Stainless Steel Coil Tube — Steam Heat Exchanger Grade (Coil Tube Series)
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product formed into continuous spiral or helical configurations, specifically designed for heat transfer applications including steam heat exchangers, condensers, evaporators, and process heating systems. Unlike conventional straight pipes, coil tubes offer significantly enhanced surface-area-to-volume ratios, enabling superior thermal exchange efficiency within compact installation footprints.
This product line has been validated through finite element simulation analysis (FEA) and structural optimization studies, ensuring that the coil geometry maintains mechanical integrity under cyclic thermal loading, internal pressure differentials, and fluid dynamic stresses inherent to steam service environments.
2. Material & Properties
Coil tubes are fabricated from austenitic and duplex stainless steel grades selected for their exceptional corrosion resistance, thermal stability, and long-term structural performance in high-temperature steam environments.
- Austenitic Grades: SUS304 (UNS S30400), SUS304L (UNS S30403), SUS316 (UNS S31600), SUS316L (UNS S31603), SUS321 (UNS S32100), SUS310S (UNS S31008)
- Duplex Grades: SUS316Ti, 2205 (UNS S32205), 2507 Super Duplex (UNS S32750)
- Key Mechanical Properties: Yield strength ≥ 205 MPa (austenitic), tensile strength ≥ 515 MPa, elongation ≥ 40% (A5M)
- Thermal Conductivity: 14.6–25 W/(m·K) depending on grade and temperature
- Maximum Service Temperature: Up to 870°C (SUS310S); 600–815°C for standard austenitic grades
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and intergranular corrosion in steam and condensate environments
3. Technical Specifications
| Parameter | Specification / Range |
|---|---|
| Outer Diameter (OD) | φ6.0 mm – φ50.8 mm (custom available) |
| Wall Thickness | 0.3 mm – 3.0 mm |
| Coil Inner Diameter (CID) | φ50 mm – φ600 mm |
| Coil Pitch | 10 mm – 50 mm (adjustable per design) |
| Coil Length | 1 m – 50 m per continuous coil |
| Coil Diameter Tolerance | ±1.0% |
| Wall Thickness Tolerance | ±10% (per ASTM A213 / ASME SA-213) |
| Surface Finish | Bright Annealed (BA), No.4 Brushed, or 2B |
| Maximum Working Pressure | Up to 4.0 MPa (design-dependent) |
| Operating Temperature Range | -40°C to +870°C |
| Applicable Standards | ASTM A213, ASME SA-213, EN 10216-5, GB/T 12771 |
4. Manufacturing Process
The production of high-performance stainless steel coil tubes follows a rigorous multi-stage process to ensure dimensional accuracy, mechanical integrity, and metallurgical quality:
- Raw Material Selection: Cold-rolled stainless steel strip or seamless tube blanks sourced from certified mills, verified via mill test certificates (MTC) and chemical composition analysis (spectrometry).
- Tubing Forming: Precision roll-forming or drawing operations to achieve the target OD and wall thickness with tight tolerances.
- Welding (if applicable): Automatic TIG (Tungsten Inert Gas) welding with argon gas back-purging to ensure full-penetration, corrosion-resistant weld seams. Weld beads are mechanically ground and passivated.
- Coil Forming: CNC-controlled coiling machines wind the formed tube into precise helical or spiral geometries. Coil diameter, pitch, and lead angle are programmatically controlled to maintain uniformity.
- Heat Treatment: Solution annealing at 1010–1150°C followed by water quenching to restore full austenitic microstructure, eliminate residual stresses from forming, and maximize corrosion resistance.
- Pickling & Passivation: Acid pickling removes oxide scale and mill residue; passivation forms a protective chromium oxide layer on the surface.
- Non-Destructive Testing (NDT): 100% hydrostatic pressure testing; spot Eddy Current Testing (ECT) and X-ray radiographic inspection for weld quality verification.
- Structural Simulation Validation: Finite Element Analysis (FEA) using ANSYS or equivalent software to model thermal-mechanical behavior under steam cycling conditions, verifying hoop stress distribution, fatigue life, and buckling resistance.
5. Applications
Stainless steel coil tubes from this series are deployed across a broad spectrum of industrial and commercial heat exchange applications:
- Steam Heat Exchangers: Primary and secondary steam coils in shell-and-coil heat exchangers for process heating, preheating, and condensation duty.
- Food & Beverage Industry: CIP (Clean-in-Place) compatible coils for pasteurization, sterilization, and hot water circulation systems (FDA-compliant grades available).
- Pharmaceutical & Biotech: GMP-compliant heat exchange coils for bioreactor jacketing, steam sterilization (SIP), and clean steam generation.
- Power Generation: Steam generator tubes and economizer coils in cogeneration (CHP) and waste heat recovery systems.
- Chemical Processing: Corrosion-resistant coils for reactive chemical heating, distillation columns, and reactor jacket cooling.
- Marine & Offshore: Condensate recovery coils and steam traps in marine propulsion auxiliary systems.
- HVAC & District Heating: Compact coil assemblies for plate-fin heat exchangers and district heating distribution terminals.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring traceability, compliance, and performance reliability:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System
- EN 10204 3.1 / 3.2 — Material Test Certificates per European standards
- ASME "S" Stamp / "R" Stamp — Authorization for pressure vessel and heat exchanger components (where applicable)
- CE Marking — Conformity with EU Pressure Equipment Directive (PED 2014/68/EU)
- Material Certifications: 100% MTC traceability with chemical composition and mechanical property reports per heat number
- NDT Reporting: Full hydrostatic test reports and available ECT/X-ray documentation upon request
7. Unique Selling Points
This coil tube product line distinguishes itself through the following value propositions:
- Simulation-Validated Design: Each coil geometry is backed by FEA-based structural optimization, ensuring that thermal fatigue life, pressure containment, and vibration resistance are engineered — not assumed.
- Compact High-Efficiency Architecture: The coiled configuration delivers 3–5× the heat transfer surface area per unit volume compared to equivalent straight-tube bundles, reducing equipment footprint and installation cost.
- Full Traceability: End-to-end material traceability from mill certificate to finished coil, supporting audit requirements in regulated industries (pharma, food, aerospace).
- Custom Geometry Capability: CNC-controlled coiling enables bespoke pitch, diameter, and length configurations tailored to specific heat exchanger design parameters.
- Corrosion-Free Longevity: Austenitic and duplex stainless steel construction provides a design life exceeding 25 years in steam service without degradation of mechanical or corrosion-resistant properties.
- Hygienic Surface Finish: Bright annealed (BA) finish with Ra ≤ 0.4 μm surface roughness meets sanitary and pharmaceutical cleanliness requirements without additional polishing.
8. Ordering & Technical Support
Customers are advised to provide the following parameters for accurate quotation and design validation:
- Required OD and wall thickness (per applicable standard)
- Target coil inner diameter and pitch
- Total coil length or required heat transfer duty (kW)
- Operating temperature, pressure, and fluid medium
- Applicable code/standard (ASME, EN, GB, etc.)
- Required certifications and NDT scope
Wenzhou Jixing Metal Materials Co., Ltd. provides complimentary preliminary FEA-based feasibility assessment for custom coil tube designs upon submission of process parameters and application requirements.