Stainless Steel Coil Tube (盘管) — TEG Regeneration Column Heat Exchanger Application
Product Overview
The Stainless Steel Coil Tube (盘管) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubular component designed for high-performance heat exchange applications, particularly within the Triethylene Glycol (TEG) Regeneration Column systems used in natural gas and refinery dehydration processes. This product is specifically engineered as a coil-type condenser (盘管式冷凝器), leveraging the enhanced heat transfer surface area and compact geometry inherent to coiled configurations to achieve superior thermal efficiency under continuous industrial operating conditions.
The coil tube serves as the core heat exchange element in TEG regeneration systems, where it facilitates the condensation of water vapor and solvent vapor during the regeneration cycle. The coiled geometry provides a high surface-area-to-volume ratio, enabling rapid heat transfer between the process fluid and the surrounding medium while maintaining a compact installation footprint.
Material & Properties
The coil tubes are fabricated from high-grade austenitic stainless steel, selected for its exceptional corrosion resistance, mechanical strength, and thermal stability across a wide temperature range.
- Primary Alloy Grades: SUS304 (ASTM A213 TP304), SUS316L (ASTM A213 TP316L), and SUS321 (ASTM A213 TP321)
- Corrosion Resistance: Superior resistance to chloride pitting, acid corrosion, and sulfur-containing compounds prevalent in natural gas processing environments
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 25°C, providing efficient heat transfer performance
- Operating Temperature Range: −196°C to +870°C (depending on grade selection)
- Mechanical Properties: Tensile strength ≥520 MPa; yield strength ≥205 MPa; elongation ≥40%
- Surface Finish: Ra ≤ 0.4 μm (electropolished) or Ra ≤ 0.8 μm (mechanical polished)
- Welding Compatibility: Fully compatible with TIG (GTAW) and orbital welding processes without sensitization concerns when properly controlled
Technical Specifications
| Parameter | Specification |
|---|---|
| Tube Outer Diameter (OD) | φ6 mm – φ25 mm (custom sizes available) |
| Tube Wall Thickness | 0.5 mm – 2.0 mm |
| Coil Inner Diameter (ID) | φ100 mm – φ800 mm (adjustable per application) |
| Coil Pitch (Spacing) | 10 mm – 50 mm (configurable) |
| Coil Length (Developed) | Up to 200 m per coil assembly |
| Coil Turns | 50 – 500+ turns (application-dependent) |
| End Connections | Flanged, threaded (NPT/BSP), or welded stub connections |
| Surface Treatment | Pickling, passivation, electropolishing, or PTFE coating (on request) |
| Pressure Rating | Up to 4.0 MPa (design pressure, subject to hydrostatic testing) |
| Hydrostatic Test Pressure | 1.5× design pressure (minimum 5.0 MPa) |
| Heat Transfer Coefficient (Enhanced) | 1,200 – 2,800 W/(m²·K) (compared to 400–900 W/(m²·K) for straight tubes) |
| Applicable Standards | ASTM A213, GB/T 14976, EN 10216-5, ASME B31.3 |
| Manufacturing Standard | ISO 9001:2015, PED 2014/68/EU (CE marking) |
Manufacturing Process
The production of precision coil tubes follows a rigorous multi-stage manufacturing workflow to ensure dimensional accuracy, mechanical integrity, and metallurgical quality:
- Material Selection & Inspection: Incoming stainless steel seamless tubes are verified through chemical composition analysis (OES/Spectroscopy) and mechanical property testing in accordance with ASTM E415 and ASTM E10 protocols.
- Heat Treatment & Annealing: Tubes undergo solution annealing at 1050–1150°C followed by controlled cooling to relieve residual stresses and ensure uniform microstructure.
- Precision Coiling: Cold coiling is performed using CNC-controlled coiling machines with servo-driven tension control to maintain uniform coil geometry, consistent pitch, and minimal ovality (≤2% of OD).
- Welding & Joining: End connections are fabricated using orbital TIG welding (GTAW) with inert gas shielding (Ar or Ar/He mix) to ensure full-penetration, defect-free welds. Weld parameters are validated per ASME Section IX.
- Pickling & Passivation: Post-welding pickling removes oxide scale, followed by citric or nitric acid passivation to restore the passive chromium oxide layer (minimum 30 wt% Cr₂O₃ coverage).
- Non-Destructive Testing (NDT): 100% helium leak testing (helium partial pressure method, detection limit ≤1×10⁻⁹ Pa·m³/s) and radiographic inspection (RT) of critical welds per ASME Section V, Article 2.
- Hydrostatic Pressure Testing: Each coil assembly undergoes hydrostatic testing at 1.5× design pressure with a minimum hold time of 30 minutes to verify pressure integrity.
- Final Dimensional Inspection: Coordinate Measuring Machine (CMM) verification of coil geometry, OD, wall thickness, and end connection alignment to ±0.1 mm tolerance.
Applications
The Stainless Steel Coil Tube is specifically designed for the following industrial applications:
- TEG Regeneration Column Condensers: Primary application — the coil tube serves as the condenser element in triethylene glycol regeneration columns, where it condenses overhead vapor (water + TEG vapor) during the stripping/regeneration process. Numerical simulation studies (CFD-based thermal-hydraulic modeling) have confirmed that coil-type condensers in TEG columns achieve 15–30% higher heat transfer efficiency compared to conventional shell-and-tube designs due to flow-induced secondary circulation within the coiled geometry.
- Natural Gas Dehydration Systems: Integration into glycol dehydration units for sweet natural gas production in oil and gas processing facilities.
- Chemical Processing: Condensers, reboilers, and heat exchangers in petrochemical, pharmaceutical, and fine chemical manufacturing.
- Food & Beverage Industry: Condensation and cooling systems where hygiene-grade stainless steel (SUS316L) is required.
- Cryogenic Applications: Low-temperature condensation and liquefaction processes where SUS321 or custom cryogenic grades are specified.
- Power Generation: Auxiliary heat exchange systems in combined cycle power plants and waste heat recovery units.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality assurance and certification frameworks to ensure product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health and Safety Management System
- CE Marking (PED 2014/68/EU) — European Pressure Equipment Directive compliance
- ASME "U" Stamp — Authorization for pressure vessel and pressure piping component manufacturing
- NACE MR0175 / ISO 15156 — Compliance for sour service (H₂S-containing) applications
- Third-Party Inspection (TPI): Available upon request — SGS, Bureau Veritas, DNV, or Lloyd's Register
- Mill Test Reports (MTR): Provided with every shipment, including chemical composition, mechanical properties, and NDT results
- Material Traceability: Full heat number traceability from raw material to finished product, with digital documentation
Unique Selling Points
- Enhanced Heat Transfer Performance: The coiled geometry induces Dean vortices (二次涡流), enhancing turbulent mixing and achieving 15–30% higher overall heat transfer coefficients compared to straight-tube configurations, as validated by CFD numerical simulation studies on TEG regeneration column condensers.
- Compact Design: Significantly reduced installation footprint compared to equivalent-capacity shell-and-tube heat exchangers, ideal for space-constrained process plants.
- Superior Corrosion Resistance: SUS316L and SUS321 grades provide outstanding resistance to the corrosive environments encountered in natural gas processing, including H₂S, CO₂, and chloride-containing media.
- High Pressure & Temperature Capability: Designed and tested to withstand pressures up to 4.0 MPa and temperatures exceeding 400°C, ensuring long-term reliability in demanding industrial conditions.
- Custom Engineering: Full customization of coil diameter, pitch, tube specifications, and end connections to match specific process requirements and installation constraints.
- Rigorous Quality Control: 100% leak testing, NDT, and hydrostatic verification on every unit, backed by complete traceability documentation.
- Extended Service Life: Expected operational lifespan of 20–25 years with proper maintenance, significantly reducing lifecycle costs compared to carbon steel alternatives.
Technical Note: Numerical simulation research on the heat exchange characteristics of coil-type condensers in TEG regeneration columns has demonstrated that the coiled geometry provides a significant enhancement in heat transfer through the generation of secondary flow patterns (Dean number effect). The dimensionless heat transfer enhancement factor (h_coil/h_straight) reaches values of 1.15–1.30 under typical operating conditions (Re = 5,000–50,000), confirming the superior performance of coil tube configurations for condensation duty in glycol regeneration systems.