Stainless Steel Coil Tube (Coiltube) — Industrial & HVAC Applications
1. Product Overview
The Stainless Steel Coil Tube (also known as Coiltube or Coil Pipe) is a precision-engineered stainless steel tubing product supplied in continuous coil form by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for applications requiring high thermal efficiency, corrosion resistance, and compact heat exchange performance — most notably in Fan Coil Units (FCU), industrial heat exchangers, refrigeration systems, and process engineering equipment.
Unlike straight-length tubing, coil tubes are wound into continuous spirals, enabling seamless integration into heat exchanger assemblies without the need for field welding or brazing joints, thereby eliminating potential leakage points and improving overall system reliability.
2. Material & Properties
Coil tubes are manufactured from high-grade austenitic stainless steel grades, selected for their exceptional combination of corrosion resistance, mechanical strength, and thermal conductivity.
- Common Grades: SUS304 (UNS S30408), SUS316 (UNS S31608), SUS321 (UNS S32108), SUS304L (UNS S30403)
- Corrosion Resistance: Superior resistance to pitting, crevice corrosion, and intergranular corrosion, particularly in 316-grade alloys containing ≥2.0% Molybdenum
- Operating Temperature Range: −196°C to +870°C (depending on grade)
- Thermal Conductivity: Approximately 14.9–16.3 W/(m·K) for 304-grade stainless steel at 20°C
- Mechanical Strength: Yield strength ≥205 MPa; Tensile strength ≥515 MPa (annealed condition)
- Surface Finish: No.1 (2B), BA (Bright Annealed), or pickled & passivated finish
- Welding Suitability: Excellent weldability without preheating; suitable for TIG, MIG, and orbital welding processes
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.35 mm – 50.8 mm (¼" – 2") |
| Wall Thickness | 0.5 mm – 3.0 mm |
| Coil Inner Diameter | 300 mm – 600 mm |
| Coil Length (Continuous) | Up to 500 m per coil |
| OD Tolerance | ±0.05 mm (precision drawn) / ±0.1 mm (standard) |
| Wall Thickness Tolerance | ±10% of nominal |
| Roundness | ≤0.5% of OD |
| Surface Roughness (Ra) | ≤0.8 μm (BA finish); ≤1.6 μm (2B finish) |
| Hardness (Annealed) | ≤95 HRB (304 grade) |
| Pressure Test | Hydrostatic test at 1.5× working pressure; minimum 30 sec hold |
| Applicable Standards | ASTM A213/A213M, ASTM A269/A269M, EN 10217-7, GB/T 12771 |
4. Manufacturing Process
The production of stainless steel coil tubes involves a multi-stage precision manufacturing process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Hot Rolling & Annealing: Stainless steel ingots are hot-rolled into seamless tubes or perforated strips (for welded tube production), followed by controlled annealing to relieve residual stresses.
- Piercing / Forming: Seamless tubes are produced via hot piercing or plug piercing; alternatively, cold-formed tubes are produced through roll-forming of precision-cut strip.
- Cold Drawing: Tubes are cold-drawn through precision dies to achieve tight dimensional tolerances and superior surface finish. Multiple drawing passes may be employed for high-precision applications.
- Intermediate Annealing: Periodic solution annealing (typically at 1050°C – 1150°C) in a protective atmosphere is performed to restore ductility and prevent cold work hardening.
- Final Coiling: The finished tube is wound onto precision coil reels under controlled tension to prevent kinking, ovality, or surface damage.
- Surface Treatment: Pickling and passivation (acid immersion) or Bright Annealing (BA) in a reducing atmosphere furnace to achieve the required surface finish and corrosion resistance.
- Quality Inspection: 100% hydrostatic pressure testing, ultrasonic flaw detection, dimensional measurement, and surface visual inspection.
5. Applications
Stainless steel coil tubes are widely utilized across multiple industrial sectors due to their corrosion resistance, thermal performance, and hygienic properties:
- Heating, Ventilation & Air Conditioning (HVAC): Primary application in Fan Coil Units (FCU), air handling units, and chiller coils where high thermal exchange efficiency is critical
- Refrigeration & Cryogenics: Evaporator and condenser coils in commercial refrigeration, cold storage, and cryogenic processing systems
- Food & Beverage Industry: Heat exchangers, pasteurization equipment, and CIP (Clean-in-Place) systems requiring hygienic-grade tubing
- Pharmaceutical & Biotechnology: Sterilizable heat exchange circuits and process piping in GMP-compliant facilities
- Chemical Processing: Corrosion-resistant heat exchangers for aggressive chemical environments
- Power Generation: Condenser tubes and auxiliary heat exchanger coils in thermal and nuclear power plants
- Automotive & Aerospace: Radiator cores, intercoolers, and hydraulic system tubing
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and product certifications to ensure global market compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health & Safety Management System
- CE Marking — Compliance with European Union machinery and pressure equipment directives
- EN 10204 3.1 — Material Test Certificate (independent inspection)
- ASME / PED — Pressure Equipment Directive compliance for pressure-containing applications
- Mill Test Reports (MTR): Provided with every shipment, including chemical composition analysis, mechanical test data, and traceability documentation
7. Unique Selling Points
Seamless Coil Form: Eliminates longitudinal weld seams, reducing fatigue failure risk and providing uniform corrosion resistance around the entire circumference.
Precision Dimensional Control: Tolerances as tight as ±0.05 mm ensure drop-in compatibility with heat exchanger headers and expansion joints.
Superior Thermal Performance: Optimized wall thickness and surface finish maximize convective and conductive heat transfer coefficients.
Extended Service Life: Resistance to scaling, fouling, and corrosion under operating conditions extends equipment lifecycle by 3–5× compared to carbon steel alternatives.
Hygienic Design: BA finish with Ra ≤ 0.8 μm meets FDA and 3-A Sanitary Standards for food-grade and pharmaceutical applications.
Custom Coiling Configuration: Flexible coil diameters and lengths accommodate diverse downstream processing requirements without intermediate storage.
8. Packaging & Delivery
Coil tubes are packaged on robust steel or wooden coil reels, wrapped with moisture-proof protective film and secured with steel strapping bands. Each coil is clearly labeled with product identification, grade, dimensions, heat number, and quantity for traceability throughout the supply chain.