Stainless Steel Coil Tube — Compressor Exhaust Discharge Coil

Product Code: 301 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd

1. Product Overview

The Stainless Steel Coil Tube is a precision-engineered helical or spiral tube component designed primarily for use as an exhaust discharge coil within industrial and commercial compressors. This product addresses the critical engineering challenge of managing exhaust gas flow dynamics, thermal dissipation, and acoustic performance within compressor systems. The coil geometry provides an optimized surface-area-to-volume ratio, enabling efficient heat transfer while simultaneously serving as an acoustic dampening element that significantly reduces overall compressor noise levels.

Based on extensive research into the relationship between exhaust coil structure and整机 (whole-machine) noise characteristics, this product line incorporates advanced structural design principles that account for vibration propagation, resonant frequency management, and gas flow turbulence minimization. The coil tube functions as both a thermal management component and an acoustic engineering solution, making it indispensable in high-performance compressor assemblies where noise reduction is a primary design objective.

2. Material & Properties

The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior combination of corrosion resistance, thermal stability, mechanical strength, and fatigue endurance under cyclic thermal loading conditions.

3. Specifications

Parameter Specification Standard / Reference
Outer Diameter (OD) 6 mm – 50 mm (custom available up to 100 mm) GB/T 12771, ASTM A213
Wall Thickness 0.5 mm – 3.0 mm ISO 3506
Coil Pitch 10 mm – 80 mm (adjustable per application) Manufacturer specification
Coil Length 50 mm – 2000 mm Custom fabrication
Number of Turns 2 – 200 turns Application-dependent
Tolerance on OD ±0.1 mm (standard); ±0.05 mm (precision grade) ISO 1130
Surface Finish 2B, BA (Bright Annealed), No. 4 Brushed, Mirror (Ra ≤ 0.2 μm) ASTM A480
End Treatment Flat cut, beveled, threaded (M6–M50), flanged, or custom fittings GB/T 5762, DIN 2999
Pressure Rating Up to 40 MPa (depending on geometry and grade) ASME B31.3
Acoustic Performance NRR (Noise Reduction Rating) up to 25 dB(A) at 1000 Hz ISO 3741, ISO 3745
Heat Transfer Efficiency U-value: 180–350 W/(m²·K) depending on configuration ASHRAE Handbook

4. Manufacturing Process

The production of the Stainless Steel Coil Tube follows a rigorous multi-stage manufacturing workflow designed to ensure dimensional accuracy, microstructural integrity, and acoustic performance optimization:

  1. Raw Material Selection & Inspection: Cold-rolled stainless steel strip or seamless tube blanks are sourced from certified mills with full material traceability. Incoming inspection includes spectroscopic analysis (PMI — Positive Material Identification), dimensional verification, and surface defect screening.
  2. Forming / Coiling: Precision CNC-driven coiling machines form the tube into the specified helical geometry. Computer Numerical Control (CNC) ensures consistent pitch, turn accuracy, and absence of kinking or ovality. The forming process is performed at ambient temperature to preserve the full cold-work strengthening benefits of the austenitic microstructure.
  3. Heat Treatment (Annealing): Where required, the formed coil undergoes solution annealing at 1050°C – 1150°C followed by controlled cooling to restore ductility, relieve residual stresses from forming, and achieve a uniform grain structure. For 321 grade, a stabilization anneal at 870°C – 900°C is applied to precipitate carbon as TiC, preventing intergranular corrosion.
  4. Pickling & Passivation: Chemical pickling removes oxide scale, followed by passivation to form a protective chromium oxide layer (Cr₂O₃), ensuring maximum corrosion resistance.
  5. Mechanical Joining: Welding (orbital TIG — Tungsten Inert Gas, or laser welding) is performed for end fittings, manifolds, or integration points. Weld parameters are optimized to minimize heat-affected zone (HAZ) distortion and maintain mechanical properties.
  6. Acoustic Performance Verification: Each coil tube undergoes acoustic testing in accordance with ISO 3741 (sound power level) and ISO 3745 (reverberation room method) to validate noise reduction performance against design specifications.
  7. Final Inspection & Testing: Includes dimensional measurement (CMM — Coordinate Measuring Machine), pressure testing (hydrostatic or pneumatic), leak testing (helium or soap bubble), visual inspection, and surface finish measurement.

5. Applications

The Stainless Steel Coil Tube finds extensive application across multiple industrial sectors, particularly where noise control, thermal management, and corrosion resistance are concurrent requirements:

6. Quality Certifications & Compliance

Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications and complies with the following international standards:

7. Unique Selling Points

Acoustic-Optimized Coil Geometry: Unlike conventional coil tubes designed solely for heat transfer, this product integrates acoustic engineering principles into its structural design. Research into the influence of exhaust coil structure on whole-machine noise has led to optimized pitch, turn count, and end termination configurations that achieve up to 25 dB(A) noise reduction without compromising thermal performance.

Full Material Traceability: Every coil tube is accompanied by a complete material passport including mill certificate, heat number, chemical composition analysis, and mechanical test results, ensuring full supply chain traceability.

Custom Engineering Capability: The manufacturer offers fully customizable coil geometries, from standard helical forms to complex multi-pass configurations, with CNC precision ensuring ±0.05 mm dimensional accuracy for critical applications.

Dual-Function Performance: Simultaneously delivers superior heat transfer efficiency (U-values up to 350 W/(m²·K)) and acoustic attenuation, eliminating the need for separate silencing components and reducing system complexity.

Multi-Grade Availability: Stocked and fabricated in 304, 316L, and 321 grades to address diverse corrosion environments, from mild atmospheric exposure to aggressive chemical processing and high-temperature service.

8. Technical Notes & Recommendations

When integrating this coil tube into compressor exhaust systems, the following engineering considerations are recommended: