Stainless Steel Coil Tube (Coiltube) — Dry Coil & Bypass Valve System Integration
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered rolled tube product specifically designed for integration into dry coil and bypass valve systems used in clean air conditioning (Clean HVAC) environments. The coil tube is supplied in continuous coil form, enabling seamless fabrication of heat exchangers, air handling units, and terminal ventilation components that demand high purity, corrosion resistance, and thermal efficiency.
This product line is engineered to meet the rigorous requirements of pharmaceutical, semiconductor manufacturing, hospital, and food processing facilities where particulate control and chemical resistance are paramount. The coil geometry facilitates compact heat exchange surface area while minimizing pressure drop, making it ideal for low-velocity laminar airflow systems.
Material & Properties
Base Alloy Composition
The coil tube is fabricated from austenitic stainless steel, with the primary grade being SAE 304 (UNS S30400) and SAE 316L (UNS S31603), selected for their superior corrosion resistance, weldability, and formability in high-purity environments.
- Grade 304 (UNS S30400): Chromium (Cr) 18–20%, Nickel (Ni) 8–10.5%, Molybdenum (Mo) <0.08%, Carbon (C) ≤0.08%
- Grade 316L (UNS S31603): Chromium (Cr) 16–18%, Nickel (Ni) 10–14%, Molybdenum (Mo) 2–3%, Carbon (C) ≤0.03%
Mechanical Properties
- Tensile Strength (Ultimate): 515–720 MPa (depending on grade and wall thickness)
- Yield Strength (0.2% Offset): ≥205 MPa
- Elongation at Break: ≥40% (annealed condition)
- Hardness (Rockwell B): 80–95 HRB (annealed)
- Thermal Conductivity: 16.3 W/(m·K) at 25°C (Grade 304)
Surface Finish Options
- 2B Finish: Standard cold-rolled, annealed, and pickled surface with uniform matte appearance
- No. 4 Brushed: Directional grain pattern suitable for visible installations
- BA (Bright Annealed): Mirror-like finish achieved in controlled-atmosphere annealing; ideal for pharmaceutical and semiconductor applications
- Electropolished: Ra ≤ 0.5 μm surface roughness for ultra-clean fluid handling
Specifications
| Parameter | Specification | Tolerance |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") | ±0.1 mm |
| Wall Thickness (WT) | 0.5 mm – 3.0 mm | ±10% |
| Coil Inner Diameter (ID) | 200 mm – 600 mm | ±5 mm |
| Coil Length (per piece) | 50 m – 500 m (customizable) | ±2% |
| Material Grade | SAE 304 / 316L / 321 / 316Ti | — |
| Surface Roughness (Ra) | 0.4 – 1.6 μm (electropolished) | — |
| Operating Temperature Range | −196°C to +600°C | — |
| Maximum Working Pressure | Up to 4.0 MPa (design dependent) | — |
| Standards Compliance | ASTM A213 / A269, ASME B36.19M, EN 10217-7 | — |
| Coil Packing | Wooden pallet with VCI (Vapor Corrosion Inhibitor) film | — |
Manufacturing Process
Production Flow
- Slab Casting & Hot Rolling: Virgin stainless steel slabs are cast via Continuous Casting (CC) and subsequently hot-rolled into strip of target thickness.
- Pickle & Anneal (Pickling and Acid Washing): The hot-rolled strip undergoes pickling in mixed acid baths (HNO₃ + HF or H₂SO₄ + HNO₃) to remove oxide scale, followed by annealing to restore ductility.
- Cold Rolling: The strip is cold-rolled to achieve precise dimensional tolerances and desired mechanical properties. Multiple passes may be employed with intermediate annealing to prevent excessive work hardening.
- Slitting & Tubing Forming: The cold-rolled strip is slit to precise width, then formed into tube via Seamless (Autoclave) or Welded (Orbital TIG / Laser Welded) processes depending on application requirements.
- Post-Weld Heat Treatment: Welded tubes undergo solution annealing at 1050–1150°C in a controlled atmosphere to homogenize the Heat-Affected Zone (HAZ) and restore full corrosion resistance.
- Coiling: The finished tube is wound into coil form on precision-controlled winder equipment to maintain consistent tension, preventing deformation or kinking.
- Quality Inspection: Each coil undergoes ultrasonic testing (UT), eddy current testing (ECT), hydrostatic pressure testing, and visual/surface inspection prior to packaging.
Key Process Controls
- Online Dimensional Monitoring: Laser gauging systems continuously measure OD and wall thickness during coiling.
- Atmosphere Control: Bright annealing conducted in dew-point-controlled hydrogen/nitrogen mixtures (dew point ≤ −60°C) to prevent oxidation.
- Traceability: Each coil is heat-numbered and associated with full mill test certificates (MTC) per EN 10204 3.1.
Applications
Primary Application: Clean Air Conditioning Systems
The coil tube is specifically optimized for integration into Dry Coil and Bypass Valve configurations in clean HVAC systems. In these systems, the coil tube serves as the heat transfer element within air handling units (AHUs) and Variable Air Volume (VAV) terminals, where:
- Dry Cooling Operation: The coil operates above the dew point, preventing condensation and moisture-related contamination in sensitive environments.
- Bypass Valve Integration: The coil tube's dimensional precision ensures tight fit within bypass valve assemblies, enabling precise modulation of air temperature without introducing turbulence or particle generation.
- Low-Particulate Design: The electropolished or BA surface finish minimizes particle shedding, critical for ISO 14644 Class 1–5 cleanroom environments.
Additional Applications
- Pharmaceutical Manufacturing: GMP-compliant cleanroom HVAC systems, CIP (Clean-in-Place) piping loops
- Semiconductor Fabrication: Ultra-cleanroom air distribution, Ultra-Pure Water (UPW) recirculation
- Food & Beverage Processing: Hygienic air handling, fermentation temperature control
- Medical Facilities: Operating theater ventilation, laminar flow hood construction
- Chemical & Petrochemical: Corrosive environment heat exchangers, condenser tube bundles
- Marine & Offshore: Saltwater-resistant coil assemblies for deck ventilation
Quality Certifications & Standards
Company Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management
- EN 10204 Type 3.1 — Inspection Certificates per batch
Product Standards Compliance
- ASTM A213 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubes
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubes for General Applications
- ASME B36.19M — Welded and Seamless Wrought Stainless Steel Pipe
- EN 10217-7 — Tubes for Heat Exchangers and Heat Sinks (Stainless Steel)
- ASME BPE — Bioprocessing Equipment (for pharmaceutical grade applications)
- 3-A Sanitary Standards — For food and dairy industry applications
Testing & Inspection Protocols
| Test Method | Standard | Purpose |
|---|---|---|
| Hydrostatic Pressure Test | ASTM A213 | Verify weld integrity and pressure resistance |
| Ultrasonic Testing (UT) | ASTM E1277 | Detect internal defects (voids, inclusions) |
| Eddy Current Testing (ECT) | ASTM E709 | Identify surface and near-surface discontinuities |
| Spectrochemical Analysis | ASTM E1254 | Confirm chemical composition compliance |
| Pitting Corrosion Test | ASTM G48 | Assess chloride resistance (particularly Grade 316L) |
| Intergranular Corrosion Test | ASTM A262 Practice E | Verify sensitization resistance |
| Surface Roughness Measurement | ASTM B466 | Confirm Ra values for hygienic applications |
Unique Selling Points
- Precision Coiling Technology: State-of-the-art tension-controlled winding ensures zero kink or deformation across the entire coil length, reducing downstream fabrication waste by up to 15%.
- Integrated Cleanroom-Grade Surface Options: Electropolished finish with Ra ≤ 0.5 μm meets ASME BPE and 3-A sanitary requirements, eliminating the need for post-fabrication surface treatment.
- Full Traceability System: Every coil is laser-marked with heat number, grade, dimensions, and production date, enabling complete supply chain traceability for regulated industries.
- Custom Coil Configuration: OD, wall thickness, coil diameter, and length are fully customizable to match specific AHU or heat exchanger design parameters.
- Proven HVAC Integration: Validated performance in dry coil and bypass valve systems for ISO 14644 Class 1–5 cleanrooms, with documented case studies in semiconductor and pharmaceutical installations.
- Environmental Commitment: Production facilities utilize recycled water systems and solar-assisted annealing furnaces, reducing carbon footprint by 30% compared to industry average.
Technical Data Sheet Summary
Product: Stainless Steel Coil Tube (Coiltube)
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Primary Grades: SAE 304 / 316L (austenitic stainless steel)
OD Range: 6.0 – 50.8 mm | WT Range: 0.5 – 3.0 mm
Surface: 2B / No.4 / BA / Electropolished
Key Standard: ASTM A213, A269; ASME B36.19M; EN 10217-7
Primary Application: Dry Coil & Bypass Valve Clean HVAC Systems
Certification: ISO 9001:2015, EN 10204 3.1 MTC
Country of Origin: People's Republic of China