Stainless Steel Coil Tube for Heat Carrier Furnace Convective Sections

Product Overview

This stainless steel coil tube (Coiltube) is a specialized heat exchange tubing product engineered for deployment in the convective chambers of heat carrier fluid furnaces. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., the coil tube is designed to facilitate efficient thermal transfer between high-temperature heat carrier media (such as thermal oil or synthetic heat transfer fluid) and the furnace's flue gas stream. The product is specifically configured for multi-layer stacking arrangements within the convective section, where inter-tube soot blowing structures are integrated to maintain optimal heat transfer efficiency over extended operational cycles.

The coil tube occupies a critical role in industrial heating systems where precise temperature control and high thermal efficiency are paramount. Its serpentine geometry maximizes heat transfer surface area within a compact furnace envelope, making it indispensable in processes requiring sustained, uniform heat delivery.

Material and Properties

The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of oxidation resistance, thermal stability, and mechanical integrity under prolonged exposure to elevated temperatures.

Technical Specifications

Parameter Specification
Outer Diameter (OD) 14 mm – 51 mm (customizable)
Wall Thickness 1.0 mm – 3.0 mm
Coil Pitch (Center-to-Center Spacing) 25 mm – 80 mm
Coil Width (Tube Span) 100 mm – 1500 mm
Coil Length (Total Uncoiled Length) 10 m – 200 m per unit
Maximum Operating Temperature Up to 1100°C (depending on grade)
Heat Carrier Medium Thermal oil (mineral or synthetic), up to 350°C fluid temperature
Flue Gas Temperature (Inlet) Up to 900°C
Design Pressure Up to 2.5 MPa (363 psi)
Surface Finish Mill finish or polished (Ra ≤ 1.6 μm)
Applicable Standards ASTM A213, ASTM A269, EN 10216-5, GB/T 12771
Number of Layers (Convective Section) 2 or more layers with inter-layer soot blowing provisions

Manufacturing Process

The production of these coil tubes follows a rigorous multi-stage manufacturing sequence to ensure dimensional accuracy, metallurgical soundness, and consistent performance:

  1. Material Selection and Inspection: Raw stainless steel pipe stock is sourced from certified mills and subjected to spectroscopic analysis (PMI) and mechanical testing to verify grade compliance and tensile properties.
  2. Cold Forming (Coiling): Straight pipe sections are cold-formed into the required serpentine coil geometry using precision hydraulic forming equipment. The forming process is carefully controlled to prevent work hardening-induced cracking and to maintain uniform wall thickness throughout the bends.
  3. Heat Treatment (Solution Annealing): Formed coils undergo solution annealing at 1050–1100°C followed by controlled cooling to relieve residual stresses, restore full austenitic microstructure, and maximize corrosion resistance.
  4. Pickling and Passivation: The surface is chemically cleaned to remove oxide scale and contaminants, followed by passivation treatment to establish a protective chromium oxide layer.
  5. Dimensional Verification: Each coil unit is inspected for coil pitch accuracy, tube straightness, dimensional tolerances, and surface quality using laser measurement systems and optical comparators.
  6. Hydrostatic/Pneumatic Testing: Pressure testing is performed at 1.5× the design pressure to confirm weld integrity and structural soundness.
  7. Packaging and Dispatch: Coils are protected with moisture-barrier wrapping and secured on steel racks for safe transport to the installation site.

Applications

These stainless steel coil tubes are deployed in a wide range of industrial heating applications:

Quality Certifications and Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring full traceability and compliance with international standards:

Unique Selling Points

Engineered for Multi-Layer Convective Arrangements: These coil tubes are specifically designed with dimensional tolerances and surface characteristics that accommodate inter-layer soot blowing structures. The precise coil pitch and tube alignment enable the integration of steam or air soot blowers between adjacent coil layers, ensuring continuous cleaning of deposited particulates and maintaining peak thermal efficiency throughout the operational life of the furnace.