Stainless Steel Coil Tube (Coiltube) — Product No. 1072
1. Product Overview
The Stainless Steel Coil Tube (Product No. 1072) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered cold-drawn seamless tube supplied in continuous coil form. Designed for demanding applications in HVAC (Heating, Ventilation, and Air Conditioning), evaporative cooling systems, dry-type fan coil units, and semi-centralized air conditioning networks, this product delivers exceptional thermal conductivity, corrosion resistance, and dimensional accuracy.
The coil tube format enables high-efficiency automated forming, bending, and heat exchanger assembly processes, significantly reducing material waste and labor costs compared to straight-length pipe delivery. This product is particularly suited for integration into evaporative cooling and dry-type fan coil tube combined semi-centralized air conditioning systems, where reliable heat transfer performance and long-term durability are paramount.
2. Material & Properties
2.1 Base Material
- Primary Alloy Grades: AISI 304, AISI 316, AISI 321, AISI 316L, and custom duplex grades upon request
- Standard Compliance: ASTM A213/A213M, ASME SB99, EN 10217-7, GB/T 14976
- Chemical Composition (Typical — 304): C ≤ 0.08%, Si ≤ 1.00%, Mn ≤ 2.00%, P ≤ 0.045%, S ≤ 0.030%, Cr 18.0–20.0%, Ni 8.0–10.5%, Fe balance
2.2 Mechanical Properties
- Tensile Strength (UTS): ≥ 515 MPa (75,000 psi)
- Yield Strength (0.2% offset): ≥ 205 MPa (29,750 psi)
- Elongation at Break: ≥ 40% (minimum, per ASTM A213)
- Hardness: ≤ 92 HRB (annealed condition)
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and mildly acidic environments; 316 grade offers superior resistance to chlorides and pitting
- Thermal Conductivity: 16.3 W/(m·K) at 100°C (304 grade)
- Operating Temperature Range: −196°C to +870°C (continuous service)
3. Technical Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.18 mm – 32.0 mm (1/8" – 1-1/4") | ASTM A213 / ISO 3507 |
| Wall Thickness | 0.30 mm – 3.00 mm | ASTM A213 / EN 10217-7 |
| OD Tolerance | ±0.10 mm (standard); ±0.05 mm (precision grade) | ASME B36.19M |
| Wall Thickness Tolerance | ±10% of nominal (standard); ±5% (precision grade) | ASTM A213 |
| Coil Inner Diameter | 150 mm – 500 mm (adjustable per order) | Company standard |
| Coil Length (Continuous) | 50 m – 500 m (custom lengths available) | Company standard |
| Surface Finish | Pickled & passivated (2B); Mirror polished (Ra ≤ 0.4 μm); Brushed | ASTM A480 / GB/T 3280 |
| End Condition | Plain cut; Beveled; Threaded; Flanged (upon request) | ASME B36.19M |
| Heat Treatment | Full annealing (solution annealing at 1050–1100°C, followed by water quench) | ASTM A213 |
| Coil Packaging | Wooden reel with protective wrapping; moisture-barrier film; desiccant included | ISO 4180 |
| Minimum Order Quantity (MOQ) | 500 kg per grade | Company standard |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Selection: Virgin stainless steel billets or continuous casting slabs sourced from certified mills, with full mill test certificates (MTC) per EN 10204 Type 3.1 or Type 3.2.
- Piercing & Hot Rolling: Billets are heated to 1150–1250°C and pierced into hollow rounds, then hot-rolled to approximate dimensions.
- Pickle & Decarburize: Hot-rolled tubes undergo acid pickling (H₂SO₄ + HNO₃ blend) to remove scale and decarburize the surface layer, ensuring a clean oxide-free substrate.
- Cold Drawing (Coil Drawing): Tubes are cold-drawn through precision tungsten carbide or diamond dies to achieve final OD and wall thickness tolerances. The continuous coil drawing process ensures uniform microstructure and dimensional consistency.
- Intermediate Annealing: Periodic solution annealing at 1050–1100°C with rapid water quenching restores ductility during multi-pass cold working, preventing work hardening and cracking.
- Final Annealing: A final solution treatment stabilizes the austenitic microstructure, relieves residual stresses, and optimizes corrosion resistance.
- Pickling & Passivation: Final acid cleaning removes any residual oxide, followed by passivation treatment to establish a stable chromium oxide protective film.
- Surface Finishing: Optional mirror polishing (electropolishing or mechanical polishing) or brushing per customer specification.
- Coiling & Inspection: Tubes are wound onto precision reels with controlled tension to prevent deformation. 100% visual and dimensional inspection is performed prior to packaging.
- Non-Destructive Testing (NDT): Eddy current testing (ECT) and hydrostatic pressure testing (typically 1.5× working pressure, minimum 30 MPa for small-bore tubes) are conducted per ASTM A213 requirements.
4.2 Quality Control Milestones
- Raw material incoming inspection (chemical analysis via OES/Spectroscopy)
- In-process dimensional checks at each drawing station
- Post-annealing hardness and grain size verification
- Final ECT scanning at ≥ 30 m/min with automated defect flagging
- Hydrostatic test at 100% coverage with pass/fail logging
- Final surface quality audit per ASTM A480 visual standards
5. Applications
5.1 Primary Application Domains
- Evaporative Cooling Systems: The coil tube serves as the primary heat exchange element in evaporative coolers, where its high thermal conductivity and resistance to moisture-induced corrosion ensure efficient latent heat transfer in humid environments.
- Dry-Type Fan Coil Units (FCU): Used in commercial and industrial semi-centralized air conditioning systems, where the coil tube forms the core of fan coil heat exchangers for sensible cooling and heating.
- Semi-Centralized Air Conditioning Networks: The continuous coil format facilitates automated coil winding and brazing processes, enabling rapid fabrication of large-scale air distribution systems for hospitals, cleanrooms, and data centers.
- Refrigeration & Heat Pumps: Employed in evaporators and condensers where long-term reliability and resistance to refrigerant-induced stress corrosion cracking (particularly with R-134a, R-410A, and ammonia) are critical.
- Food & Pharmaceutical Processing: Sanitary-grade coil tubes (316L, electropolished) used in CIP (Clean-in-Place) compatible heat exchangers for pasteurization, sterilization, and temperature-controlled fluid handling.
- Chemical Processing: 316 and duplex grade coil tubes resist aggressive chemical media including dilute acids, alkaline solutions, and chloride-containing process streams.
- Marine & Offshore Applications: 316L grade coil tubes withstand saltwater corrosion in seawater cooling loops and ballast water treatment systems.
5.2 System Integration Advantages
In the context of the evaporative cooling and dry-type fan coil tube combined semi-centralized air conditioning system, the stainless steel coil tube offers synergistic benefits: the evaporative pre-cooling stage reduces the wet-bulb temperature of incoming air, while the downstream dry-type FCU coil tube handles precise sensible cooling. The coil tube's superior thermal performance and corrosion resistance minimize fouling and efficiency degradation over the system lifecycle, directly contributing to lower energy consumption (COP improvement of 15–25% compared to copper alternatives in certain configurations) and extended maintenance intervals.
6. Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification for manufacturing and quality assurance processes |
| ISO 14001:2015 | Environmental Management System certification covering waste reduction and emissions control |
| ISO/TS 22163 | Automotive-specific quality management system (available upon request for automotive-grade coil tube) |
| CE Marking (EU) | Conformity with European directives for pressure equipment and construction products |
| ASME "S" Stamp | Authorization for manufacturing pressure-containing components per ASME Boiler and Pressure Vessel Code |
| NSF/ANSI 61 | Drinking water system components certification (for 304/316L sanitary applications) |
| EN 10204 Type 3.1/3.2 | Mill Test Certificates (MTC) with chemical and mechanical property verification per batch |
| GB/T 14976 | Chinese national standard compliance for fluid transport seamless stainless steel tubes |
| RoHS / REACH | Restriction of Hazardous Substances and chemical regulation compliance for EU market export |
7. Unique Selling Points
- Superior Corrosion Resistance: Austenitic stainless steel composition provides 5–10× longer service life compared to copper or carbon steel alternatives in corrosive HVAC and chemical environments, reducing total cost of ownership (TCO).
- Continuous Coil Delivery: Eliminates butt-weld joints inherent to straight pipe delivery, reducing leak risk by up to 90% in heat exchanger assemblies and enabling fully automated coil winding and brazing lines.
- Precision Dimensional Control: Cold-drawing process achieves ±0.05 mm OD tolerance (precision grade), ensuring optimal fit in automated assembly and brazing operations with minimal scrap rate.
- Hygienic Surface Finish: Electropolished finish (Ra ≤ 0.4 μm) meets FDA and 3-A sanitary standards, eliminating crevice corrosion sites and facilitating CIP cleaning protocols.
- Thermal Performance: Consistent wall thickness and smooth internal bore minimize flow resistance and maximize heat transfer coefficients, directly improving system COP.
- Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd. offers tailored OD, wall thickness, coil diameter, surface finish, and end-condition configurations to meet specific OEM and system integrator requirements.
- Full Traceability: Each coil lot is traceable from raw material mill certificate through final NDT results, supporting compliance with pharmaceutical GMP, ASME, and PED (Pressure Equipment Directive) documentation requirements.
8. Packaging & Delivery
- Coils are mounted on reinforced wooden reels (IWF — International Wood Federation certified) with steel banding and moisture-barrier polyethylene wrapping.
- Each reel is labeled with product identification plate showing: Product No., grade, OD × WT, coil length, heat number, and MTC reference.
- Desiccant packets included to prevent condensation during ocean freight transit.
- Standard delivery: FOB Ningbo/Zhoushan Port, China; CIF and DDP terms available upon request.
- Lead time: 15–30 calendar days for standard grades; 30–45 days for custom specifications and non-standard alloy grades.
9. Technical Support & After-Sales
Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical support including:
- Material selection guidance based on application-specific corrosion, thermal, and mechanical requirements
- Welding and brazing procedure qualification support (WPS/PQR)
- On-site technical consultation for heat exchanger design and coil winding process optimization
- Warranty coverage: 12 months from delivery date against manufacturing defects; extended warranty available for qualified applications
- Non-conformance reporting and root-cause analysis with corrective action documentation per ISO 9001:2015 Clause 10.2
For detailed quotation, technical data sheets, and sample requests, please contact Wenzhou Jixing Metal Materials Co., Ltd. with reference to Product No. 1072 — Stainless Steel Coil Tube (Coiltube).