Welded Stainless Steel Coil Tube to EN 10217-7 — Pressure-Bearing Tubing
Product Overview
The EN 10217-7 Welded Stainless Steel Coil Tube is a precision-engineered, continuous-length tubing product manufactured to the stringent requirements of the European standard EN 10217-7:2008, which governs austenitic stainless steel tubes for pressure-bearing applications. Supplied in coil form, this product offers the logistical and processing advantages of continuous tubing while maintaining the mechanical integrity, corrosion resistance, and dimensional accuracy demanded by high-pressure industrial systems.
Designed and produced by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube is suitable for a broad spectrum of demanding applications including chemical processing, petroleum refining, power generation, food and beverage processing, pharmaceutical manufacturing, and marine engineering. The coil configuration enables efficient downstream forming, cutting, and fabrication with minimal material waste.
Material & Properties
The tube is manufactured from austenitic stainless steel grades specified under EN 10217-7, including but not limited to:
- 1.4301 (X2CrNi19-10 / 304 equivalent) — Excellent general corrosion resistance, good weldability, and broad temperature applicability
- 1.4401 (X2CrNiMo17-12-2 / 316 equivalent) — Superior resistance to pitting and crevice corrosion, enhanced performance in chloride-containing environments
- 1.4571 (X6CrNiTi18-10 / 321 equivalent) — Stabilized against intergranular corrosion through titanium addition, suitable for elevated temperature service
- 1.4539 (X6CrNiNb18-10 / 347 equivalent) — Niobium-stabilized grade offering outstanding resistance to sensitization and intergranular corrosion at high temperatures
Key Mechanical Properties (Typical — Annealed Condition)
- Tensile Strength: ≥ 520 MPa (75,400 psi)
- Yield Strength (Rp0.2): ≥ 205 MPa (29,700 psi)
- Elongation: ≥ 40%
- Hardness: ≤ 235 HBW (annealed condition)
- Operating Temperature Range: −196 °C to +800 °C (−321 °F to +1,472 °F), grade-dependent
Specifications
| Parameter | Specification / Range |
|---|---|
| Standard | EN 10217-7:2008 |
| Tube Type | Welded (Longitudinally Welded), Coil Form |
| Outer Diameter (OD) | 6.0 mm to 219.1 mm (0.236 in to 8.626 in) |
| Wall Thickness | 0.5 mm to 6.0 mm (0.020 in to 0.236 in) |
| OD Tolerance | ±0.15 mm (±0.006 in) for OD ≤ 50 mm; ±0.002 × OD for larger sizes |
| Wall Thickness Tolerance | ±10% (as per EN 10217-7) |
| Weld Seam NDT Grade | Grade A (100% inspection) — Radiographic Testing (RT) or Ultrasonic Testing (UT) |
| Heat Treatment Condition | Solution Annealed (Stress Relieved) per EN 10217-7; optionally pickled and passivated |
| Surface Finish | Pickled and Passivated (2B); available in ground, polished (4K, 8K), or hairline finishes upon request |
| End Condition | Cut-to-length from coil or continuous coil as supplied |
| Coil Diameter | 600 mm to 1,200 mm (23.6 in to 47.2 in), customizable |
| Material Grades | 1.4301, 1.4401, 1.4571, 1.4539, 1.4509, 1.4541, and other EN-specified grades |
| Pressure Rating | Up to 40 MPa (5,800 psi) depending on grade, OD, and wall thickness |
Manufacturing Process
The production of EN 10217-7 welded stainless steel coil tubes follows a rigorously controlled multi-stage process to ensure conformance with European pressure-vessel and pressure-piping standards:
- Strip Selection & Incoming Inspection: Cold-rolled stainless steel strip is sourced from certified mills and subjected to chemical composition analysis (spectrometry), mechanical property verification, and surface quality inspection prior to processing.
- Coil Unwinding & Forming: The strip is unwound and fed through a series of precision rolls that progressively form the flat strip into a seamless helical coil, maintaining tight dimensional control throughout the forming operation.
- Longitudinal Welding: The formed strip is welded along its longitudinal seam using a high-frequency induction welding (HFW) or TIG (Tungsten Inert Gas) welding process under a continuous inert gas shielding environment (argon or argon-helium mixture) to prevent oxidation and ensure a clean, defect-free weld.
- Weld Seam Inspection (NDT): Every inch of the weld seam undergoes 100% non-destructive testing per EN 10217-7 Grade A requirements. Radiographic Testing (RT) and/or Ultrasonic Testing (UT) are employed to detect and reject any internal or surface discontinuities, ensuring the weld integrity meets pressure-bearing service standards.
- Solution Annealing & Stress Relief: The welded coil tube is subjected to a controlled solution annealing heat treatment at temperatures between 1,010 °C and 1,150 °C (1,850 °F to 2,102 °F), followed by rapid quenching. This restores full austenitic microstructure, relieves residual welding stresses, and maximizes corrosion resistance and ductility.
- Pickling & Passivation: The annealed tube undergoes acid pickling (typically nitric-hydrofluoric acid or citric acid) to remove oxide scale, followed by passivation to establish a protective chromium oxide surface layer, enhancing long-term corrosion resistance.
- Final Dimensional & Mechanical Testing: Each coil lot is sampled for dimensional verification, hydrostatic pressure testing, and mechanical property confirmation (tensile, impact, and hardness testing) to certify compliance with EN 10217-7.
- Coiling & Packaging: The finished tube is recoiled to the specified coil diameter, protected with appropriate end caps and moisture-barrier wrapping, and palletized for shipment.
Applications
EN 10217-7 welded stainless steel coil tubes are engineered for pressure-bearing service and are widely deployed across multiple industries:
- Oil & Gas: Piping systems for upstream, midstream, and downstream processing; wellhead equipment; separator internals; and subsea flow lines
- Chemical Processing: Reactor piping, heat exchanger tubes, distillation columns, and process lines handling aggressive chemicals and corrosive media
- Power Generation: Steam lines, feedwater systems, boiler economizers, and nuclear-grade auxiliary piping systems
- Food & Beverage: Sanitary process lines, pasteurization equipment, brewing systems, and dairy processing installations requiring hygienic-grade tubing
- Pharmaceutical: Clean-in-place (CIP) piping, sterilization systems, and bioreactor connections where purity and corrosion resistance are critical
- Marine & Offshore: Ballast water systems, fire suppression lines, and deck piping in marine environments where chloride corrosion resistance is essential
- Automotive & Aerospace: Fuel lines, exhaust system components, hydraulic lines, and structural tubing in high-performance applications
- Construction & Architectural: Structural supports, handrails, and decorative elements requiring both load-bearing capacity and aesthetic finish
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system to ensure every product meets or exceeds international standards:
- EN 10217-7:2008 — Full conformance to the European standard for austenitic stainless steel tubes for pressure-bearing applications
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control
- ISO 3834 — European welding quality certification covering welding procedures, welder qualification, and weld inspection protocols
- EN 10204 — Type 3.1 mill test certificates (MTC) provided with every shipment, including chemical composition, mechanical properties, and NDT results
- NDT Grading: Weld seam inspection to EN 10217-7 Grade A (100% RT/UT) with documented traceability
- Hydrostatic Testing: All coils tested per EN 10217-7 pressure test protocols with test records included in documentation
- Traceability: Full heat-to-heat traceability from raw material mill certificate through final product delivery
Unique Selling Points
EN 10217-7 Grade A Weld Seam Integrity: Unlike standard welded tubing, every weld seam in this product undergoes 100% radiographic and/or ultrasonic testing to Grade A standards, providing documented proof of weld integrity for pressure-vessel and pressure-piping applications.
Coil Form Efficiency: Supplied as continuous coils, this product eliminates the need for butt-welding multiple straight lengths, reducing installation time, minimizing leak points, and lowering total cost of ownership for large-scale piping projects.
Comprehensive Heat Treatment: The solution-annealed condition specified under EN 10217-7 ensures full recovery of austenitic microstructure, maximum corrosion resistance, and predictable mechanical behavior — critical for long-term pressure service reliability.
Full Traceability & Documentation: Every coil is accompanied by EN 10204 Type 3.1 mill test certificates with complete chemical analysis, mechanical test data, NDT reports, and heat treatment records, facilitating seamless client-side quality assurance and regulatory compliance.
Multi-Grade Availability: A wide selection of EN-specified austenitic grades — from standard 1.4301 to high-alloy 1.4539 and 1.4509 — allows engineers to precisely match material properties to their specific service environment and pressure requirements.
Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd. offers tailored OD, wall thickness, coil diameter, surface finish, and end-condition configurations to meet project-specific requirements, backed by an experienced engineering team for technical consultation and specification support.