Online Solution-Annealed Stainless Steel Coil Tube — Welded & Quenched
Product Overview
The Online Solution-Annealed Stainless Steel Coil Tube is a precision-engineered welded coil tube produced by Wenzhou Jixing Metal Materials Co., Ltd. This product distinguishes itself through an advanced online solution annealing process — a rapid water quench or gas quench performed immediately after the welding operation. This critical heat treatment step restores full corrosion resistance in the weld heat-affected zone (HAZ) and effectively prevents chromium carbide precipitation (sensitization), ensuring homogeneous metallurgical properties across the entire tube circumference.
Unlike conventional post-weld heat treatment methods that subject the entire coil to furnace annealing, the online quench approach delivers superior efficiency, tighter dimensional control, and consistent microstructural integrity — making it the preferred solution for high-performance stainless steel tubing applications.
Material & Properties
Available Grades
- 304 / 304L (UNS S30400 / S30403) — General-purpose austenitic stainless steel with excellent corrosion resistance and formability
- 316 / 316L (UNS S31600 / S31603) — Enhanced resistance to chlorides and pitting corrosion
- 321 (UNS S32100) — Columbium-stabilized for high-temperature applications
- 347 (UNS S34700) — Niobium-stabilized alternative for elevated-temperature service
- Custom grades available upon request
Key Metallurgical Properties
- Microstructure: Fully austenitic, uniform grain structure throughout the base metal and weld zone
- Corrosion resistance: Restored to base-metal equivalent in the HAZ after online solution treatment
- Sensitization prevention: Rapid quench eliminates the 450–850 °C (842–1562 °F) sensitization temperature window, preventing chromium depletion at grain boundaries
- Mechanical properties: Maintains tensile strength and ductility consistent with solution-annealed condition
- Surface finish: Clean, oxide-free interior and exterior surfaces following quench treatment
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 219.1 mm (0.236 in – 8.626 in) |
| Wall Thickness | 0.5 mm – 6.0 mm (0.020 in – 0.236 in) |
| Coil Length | Up to 120 m (394 ft) per coil (custom lengths available) |
| Welding Method | Automatic TIG (GTAW) / Laser welding |
| Heat Treatment | Online solution annealing — immediate water quench or gas quench post-weld |
| Surface Finish | 2B, BA (Bright Annealed), No. 4, No. 8, Mirror |
| Applicable Standards | ASTM A554, ASTM A213, EN 10216-5, GB/T 12771 |
| Weld Bead | Flush ground and polished to near-seamless appearance |
| Delivery Form | Coiled (coiltube), cut-to-length |
| Minimum Order Quantity | 1 ton per grade |
Manufacturing Process
Step-by-Step Production Flow
- Raw Material Selection: High-purity stainless steel strip is sourced from certified mills with full chemical and mechanical traceability.
- Strip Processing: The coil strip undergoes precision slitting, leveling, and edge preparation to ensure uniform feeding into the forming station.
- Forming: Multi-roller forming stations shape the flat strip into a precise tube geometry with controlled tolerances on OD and wall thickness.
- Welding: High-frequency TIG or laser welding joins the tube seam with minimal heat input, producing a narrow, clean weld zone.
- Online Solution Annealing (Key Process):
- Water Quench: The tube passes immediately through a controlled water jet quench station, achieving cooling rates exceeding 100 °C/s (176 °F/s) to arrest carbide precipitation.
- Gas Quench: Alternatively, high-velocity inert gas (argon or nitrogen) quenching is employed for applications requiring reduced thermal shock and superior surface finish.
- Weld Finishing: The weld seam is ground flush and polished to achieve a smooth, near-seamless internal surface, minimizing flow turbulence and stress concentration.
- Surface Treatment: Passivation, pickling, or mechanical finishing is applied to achieve the specified surface condition.
- Quality Inspection: Each coil undergoes ultrasonic testing, visual inspection, hydrostatic pressure testing, and spectrometric chemical analysis.
- Coiling & Packaging: Finished tubing is coiled, wrapped in protective film or paper, and crated for shipment.
Why Online Solution Annealing Matters
Conventional post-weld furnace annealing subjects the entire tube coil to prolonged exposure at 1050–1100 °C (1922–2012 °F) followed by controlled cooling. While effective, this method risks grain growth, surface scaling, and reduced dimensional accuracy. The online quench process used by Wenzhou Jixing eliminates these drawbacks by achieving metallurgical restoration in seconds — preserving the original grain structure, maintaining dimensional tolerances, and delivering a superior surface finish without the need for post-annealing pickling.
Unique Selling Points
- Immediate post-weld quench: Eliminates sensitization window entirely — weld zone achieves full corrosion resistance equivalent to base metal
- No post-weld furnace annealing required: Reduces production lead time by up to 40% and eliminates scale formation
- Superior dimensional accuracy: No thermal distortion from furnace cycling — tolerances maintained to ±0.05 mm
- Homogeneous microstructure: Uniform austenitic grains across base metal and weld HAZ
- Flexible quench selection: Water quench for maximum cooling rate; gas quench for surface-sensitive applications
- Cost-effective near-seamless performance: Offers seamless-grade corrosion resistance at welded-tube economics
- Scalable production: Continuous online process supports high-volume output with consistent quality
Applications
- Chemical & Petrochemical Processing: Reactor tubing, heat exchanger bundles, and process piping where weld-zone corrosion resistance is critical
- Food & Beverage Industry: Hygienic process lines, CIP-compatible tubing, and sanitary-grade piping systems
- Pharmaceutical Manufacturing: GMP-compliant fluid handling and pharmaceutical-grade transfer tubing
- Heat Exchangers & Boilers: Condenser tubes, evaporator coils, and radiator components requiring high thermal cycling resistance
- Automotive Industry: Fuel lines, exhaust system components, and turbocharger piping
- Oil & Gas: Downhole tubing, wellhead components, and offshore platform piping
- Architectural & Decorative: Structural tubing, railings, and high-visibility architectural elements
- Medical Equipment: Sterilizable fluid lines, instrument tubing, and diagnostic equipment housings
Quality Certifications & Testing
- ISO 9001:2015 — Quality Management System certified manufacturing
- ISO 14001:2015 — Environmental Management System compliance
- ASTM / ASME — Product conformance to international material standards
- EN 10204 3.1 — Material test certificates with third-party inspection available
- Mill Test Reports (MTR): Full chemical composition and mechanical property documentation per heat number
- Non-Destructive Testing: Ultrasonic (UT), eddy current (ET), and penetrant testing (PT) performed on weld seams
- Hydrostatic Testing: 100% pressure testing at 1.5× working pressure to verify weld integrity
- Intergranular Corrosion Testing: ASTM A262 Practice E (acid solution test) to verify sensitization resistance
- Third-Party Inspection: Available upon request (SGS, Bureau Veritas, TUV)
Conclusion
Wenzhou Jixing Metal Materials Co., Ltd's Online Solution-Annealed Stainless Steel Coil Tube represents the optimal balance of corrosion resistance, mechanical performance, dimensional precision, and manufacturing efficiency. By integrating rapid water or gas quenching directly into the production line — immediately after welding — the company delivers a product that meets or exceeds the performance of traditionally furnace-annealed tubing, while reducing lead times and total cost of ownership. This technology positions the product as a premier choice for demanding industrial applications where weld integrity and long-term corrosion resistance are non-negotiable requirements.