Stainless Steel Coil Tube — EN 10296-2 Non-Pressure Heat Exchanger Tubes
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered welded stainless steel tube conforming to the European standard EN 10296-2 — Welded steel tubes for mechanical and engineering purposes — Part 2: Tubes with a circular cross-section for mechanical and engineering purposes. These coil tubes are specifically designed and qualified for use as non-pressure heat exchanger tubes, providing superior thermal conductivity, corrosion resistance, and mechanical integrity in demanding industrial thermal management systems.
Delivered in continuous coil form, these tubes offer significant advantages in downstream processing — including bending, cutting, and forming — without the need for welding joints at tube-to-tube connections, thereby enhancing structural reliability and reducing leak risks in heat exchanger assemblies.
2. Material & Properties
The coil tubes are fabricated from high-grade austenitic and duplex stainless steel grades, selected for their exceptional combination of thermal performance, corrosion resistance, and mechanical properties. Commonly available grades include:
- AISI 304 / 1.4301 (EN 10088-1) — General-purpose austenitic grade with excellent corrosion resistance and formability
- AISI 316 / 1.4401 (EN 10088-1) — Enhanced pitting and crevice corrosion resistance due to molybdenum addition
- AISI 316L / 1.4404 (EN 10088-1) — Low-carbon variant suitable for welding and harsh chemical environments
- AISI 321 / 1.4541 (EN 10088-1) — Titanium-stabilized grade for elevated temperature service
- AISI 310S / 1.4845 (EN 10088-1) — High-temperature grade for extreme thermal applications
Mechanical Properties (Typical — EN 10296-2)
- Tensile Strength (Rm): ≥ 520 MPa (Grade 304/316)
- Yield Strength (Rp0.2): ≥ 205 MPa (Grade 304/316)
- Elongation (A50): ≥ 35% (minimum)
- Hardness (HV10): ≤ 210 HBW (annealed condition)
Chemical Composition (Typical — EN 10088-1)
| Element | Grade 1.4301 (304) | Grade 1.4401 (316) | Grade 1.4404 (316L) |
|---|---|---|---|
| C (Carbon) | ≤ 0.08% | ≤ 0.08% | ≤ 0.03% |
| Si (Silicon) | ≤ 0.75% | ≤ 0.75% | ≤ 0.75% |
| Mn (Manganese) | ≤ 2.00% | ≤ 2.00% | ≤ 2.00% |
| P (Phosphorus) | ≤ 0.045% | ≤ 0.045% | ≤ 0.045% |
| S (Sulfur) | ≤ 0.030% | ≤ 0.030% | ≤ 0.030% |
| Cr (Chromium) | 18.00 – 20.00% | 16.50 – 18.50% | 16.50 – 18.50% |
| Ni (Nickel) | 8.00 – 10.50% | 10.00 – 14.00% | 12.00 – 14.00% |
| Mo (Molybdenum) | — | 2.00 – 3.00% | 2.00 – 3.00% |
3. Specifications
| Parameter | Specification |
|---|---|
| Governing Standard | EN 10296-2 (Welded steel tubes for mechanical and engineering purposes) |
| Product Form | Continuous Coil Tube (Coiltube) |
| Application Category | Non-Pressure Heat Exchanger Tubes |
| Outer Diameter (OD) | 6.0 mm – 42.0 mm (custom sizes available upon request) |
| Wall Thickness (WT) | 0.4 mm – 3.0 mm (tolerance ±10% per EN 10296-2) |
| Coil Weight | 200 kg – 2,000 kg per coil (typical) |
| Welding Process | Automated TIG (GTAW) or EFW (Electric Resistance Welding) |
| Surface Finish | Ba & Ae (bright annealed), 2B, or custom finishes |
| End Condition | Plain ends, deburred and squared |
| Tolerance — OD | ±0.1 mm (for OD ≤ 25 mm); ±0.15 mm (for OD > 25 mm) |
| Tolerance — WT | ±10% of nominal wall thickness |
| Heat Treatment | Solution annealing (1050°C – 1150°C, water quench) |
| Operating Temperature Range | −196°C to +900°C (grade-dependent) |
| Pressure Rating | Non-pressure application (designed for thermal transfer duty) |
| Delivery Condition | Coiled, palletized, or cut-to-length as specified |
4. Manufacturing Process
The production of EN 10296-2 compliant stainless steel coil tubes follows a rigorous, multi-stage manufacturing process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Strip Preparation — Cold-rolled stainless steel strip is procured from certified mills, inspected for chemical composition (via spectrometry), and verified for mechanical properties and surface condition.
- Coil Forming — The strip is fed through a series of precision rollers that gradually form it into a circular cross-section. High-precision tooling ensures consistent OD and wall thickness throughout the coil length.
- Welding — The formed strip is joined using automated TIG (Gas Tungsten Arc Welding) or EFW (Electric Resistance Welding) processes under inert gas shielding (argon or argon/helium mix), ensuring a high-quality, contamination-free weld seam.
- Weld Seam Inspection — 100% of the weld seam is inspected using automated eddy current testing (ECT) and/or ultrasonic testing (UT) to detect any discontinuities, porosity, or lack of fusion.
- Heat Treatment (Solution Annealing) — Tubes are solution-annealed at temperatures between 1050°C and 1150°C followed by rapid water quenching to restore full austenitic structure, relieve residual stresses, and achieve optimal corrosion resistance.
- Pickling & Passivation — Tubes undergo chemical pickling (HNO₃/HF blend) to remove oxide scale, followed by passivation treatment to establish a protective chromium oxide layer.
- Dimensional Inspection — Final OD, wall thickness, roundness, and straightness are verified using laser measurement systems and calipers, with statistical process control (SPC) documentation.
- Coiling & Packaging — Tubes are coiled onto precision-machined coil cores, wrapped in protective film, and palletized with moisture-absorbing desiccants for shipment.
5. Applications
These EN 10296-2 stainless steel coil tubes are purpose-engineered for non-pressure heat exchanger applications across a broad spectrum of industries:
- Air Conditioning & Refrigeration (HVAC/R) — Evaporator and condenser tube bundles in split systems, chillers, and heat pumps
- Automotive Heat Exchangers — Intercoolers, oil coolers, and transmission fluid coolers for passenger and commercial vehicles
- Process Heat Exchangers — Shell-and-tube and plate-fin heat exchangers in chemical, pharmaceutical, and food processing plants
- Power Generation — Condenser tubes and economizer tubes in thermal power stations and cogeneration systems
- Marine Engineering — Seawater coolers and heat recovery units in shipboard installations
- Food & Beverage Industry — Pasteurization systems, condensers, and thermal processing equipment requiring hygienic-grade tubing
- Industrial Cooling Systems — Heat recovery air handlers, dry coolers, and process water chillers
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring full traceability and compliance with international standards:
- EN 10204 — Type 3.1 test certificates (with inspection reports) available upon request for all shipments
- EN 10296-2 — Full compliance with dimensional tolerances, mechanical properties, and technical delivery conditions for welded steel tubes
- EN 10088-1 — Material grades certified per European stainless steel designation system
- EN 10204-3.1 — Manufacturer's test report with witnessed test results
- ISO 9001:2015 — Quality Management System certification
- EN 10204 — Third-party inspection (TPI) available upon request (e.g., BV, SGS, DNV)
Unique Selling Points: Continuous coil delivery eliminates butt-weld joints in heat exchanger tube bundles, significantly reducing potential leak points and improving thermal efficiency. Full compliance with EN 10296-2 ensures interoperability with European-specification heat exchanger designs. Precision manufacturing tolerances of ±0.1 mm on OD guarantee optimal tube-to-tubesheet fit for reliable expansion and brazing operations.