EN 10217-7 Stainless Steel Welded Coiltube for Pressure Service
1. Product Overview
The EN 10217-7 Stainless Steel Welded Coiltube is a precision-engineered, continuously formed austenitic stainless steel tube supplied in coil form, manufactured and certified in strict compliance with the European standard EN 10217-7 — Non-ferrous metallic materials — Tubes and pipes for pressure purposes — Part 7: Austenitic stainless steel tubes. This product line is specifically designed for pressure-bearing applications where high corrosion resistance, mechanical integrity, and dimensional consistency are paramount.
Produced by Wenzhou Jixing Metal Materials Co., Ltd., this coiltube is delivered in a cold-worked, solution-annealed (or solution-annealed and pickled) condition, ensuring optimal metallurgical stability and long-term service performance under elevated temperature and pressure conditions. The coiled delivery format facilitates downstream processing — including straightening, cutting, bending, and further forming — with minimal material waste and maximum production efficiency.
2. Material & Properties
2.1 Chemical Composition
The base material conforms to the austenitic stainless steel grades specified under EN 10217-7, with typical designations including:
- 1.4301 / X2CrNi18-10 (equivalent to AISI 304) — general-purpose corrosion resistance
- 1.4401 / X2CrNiMo17-12-2 (equivalent to AISI 316) — enhanced chloride and acid resistance
- 1.4571 / X6CrNiTi18-10 (equivalent to AISI 321) — stabilized against intergranular corrosion
2.2 Mechanical Properties (Solution-Annealed Condition)
- Yield Strength (Rp0.2): ≥ 205 MPa
- Tensile Strength (Rm): 520 – 750 MPa
- Elongation (A50): ≥ 35%
- Hardness: ≤ 210 HV
2.3 Thermal & Corrosion Resistance
- Continuous service temperature range: −196 °C to +800 °C
- Outstanding resistance to atmospheric corrosion, dilute mineral acids, organic acids, and aqueous environments
- Non-magnetic in solution-annealed condition; slight magnetic response may occur after cold working
3. Specifications
| Parameter | Specification / Range |
|---|---|
| Governing Standard | EN 10217-7 |
| Product Form | Welded Coiltube (盘管) |
| Outer Diameter (OD) | 6.0 mm – 102.0 mm |
| Wall Thickness | 0.5 mm – 6.0 mm |
| Coil Length | Typically 50 – 200 m per coil (negotiable) |
| Welding Process | Automatic TIG (GTAW) or Plasma Welding |
| Weld Seam NDT Grade | 100% volumetric inspection — ultrasonic testing (UT) or radiographic testing (RT) per EN ISO 17636 / EN ISO 17640 |
| Heat Treatment Status | Solution annealing (1050 – 1150 °C) followed by rapid quenching; optional pickling and passivation |
| Surface Finish | Mill finish, pickled, or polished (Ra ≤ 0.8 μm available upon request) |
| End Condition | Coiled (un-cut) or cut-to-length with plain ends |
| Acceptance Criteria | EN 10204 Type 3.1 or Type 3.2 material certificates; EN 10204 2.2 available on request |
| Test Standards | EN 10204, EN ISO 3506, EN ISO 15488 (hydrostatic), EN ISO 6508 (hardness) |
4. Manufacturing Process
- Coil Slitting: Cold-rolled stainless steel strip (coil) is slit to precise width tolerances (±0.1 mm) on high-precision slitting lines to ensure uniform feed into the forming process.
- Tube Forming (Roll Forming): The slit strip passes through a series of progressively shaped rolls, forming it into a continuous tubular profile with controlled wall thickness uniformity and ovality within ±0.1% of nominal OD.
- Seam Welding: The formed strip is joined at the seam using automatic TIG (GTAW) or plasma welding under continuous inert gas (argon) shielding, producing a single-pass, full-penetration weld with minimal heat-affected zone (HAZ).
- Weld Seam Inspection (NDT): Every weld seam undergoes 100% non-destructive testing — ultrasonic testing (UT) or radiographic testing (RT) — in accordance with EN ISO 17636 and EN ISO 17640. Acceptance criteria are set at a minimum quality level of Level B per EN ISO 17636-1, ensuring zero tolerance for cracks, lack of fusion, or undercut exceeding 0.3 mm.
- Solution Annealing: The welded coil tube is heated to 1050 – 1150 °C in a continuous annealing furnace with controlled atmosphere, followed by rapid water quenching. This restores the full austenitic microstructure, eliminates residual welding stresses, and maximizes corrosion resistance and ductility.
- Pickling & Passivation: The annealed tube is acid-pickled to remove the heat-tint oxide layer, then passivated to form a protective chromium oxide film, ensuring long-term corrosion protection.
- Final Dimensional Inspection: OD, wall thickness, straightness, and coil geometry are verified using automated laser measuring systems.
- Coiling & Packaging: The finished tube is re-coiled on mandrels, wrapped in moisture-proof film, and secured with steel strapping for shipment.
5. Applications
EN 10217-7 stainless steel welded coiltubes are employed in a wide range of pressure-bearing applications across multiple industries:
- Process Engineering: Heat exchangers, condensers, evaporators, and reactor piping in chemical and petrochemical plants
- Food & Pharmaceutical Industry: Hygienic piping systems, CIP/SIP loops, and process lines requiring sanitary-grade corrosion resistance
- Pressure Vessel Construction: Internal tube bundles, support structures, and instrumentation piping
- Automotive & Aerospace: Fuel lines, hydraulic lines, and exhaust system components
- Energy Sector: Solar thermal collectors, geothermal heat exchange systems, and hydrogen pipeline infrastructure
- Marine & Offshore: Seawater cooling circuits, ballast systems, and underwater equipment housings
6. Quality Certifications & Assurance
Every production lot of EN 10217-7 stainless steel coiltube supplied by Wenzhou Jixing Metal Materials Co., Ltd. is backed by a comprehensive quality assurance framework:
- Material Certification: EN 10204 Type 3.1 (test report with chemical composition and mechanical test results) or Type 3.2 (witnessed test report) issued per batch
- Weld Seam Integrity: 100% NDT inspection (UT/RT) with documented traceability to each coil lot number
- Heat Treatment Documentation: Furnace temperature logs, cooling rate records, and post-annealing hardness verification
- Hydrostatic Testing: Performed per EN ISO 15488 at 1.5× maximum allowable working pressure, with minimum dwell time of 10 seconds
- Mill Test Reports (MTR): Full chemical analysis (ICP-OES), mechanical testing (tensile, hardness, impact), and dimensional verification reports provided with each shipment
- Compliance: Products manufactured under ISO 9001:2015 quality management system; CE marking available for pressure equipment applications under PED 2014/68/EU
Key Differentiator: The combination of 100% weld seam NDT inspection (NDT等级), precisely controlled solution annealing (热处理状态), and full EN 10217-7 traceability makes this coiltube product uniquely suited for critical pressure applications where weld integrity and metallurgical consistency are non-negotiable safety requirements.