Stainless Steel Coil Tube (Coiltube) — Steam Heating Coil Tube System
Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered tubular product designed specifically for indirect heat transfer applications, particularly steam heating of water. The coil tube is formed into a continuous helical or serpentine configuration to maximize the surface-area-to-volume ratio, thereby optimizing thermal exchange efficiency. This product is widely deployed in industrial heating systems, district heating networks, water heating installations, and process engineering applications where reliable steam-to-water heat transfer is critical.
The design philosophy of this coil tube is grounded in the fundamental thermodynamic principles governing steam condensation and convective heat transfer. By utilizing a coiled geometry, the system achieves superior heat transfer coefficients compared to straight-tube alternatives, reducing overall steam consumption and improving energy utilization efficiency.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, mechanical strength, and thermal stability under prolonged exposure to steam and hot water environments.
- Primary Grades: SUS304 (ASTM 304), SUS316L (ASTM 316L), SUS321 (ASTM 321), and custom duplex grades available upon request
- Corrosion Resistance: Superior resistance to pitting, crevice corrosion, and stress-corrosion cracking (SCC) in aqueous environments
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C, ensuring efficient heat transfer from steam to process water
- Mechanical Strength: Tensile strength of 515–720 MPa with elongation of 35–45%, providing excellent resistance to thermal cycling fatigue
- Temperature Range: Operational service temperatures from -196°C to +870°C, accommodating both cryogenic and high-temperature steam conditions
- Chemical Composition: Low carbon content (≤0.03% C for 316L) to minimize intergranular sensitization during welding and heat treatment
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Code | No. 1516 |
| Outer Diameter (OD) | Φ6.0 mm – Φ108.0 mm (customizable) |
| Wall Thickness | 0.3 mm – 3.0 mm (per application requirement) |
| Coil Pitch | 10 mm – 50 mm (adjustable for heat transfer optimization) |
| Coil Diameter | Φ50 mm – Φ2000 mm |
| Tube Length (Uncoiled) | Up to 12,000 mm continuous length |
| Surface Finish | No. 4 brushed, BA (Bright Annealed), or sanitary electropolished (Ra ≤ 0.4 μm) |
| Pressure Rating | Up to 4.0 MPa (working pressure), 6.0 MPa (test pressure) |
| Steam Pressure (Typical) | 0.1 – 1.6 MPa (saturated or superheated steam) |
| Heat Transfer Efficiency | U-value: 1,500 – 3,200 W/(m²·K) depending on flow conditions |
| Standards Compliance | ASTM A213/A269, GB/T 12771, EN 10217-7, JIS G3459 |
| End Connection | Welded, threaded, flanged, or socket-welded per customer specification |
| Minimum Order Quantity | 100 kg or as negotiated |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and long-term operational reliability:
- Raw Material Procurement: Cold-rolled stainless steel strip or seamless tube stock sourced from certified mills, with full chemical composition analysis (spectrometric verification) and mechanical property testing prior to acceptance.
- Coil Forming: Precision CNC-controlled coiling machines form the straight tube into the required helical or serpentine geometry, maintaining tight tolerances on coil pitch (±0.5 mm) and coil diameter (±1.0 mm).
- Welding (where applicable): Longitudinal welds are produced using TIG (Tungsten Inert Gas) welding with argon internal shielding to ensure a clean, corrosion-free weld bead. Weld penetration is verified through radiographic testing (RT) or ultrasonic testing (UT).
- Heat Treatment: Solution annealing at 1010–1150°C followed by controlled water quenching to restore full austenitic microstructure and maximize corrosion resistance.
- Surface Finishing: Mechanical polishing, chemical passivation (nitric acid or citric acid treatment), and optional electropolishing to achieve the required surface roughness and corrosion protection.
- Quality Inspection: 100% dimensional inspection, hydrostatic pressure testing at 1.5× working pressure, and visual examination of all welds and surface finishes.
Applications
The stainless steel coil tube is engineered for demanding thermal applications across multiple industries:
- Industrial Steam Heating: Primary application in indirect steam-heated water systems, where the coil tube serves as the heat exchange medium between saturated steam and process water. The coiled geometry maximizes heat transfer area within compact vessel footprints.
- District Heating Systems: Utilized in central heating plants and district heating networks for efficient steam-to-water heat exchange in large-scale residential and commercial heating installations.
- Food & Beverage Industry: Sanitary-grade coil tubes used in pasteurization systems, CIP (Clean-in-Place) heating loops, and hot water generation for brewing and dairy processing.
- Pharmaceutical Manufacturing: High-purity coil tubes for steam sterilization systems, jacketed reactor heating, and pharmaceutical-grade hot water distribution.
- Chemical Processing: Corrosion-resistant coil tubes for heat exchangers handling aggressive chemical solutions, acid recovery systems, and process heating in petrochemical plants.
- Power Generation: Auxiliary heating systems in power plants for feedwater preheating, deaerator heating, and boiler support systems.
- Marine Applications: Seawater-resistant coil tubes (316L grade) for shipboard heating systems, bilge water heating, and marine HVAC systems.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring product compliance with international standards:
- 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 — Conformity with European Directives for pressure equipment (PED 2014/68/EU)
- ASME Stamp — Section VIII Div. 1 compliance for pressure vessels and heat exchangers
- NSF/ANSI 61 — Drinking water system components certification (available for sanitary grades)
- 3-A Sanitary Standards — Food industry equipment compliance (available upon request)
Each batch of coil tube is accompanied by a Mill Test Certificate (MTC) per EN 10204 Type 3.1, detailing chemical composition, mechanical properties, heat treatment records, and dimensional inspection results. Third-party inspection by organizations such as SGS, Bureau Veritas, or TÜV is available for critical applications.
Unique Selling Points
The Wenzhou Jixing Stainless Steel Coil Tube distinguishes itself through the following competitive advantages:
- Optimized Steam Consumption: The coil tube geometry, combined with precision manufacturing tolerances, achieves superior heat transfer coefficients that directly reduce steam consumption. Engineering studies confirm that properly designed coil tube systems can reduce steam usage by 15–25% compared to conventional straight-tube heat exchangers under identical operating conditions.
- Extended Service Life: The selection of high-purity austenitic stainless steel grades with controlled carbon content ensures resistance to intergranular corrosion, even after repeated thermal cycling and welding operations. Expected service life exceeds 20 years under normal operating conditions.
- Custom Engineering Capability: Full customization of coil pitch, diameter, tube dimensions, and end connections allows the product to be tailored to specific thermal load requirements and vessel geometries, ensuring optimal heat transfer performance for each application.
- Sanitary-Grade Availability: Electropolished coil tubes with surface roughness Ra ≤ 0.4 μm meet the stringent hygiene requirements of food, pharmaceutical, and bioprocessing industries, eliminating dead-leg areas where microbial contamination could occur.
- Comprehensive Technical Support: Wenzhou Jixing provides engineering consultation on steam consumption calculation, heat transfer optimization, and system design to ensure the coil tube performs at peak efficiency throughout its operational life.
- Traceability & Documentation: Full material traceability from raw steel mill to finished coil tube, with complete documentation supporting regulatory compliance and quality assurance audits.
Thermal Performance Notes
When calculating steam consumption for water heating using this coil tube system, the following engineering parameters should be considered:
- Steam Latent Heat: At typical operating pressures of 0.1–1.6 MPa, the latent heat of vaporization ranges from approximately 2,257 kJ/kg (at 0.1 MPa) to 2,003 kJ/kg (at 1.6 MPa).
- Overall Heat Transfer Coefficient (U): For steam condensing on the coil tube inner surface with water flowing on the outer surface (or vice versa), typical U-values range from 1,500 to 3,200 W/(m²·K), depending on flow velocity, fouling factors, and tube geometry.
- Fouling Factor: Recommended design fouling factor of 0.0001–0.0002 m²·K/W for clean steam/water service, with periodic cleaning intervals based on water quality analysis.
- Heat Transfer Area: The coiled geometry provides significantly greater heat transfer area per unit volume than equivalent straight-tube arrangements, enabling more compact system design.
Wenzhou Jixing Metal Materials Co., Ltd. offers technical assistance for steam consumption calculations, thermal performance verification, and system optimization to ensure the coil tube delivers maximum energy efficiency in every application.