Stainless Steel Coil Tube (Coiltube) — Technical Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Category: Stainless Steel Coil Tube / Coiltube
Reference No.: 1572
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous-length tubular product supplied in a coiled configuration. This product is specifically designed for applications requiring seamless, flexible, and corrosion-resistant tubing, including heat exchange systems, HVAC (Heating, Ventilation, and Air Conditioning) fan coil units, refrigeration circuits, and hydronic piping networks. The coiltube is delivered in a continuous spiral coil form, which facilitates downstream processing such as cutting, bending, and forming without the need for additional welding or joining operations.
The product line draws upon rigorous engineering standards and industry best practices, including considerations related to noise attenuation in enclosed environments such as hotel guest rooms and commercial facilities. This makes the coiltube particularly suitable for HVAC and fan coil unit (FCU) installations where acoustic performance is a critical design parameter.
2. Material & Properties
2.1 Grade Composition
- Primary Grades: AISI 304, AISI 316, AISI 321, AISI 316L
- Alternative Grades: AISI 304L, AISI 310S, AISI 904L (upon request)
2.2 Mechanical Properties
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (AISI 304); ≥ 515 MPa (AISI 316) | ASTM A213 / GB/T 14976 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa | ASTM A213 |
| Elongation (A50) | ≥ 40% | ASTM A213 / GB/T 228 |
| Hardness (Rockwell B) | ≤ 92 HRB (Annealed Condition) | ASTM E140 |
| Thermal Conductivity (at 20°C) | 14.5 – 16.3 W/(m·K) (AISI 304) | ASTM E153 |
| Thermal Expansion Coefficient (20–100°C) | 17.3 × 10⁻⁶ /°C | ASTM E153 |
2.3 Corrosion Resistance
The austenitic stainless steel grades employed provide exceptional resistance to atmospheric corrosion, acid environments, chlorinated solutions, and saline conditions. AISI 316 and AISI 316L grades offer enhanced molybdenum (Mo) content (2.0–3.0% by weight), conferring superior pitting and crevice corrosion resistance suitable for marine and chemical processing environments.
2.4 Surface Finish
- Standard Finish: 2B (Cold Rolled and Annealed with Bright Pass)
- Available Finishes: BA (Bright Annealed), No. 4 Brushed, Mirror (8K), Matte (Hairline)
- Surface Roughness (Ra): ≤ 0.8 μm (2B); ≤ 0.4 μm (BA); ≤ 0.2 μm (Mirror)
3. Specifications
| Parameter | Range / Value | Notes |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 38.1 mm (⅛" – 1½") | Custom sizes available |
| Wall Thickness | 0.3 mm – 3.0 mm | Tolerance: ±10% |
| Inner Diameter (ID) | 2.0 mm – 35.0 mm | Derived from OD and wall thickness |
| Coil Length | 50 m – 500 m (standard); up to 1000 m (special order) | Continuous length without seams |
| Coil Weight | 50 kg – 500 kg per coil | Dependent on OD and wall thickness |
| Coil Inner Diameter | 150 mm – 300 mm | For handling and storage |
| Coil Outer Diameter | 400 mm – 1200 mm | Varies by specification |
| Manufacturing Method | Seamless (Cold Drawn / Cold Rolled) | No longitudinal weld seam |
| Applicable Standards | ASTM A213, ASTM A269, GB/T 14976, GB/T 12771, JIS G3459, EN 10217 | Multi-standard compliance |
| Pressure Rating | Up to 15.0 MPa (2,175 psi) | Dependent on OD and wall thickness |
| Operating Temperature Range | −196°C to +870°C (AISI 304); −196°C to +800°C (AISI 316) | Cryogenic to high-temperature service |
| End Treatment | Plain cut, beveled, or threaded (upon request) | Customizable |
| Packaging | Wooden pallet with protective wrapping; export-grade packaging available | Moiré-proof and rust-preventive |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube follows a meticulously controlled multi-stage manufacturing process to ensure dimensional accuracy, metallurgical integrity, and surface quality.
- Raw Material Selection: High-purity stainless steel billets or slabs conforming to the specified grade (e.g., AISI 304, AISI 316) are sourced from certified mills. Incoming material undergoes spectroscopic analysis (OES — Optical Emission Spectroscopy) to verify chemical composition compliance.
- Hot Rolling / Forging: Selected billets are heated to forging temperatures (1050°C – 1200°C) and subjected to hot rolling or piercing to produce initial tube blanks with approximate dimensions.
- Acid Pickling and Descaling: The hot-rolled tube blanks are immersed in a controlled acid bath (typically a mixture of sulfuric acid and hydrofluoric acid) to remove oxide scale and impurities from the surface.
- Cold Drawing / Cold Rolling: The pickled tubes are passed through a series of progressively reducing dies or roller mills. This cold working process achieves precise dimensional tolerances, enhances mechanical strength through strain hardening, and produces a smooth surface finish.
- Intermediate Annealing: At predetermined stages of cold working, the tube is annealed (heated to 1050°C – 1100°C and rapidly cooled) to relieve accumulated residual stresses, restore ductility, and prevent cracking during subsequent forming operations.
- Final Annealing and Passivation: The finished tube undergoes a final solution annealing cycle followed by controlled cooling. Subsequent passivation treatment (using nitric acid or citric acid) forms a stable chromium oxide passive layer, enhancing corrosion resistance.
- Coiling: The continuous-length tube is wound onto a precision coiler to produce the final coil configuration. Coil dimensions (inner diameter, outer diameter, length) are controlled to customer specifications.
- Quality Inspection: Every coil undergoes comprehensive non-destructive testing (NDT), including ultrasonic testing (UT) for internal defects, eddy current testing (ECT) for surface and near-surface discontinuities, and dimensional inspection using laser measurement systems.
- Packaging and Dispatch: Inspected coils are wrapped with protective film, secured on wooden pallets, and prepared for domestic or international shipment.
5. Applications
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. is engineered for demanding industrial, commercial, and residential applications:
- HVAC and Fan Coil Units (FCU): The coiltube serves as the primary heat transfer element in fan coil units installed in hotels, hospitals, office buildings, and residential complexes. Its seamless construction and smooth internal surface minimize flow resistance and pressure drop, contributing to efficient heat exchange and reduced operational noise — a critical consideration in environments governed by strict acoustic standards such as those specified for hotel guest rooms (e.g., GB/T 3096 — Environmental Noise Limits).
- Refrigeration and Air Conditioning Systems: Used as refrigerant piping and condensers in commercial refrigeration units, split air conditioners, and cold storage systems.
- Automotive and Transportation: Applied in automotive exhaust systems, brake fluid lines, fuel delivery systems, and heat exchangers in vehicle thermal management systems.
- Food and Beverage Processing: Conforms to sanitary requirements for milk, beverage, and food processing equipment where cleanability and corrosion resistance are paramount.
- Chemical and Petrochemical Industries: Employed in chemical transfer lines, heat exchangers, and process piping where resistance to aggressive chemical media is essential.
- Medical and Pharmaceutical Equipment: Utilized in medical gas delivery systems, sterilization equipment, and pharmaceutical processing apparatus requiring high-purity, biocompatible tubing.
- Building and Architectural Applications: Used in decorative railings, structural elements, and plumbing systems in high-end commercial and residential construction.
- Heat Exchanger Manufacturing: The coil form facilitates efficient coiling into tube bundles for shell-and-tube heat exchangers, plate heat exchangers, and air-to-water heat exchangers.
6. Quality Certifications and Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework to ensure consistent product performance and regulatory compliance:
- ISO 9001:2015 — Quality Management Systems certification, ensuring systematic process control and continuous improvement.
- ISO 14001 — Environmental Management Systems certification, demonstrating commitment to sustainable manufacturing practices.
- CE Marking — Conformity with European health, safety, and environmental protection standards for export to the European Economic Area (EEA).
- GB/T Standards Compliance — Full adherence to Chinese national standards including GB/T 14976 (Seamless Steel Tubes for Fluid Transport), GB/T 12771 (Stainless Steel Seamless Tubes), and GB/T 4237 (Cold-Rolled Stainless Steel Sheets and Strips).
- Mill Test Certificates (MTC): Each shipment is accompanied by a detailed Mill Test Certificate documenting chemical composition, mechanical properties, and heat treatment history, traceable to the specific heat number.
- Third-Party Inspection: Products are available for third-party inspection by recognized agencies including SGS, BV (Bureau Veritas), and TÜV upon customer request.
- Pressure Testing: All coils undergo hydrostatic pressure testing at 1.5 times the maximum operating pressure to verify structural integrity and absence of leakage paths.
7. Unique Selling Points
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. distinguishes itself through the following value propositions:
- Seamless Construction: The absence of a longitudinal weld seam eliminates potential failure points, ensuring superior pressure containment and extended service life in critical applications.
- Continuous Coil Form: Delivered in continuous lengths up to 500 meters (standard) or 1000 meters (special order), minimizing the need for field welding and reducing installation labor costs.
- Multi-Grade Availability: A broad range of stainless steel grades (AISI 304, 316, 321, 316L, and specialty grades) allows precise material selection tailored to specific service environments and corrosion challenges.
- Acoustic Performance Optimization: Engineered with consideration for noise reduction in HVAC and fan coil unit applications, supporting compliance with stringent indoor noise standards for hospitality and residential environments.
- Dimensional Precision: Tight tolerances on outer diameter (±0.1 mm), wall thickness (±10%), and roundness ensure reliable fit-up in automated manufacturing processes and heat exchanger tube bundle assembly.
- Customization Capability: Flexible customization options for dimensions, surface finish, end treatment, and packaging accommodate diverse customer specifications and project requirements.
- Full Traceability: Complete material traceability from raw steel mill to finished coil, supported by comprehensive documentation and digital batch tracking systems.
8. Ordering Information
Customers are advised to specify the following parameters when placing orders:
- Stainless steel grade (e.g., AISI 304, AISI 316)
- Outer diameter (OD) and wall thickness (WT)
- Required coil length and coil dimensions (inner/outer diameter)
- Surface finish specification
- Applicable standard (ASTM, GB, JIS, EN)
- End treatment requirements