Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (also referred to as Coiled Tubing or Coiltube) is a continuous, helically wound tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. Engineered from high-grade austenitic and duplex stainless steel alloys, this coil tube is supplied in coiled form to facilitate downstream processing, bending, forming, and installation with minimal waste and maximum flexibility.
The product is particularly suited for applications requiring hygienic, corrosion-resistant, and mechanically robust tubing — including HVAC (Heating, Ventilation, and Air Conditioning) systems, fresh air distribution networks, fan coil unit (FCU) assemblies, food processing equipment, pharmaceutical manufacturing lines, and chemical processing installations. The coiled configuration enables efficient material utilization and streamlined fabrication workflows.
2. Material & Properties
2.1 Alloy Grades
The coil tube is available in the following standard and specialty stainless steel grades:
- 304 (AISI 304 / UNS S30408) — General-purpose austenitic grade with excellent corrosion resistance and formability
- 304L (AISI 304L / UNS S30403) — Low-carbon variant optimized for welding applications without sensitization risk
- 316 (AISI 316 / UNS S31608) — Molybdenum-enhanced grade offering superior resistance to chlorides and acidic environments
- 316L (AISI 316L / UNS S31603) — Low-carbon, molybdenum-bearing grade for critical welding and high-corrosion scenarios
- 321 (AISI 321 / UNS S32108) — Titanium-stabilized grade for elevated-temperature service
- 316Ti (AISI 316Ti / UNS S31635) — Titanium-stabilized, molybdenum-bearing grade for high-temperature and high-corrosion duty
2.2 Key Mechanical and Physical Properties
- Tensile Strength (Rm): ≥ 520 MPa (Grade 304); ≥ 550 MPa (Grade 316)
- Yield Strength (Rp0.2): ≥ 205 MPa (Grade 304); ≥ 275 MPa (Grade 316)
- Elongation (A50mm): ≥ 40%
- Hardness: ≤ 210 HB (Annealed condition)
- Operating Temperature Range: −196 °C to +870 °C (non-cyclic, non-load-bearing)
- Surface Finish: 2B, BA (Bright Annealed), No. 4 Brushed, Mirror (Ra ≤ 0.4 μm)
3. Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 3.0 mm – 32.0 mm (custom sizes available upon request) |
| Wall Thickness (WT) | 0.3 mm – 2.5 mm |
| Coil Inner Diameter (ID) | 100 mm – 500 mm |
| Coil Length | Continuous — typically 50 m to 500 m per coil |
| OD Tolerance | ±0.1 mm (standard); ±0.05 mm (precision grade) |
| WT Tolerance | ±10% of nominal wall thickness |
| Roundness | ≤ 0.5% of OD |
| Surface Roughness | Ra ≤ 0.8 μm (2B/BA); Ra ≤ 0.4 μm (Mirror finish) |
| Standards Compliance | ASTM A213 / A269 / A511, EN 10217-7, ISO 3506, GB/T 12771 |
| Heat Treatment | Full Annealing (Solution Annealing at 1050–1150 °C, water quench) |
| Packaging | Wooden crate / steel frame with moisture-proof wrapping and desiccant |
4. Manufacturing Process
The production of stainless steel coil tube at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorous multi-stage process:
- Raw Material Selection: Certified ingots or slab from approved mills, verified by mill test certificates (MTC) conforming to EN 10204 3.1.
- Hot Rolling & Annealing: Initial hot-rolling to reduce the billet to semi-finished tube stock, followed by solution annealing to restore ductility.
- Piercing & Sizing: The tube blank is pierced and progressively reduced to intermediate dimensions through hot sizing mills.
- Cold Drawing / Cold Rolling: Precision cold drawing through calibrated dies or cold rolling through grooved rolls to achieve exact OD, WT, and surface finish specifications. This step ensures dimensional accuracy and enhanced mechanical properties.
- Pickling & Passivation: Acid pickling removes oxide scale; subsequent passivation treatment forms a protective chromium oxide layer, enhancing corrosion resistance.
- Final Annealing (if required): A final solution anneal to relieve residual stresses introduced during cold working, restoring the material to a fully annealed, stress-free condition.
- Coiling: The finished tube is wound onto a coil at controlled tension to prevent deformation or kinking.
- Quality Inspection: 100% dimensional verification via laser gauging; sampling for chemical composition (OES/Spectrometry), mechanical testing (tensile, hardness), and hydrostatic testing per ASTM A269.
- Packaging & Dispatch: Coils are wrapped in moisture-proof material, secured on wooden crates or steel frames, and labeled with full traceability documentation.
5. Applications
The stainless steel coil tube finds extensive use across multiple industries:
- HVAC & Fresh Air Systems: As coil elements in fan coil units (FCU), air handling units (AHU), and fresh air distribution networks — where the helical coil geometry maximizes heat transfer surface area per unit volume.
- Food & Beverage Processing: Hygienic fluid conveyance, heat exchangers, pasteurization coils, and sanitary piping systems compliant with FDA and 3-A standards.
- Pharmaceutical Manufacturing: CIP (Clean-In-Place) systems, steam coils, and process tubing requiring biocompatible, corrosion-resistant materials.
- Chemical Processing: Reaction coils, heat exchangers, and transfer lines in environments with aggressive chemical exposure.
- Automotive & Aerospace: Fuel lines, hydraulic tubing, brake lines, and exhaust system components requiring high-temperature and fatigue resistance.
- Medical Equipment: Tubing for surgical instruments, dialysis machines, and sterilization systems.
- Architecture & Decoration: Structural and decorative elements, handrails, and facade components in coastal or corrosive environments.
6. Quality Certifications & Standards
Wenzhou Jixing Metal Materials Co., Ltd maintains the following quality management and product certifications:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- CE Marking — Conformity with European directives for construction products and pressure equipment (PED 2014/68/EU)
- EN 10204 3.1 — Mill Test Certificates with specific inspection results
- NSF/ANSI 61 — Drinking water system components compliance (available upon request)
- ASME BPE — Bioprocessing Equipment standards compliance (available upon request)
7. Unique Selling Points
- Continuous Coil Supply: Eliminates butt welds inherent in cut-length tubing, reducing contamination risk and improving flow uniformity in critical applications.
- Precision Dimensional Control: Cold-drawing and laser-gauge verification ensure tight tolerances (±0.05 mm OD), enabling seamless integration into automated fabrication lines.
- Multi-Grade Availability: Full range of austenitic and stabilized grades in a single coiled product line, simplifying procurement and inventory management.
- Hygienic Surface Options: Mirror-polished finishes (Ra ≤ 0.4 μm) meet the stringent cleanliness requirements of pharmaceutical and food-grade applications.
- Full Traceability: Every coil is traceable to its mill heat number, ensuring complete material provenance documentation.
- Custom Fabrication Support: Custom OD, WT, coil ID, and surface finish configurations available to meet project-specific engineering requirements.
8. Technical Reference
This product specification references the engineering principles outlined in "Calculation and Review of Fresh Air Plus Fan Coil Tube System" — a technical study addressing thermal-hydraulic performance optimization of fan coil unit systems integrated with fresh air ventilation. The coil tube geometry described herein is specifically optimized for the heat exchange and airflow distribution characteristics identified in that analysis, ensuring efficient thermal transfer and minimal pressure drop in HVAC coil applications.