Stainless Steel Coil Tube (SSCT) — Precision-Fabricated Coil Pipe for Ventilation & Heating Systems
Product Overview
The Stainless Steel Coil Tube (SSCT), manufactured by Wenzhou Jixing Metal Materials Co., Ltd, is a high-performance, continuous-length coiled pipe product engineered for demanding industrial and commercial applications. Designed specifically for ventilation air-handling systems, radiant floor heating (hydronic floor heating), and process fluid distribution in large-scale industrial facilities, this coil tube product line delivers superior corrosion resistance, mechanical integrity, and thermal performance over the full service life of the installation.
Unlike conventional straight-length pipe requiring extensive on-site welding and joint fabrication, the coil tube format enables rapid, continuous deployment with minimal connection points — significantly reducing installation time, labor costs, and potential leak paths. The product is supplied in standardized coil diameters and lengths, optimized for roll-out installation in large factory buildings, commercial complexes, and industrial process plants.
Material & Properties
Base Material Grades
- AISI 304 (UNS S30408) — General-purpose austenitic stainless steel with excellent corrosion resistance and formability. Ideal for non-aggressive ventilation and heating circuits.
- AISI 316 (UNS S31608) — Molybdenum-enhanced austenitic stainless steel offering superior resistance to pitting and crevice corrosion. Recommended for aggressive chemical environments and coastal applications.
- AISI 316L (UNS S31603) — Low-carbon variant of 316L grade, providing enhanced weldability and resistance to intergranular corrosion in sensitized conditions.
- AISI 321 (UNS S32108) — Titanium-stabilized austenitic stainless steel, suitable for elevated-temperature applications exceeding 450 °C.
Key Material Properties (AISI 304 Reference Values)
| Property | Specification |
|---|---|
| Chromium Content | 18.0 – 20.0 % (wt) |
| Nickel Content | 8.0 – 10.5 % (wt) |
| Carbon Content (max) | 0.08 % (wt) |
| Tensile Strength (UTS) | ≥ 515 MPa |
| Yield Strength (0.2% offset) | ≥ 205 MPa |
| Elongation (at break) | ≥ 40 % |
| Thermal Conductivity (at 20 °C) | 16.3 W/(m·K) |
| Operating Temperature Range | −196 °C to +870 °C |
| Corrosion Resistance | Excellent in atmospheric, dilute acid, and alkaline environments |
| Surface Finish | Bright annealed (2B), polished, or passivated (electrolytic passivation) |
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管 / Coil Tube) |
| Item No. | 1097 |
| Outer Diameter (OD) | Ø 8 mm – Ø 108 mm (custom sizes available) |
| Wall Thickness | 0.5 mm – 4.0 mm |
| Coil Outer Diameter | Ø 300 mm – Ø 1500 mm |
| Coil Length per Reel | 50 m – 300 m (configurable) |
| Manufacturing Standard | ASTM A213 / ASTM A269 / GB/T 12771 / EN 10216-5 |
| End Treatment | Plain end, beveled end, or pre-flanged (per customer specification) |
| Surface Condition | Mirror polished (Ra ≤ 0.4 μm), satin finish, or industrial bright annealed |
| Dimensional Tolerance (OD) | ± 0.1 mm (standard); ± 0.05 mm (precision grade) |
| Dimensional Tolerance (Wall) | ± 10 % of nominal |
| Pressure Rating | Up to 25 bar (PN25) at 20 °C, depending on OD and wall thickness |
| Packaging | Wooden pallet with stretch film wrap; moisture-absorbing desiccant included |
Manufacturing Process
The production of the Wenzhou Jixing SSCT follows a rigorous multi-stage manufacturing workflow to ensure dimensional accuracy, surface integrity, and mechanical reliability:
- Raw Material Procurement & Inspection — Stainless steel strip or seamless tube blanks are sourced from certified mills (e.g., Outokumpu, POSCO, Taigang). Incoming material undergoes spectroscopic verification (PMI — Portable Metal Identifier) to confirm chemical composition, along with visual and dimensional inspection per ASTM E1950 and ISO 15663.
- Coiling / Cold Forming — Seamless stainless steel tube or formed strip is cold-coiled onto precision mandrels using CNC-controlled coiling machines. The coiling process maintains uniform curvature with controlled spring-back compensation to achieve target coil diameter within ± 2 % tolerance.
- Welding (for formed coil) — Where formed coil construction is employed, longitudinal seam welding is performed via TIG (Tungsten Inert Gas) welding under argon gas shielding, ensuring full-penetration welds with minimal heat-affected zone (HAZ) distortion. Weld integrity is verified by dye penetrant testing (DPT) per ASTM E709.
- Heat Treatment & Annealing — Coiled product undergoes solution annealing at 1050 – 1150 °C followed by controlled cooling to restore full austenitic microstructure, relieve cold-work stresses, and maximize corrosion resistance. This step is critical for preventing stress-corrosion cracking (SCC) susceptibility.
- Pickling & Passivation — The coil is immersed in a mixed acid pickling bath (nitric acid / hydrofluoric acid blend) to remove scale and discoloration. Subsequently, an electrolytic passivation treatment (per ASTM A967) forms a uniform chromium oxide layer, enhancing passive film stability.
- Surface Finishing — Depending on application requirements, the coil may undergo mechanical polishing (to achieve mirror finish with surface roughness Ra ≤ 0.4 μm), electropolishing, or brushing.
- Quality Control & Testing — Final product is subjected to hydrostatic pressure testing (per ASTM A530), dimensional verification via laser gauging, visual inspection of weld seams and surface finish, and optional NDE (Non-Destructive Examination) including ultrasonic testing (UT) per ASTM E127 for wall thickness confirmation.
- Packaging & Shipping — Coils are securely strapped, wrapped in protective film, and loaded onto wooden pallets with corner protection to prevent mechanical damage during transit.
Applications
Primary Application Domains
- Industrial Ventilation Systems (HVAC — Heating, Ventilation, and Air Conditioning) — Coil tubes serve as air-cooling and air-heating coils in large factory ventilation units. The continuous coil geometry maximizes heat transfer surface area within compact coil pack housings, enabling efficient temperature regulation of large industrial hall spaces.
- Radiant Floor Heating (Hydronic Underfloor Heating) — Stainless steel coil tubes are deployed as heating circuits beneath concrete slabs in commercial and industrial facilities. The coil format allows continuous, joint-free installation across large floor areas, minimizing thermal bridging and pressure loss compared to segmented pipe installations.
- Process Fluid Distribution — Used in chemical processing, pharmaceutical, and food & beverage industries for conveying corrosive or high-purity fluids. The corrosion-resistant properties of 316/316L grade ensure long service life in aggressive chemical environments.
- Heat Exchanger Coils — Employed in shell-and-coil heat exchangers, condensers, and evaporators where high thermal conductivity and mechanical strength are required.
- Solar Thermal Systems — Utilized in solar water heating collectors where the coil tube is immersed in thermal fluid tanks for efficient heat extraction from solar collectors.
Value Engineering Application Context
In the context of Value Engineering (VE) applied to ventilation and floor heating coil tube scheme selection for large factory buildings, the Wenzhou Jixing SSCT product has been evaluated and selected for its optimal balance of initial capital cost, lifecycle maintenance cost, thermal performance, and installation efficiency. The coil tube format reduces on-site fabrication waste by up to 30 %, eliminates numerous butt-weld joints (each a potential failure point), and accelerates installation timelines — directly contributing to reduced total cost of ownership (TCO) over the system's 20–25 year design life.
Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent production quality and process control |
| ISO 14001:2015 | Environmental Management System certification covering sustainable manufacturing practices |
| ASTM A213 / A269 | Material and product specification compliance for stainless steel seamless and welded tube |
| GB/T 12771 | Chinese National Standard for welded stainless steel tubes (seamless and welded) |
| EN 10216-5 | European standard for non-ferrous metal tubes — stainless steel |
| CE Marking | Conformity to European Union health, safety, and environmental protection standards |
| Mill Test Report (MTR) | Full chemical composition and mechanical property documentation provided with each batch |
| Third-Party Inspection | Available upon request (SGS, BV, or TÜV certified inspection) |
Unique Selling Points
- Continuous Coil Architecture: Eliminates intermediate joints and fittings, reducing leak points by up to 90 % compared to segmented pipe installations — critical for maintaining system integrity in pressurized ventilation and heating circuits.
- Rapid Deployment: Roll-out installation capability enables coverage of large factory floor areas at 3–5× the speed of traditional pipe installation methods, directly reducing project schedule and labor costs.
- Superior Corrosion Resistance: Available in 304, 316, and 316L grades with electrolytic passivation, providing service life exceeding 25 years even in chemically aggressive environments.
- Precision Dimensional Control: CNC-controlled coiling with ± 0.1 mm OD tolerance ensures compatibility with standard coil pack housings and heat exchanger frames.
- Value Engineering Optimized: Product line specifically developed and validated through VE analysis for large-scale industrial ventilation and radiant heating applications, delivering proven TCO advantages.
- Custom Configuration: Flexible customization of coil diameter, tube OD, wall thickness, surface finish, and end treatment to meet project-specific engineering requirements.
Technical Support & After-Sales Service
Wenzhou Jixing Metal Materials Co., Ltd provides comprehensive technical support including: application engineering consultation for ventilation and heating system design, coil layout optimization for specific building geometries, installation guidance documentation, and a warranty period of 12 months from delivery date covering material and manufacturing defects. Custom technical data packages (including CAD drawings, P&ID integration support, and thermal performance calculations) are available upon request to facilitate seamless integration into project design workflows.