Stainless Steel Coil Tube — Coiltube for Industrial Heat Exchanger Applications

Product Overview

The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered seamless or welded tubular product supplied in continuous coil form, specifically designed for high-temperature heat exchange service in heavy industrial environments. This product category encompasses a wide range of coil-wound stainless steel tubes that offer superior thermal conductivity, corrosion resistance, and mechanical integrity under sustained thermal cycling conditions. The coiltube configuration enables efficient deployment in compact heat exchanger geometries, including coil-type rising tube heat exchangers utilized in large-scale metallurgical and energy production systems, such as 6.25 m coke oven installations.

Coiltube products are distinguished from straight-length tubes by their continuous helical winding, which eliminates the need for butt-welded joints during installation, thereby reducing potential failure points and improving overall system reliability. This manufacturing and supply format is particularly advantageous for applications involving convoluted flow paths, spirally wound heat exchangers, and high-velocity fluid transport systems where minimizing pressure drop and maximizing heat transfer surface area are critical design objectives.

Material & Properties

The Coil Tube is available in a comprehensive range of austenitic, ferritic, and duplex stainless steel grades, each selected to meet specific service environment requirements:

Mechanical Properties (Typical Values for 304/304L Grade)

Chemical Composition (Typical — 304/304L)

Element 304 (max %) 304L (max %)
Carbon (C) 0.08 0.03
Chromium (Cr) 18.0 – 20.0 18.0 – 20.0
Nickel (Ni) 8.0 – 10.5 8.0 – 10.5
Manganese (Mn) 2.00 2.00
Silicon (Si) 1.00 1.00
Phosphorus (P) 0.045 0.045
Sulfur (S) 0.030 0.030
Nitrogen (N) 0.10 0.10

Specifications

Parameter Specification / Range
Product Name Stainless Steel Coil Tube (Coiltube)
Product Category Industrial Heat Exchanger Tubing
Available Grades 304, 304L, 316, 316L, 321, 310S, 316Ti, 2205 Duplex, and custom grades upon request
Outer Diameter (OD) Φ3.0 mm – Φ108 mm (custom diameters available)
Wall Thickness 0.3 mm – 6.0 mm (tolerance: ±10% for thin-wall; ±0.1 mm for thick-wall)
Coil Length Continuous coil up to 3,000 m per coil (custom lengths available)
Coil Inner Diameter (ID) 300 mm – 1,200 mm (configurable to customer requirement)
Surface Finish Mill finish (No. 1), Pickled & Oiled (P&O), Bright Annealed (BA), Polished (2B, #4, #8), or Custom
Manufacturing Method Seamless (Pierced / Extruded) or Welded (ERW / Automatic Welding with Post-Weld Heat Treatment)
Applicable Standards ASTM A213/A213M, ASTM A312/A312M, EN 10216-5, EN 10217-7, GB/T 12771, GB/T 21832, JIS G3459
Heat Treatment Solution Annealing (1010–1150°C followed by rapid quench), Stress Relief, or Custom
Maximum Operating Temperature Up to 1150°C (grade-dependent; refer to individual grade specifications)
Packaging Wooden pallet with moisture-proof wrapping, steel banding, and protective caps; export-standard packaging available
Production Capacity High-volume continuous production with flexible customization

Manufacturing Process

The production of high-quality stainless steel coil tubes follows a rigorous multi-stage manufacturing sequence designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:

  1. Raw Material Preparation:

    High-purity stainless steel wire rod or strip, conforming to ASTM A276 or equivalent specifications, is inspected for chemical composition (via spectrographic analysis) and mechanical properties prior to processing. Incoming materials are certified with mill test reports (MTRs).

  2. Forming & Welding (for welded tubes) / Piercing & Extrusion (for seamless tubes):

    For welded coil tubes, cold-rolled strip is fed through precision roll-forming dies to achieve the target OD and wall thickness. A high-energy welding process — typically Electromagnetic Resistance Welding (ERW) or Automatic Submerged Arc Welding (SAW) — creates a consistent, full-penetration weld seam. Seamless tubes are produced via the Mannesmann piercing or hydraulic extrusion method, eliminating the weld seam entirely.

  3. Sizing & Calibration:

    Formed tubes pass through precision sizing rolls and calibration stations to achieve the required dimensional tolerances in both OD and wall thickness. Laser measurement systems provide real-time dimensional feedback for closed-loop process control.

  4. Heat Treatment (Solution Annealing):

    Welded tubes undergo solution annealing at temperatures between 1010°C and 1150°C, followed by controlled water quenching. This process dissolves chromium carbides precipitated during welding, restores full austenitic microstructure, eliminates residual welding stresses, and ensures maximum corrosion resistance. The resulting microstructure is verified through metallographic examination.

  5. Pickling & Descaling:

    Post-annealing oxide scale is removed through controlled acid pickling (typically using a mixture of nitric acid and hydrofluoric acid) or electrochemical descaling. This step ensures a clean, uniform surface suitable for subsequent finishing operations.

  6. Surface Finishing:

    Depending on the customer specification, tubes may receive additional surface treatments including mechanical polishing (to achieve Ra ≤ 0.8 μm for sanitary applications), passivation (to enhance passive chromium oxide film formation), or specialized coating applications.

  7. Coil Winding:

    Finished tubes are wound onto precision steel or aluminum coil cores using automated winding systems that maintain consistent inter-layer spacing and uniform tension. This prevents surface damage, deformation, and stress concentration during storage and transport.

  8. Quality Inspection & Testing:

    Comprehensive quality assurance protocols are applied at multiple stages, including: hydrostatic pressure testing (per ASTM A312), eddy current testing for seam integrity, ultrasonic testing for internal defects, visual surface inspection, dimensional measurement, and chemical composition verification. Non-destructive testing (NDT) results are documented and included in the final product certification package.

  9. Packaging & Dispatch:

    Inspected coils are wrapped with moisture-proof polyethylene film, secured with steel strapping, and mounted on export-grade wooden pallets or steel cradles. Each shipment is accompanied by a full certification dossier including Mill Test Reports (MTRs), Certificate of Conformance (CoC), and, where applicable, third-party inspection reports.

Applications

The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. is engineered for demanding industrial applications where corrosion resistance, thermal performance, and mechanical reliability are paramount:

1. Metallurgical & Coke Oven Systems

A primary application domain is the coil-type rising tube heat exchanger used in large-scale coke oven operations, including 6.25 m coke oven installations. In these systems, coil tubes carry heat transfer medium through the rising gas ducts, recovering thermal energy from high-temperature coke oven gases (typically 700–900°C). The continuous coil configuration allows for efficient heat recovery in a compact footprint, while the stainless steel material resists thermal fatigue, scaling, and corrosion from the aggressive chemical environment of coke oven off-gases (containing hydrogen sulfide, ammonia, and phenolic compounds). The application of coil-type heat exchangers in 6.25 m coke ovens represents a significant advancement in energy efficiency, enabling thermal recovery rates that contribute to overall plant energy optimization and reduced carbon emissions.

2. Petrochemical & Refinery Heat Exchangers

Coil tubes are extensively used in spiral-wound heat exchangers for refinery and petrochemical processes, including crude oil fractionation, distillation, and catalytic cracking units. Grades such as 316L and 321 provide resistance to sour service (H₂S-containing environments) and high-temperature oxidation, respectively.

3. Power Generation & Energy Systems

Application in steam generators, waste heat boilers, and solar thermal collector systems where continuous coil configurations maximize heat transfer surface area within constrained installation spaces.

4. Chemical Processing & Pharmaceutical

Used in reactor cooling coils, heat exchangers, and process piping systems requiring high purity and resistance to aggressive chemical media. Bright annealed and polished finishes meet sanitary requirements for pharmaceutical and food-grade applications.

5. HVAC & Refrigeration

Compact coil tubes are employed in evaporator and condenser coils for industrial HVAC systems, chillers, and heat pump applications, leveraging the inherent corrosion resistance of stainless steel for extended service life in humid and chemically aggressive environments.

6. Marine & Offshore Engineering

Duplex 2205 and super-austenitic 316L coil tubes serve in marine heat exchangers, ballast water system components, and offshore platform utility systems where resistance to chloride-induced stress corrosion cracking is essential.

Quality Certifications

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product conformity with international standards: