Stainless Steel Coil Tube for Coil Heat Exchange Flocculation Tank
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
Product Code: 947
Classification: Technical Literature & Engineering Reference
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered heat transfer element specifically designed for integration into Coil Heat Exchange Type Flocculation Tanks (盘管换热型絮凝罐). This product represents a critical component in advanced water treatment and wastewater processing systems where thermal regulation and chemical coagulation must be achieved simultaneously within a single vessel.
Unlike conventional straight-pipe heat exchangers, the coil tube configuration maximizes the heat transfer surface area within a confined tank volume, enabling efficient thermal conditioning of flocculant solutions or process water prior to and during the coagulation reaction. The helical geometry promotes turbulent flow within the coil, significantly enhancing convective heat transfer coefficients compared to laminar flow in straight conduits.
2. Material & Properties
2.1 Material Composition
The coil tube is manufactured from high-grade austenitic stainless steel, typically conforming to the following grades:
- 304 (UNS S30408): General-purpose corrosion resistance; suitable for potable water treatment and mild chemical environments.
- 316L (UNS S31603): Enhanced pitting and crevice corrosion resistance due to molybdenum (Mo) addition; recommended for seawater treatment, chloride-rich environments, and aggressive chemical applications.
- 321 (UNS S32103): Titanium-stabilized variant for elevated temperature service where sensitization must be avoided.
2.2 Key Physical & Mechanical Properties
| Property | 304 Grade | 316L Grade |
|---|---|---|
| Density (g/cm³) | 8.00 | 8.03 |
| Thermal Conductivity (W/m·K) at 20°C | 16.3 | 14.6 |
| Thermal Expansion Coefficient (10⁻⁶/K) 20–100°C | 17.3 | 16.0 |
| Tensile Strength (MPa) min. | 520 | 485 |
| Yield Strength (0.2% Proof, MPa) min. | 205 | 170 |
| Elongation (%) min. | 40 | 40 |
| Operating Temperature Range (°C) | -196 to +870 | -273 to +870 |
| Pitting Resistance Number (PREN) | 19 | 24–26 |
3. Specifications
| Parameter | Specification |
|---|---|
| Tube Outer Diameter (OD) | Φ12 mm / Φ16 mm / Φ19 mm / Φ25 mm / Φ32 mm (customizable) |
| Wall Thickness | 0.5 mm – 2.0 mm (typical: 1.0 mm – 1.5 mm) |
| Coil Pitch | 10 mm – 50 mm (optimized per heat transfer requirement) |
| Coil Diameter | 100 mm – 600 mm (determined by tank internal diameter) |
| Total Tube Length | 5 m – 120 m (dependent on thermal duty) |
| Heat Transfer Surface Area | 0.5 m² – 20 m² (configurable) |
| Design Pressure | 0.6 MPa – 1.6 MPa (typical) |
| Design Temperature | -20°C to +200°C |
| Surface Finish | No. 4 Brushed / Electropolished (Ra ≤ 0.4 μm) |
| Connection Type | Flanged / Threaded / Welded (ASME B16.5 / DIN flanges) |
| Applicable Standards | GB/T 12771, ASTM A269/A270, EN 10217-7 |
4. Manufacturing Process
4.1 Raw Material Selection & Inspection
Only certified stainless steel seamless tubes or welded tubes (per ASTM A269) from accredited mills are procured. Each batch undergoes spectrographic analysis to verify chemical composition and meets the specified grade requirements.
4.2 Coil Forming
- Cold Coiling: Straight tube stock is fed through a programmable coiling machine with precision rollers to form the helical geometry. The coiling process is performed at ambient temperature to preserve the metallurgical properties and avoid work-hardening sensitization.
- Pitch Control: CNC-controlled feed mechanisms ensure uniform pitch throughout the coil length, critical for consistent heat transfer performance and flow distribution.
- Spring-Back Compensation: The coiling equipment incorporates algorithmic spring-back compensation to achieve the final coil diameter within ±0.5 mm tolerance.
4.3 Heat Treatment (if applicable)
Post-coiling solution annealing (1050–1100°C followed by rapid quench) may be performed for coils experiencing significant cold work, restoring full ductility and corrosion resistance.
4.4 Surface Treatment
- Acid pickling and passivation to remove mill scale and form a protective chromium oxide layer.
- Optional electropolishing for biologically active applications, reducing surface roughness to Ra ≤ 0.4 μm to inhibit bacterial adhesion.
4.5 Quality Inspection
- Dimensional Verification: Coordinate measuring machine (CMM) or laser scanning for coil diameter, pitch, and tube OD conformance.
- Pressure Testing: Hydrostatic test at 1.5× design pressure, held for minimum 30 seconds.
- Non-Destructive Testing (NDT): Eddy current inspection or penetrant testing on weld joints and coil body.
- Surface Inspection: Visual and magnetic particle inspection for surface defects.
4.6 Assembly & Integration
The completed coil tube is installed within the flocculation tank with appropriate support saddles and expansion loops to accommodate thermal expansion. Inlet and outlet connections are welded or flanged per the specified pressure class.
5. Applications
5.1 Primary Application: Coil Heat Exchange Flocculation Tank
In a Coil Heat Exchange Type Flocculation Tank, the coil tube serves a dual function:
- Thermal Conditioning: Heating or cooling the process water to the optimal temperature for flocculant dissolution and coagulation reaction kinetics. Temperature control improves floc formation density and settling velocity.
- Enhanced Mixing: The coil geometry disrupts stratification and promotes radial mixing within the tank, reducing dead zones and improving treatment uniformity.
5.2 Industry Applications
| Industry | Application |
|---|---|
| Municipal Water Treatment | Coagulation/flocculation pretreatment for drinking water purification |
| Wastewater Treatment | Thermally assisted chemical precipitation for industrial effluent |
| Food & Beverage Processing | Clarification and filtration of process streams (dairy, brewing, juice) |
| Pulp & Paper | Waste paper water treatment with temperature-controlled flocculation |
| Pharmaceutical | Clean water system heat exchangers meeting GMP requirements |
| Chemical Processing | Reactor effluent treatment with aggressive chemical compatibility |
| Textile Dyeing | Dye wastewater treatment requiring high-temperature flocculation |
6. Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- GB/T 12771 — Chinese National Standard for Stainless Steel Seamless Tubes for General Cold-Rolled Use
- ASTM A269 / A270 — American Standards for Welded and Seamless Austenitic Stainless Steel Tubing
- EN 10217-7 — European Standard for Stainless Steel Tubes for Technical Applications
- ASME BPE — Bioprocessing Equipment Standard (for pharmaceutical applications)
- NSF/ANSI 61 — Drinking Water System Components (where applicable)
- Material Test Reports (MTR) — Full chemical and mechanical property certification per EN 10204 3.1
7. Unique Selling Points
Integrated Thermal-Chemical Process Design: The coil tube enables simultaneous heat exchange and flocculation within a single vessel, reducing equipment footprint, piping complexity, and capital expenditure compared to separate heat exchanger + flocculation tank configurations.
- Maximized Heat Transfer Efficiency: The helical coil geometry generates secondary Dean vortex flow, increasing the Nusselt number by 1.5–2.0× compared to straight tube of equivalent length.
- Space-Optimized Design: High surface-area-to-volume ratio allows compact installation within standard tank diameters, ideal for retrofit applications.
- Corrosion-Resistant Construction: Full stainless steel wetted parts ensure long service life (15–25 years) even in chemically aggressive environments.
- Temperature-Controlled Flocculation: Precise thermal management of the coagulant solution optimizes polymer chain conformation and floc aggregation kinetics, yielding denser, faster-settling flocs.
- Customizable Engineering: Coil diameter, pitch, tube specification, and total heat transfer area are tailored to the specific thermal duty and hydraulic requirements of each project.
- Low Fouling Susceptibility: Smooth electropolished surface finish combined with turbulent internal flow minimizes scale and biofilm accumulation, reducing maintenance intervals.
- Structural Integrity: Cold-formed coil geometry provides inherent structural rigidity, reducing the need for external support structures within the tank.
8. Design Considerations
When specifying the coil tube for a flocculation tank application, the following engineering parameters must be evaluated:
- Thermal Duty Calculation: Determine the required heat transfer rate (Q = UAΔT_lm) based on flow rate, inlet/outlet temperatures, and allowable temperature differential.
- Pressure Drop Analysis: Ensure the coil pressure drop does not exceed the available pump head; typical allowable ΔP is 50–150 kPa for process water circuits.
- Thermal Expansion Management: Incorporate expansion loops or flexible joints to accommodate differential thermal expansion between the coil and tank shell.
- Flow Distribution: Verify uniform velocity distribution across the coil inlet to prevent localized stagnation or excessive erosion.
- Chemical Compatibility: Confirm the selected alloy grade is suitable for the specific flocculant chemistry (e.g., ferric chloride, polyaluminum chloride, polyacrylamide) and process water composition.
9. Maintenance & Service Life
- Expected Service Life: 15–25 years under normal operating conditions with proper water quality management.
- Cleaning Interval: 12–24 months depending on water quality and fouling propensity; chemical cleaning or CIP (Clean-In-Place) procedures recommended.
- Inspection Frequency: Annual visual inspection of coil supports, weld joints, and surface condition; NDT every 5 years for high-pressure applications.
- Replacement Criteria: Wall thinning exceeding 20% of original thickness, detectable leaks, or significant loss of heat transfer performance.
10. Conclusion
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd represents a purpose-engineered heat transfer solution for coil heat exchange type flocculation tanks. By integrating thermal management directly into the coagulation process vessel, this product delivers superior process efficiency, compact installation, and long-term reliability across a wide spectrum of water treatment applications. Its compliance with international standards and customizable engineering approach make it a preferred choice for industrial and municipal water treatment projects worldwide.