Stainless Steel Coil Tube (盘管) — Technical Specification
Product Overview
The Stainless Steel Coil Tube (Chinese: 盘管, pinyin: pán guǎn) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product Catalog No. 567) is a precision-engineered coiled tubular product designed for high-performance thermal exchange, fluid conveyance, and structural applications. This product is supplied in continuous coil form, enabling efficient downstream processing such as cut-to-length, bending, and welding without the need for jointed pipe segments.
The coil tube configuration offers significant advantages in terms of material utilization efficiency, reduced welding points, and enhanced hydrodynamic and aerodynamic performance. Research into the interaction between static pressure (静压) and nozzle geometry (喷口) in fan coil units (风机盘管) has demonstrated that the geometric consistency and dimensional precision of coil tubes directly influence airflow distribution, thermal transfer efficiency, and overall system performance. Wenzhou Jixing Metal Materials applies these engineering insights to produce coil tubes that meet the demanding requirements of HVAC (Heating, Ventilation, and Air Conditioning), refrigeration, and industrial process applications.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, ensuring superior corrosion resistance, mechanical integrity, and long-term service reliability.
- Primary Material Grades: AISI 304 (UNS S30400), AISI 316 (UNS S31600), AISI 321 (UNS S32100), AISI 316L (UNS S31603), AISI 304L (UNS S30403)
- Equivalent Chinese Standards: 06Cr19Ni10 (304), 06Cr17Ni12Mo2 (316), 06Cr25Ni20 (310S)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, mild acids, alkalis, and chlorinated environments (particularly for 316/316L grades)
- Temperature Range: Serviceable from cryogenic temperatures (−196°C / −320°F) up to 870°C (1,600°F) for 304 grade; up to 925°C (1,700°F) for 316 grade
- Mechanical Properties: Minimum tensile strength of 515 MPa (74.7 ksi) for 304 grade; minimum yield strength of 205 MPa (29.7 ksi)
- Surface Finish Options: 2B (Cold Rolled and Annealed), BA (Bright Annealed), No. 4 Brushed, Mirror Polish (Ra ≤ 0.2 μm)
- Chemical Composition (304 Grade): C ≤ 0.08%, Si ≤ 1.0%, Mn ≤ 2.0%, P ≤ 0.045%, S ≤ 0.030%, Cr 18.0–20.0%, Ni 8.0–10.5%
Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 108.0 mm (0.236" – 4.252") | ASTM A554 / GB/T 14976 |
| Wall Thickness (WT) | 0.5 mm – 6.0 mm (0.020" – 0.236") | ASTM A554 / GB/T 14976 |
| Coil Inner Diameter (ID) | 200 mm – 600 mm (7.87" – 23.62") | Manufacturer Specification |
| Coil Length per Spool | 20 m – 200 m (65.6 ft – 656.2 ft) | Customizable |
| Coil Weight per Spool | 50 kg – 500 kg (110 lb – 1,102 lb) | Customizable |
| Dimensional Tolerance (OD) | ±0.05 mm – ±0.15 mm (depending on OD range) | ASTM A554 / EN 10217 |
| Dimensional Tolerance (WT) | ±10% of nominal thickness | ASTM A554 |
| Roundness Tolerance | ≤ 0.1% of OD | ISO 1128 |
| Surface Roughness (Internal) | Ra ≤ 0.8 μm (standard); Ra ≤ 0.4 μm (EP grade) | ASTM A269 |
| Heat Treatment | Solution Annealed (1050–1150°C) followed by controlled cooling | ASTM A554 |
| End Condition | Plain, beveled, or threaded (custom) | Customer Specification |
| Testing | Hydrostatic Test (per ASTM A554), Spectroscopic Analysis, Dimensional Inspection | ASTM A554 / GB/T 24511 |
Manufacturing Process
The production of the Stainless Steel Coil Tube at Wenzhou Jixing Metal Materials follows a rigorous multi-stage manufacturing sequence to ensure dimensional accuracy, metallurgical quality, and surface integrity:
- Hot Rolling (Hot Rolled Billet Processing): Austenitic stainless steel billets are heated to 1,200–1,300°C and hot-rolled into seamless tube blanks with controlled outer diameter and wall thickness tolerances.
- Piercing & Elongation: The heated billets are pierced to form hollow tubes, followed by multi-pass elongation to achieve the target wall thickness and diameter.
- Pickling & Descaling: The hot-rolled tubes undergo acid pickling (typically using a mixture of sulfuric acid and hydrofluoric acid) to remove oxide scale and restore the passive chromium oxide layer.
- Cold Drawing / Cold Pilgering: The tubes are cold-worked through a series of dies to achieve precise dimensional tolerances (±0.05 mm OD tolerance) and enhanced mechanical properties through strain hardening.
- Intermediate Annealing: Periodic annealing at 1,050–1,150°C restores ductility and eliminates residual cold-work stresses during multi-pass drawing.
- Final Solution Annealing: A controlled solution anneal at 1,050–1,150°C followed by water quenching ensures full austenitic microstructure, optimal corrosion resistance, and stress-free condition.
- Surface Finishing: Tubes receive final surface treatment including mechanical polishing, electropolishing (EP), or chemical passivation to achieve the specified surface roughness and chemical inertness.
- Coiling: The finished tubes are wound into coils using precision coiling equipment that maintains constant tension to prevent kinking, ovality, or surface damage. Coil ID and winding pattern are controlled to facilitate downstream processing.
- Quality Inspection & Testing: Each coil undergoes 100% hydrostatic testing, ultrasonic flaw detection (UT), visual inspection, spectroscopic chemical analysis (OES), and dimensional verification per ASTM A554 and applicable standards.
- Packaging: Coils are wrapped in protective film, secured with steel strapping, and packaged for export or domestic distribution with full material traceability documentation.
Applications
The Stainless Steel Coil Tube is employed across a wide spectrum of industrial and commercial sectors, leveraging its corrosion resistance, formability, and hygienic properties:
- HVAC & Fan Coil Units (风机盘管): Coil tubes serve as the core heat exchange elements in fan coil units, air handling units (AHUs), and chiller systems. The geometric precision of the coil tube directly impacts static pressure distribution and nozzle airflow performance, as confirmed by research on the influence of static pressure and nozzle geometry on fan coil unit performance. Optimized coil tube dimensions ensure uniform airflow, reduced pressure drop, and enhanced thermal transfer efficiency.
- Refrigeration & Air Conditioning: Used in evaporators, condensers, and chiller coils where resistance to refrigerant corrosion and thermal cycling is critical.
- Food & Beverage Processing: Hygienic-grade coil tubes (EP finish, Ra ≤ 0.4 μm) are used in milk pasteurizers, beer brewing systems, and pharmaceutical CIP (Clean-in-Place) systems per 3-A Sanitary Standards and FDA 21 CFR compliance.
- Chemical & Petrochemical Industry: 316/316L coil tubes resist aggressive chemical media including chlorides, acids, and caustic solutions in heat exchangers and process piping.
- Marine & Offshore: Resistant to seawater corrosion; used in desalination plants, ballast water systems, and offshore platform piping.
- Power Generation: Steam generator tubes, feedwater heaters, and condensate recovery systems in thermal and nuclear power plants.
- Medical & Pharmaceutical: Sterilizable coil tubes for autoclave-compatible equipment, medical gas delivery systems, and bioreactor heat transfer elements.
- Automotive: Heat exchangers for electric vehicle (EV) battery thermal management systems, exhaust gas recirculation (EGR) cooling, and transmission oil coolers.
- Solar Thermal Energy: Coil tubes in concentrated solar power (CSP) collectors and solar water heating systems.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and certifications to ensure product reliability and global market compliance:
- ISO 9001:2015 — Quality Management System certification for consistent production quality
- ISO 14001:2015 — Environmental Management System certification
- ISO 45001:2018 — Occupational Health and Safety Management System
- CE Marking — Compliance with European Union directives for pressure equipment (PED 2014/68/EU)
- ASTM A554 — Standard Specification for Stainless Steel Tube, Cold-Drawn, Seamless, for General Applications
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Chromium-Chromium-Nickel Stainless Steel Tubing for Chemical and Similar Severe Service Applications
- EN 10217 — European standard for heat exchanger and boiler tubes
- GB/T 14976 — Chinese national standard for cold-rolled or cold-drawn seamless stainless steel tubes
- GB/T 24511 — Chinese national standard for pressure vessel welded parts
- NORSOK M-640 — Offshore stainless steel product standard (for marine/offshore applications)
- Mill Test Certificates (MTC): EN 10204 Type 3.1 certificates provided with each shipment, including chemical composition, mechanical properties, and test results
Unique Selling Points (USPs)
1. Precision-Coiled Geometry: Advanced coiling technology ensures uniform coil ID, consistent tension winding, and zero kinking — critical for downstream automated processing and optimal heat exchanger performance.
2. Research-Driven Engineering: Product design incorporates findings from academic research on static pressure (静压) and nozzle (喷口) effects on fan coil unit performance, ensuring that coil tube dimensions are optimized for real-world thermal-hydraulic applications.
3. Full Traceability: Every coil is traceable from raw material heat number through all manufacturing stages, with complete documentation per EN 10204 3.1 requirements.
4. Multi-Grade Capability: Production of 304, 316, 316L, 321, and 310S grades from a single manufacturing line ensures supply chain simplification for multi-grade projects.
5. Hygienic & EP-Grade Surface Finish: Electropolished surfaces (Ra ≤ 0.4 μm) with citric acid passivation meet 3-A Sanitary and FDA compliance for food, beverage, and pharmaceutical applications.
6. Custom Coiling: Flexible coil ID (200–600 mm), coil length (20–200 m), and end treatment options enable seamless integration into customer-specific manufacturing workflows.