TIG Autogenous-Welded Stainless Steel Coil Tube — Thin-Wall Precision Formed
Product Overview
The TIG Autogenous-Welded Stainless Steel Coil Tube is a precision-engineered thin-wall welded tube supplied in continuous coil form, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product represents the industry-leading approach to thin-gauge stainless steel tubing, utilizing Tungsten Inert Gas (TIG) autogenous welding technology — a process that requires no filler wire, producing welds of exceptional purity and surface integrity.
Supplied as a continuous coil (coiltube), this product offers superior flexibility in downstream processing, minimizing material waste and enabling efficient automated cutting, bending, and forming operations. The autogenous welding technique ensures a chemically clean weld zone, making this tube ideal for applications demanding high purity, hygienic conditions, and resistance to corrosion at the weld seam.
Material & Properties
Available Grades
- 304 (UNS S30400): General-purpose austenitic stainless steel offering excellent corrosion resistance and formability.
- 304L (UNS S30403): Low-carbon variant optimized for welding applications with reduced sensitization risk.
- 316 (UNS S31600): Molybdenum-enhanced grade providing superior resistance to pitting and crevice corrosion.
- 316L (UNS S31603): Low-carbon 316 variant for maximum weldability and corrosion performance.
- 321 (UNS S32100): Titanium-stabilized grade suitable for elevated-temperature service.
Key Material Properties
- Weld Purity: Autogenous welding eliminates filler material contamination, resulting in a weld zone with metallurgical composition matching the base metal.
- Surface Finish: Smooth, mirror-like inner wall surface with no weld bead protrusion — critical for fluid flow and sanitary applications.
- Corrosion Resistance: The absence of heterogeneous filler material eliminates galvanic corrosion risk at the weld seam.
- Thin-Wall Integrity: TIG autogenous welding provides precise heat input control, preventing distortion and burn-through in thin-gauge walls.
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Manufacturing Method | TIG Autogenous Welding (No Filler Wire) |
| Outer Diameter Range | 3.0 mm – 50.8 mm (0.118 in – 2.0 in) |
| Wall Thickness Range | 0.3 mm – 2.0 mm (0.012 in – 0.079 in) |
| Coil Length | Customizable; typical 50 m – 200 m (164 ft – 656 ft) per coil |
| Available Grades | 304, 304L, 316, 316L, 321, 321L |
| Inner Surface Finish | Smooth, Ra ≤ 0.4 μm (16 μin) achievable |
| Outer Surface Finish | No. 1, 2B, BA (Bright Annealed), or custom |
| Weld Purity | Autogenous — no filler metal; base-metal equivalent composition |
| Dimensional Tolerance | OD: ±0.05 mm; Wall: ±0.03 mm |
| Standards Compliance | ASTM A213/A269, EN 10216-5, GB/T 12771 |
Manufacturing Process
The production of TIG autogenous-welded stainless steel coil tube follows a rigorous, multi-stage process designed to maximize weld quality, dimensional accuracy, and surface integrity:
- Strip Preparation: Cold-rolled stainless steel strip is slit to precise width and thickness, with surface cleaned and inspected for defects.
- Forming: The strip is fed through a series of progressive roll-forming stations that progressively bend the flat strip into a circular tube shape without introducing folds or wrinkles.
- TIG Autogenous Welding: A high-precision TIG welding head joins the tube seam using a tungsten electrode and inert shielding gas (argon or argon/helium mix) — critically, no filler wire is added. The base metal melts at the seam to form a fusion weld, ensuring chemical homogeneity between the weld zone and the tube body.
- Internal Gas Purging: A continuous inert gas purge is applied to the interior of the forming tube during welding, preventing oxidation and maintaining a clean, smooth inner wall surface.
- Weld Passivation & Inspection: The weld seam undergoes passivation treatment to restore the passive chromium oxide layer, followed by visual and/or automated ultrasonic inspection.
- Post-Weld Annealing: Continuous annealing in a controlled atmosphere relieves residual stresses, homogenizes microstructure, and improves ductility.
- Precision Sizing: The tube passes through a sizing die set to achieve final dimensional tolerances on both OD and wall thickness.
- Coiling & Packaging: The finished tube is wound into coils on precision core mandrels, wrapped in protective film, and packaged for shipment.
Unique Selling Point: The autogenous TIG welding process — using no filler wire — delivers a weld seam that is metallurgically indistinguishable from the base material. This eliminates the risk of filler-induced corrosion, ensures a perfectly smooth inner wall with zero protrusion, and provides superior long-term reliability in aggressive chemical and sanitary environments.
Applications
The combination of thin-wall precision, pure weld integrity, and continuous coil supply makes this product suitable for a wide range of demanding industrial applications:
- Food & Beverage Industry: Hygienic process piping, CIP/SIP systems, and transfer lines where surface cleanliness and weld purity are critical.
- Pharmaceutical & Biotechnology: GMP-compliant process tubing, reactor feed lines, and sterile fluid transfer systems.
- Automotive: Fuel lines, brake lines, turbocharger intercooler piping, and emissions control systems.
- Medical Devices: Endoscope tubing, infusion set components, and surgical instrument tubing.
- Heat Exchangers & Refrigeration: Thin-wall tubing for high-efficiency heat exchange surfaces where internal smoothness maximizes fluid dynamics.
- Solar Thermal Systems: Vacuum tube absorber tubes and heat pipe components requiring high-purity welds and thin walls.
- Chemical Processing: Corrosive fluid transfer lines where weld seam integrity under chemical attack is paramount.
- Wire Drawing & Metal Forming: As a parent tube for subsequent machining, cutting, or component fabrication.
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System certification ensuring consistent manufacturing excellence.
- ISO 14001 — Environmental Management System compliance for sustainable production practices.
- CE Marking — European Conformity for compliance with applicable EU directives.
- Mill Test Certificates (MTC): Full EN 10204 3.1 certificates provided with every shipment, documenting chemical composition, mechanical properties, and traceability.
- Non-Destructive Testing (NDT): 100% automated ultrasonic or eddy-current inspection of the weld seam for full-length quality assurance.
- Standards Compliance: Manufactured to ASTM A213/A269, EN 10216-5, JIS G3459, and GB/T 12771 specifications.
Why Choose Wenzhou Jixing Metal Materials Co., Ltd.
- Pure Weld Technology: TIG autogenous welding without filler wire — the gold standard for thin-wall tube weld integrity.
- Smooth Inner Wall: Internal gas purging during welding ensures a defect-free, smooth bore surface ideal for sanitary and fluid-handling applications.
- Continuous Coil Supply: Maximized material utilization with minimal offcuts, reducing downstream processing costs.
- Precision Dimensional Control: Tight tolerances on OD and wall thickness ensure consistent fit and performance in assemblies.
- Full Traceability: Every coil is accompanied by complete material documentation and test certificates.