Stainless Steel Coil Tube — Medium Diameter Grade (OD Φ12mm – Φ25mm)
Product Overview
The Stainless Steel Coil Tube Medium Diameter Grade, manufactured by Wenzhou Jixing Metal Materials Co., Ltd., represents a precision-engineered intermediate-diameter coil tube solution designed for demanding industrial applications. This product line occupies the critical transitional range between micro-bore tubing and standard large-diameter seamless pipes, delivering exceptional versatility for heat exchanger U-bundles, hydraulic circuitry, and CIP (Cleaning-In-Place) sanitary systems.
Coil tubes in the Φ12mm to Φ25mm outer diameter range are supplied in continuous coil form, enabling high-speed automated processing, minimal material waste, and efficient fabrication workflows. The medium diameter classification balances flow capacity with compact installation footprints, making these tubes the preferred choice for applications requiring high surface-area-to-volume ratios and reliable pressure integrity.
Material & Properties
Wenzhou Jixing Metal Materials Co., Ltd. offers the Medium Diameter Grade coil tube in a comprehensive range of austenitic and duplex stainless steel grades, each selected to meet specific corrosion resistance, mechanical strength, and temperature endurance requirements:
- Grade 304 (UNS S30400 / 1.4301): General-purpose corrosion resistance; excellent formability; suitable for food-grade and chemical processing environments.
- Grade 316L (UNS S31603 / 1.4404): Enhanced pitting and crevice corrosion resistance due to molybdenum addition (2.0–3.0% Mo); preferred for marine, pharmaceutical, and aggressive chemical applications.
- Grade 321 (UNS S32100 / 1.4541): Titanium-stabilized austenitic grade with superior resistance to intergranular corrosion at elevated temperatures (up to 870°C).
- Grade 316Ti (UNS S31635 / 1.4571): Titanium-stabilized variant of 316L offering enhanced resistance to sensitization and stress corrosion cracking.
- Grade 904L (UNS N08904 / 1.4539): High-alloy austenitic grade with outstanding resistance to oxidizing and reducing acids; designed for extreme chemical environments.
- Grade 2205 Duplex (UNS S32205 / 1.4462): Dual-phase microstructure providing approximately twice the yield strength of 304/316 with superior resistance to chloride-induced stress corrosion cracking.
All grades are available in annealed (Solution Treated, SA) and pickled & passivated (SA-P) surface conditions to ensure optimal corrosion resistance and dimensional stability.
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube — Medium Diameter Grade |
| Outer Diameter (OD) | Φ12 mm – Φ25 mm |
| Wall Thickness | 0.5 mm – 3.0 mm (customizable per application) |
| Coil Inner Diameter (ID) | Φ100 mm – Φ600 mm (adjustable for downstream machinery) |
| Coil Length per Spool | 50 m – 500 m (standard); custom lengths available |
| Surface Finish | Pickled & Passivated; 2B Annealed; Polished (Ra ≤ 0.8 μm available) |
| Pressure Rating | Up to 25 MPa (dependent on grade and wall thickness) |
| Temperature Range | −196°C to +870°C (grade-dependent) |
| Tolerance Class | OD: ±0.05 mm to ±0.15 mm; Wall: ±0.03 mm to ±0.10 mm |
| Applicable Standards | ASTM A269, ASTM A270, EN 10216-5, GB/T 12771, JIS G3459 |
Manufacturing Process
The production of Medium Diameter Grade coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorously controlled multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Hot Rolling & Hot Finishing: Continuous casting billets are hot-rolled into seamless tube blanks at temperatures exceeding 1,100°C, establishing the initial microstructure and approximate dimensions.
- Piercing & Elongation: The billets are pierced and elongated through multi-stand rolling mills to achieve the target outer diameter and wall thickness within the Φ12–Φ25 mm range.
- Intermediate Annealing: Tubes undergo controlled furnace annealing to relieve residual stresses accumulated during cold working and to restore full austenitic grain structure.
- Cold Drawing / Cold Pilgering: Precision cold-drawing through calibrated tungsten carbide dies achieves final dimensional tolerances (±0.05 mm OD) and superior surface finish. Multiple passes may be employed for thin-wall configurations.
- Final Annealing & Pickling: Tubes are annealed in a continuous belt furnace under controlled atmosphere to achieve uniform mechanical properties, followed by acid pickling (HNO₃/HF blend) to remove surface scale and iron contamination.
- Passivation: A final passivation treatment using nitric acid or citric acid solutions establishes a stable chromium oxide passive film, enhancing corrosion resistance.
- Coiling & Winding: Tubes are wound onto precision coiling machines with controlled tension to prevent kinking or ovality, producing uniform coils ready for downstream processing.
Applications
Heat Exchanger U-Tubes
The Medium Diameter Grade coil tube is the industry-preferred material for manufacturing U-bundle tubes in shell-and-tube heat exchangers. The continuous coil form allows automated U-bending without welding, eliminating potential leak points. The Φ12–Φ25 mm range optimizes the trade-off between heat transfer efficiency (high surface area per unit length) and pressure drop, making these tubes ideal for:
- Power generation condensers and feedwater heaters
- Petrochemical and refinery process heat exchangers
- Marine and offshore heat recovery systems
- Food and beverage pasteurization and sterilization equipment
Hydraulic Circuitry & Fluid Power
In hydraulic systems, the mechanical strength and fatigue resistance of stainless steel coil tubes in this diameter range provide reliable fluid conveyance under cyclic pressure loads. Applications include:
- High-pressure hydraulic lines in aerospace actuators
- Industrial automation fluid power circuits
- Offshore drilling hydraulic control systems
- Automotive braking and fuel injection lines
CIP (Cleaning-In-Place) Sanitary Systems
For pharmaceutical, dairy, and bioprocessing industries, the Medium Diameter Grade coil tube meets stringent sanitary requirements:
- Low surface roughness (Ra ≤ 0.4 μm available) prevents microbial adhesion and biofilm formation
- Resistance to repeated CIP cycles with caustic soda, nitric acid, and peracetic acid solutions
- Compliance with 3-A Sanitary Standards and FDA 21 CFR regulations
- Used in sterile filtration manifolds, process piping, and in-process analytical probes
Quality Certifications & Testing
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring every coil of Medium Diameter Grade tube meets or exceeds international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- CE Marking — European Conformity for pressure equipment and components
- PED (Pressure Equipment Directive 2014/68/EU) — Compliance for pressure system applications
- EN 10204 3.1 — Third-party material test certificates with full traceability
- ASME BPV Code — Section I and VIII compliance for pressure vessel applications
- API 5L / API 5CT — Where applicable for oil and gas sector specifications
Incoming and In-Process Inspection
- Chemical composition verification via Optical Emission Spectroscopy (OES) on every heat
- Mechanical testing: Tensile, yield strength, elongation, and hardness (per ASTM A370)
- Dimensional inspection: Laser micrometers for OD and wall thickness on 100% of production
- Non-Destructive Testing (NDT): Eddy current inspection (per ASTM E309) for surface and near-surface defect detection
- Hydrostatic testing: 100% water pressure testing at 1.5× design pressure with minimum dwell time
- Intergranular corrosion testing: ASTM A262 Practice E (for stabilized grades)
Unique Selling Points
1. Precision Dimensional Control: Tolerances as tight as ±0.05 mm on outer diameter ensure seamless integration into automated U-bending and fabrication lines, reducing scrap rates and maximizing yield.
2. Continuous Coil Supply: Elimination of butt welds in heat exchanger applications dramatically improves leak-tightness and fatigue life compared to straight-length tube assemblies.
3. Multi-Grade Flexibility: A single coil-form product platform spans from standard 304 to high-alloy 904L and duplex 2205, providing engineers with material selection freedom without sacrificing supply continuity.
4. Full Traceability: Every coil is heat-number traceable from raw material through final delivery, enabling rapid root-cause analysis and regulatory compliance documentation.
5. Custom Configuration: Tailored coil diameters, lengths, surface finishes, and wall thicknesses accommodate project-specific requirements, reducing downstream processing costs.
Wenzhou Jixing Metal Materials Co., Ltd. delivers the Medium Diameter Grade Stainless Steel Coil Tube as a reliable, high-performance solution for global industrial markets, combining metallurgical excellence with manufacturing precision and unwavering quality commitment.