Sizing: Multi-pass cold drawing or rolling to achieve final OD and wall thickness within specified tolerances.
- Surface Treatment: Pickling and passivation (acid bath or electrolytic) to remove scale and establish a protective chromium oxide film. Optional electropolishing for ultra-smooth finishes.
- Coiling: Finished tubing is wound onto precision coil reels with controlled tension to prevent deformation or kinking.
- Quality Inspection: Dimensional measurement, hydrostatic testing, eddy current flaw detection, and visual surface inspection.
Applications
The stainless steel coil tube finds extensive use across multiple industries due to its combination of corrosion resistance, formability, and hygienic properties:
- Heat Exchangers & Cooling Systems: Coil tubes are ideal for shell-and-coil heat exchangers, condenser coils, and evaporator assemblies where enhanced heat transfer surface area is required. Research has demonstrated that water film cooling of coiled configurations yields superior thermal performance due to the increased turbulence and surface renewal.
- Food & Beverage Industry: Hygienic-grade tubing for dairy processing, brewing, pharmaceutical fluid transfer, and CIP (Clean-in-Place) systems.
- Petrochemical & Chemical Processing: Corrosion-resistant piping for acid transfer, reactor effluent handling, and distillation columns.
- Medical Devices: Biocompatible tubing for dialysis machines, infusion pumps, and endoscopic instruments.
- Automotive & Aerospace: Exhaust systems, fuel lines, hydraulic circuits, and cryogenic fuel delivery systems.
- Building & Construction: Structural tubing for railings, handrails, and decorative architectural elements.
- Solar Water Heating: Collector tubes and heat exchange coils in thermosiphon and forced-circulation solar thermal systems.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system ensuring product conformity and traceability:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health and Safety Management
- CE Marking — European Conformity for pressure equipment (PED 2014/68/EU)
- NADCAP / AS9100 — Aerospace quality assurance (where applicable)
- EN 10204 3.1 / 3.2 — Third-party material certification
- API 5L / API 5CT — Petroleum and natural gas industry compliance (where applicable)
- 3-A Sanitary Standards — Food-grade equipment certification
- Mill Test Certificates (MTC): Provided with every shipment, including chemical analysis, mechanical test results, and heat treatment records
Unique Selling Points
- Enhanced Thermal Performance: The coiled geometry provides inherently higher heat transfer coefficients compared to straight tubes, validated by experimental studies on water film cooling of plastic and metal coil configurations.
- Seamless Continuity: Coil delivery eliminates longitudinal welds and butt joints, reducing potential leakage paths and improving fatigue life in cyclic thermal environments.
- Wide Range of Grades: Availability of austenitic (304, 316, 321), low-carbon (304L, 316L), and duplex (2205) grades accommodates diverse service conditions from cryogenic to high-temperature applications.
- Precision Manufacturing: Tight dimensional tolerances (±0.05 mm OD) enable direct insertion into pre-drilled headers and heat exchanger tube sheets without reaming.
- Customizable Coil Lengths: Coils from 50 m to 500 m reduce installation time and labor costs while minimizing field welding requirements.
- Hygienic Surface Finish: Electropolished surfaces (Ra ≤ 0.4 μm) meet pharmaceutical and food-grade sanitary requirements, preventing biofilm formation.
- Full Traceability: Every coil is heat-number traced from raw material to finished product, supporting regulatory compliance and quality audits.
Technical Note: The coil tube geometry, as studied in thermal performance research under water film cooling conditions, demonstrates that the continuous curvature enhances turbulent boundary layer development, resulting in 15–30% improvement in overall heat transfer effectiveness compared to equivalent straight-tube configurations. This makes the product particularly advantageous for compact heat exchanger designs where space efficiency and thermal performance are critical.
Ordering Information
For custom specifications, material certifications, or technical consultation, contact Wenzhou Jixing Metal Materials Co., Ltd with the following details:
- Material grade and standard reference
- Outer diameter and wall thickness
- Required coil length and coil inner diameter
- Surface finish specification
- End preparation requirements
- Applicable industry standard or project specification