Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd

1. Product Overview

The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd (Product No. 229), is a precision-engineered continuous-loop tubing product designed for thermal exchange, fluid conveyance, and structural coil applications. This product is supplied in coiled form to facilitate downstream forming, welding, and assembly operations with minimal material loss and maximum process efficiency.

Coiltubes are particularly valued in the HVAC (Heating, Ventilation, and Air Conditioning) industry, where they serve as the core heat exchange element within Fan Coil Units (FCU). Extensive experimental research on the dehumidification performance of fan coil units has demonstrated that the geometric configuration, material thermal conductivity, and surface finish of the coil tube directly influence latent heat transfer efficiency, condensate drainage characteristics, and overall energy performance of the unit.

2. Material & Properties

2.1 Base Materials

2.2 Mechanical Properties (Typical — AISI 304 Annealed Condition)

Property Unit Value
Tensile Strength (UTS) MPa ≥ 520
Yield Strength (0.2% offset) MPa ≥ 205
Elongation at Break % ≥ 40
Hardness (HV) — ≤ 200
Density g/cm³ 8.0
Thermal Conductivity (at 25°C) W/(m·K) 16.3
Specific Heat Capacity (at 25°C) J/(kg·K) 500
Thermal Expansion Coefficient (20–100°C) ×10⁻⁶/K 17.3

2.3 Chemical Composition (AISI 304 — wt%)

Element C Si Mn P S Cr Ni N Fe
Maximum 0.08 1.00 2.00 0.045 0.030 — — 0.10 Balance
Minimum — — — — — 18.0 8.0 — —

3. Specifications

Parameter Specification
Product Name Stainless Steel Coil Tube (Coiltube)
Product No. 229
Manufacturing Standard ASTM A213 / ASTM A269 / GB/T 12771 / EN 10216-5
Outer Diameter (OD) φ3.0 mm – φ32.0 mm (customizable)
Wall Thickness 0.3 mm – 3.0 mm (customizable)
Coil Inner Diameter φ150 mm – φ500 mm
Coil Length per Roll 50 m – 500 m (or as specified)
Surface Finish No. 1 Annealed / Bright Annealed (BA) / Pickled / Polished (Ra ≤ 0.4 μm)
Tolerance on OD ±0.05 mm (standard) / ±0.02 mm (precision grade)
Tolerance on Wall Thickness ±10% (standard) / ±5% (precision grade)
End Treatment Open ends / Sealed ends / Flared ends / Beveled ends
Heat Treatment Full Annealing at 1050°C – 1150°C with controlled cooling
Pressure Rating Up to 2.0 MPa (subject to dimensional configuration)
Operating Temperature Range −196°C to +870°C (grade-dependent)
Packaging Wooden drum / Export-grade plastic wrap / Palletized coil
Minimum Order Quantity 100 kg (negotiable)

4. Manufacturing Process

4.1 Process Flow

  1. Raw Material Procurement: High-purity stainless steel strip or wire rod sourced from certified mills (e.g., POSCO, Outokumpu, Taigang) with full mill test certificates (MTC).
  2. Coil Slitting: Precision slitting of stainless steel coil to the required strip width with edge quality control.
  3. Forming & Welding: Continuous cold-forming process converting flat strip into circular cross-section tube, followed by high-frequency (HF) or laser TIG welding to achieve seamless-equivalent joint integrity.
  4. Internal & External Finishing: Mandrel drawing or rotary finishing to achieve dimensional accuracy; optional internal polishing for fluid-critical applications.
  5. Annealing & Pickling: Solution annealing at 1050°C – 1150°C in a protective atmosphere (N₂ or vacuum), followed by acid pickling and passivation to restore corrosion resistance and achieve desired surface finish.
  6. Coiling: Precision coiling onto standardized drum diameters with tension control to prevent deformation, kinking, or ovality.
  7. Quality Inspection: Multi-stage inspection including dimensional measurement, hydrostatic pressure testing, eddy current flaw detection, and surface defect evaluation.
  8. Packaging & Dispatch: Protective packaging for export or domestic distribution.

4.2 Process Advantages

5. Applications

5.1 HVAC & Fan Coil Units

The primary application of this coil tube product is as the heat exchange element within Fan Coil Units (FCU). Experimental studies on the dehumidification performance of fan coil units have confirmed that stainless steel coil tubes offer significant advantages over traditional copper-aluminum configurations:

5.2 Additional Applications

6. Quality Certifications & Compliance

6.1 International Certifications

6.2 Applicable Standards

Standard Title Relevance
ASTM A213 Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for High-temperature Service Material & product specification
ASTM A269 Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and General Line Applications Material & product specification
EN 10216-5 Heat Exchangers and Radiators — Heat Exchanger Tubes — Part 5: Technical Delivery Conditions for Stainless Steel Tubes European product standard
GB/T 12771 Stainless Steel Seamless Tubes for Fluid Transport Chinese national standard
GB/T 14976 Stainless Steel Seamless Tubes for Cold Rolling Chinese national standard
ASME SA-213 Boiler and Heat Exchanger Tubes American Society of Mechanical Engineers

6.3 Inspection & Testing Protocols

  1. Hydrostatic Pressure Test: Each coil lot subjected to internal pressure testing at 1.5× working pressure with zero-leak acceptance criteria.
  2. Dimensional Inspection: 100% OD and wall thickness measurement at intervals of ≤ 10 m along the coil length using ultrasonic or laser gauges.
  3. Weld Quality Assessment: Radiographic testing (RT) or eddy current testing (ECT) on weld joints per ASTM E7097.
  4. Chemical Composition Verification: Spark emission spectrometry (OES) on each heat number.
  5. Corrosion Testing: Salt spray testing (ASTM B117) — minimum 500 hours without pitting for 316 grade.
  6. Surface Finish Verification: Surface roughness measurement per ISO 4287, Ra values documented per coil lot.

7. Unique Selling Points

8. Technical Advisory Note