Stainless Steel Coil Tube (Coiltube) — HVAC & Heat Exchanger Grade
Product Code: 615 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Classification: Literature Study / Technical Reference
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubing product manufactured in continuous coil form, specifically designed for integration into Heat Exchanger (HX) assemblies, Fan Coil Units (FCU), and Inducer Systems within commercial and hospitality HVAC (Heating, Ventilation, and Air Conditioning) applications. As a supplier of high-grade stainless steel coil tubing, Wenzhou Jixing Metal Materials Co., Ltd. provides material solutions that meet the demanding thermal efficiency, corrosion resistance, and mechanical integrity requirements of modern building climate control systems.
This product category encompasses seamless and welded stainless steel tubes supplied in coiled configurations, enabling downstream fabricators to perform bending, forming, and brazing operations with minimal material waste. The coil format supports high-throughput production of heat exchanger coils, condenser tubes, evaporator assemblies, and refrigeration circuits used extensively in hotel and commercial building HVAC infrastructure.
2. Material & Properties
Stainless steel coil tubes are fabricated from austenitic stainless steel grades that offer superior resistance to chloride-induced pitting corrosion, intergranular corrosion, and thermal fatigue cycling. The primary material specifications include:
- Grade 304 (UNS S30400 / 1.4301): The most widely specified grade for general-purpose HVAC coil tube applications, offering excellent formability, weldability, and corrosion resistance in moderate environments.
- Grade 316 (UNS S31600 / 1.4401): Enhanced molybdenum content (2.0–3.0%) provides superior resistance to chloride pitting and crevice corrosion, suitable for coastal or high-humidity hotel environments.
- Grade 316L (UNS S31603 / 1.4404): Low-carbon variant of 316 designed for welding applications where sensitization resistance is critical.
- Grade 321 (UNS S32100 / 1.4541): Titanium-stabilized grade offering resistance to intergranular corrosion at elevated operating temperatures.
Mechanical Properties (Annealed Condition)
- Tensile Strength (UTS): 515–720 MPa (depending on grade and wall thickness)
- Yield Strength (0.2% Offset): 205–310 MPa
- Elongation: ≥ 40% (minimum)
- Hardness: ≤ 230 HB (annealed condition)
- Thermal Conductivity: 14.6–16.3 W/(m·K) at 20°C (Grade 304)
- Operating Temperature Range: −196°C to +870°C (intermittent)
3. Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 3.0 mm – 12.7 mm (typical HVAC range); custom sizes available |
| Wall Thickness | 0.3 mm – 1.5 mm (tolerance ±0.05 mm) |
| Coil Length | Up to 500 m per coil (standard); continuous lengths available |
| Coil Diameter | 500 mm – 1000 mm (inner winding diameter) |
| Surface Finish | Mirror polished (Ra ≤ 0.4 μm), Electropolished, or 2B finish |
| Manufacturing Method | Seamless (Cold Drawn) or ERW (Electric Resistance Welded) with internal/external finishing |
| Applicable Standards | ASTM A269, ASTM A213, EN 10216-5, GB/T 12771, JIS G3459 |
| Material Grade | 304, 304L, 316, 316L, 321, 310S (custom on request) |
| Heat Treatment | Solution Annealed (1050–1150°C), followed by water or air quench |
| Dimensional Tolerance | OD: ±0.05 mm; Wall thickness: ±0.05 mm |
| Coil Packaging | Wooden crate with moisture-proof inner wrapping; custom packaging available |
| Minimum Order Quantity (MOQ) | 500 kg per grade |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing workflow:
- Raw Material Selection: Ingot or strip material conforming to the specified ASTM/EN grade is procured from certified mills with full Chemical Composition (CC) traceability.
- Piercing & Extrusion (Seamless Route): Hot-rolled billets are pierced and cold extruded to produce seamless tube blanks with precise OD and wall thickness.
- Cold Drawing & Sizing: Tubes undergo multiple cold-drawing passes through hardened tungsten carbide dies to achieve final dimensions within ±0.05 mm tolerance.
- Intermediate Annealing: Periodic solution annealing (1050–1150°C) relieves cold-work hardening and restores ductility between drawing operations.
- Pickling & Descaling: Acid pickling removes oxide scale formed during annealing, yielding a clean, uniform surface.
- Surface Finishing: Electropolishing or mechanical polishing is applied to achieve mirror or low-roughness surface finishes critical for fluid flow efficiency in heat exchanger applications.
- Final Annealing: A final solution treatment ensures optimal mechanical properties and corrosion resistance in the as-delivered condition.
- Quality Inspection: Each coil undergoes ultrasonic testing (UT), eddy current testing (ECT), and visual inspection for defects, followed by hydrostatic pressure testing (typically 2× working pressure).
- Coiling & Packaging: Inspected tube is wound onto precision coils with protective end caps, wrapped in moisture-barrier material, and secured in export-grade wooden crates.
5. Applications
Stainless steel coil tubes from this product line are integral to a broad spectrum of HVAC and industrial thermal management systems. Key application domains include:
5.1 Fan Coil Units (FCU) in Hotel HVAC Systems
As documented in industry research on "Fan Coil Units and Inducers in Hotel HVAC System Applications", stainless steel coil tubes serve as the primary heat transfer elements in FCU assemblies. Their high thermal conductivity combined with corrosion resistance ensures long service life in latent and sensible heat exchange cycles typical of hospitality environments where humidity control is critical.
5.2 Air Handling Units (AHU) & Inducer Systems
Coil tubes are fabricated into serpentine or zigzag heat exchanger bundles installed within AHUs and air induction systems. The coil form factor enables efficient use of material while maximizing heat transfer surface area within compact unit envelopes.
5.3 Condenser & Evaporator Assemblies
Used in chiller and heat pump systems for commercial buildings, where stainless steel coil tubes provide resistance to refrigerant degradation and water-side corrosion.
5.4 Industrial Process Heat Exchangers
Applicable in food and beverage processing, pharmaceutical clean rooms, and chemical processing where sanitary-grade (Grade 316L) coil tubing meets FDA and 3-A Sanitary Standards.
5.5 Refrigeration & Cryogenic Systems
Low-temperature grade coil tubes (304L, 316L) are employed in refrigeration circuits where ductility at sub-zero temperatures is essential.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring traceability and conformance to international standards:
- ISO 9001:2015 — Quality Management System certification covering all production processes
- ISO 14001:2015 — Environmental Management System for sustainable manufacturing practices
- ISO 45001:2018 — Occupational Health and Safety Management System
- EN 10204 3.1 — Third-party material test certificates provided with every shipment
- Mill Test Certificates (MTC): Full chemical and mechanical property certification per ASTM E29
- Material Traceability: Heat-number traceability from ingot to finished coil, enabling full lifecycle documentation
- Non-Destructive Testing (NDT): Eddy current and ultrasonic testing per ASTM E165 and ASTM E213
- Hydrostatic Testing: Per ASTM A269, Section 8, ensuring tube integrity at 2× specified working pressure
7. Unique Selling Points (USPs)
- Coil-Form Delivery: Eliminates butt-weld joints in downstream fabrication, reducing leak points in heat exchanger assemblies by up to 40% compared to straight-length tube supply.
- Tight Dimensional Tolerances: ±0.05 mm OD and wall thickness tolerance ensures consistent brazing and crimping performance in automated heat exchanger manufacturing lines.
- Mirror-Polished Surface: Ra ≤ 0.4 μm finish minimizes fouling and reduces pressure drop in refrigerant circuits, improving COP (Coefficient of Performance) of HVAC systems.
- Multi-Grade Availability: Single-source procurement for 304, 316, 316L, 321, and specialty grades simplifies supply chain management.
- HVAC-Specific Optimization: Product specifications are calibrated to the thermal cycling, vibration, and corrosion demands of hotel and commercial HVAC environments, informed by applied research on fan coil unit performance.
- Full Traceability & Certification: Every coil ships with EN 10204 3.1 test certificates, chemical analysis reports, and dimensional inspection records.
Note: This product specification is derived from technical literature study (Ref. No. 615) encompassing research on "Fan Coil Units and Inducers in Hotel HVAC System Applications." The specifications reflect industry-standard requirements for stainless steel coil tubing in commercial HVAC heat exchanger fabrication. Custom specifications, non-standard dimensions, and specialized surface treatments are available upon request through direct consultation with Wenzhou Jixing Metal Materials Co., Ltd.