Medium-Diameter Stainless Steel Coil Tube (Φ12–25 mm) for Industrial Applications
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. is proud to offer a premium range of medium-diameter stainless steel coil tubes with outer diameters spanning from Φ12 mm (0.47 in) to Φ25 mm (0.98 in). Engineered for demanding industrial environments, these coil tubes are supplied in continuous, spring-coiled configurations that eliminate the need for field welding, thereby reducing installation labor, minimizing leak points, and ensuring superior long-term integrity.
The medium-diameter class occupies a critical niche in the stainless steel tubing market, bridging the gap between fine-bore instrumentation tubing and large-diameter process piping. This size range delivers an optimal balance of flow capacity, mechanical strength, and flexibility, making it the preferred choice for heat exchanger U-tube bundles, hydraulic fluid conveyance systems, and Clean-In-Place (CIP) sanitary applications across food, beverage, pharmaceutical, and chemical processing industries.
Unique Selling Point: Wenzhou Jixing's medium-diameter coil tubes are manufactured with precision coil-winding technology that maintains consistent wall thickness tolerance of ±0.05 mm throughout the entire coil length, ensuring uniform hydraulic performance and thermal efficiency in every application.
Material & Properties
These coil tubes are available in a comprehensive selection of austenitic and duplex stainless steel grades, each selected to meet specific corrosion resistance, mechanical strength, and temperature requirements:
- 304 / 304L (A2 / 18-8): The industry-standard general-purpose grade offering excellent corrosion resistance in most atmospheric and food-grade environments. 304L provides enhanced resistance to intergranular corrosion for welded applications.
- 316 / 316L (A4 / 316Ti): Superior resistance to pitting and crevice corrosion due to 2–3% molybdenum content. Ideal for chemical processing, marine environments, and pharmaceutical applications.
- 321 (with Ti stabilization): Titanium-stabilized grade suitable for elevated temperature service up to 870 °C (1,598 °F), preventing chromium carbide precipitation.
- 310S (25-20): High-temperature grade with exceptional oxidation resistance, suitable for furnace components and high-heat industrial processes.
- 316Ti: Titanium-stabilized 316 variant offering enhanced weldability and resistance to stress corrosion cracking in chloride-containing solutions.
Key mechanical properties at room temperature (annealed condition):
- Tensile Strength: ≥ 520 MPa (75,400 psi) for 304/304L; ≥ 570 MPa (82,700 psi) for 316/316L
- Yield Strength: ≥ 205 MPa (29,700 psi) for 304/304L; ≥ 240 MPa (34,800 psi) for 316/316L
- Elongation: ≥ 40% (measured over 50 mm gauge length)
- Hardness: ≤ 200 HB (annealed condition)
- Density: 8.0 g/cm³ (0.289 lb/in³)
- Thermal Conductivity: 16.3 W/(m·K) at 100 °C (0.9 BTU/hr·ft·°F)
Specifications
The following table summarizes the dimensional specifications for the medium-diameter coil tube series:
| Parameter | Specification | Tolerance |
|---|---|---|
| Outer Diameter (OD) | Φ12 mm – Φ25 mm (0.47 – 0.98 in) | ±0.10 mm |
| Wall Thickness | 0.5 mm – 2.0 mm (0.020 – 0.079 in) | ±10% of nominal |
| Inner Diameter (ID) | Φ10 mm – Φ24 mm (0.39 – 0.94 in) | Derived from OD and wall thickness |
| Coil Diameter | Φ150 mm – Φ600 mm (5.9 – 23.6 in) | ±5 mm |
| Coil Length | 20 m – 500 m (66 – 1,640 ft) per coil | As specified by customer |
| Surface Finish | BA (Bright Annealed), 2B, No. 4 Brushed, Electropolished (Ra ≤ 0.4 μm) | Per customer requirement |
| End Condition | Plain, Beveled (37.5°), Flared (45°), Threaded (BSP/NPT) | Per drawing specification |
| Temperature Range | −196 °C to +870 °C (−321 °F to +1,598 °F) | Grade-dependent |
| Pressure Rating | Up to 40 MPa (5,800 psi) depending on wall thickness and grade | Per ASME B31.3 / EN 13480 |
| Applicable Standards | ASTM A269 / A213, EN 10217-7, ISO 1307, GB/T 12771 | — |
Manufacturing Process
Wenzhou Jixing Metal Materials Co., Ltd. employs a fully integrated manufacturing process to ensure the highest quality standards for medium-diameter coil tubes. The production workflow is as follows:
- Raw Material Selection: Only certified stainless steel wire rod from accredited mills (e.g., Outokumpu, Sandvik, ThyssenKrupp, or domestic equivalents) is sourced. Each batch undergoes spectroscopic analysis to verify chemical composition compliance.
- Wire Drawing: The selected wire rod is cold-drawn through a series of precision tungsten carbide dies to achieve the target outer diameter with tight dimensional tolerances. Drawing lubricants are food-grade (NSF certified) for sanitary applications.
- Seamless Forming: The drawn wire is helically wound and resistance-welded at the seam using advanced TIG or flash-butt welding techniques. The weld zone is subsequently annealed to achieve homogenous metallurgical properties.
- Continuous Annealing: Tubes pass through a continuous annealing furnace at 1,050 °C (1,922 °F) under a controlled nitrogen/hydrogen atmosphere. This eliminates cold-work stresses, restores full austenitic microstructure, and achieves the desired mechanical properties.
- Pickling & Passivation: Post-annealing, tubes are pickled in a citric acid or dilute nitric/hydrofluoric acid bath to remove oxide scale. A final passivation treatment forms a protective chromium oxide layer for maximum corrosion resistance.
- Coil Winding: The continuous tube is precisely wound onto coils of the specified diameter using computerized winding equipment. Spring tension is calibrated to ensure the coil maintains its shape during storage and transportation while remaining easy to uncoil during installation.
- Non-Destructive Testing (NDT): 100% of production is subjected to automated eddy-current testing and hydrostatic pressure testing. Visual inspection and dimensional gauging are performed at defined intervals.
- Packaging & Shipping: Coils are wrapped in protective film, placed on wooden pallets with steel strapping, and shipped in export-grade packaging to prevent mechanical damage and moisture exposure.
Applications
Heat Exchanger U-Tube Bundles
The medium-diameter range (Φ12–25 mm) is the industry-preferred size for U-tube bundles in shell-and-tube heat exchangers. The coil configuration allows for pre-formed U-bends without additional machining, significantly reducing fabrication time and cost. The tight coil tolerance ensures consistent tube-to-tubesheet fit, critical for pressure boundary integrity in high-pressure heat exchanger applications.
Hydraulic Tubing Systems
In hydraulic power units, mobile machinery, and industrial automation systems, these coil tubes provide reliable fluid conveyance under high-pressure conditions. The seamless construction eliminates potential leak paths at longitudinal seams, while the coil form allows for neat routing in confined spaces with minimal fittings.
CIP (Clean-In-Place) Sanitary Systems
For food, beverage, and pharmaceutical processing, the electropolished finish (Ra ≤ 0.4 μm) of these coil tubes meets the stringent hygiene requirements of CIP systems. The smooth internal surface prevents product retention and bacterial adhesion, ensuring consistent cleaning validation and compliance with FDA, 3-A, and EHEDG standards.
Additional Applications
- Automotive fuel and brake lines
- Chemical process piping and reactor internals
- Medical device tubing and endoscope channels
- Gas cylinder manifold lines
- Compressed air and pneumatic systems
- Waste heat recovery systems
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework backed by internationally recognized certifications:
- ISO 9001:2015 — Quality Management System certification demonstrating commitment to consistent product quality and continuous improvement.
- ISO 14001:2015 — Environmental Management System certification ensuring environmentally responsible manufacturing practices.
- EN 10204 3.1 — Full inspection documentation with third-party verified test certificates for every production batch.
- ASME Stamp (where applicable) — Compliance with ASME Boiler and Pressure Vessel Code for pressure-containing applications.
- NSF/ANSI 61 — Drinking water system components certification for potable water applications.
- 3-A Sanitary Standards — Compliance with the International Sanitary Foundation standards for dairy, food, and beverage processing equipment.
- CE Marking / PED 2014/68/EU — Conformity with the European Pressure Equipment Directive for Category II and above applications.
Quality Commitment: Every coil tube batch produced by Wenzhou Jixing is accompanied by a mill test certificate (MTC) traceable to the original steelmaking heat number. Full material traceability from raw wire rod to finished coil is maintained through a digital quality management system, ensuring complete supply chain transparency and regulatory compliance.
Summary of Advantages
- Optimal Size Range: Φ12–25 mm OD covers the most commonly specified diameters for heat exchangers, hydraulics, and sanitary systems — reducing SKU complexity for customers.
- Seamless Integrity: Continuous coil form eliminates field welds, reducing failure points by up to 90% compared to cut-and-welded alternatives.
- Multi-Grade Availability: Single-source procurement of 304L, 316L, 321, and 310S grades from one certified manufacturer simplifies supply chain management.
- Precision Consistency: ±0.05 mm wall thickness tolerance ensures uniform performance across the entire coil length — critical for heat exchanger thermal efficiency and CIP flow dynamics.
- Sanitary Grade Options: Electropolished surfaces with Ra ≤ 0.4 μm meet the most stringent pharmaceutical and food-grade requirements.
- Global Compliance: Full certification portfolio (ISO, ASME, CE/PED, NSF, 3-A) enables seamless integration into international projects without additional third-party inspection.