Stainless Steel Coil Tube (Coiltube) for HVAC & Heat Pump Systems

Product Overview

The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous-length tubular product designed for integration into air-cooled heat pump systems, heat exchangers, and thermal management equipment. This product addresses a critical industry challenge: achieving uniform frost distribution across finned coil surfaces during dehumidification cycles, thereby maximizing seasonal energy efficiency ratios (SEER) and reducing compressor wear in refrigeration applications.

Distinguished from standard straight-pipe configurations, the coil tube is formed into a continuous spiral or serpentine geometry that optimizes heat transfer surface area within a compact volumetric envelope. The product is particularly suited for applications where frost uniformity, corrosion resistance, and long-term thermal performance are paramount.

Material & Properties

The coil tube is fabricated from austenitic stainless steel grades, selected for their exceptional combination of mechanical strength, corrosion resistance, and thermal conductivity suitable for cryogenic and high-temperature service.

Base Alloy Composition

Mechanical Properties

Thermal & Corrosion Resistance

Specifications

Parameter Specification / Range
Outer Diameter (OD) 6.0 mm – 25.4 mm (1/4" – 1")
Wall Thickness 0.5 mm – 1.5 mm
Coil Pitch (Helical Winding) 8 mm – 25 mm (adjustable per application)
Coil Diameter (Helical Winding) 100 mm – 500 mm
Serpentine Loop Width 50 mm – 200 mm
Serpentine Loop Length (per turn) 150 mm – 600 mm
Surface Finish No. 4 Brushed / BA (Bright Annealed) / Polished Ra ≤ 0.4 μm
Tolerance on OD ±0.05 mm (precision grades)
Tolerance on Wall Thickness ±10% of nominal
Minimum Bend Radius 1.5× OD (304); 2.0× OD (316)
Maximum Continuous Length Up to 12,000 mm (spooled delivery)
Helix Angle Deviation ≤ ±2° from nominal
Flatness (for serpentine configurations) ≤ 0.5 mm per 300 mm

Manufacturing Process

The production of high-precision stainless steel coil tubes follows a rigorous multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:

  1. Raw Material Inspection: Incoming stainless steel strip or seamless tube stock is verified against material certificates (Mill Test Reports, MTRs) for chemical composition, mechanical properties, and visual surface condition. Spectroscopic analysis (OES — Optical Emission Spectroscopy) confirms alloy compliance.
  2. Surface Preparation & Cleaning: Raw stock undergoes degreasing, pickling, and passivation to remove scale, oils, and contaminants. Bright Annealed (BA) processing ensures a clean, oxide-free surface prior to forming.
  3. Precision Forming (Coiling):
    • Helical Coiling: Continuous tube is wound around precision mandrels using CNC-controlled coil-forming machines, maintaining constant pitch, helix angle, and coil diameter. Multi-roller forming systems with hydraulic tension control prevent ovality and kinking.
    • Serpentine Forming: Flat or semi-circular tubes are formed through sequential bending stations with calibrated die sets to produce uniform loop widths, consistent bend radii, and precise loop-to-loop spacing.
  4. Post-Forming Stress Relief: Annealing at 1050–1150°C followed by controlled cooling relieves residual stresses introduced during cold forming, preventing springback and dimensional drift.
  5. Dimensional Verification: Each coil lot undergoes laser-based dimensional inspection (OD, wall thickness, coil pitch, loop geometry) using Coordinate Measuring Machines (CMM) or laser scanners. Statistical Process Control (SPC) charts track critical dimensions in real time.
  6. Pressure Testing: Hydrostatic or pneumatic pressure testing at 1.5× working pressure verifies leak-tightness and structural integrity of every coil assembly.
  7. Final Surface Treatment: Optional electropolishing or chemical passivation is applied to critical applications (food-grade, pharmaceutical, or high-purity refrigerant circuits) to achieve surface roughness Ra ≤ 0.25 μm.

Applications

Primary Application: Air-Cooled Heat Pump Systems

The coil tube is engineered specifically to address frost uniformity challenges in air-cooled heat pump evaporators. By optimizing the coil geometry — including loop spacing, bend radius, and fin attachment points — the product ensures even airflow distribution across the entire heat exchange surface. This uniform frost layer formation prevents localized ice buildup that can block airflow, reduce heat transfer efficiency, and trigger premature defrost cycles. The result is improved Seasonal Coefficient of Performance (SCOP) and reduced energy consumption by an estimated 8–15% compared to conventional coil configurations.

Additional Applications

Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product conformity with international standards:

Quality Management Systems

Product & Material Standards

Industry-Specific Certifications

Testing & Inspection Protocols

Unique Selling Points