Stainless Steel Helical Coil Tube for Low-Temperature Dust Removal Systems
Product Overview
The Stainless Steel Helical Coil Tube (盘管/Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 720), is a precision-engineered tubular component designed for integration into helical coil electric heaters within low-temperature dust removal (Low-Temperature Dust Collection) systems. This product represents a critical interface component in industrial environmental control technologies, where it serves as the structural and functional backbone of spiral wound heating elements used to prevent particulate matter adhesion and condensation in flue gas treatment applications.
Unlike conventional straight or U-bend tube configurations, the helical coil tube geometry provides superior heat transfer efficiency per unit volume, enabling compact system designs while maintaining high thermal output in cryogenic and sub-ambient operating environments. The coil configuration facilitates uniform fluid distribution and enhances convective heat exchange between the working medium and the surrounding gas stream.
Material & Properties
Base Material Grades
- Austenitic Stainless Steels: SUS304 (UNS S30408), SUS316L (UNS S31603), and SUS321 (UNS S32100) for general low-temperature service
- High-Temperature Grades: SUS310S (UNS S31008) for elevated thermal cycling applications
- Cryogenic Grades: SUS304L and SUS316L for sub-zero operating conditions down to -196°C
Mechanical Properties
| Property | SUS304 / 304L | SUS316L | SUS321 |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 520 MPa | ≥ 485 MPa | ≥ 515 MPa |
| Yield Strength (Rp0.2) | ≥ 205 MPa | ≥ 170 MPa | ≥ 205 MPa |
| Elongation (A50) | ≥ 40% | ≥ 40% | ≥ 40% |
| Operating Temperature Range | -196°C to 870°C | -196°C to 870°C | -196°C to 1093°C |
| Corrosion Resistance (pH) | 1.5 – 13.0 | 1.0 – 13.5 | 1.5 – 13.0 |
Key Material Advantages
- Low-Temperature Toughness: Retains full mechanical integrity at cryogenic temperatures without ductile-to-brittle transition
- Anti-Condensation Capability: Prevents moisture accumulation on tube surfaces that would otherwise cause particulate agglomeration
- Thermal Cycling Resistance: Withstands repeated heating-cooling cycles without fatigue cracking or intergranular corrosion (IGC)
- Non-Stick Surface: Passivated oxide layer prevents electrostatic adhesion of fine dust particles
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6 mm – 51 mm (custom sizes available) |
| Wall Thickness (WT) | 0.5 mm – 4.0 mm |
| Coil Pitch (Helix Spacing) | 10 mm – 80 mm (adjustable per thermal load requirements) |
| Coil Diameter (Mean) | 100 mm – 1200 mm |
| Overall Tube Length | Up to 30,000 mm per continuous coil |
| Surface Finish | Electropolished (Ra ≤ 0.4 μm) or Passivated (ASTM A967) |
| End Preparation | Beveled (37.5° ± 1°) for butt welding; socket-weld fittings available |
| Maximum Operating Pressure | 16.0 MPa (PN160), depending on OD/WT combination |
| Heat Transfer Coefficient (Enhanced) | 1,200 – 2,800 W/m²·K (helical configuration vs. 600 – 1,500 W/m²·K straight tube) |
| Standard Compliance | ASTM A213/A269, EN 10216-5, GB/T 12771, JIS G3459 |
Manufacturing Process
- Raw Material Selection & Inspection: Certified stainless steel wire rod or seamless tube stock subjected to spectroscopic analysis (OES), chemical composition verification, and mechanical property testing per ASTM E1009.
- Cold Drawing / Seamless Forming: Precision cold-drawing through multi-stage dies to achieve exact OD and WT tolerances (±0.05 mm). Alternative seamless piercing for larger diameters.
- Solution Annealing: Continuous annealing at 1050°C – 1150°C in protective atmosphere (N₂ or vacuum) to restore austenitic microstructure and eliminate cold-work hardening.
- Helical Coiling (Spiral Forming): CNC-controlled helical coiling machine with synchronized feed and rotation, maintaining constant pitch and coil diameter within ±1.0 mm tolerance. Spring-back compensation algorithms ensure dimensional accuracy post-forming.
- Welding & Joining: TIG (Gas Tungsten Arc Welding) per AWS D10.9 for stainless steel. Internal gas shielding (Ar/He mixture) prevents internal oxidation. Weld inspection via radiographic testing (RT) or ultrasonic testing (UT).
- Surface Treatment: Acid pickling and passivation (ASTM A380/A967) to establish protective chromium oxide film. Optional electropolishing for ultra-clean surface in pharmaceutical or food-grade applications.
- Final Quality Control: Dimensional verification via laser scanning, pressure testing at 1.5× design pressure, visual inspection per ASME BPV Section VIII.
Applications
Primary Application: Low-Temperature Dust Removal Systems
In industrial flue gas treatment, particularly in cement kilns, power generation, steel mills, and chemical processing, flue gases may cool below the acid dew point (typically 120°C – 180°C), causing sulfuric acid condensation and subsequent dust agglomeration on bag filter media. The helical coil tube electric heater maintains gas temperature above the acid dew point, ensuring:
- Prevention of acid condensation on filter bags and ductwork
- Elimination of electrostatic charge buildup on particulates
- Maintenance of filter permeability and collection efficiency above 99.9%
- Extension of filter bag service life by 2–3× compared to unheated systems
Additional Applications
- Industrial Process Heating: Precise temperature control in chemical reactors, polymer extrusion, and food processing
- Cryogenic Systems: LNG (Liquefied Natural Gas) handling, liquid nitrogen distribution, and cryogenic storage
- Pharmaceutical & Biotech: Sterilization-in-place (SIP) systems, clean steam generation, and aseptic processing
- Food & Beverage: Pasteurization, pasteurization-in-place (PIP), and thermal processing equipment
- Automotive: Exhaust gas recirculation (EGR) cooling, turbocharger preheating
- Marine & Offshore: Bilge heating, fuel oil preheating, and ballast tank heating
Quality Certifications & Standards Compliance
| Standard / Certification | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification for manufacturing excellence |
| ISO 14001:2015 | Environmental Management System compliance |
| ASME BPV Section VIII Div. 1 | Pressure vessel and piping component conformity |
| EN 10204 3.1 | Certified material test reports with third-party inspection |
| NACE MR0175 / ISO 15156 | Suitability for sour service (H₂S-containing environments) |
| CE Marking (PED 2014/68/EU) | European pressure equipment directive compliance |
| NSF 61 / EN 1250 | Drinking water system suitability (for food-grade applications) |
| GB/T 12771 | Chinese national standard for stainless steel seamless tubes |
Unique Selling Points
The Wenzhou Jixing Metal Materials Co., Ltd. Coiltube (No. 720) differentiates itself in the industrial heating market through the following technical advantages:
- Superior Heat Transfer Geometry: The helical coil configuration increases effective heat transfer area by 25%–40% compared to equivalent-length straight tube installations, while reducing system footprint.
- Low-Temperature Optimization: Specifically engineered for acid dew point prevention in flue gas systems, with demonstrated reliability at operating temperatures as low as -40°C ambient with internal heating to 250°C.
- Customizable Coil Parameters: Pitch, diameter, and length are adjustable to match specific thermal load calculations, enabling optimal heater performance for each application.
- Full Traceability: Each coil tube batch is traceable from raw material heat number through final inspection, with digital quality records available upon request.
- Extended Service Life: Electropolished and passivated surfaces resist pitting corrosion and crevice corrosion, ensuring 15+ years of reliable operation in aggressive industrial environments.
- Weld-Friendly Design: End preparations optimized for TIG welding with minimum distortion, facilitating field installation and maintenance without requalification.
Technical Documentation & Learning Reference
This product specification is informed by the technical study of "Application of Helical Coil Electric Heaters in Low-Temperature Dust Removal Systems" (《螺旋盘管式电加热器在低低温除尘系统中的应用》), a comprehensive engineering analysis covering thermodynamic modeling, thermal performance validation, and field deployment case studies. The knowledge base addresses critical engineering considerations including:
- Thermal load calculation methodology for helical coil configurations
- Acid dew point determination and temperature control strategy
- Flow dynamics within helical coil passages (secondary flow effects, Dean number analysis)
- Material selection criteria under thermal cycling and corrosive gas environments
- System integration with bag filter housings and induced draft fan arrangements
For detailed engineering support, thermal performance calculations, or custom coil tube specifications, Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical consultation and application engineering services.