Online Solution Treated Stainless Steel Coil Tube — Post-Weld Quench Process

Product Overview

The Online Solution Treated Stainless Steel Coil Tube is a precision-engineered welded coil tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd, incorporating an advanced in-line solution heat treatment process. This product is specifically designed to ensure maximum corrosion resistance and metallurgical integrity in welded stainless steel tubing applications. By performing solution treatment immediately after the welding operation, the coil tube achieves superior performance characteristics that meet the most demanding industrial and commercial specifications.

Unlike conventional post-fabrication heat treatment methods, the online solution treatment process is integrated directly into the continuous production line, ensuring that the weld zone is quenched at the optimal temperature window — eliminating the risk of sensitization and carbide precipitation that commonly degrades the corrosion performance of austenitic stainless steels.

Material & Properties

This coil tube product is available in a wide range of austenitic and duplex stainless steel grades, each benefiting from the online solution treatment process:

Following online solution treatment, the weld zone achieves:

Specifications

Parameter Specification
Product Type Welded Stainless Steel Coil Tube (Continuous Coiled)
Manufacturing Method Continuous Welding (ERW / Laser / TIG) with Online Solution Treatment
Heat Treatment Process In-Line Solution Annealing — Immediate Water Quench or Air Quench Post-Weld
Available Grades 304, 304L, 316, 316L, 321, 310S, 2205, 2507, and custom grades
Outer Diameter Range Ø6.0 mm – Ø168.3 mm
Wall Thickness Range 0.3 mm – 8.0 mm
Solution Treatment Temperature 1050 °C – 1150 °C (grade-dependent)
Quench Method Water Quench (for thinner wall tubes) / Air Quench (for thicker wall tubes)
Coil Length Custom lengths; typically 50 m – 500 m per coil
Surface Finish Mirror (Ra ≤ 0.1 μm), Bright Annealed, Pickled & Passivated, or Custom
Applicable Standards ASTM A213/A269, ASME SA-213/SA-269, EN 10216-5, GB/T 12771, JIS G3459
Weld Seam Type Single-Strand ERW, Multi-Strand ERW, Laser Welded, or TIG Welded
Optional Post-Processes Pickling & Passivation, Peening, Mandrel Drawing, Precision Sizing

Manufacturing Process

Step 1 — Coil Slitting & Edge Preparation

High-purity stainless steel coils are slit to precise widths and subjected to edge cleaning and dimensional inspection to ensure uniform feedstock quality.

Step 2 — Forming & Welding

The slit coil is formed into the desired tube geometry and welded using advanced continuous welding technologies (ERW, laser, or TIG). The welding parameters are precisely controlled to minimize the Heat Affected Zone and ensure full penetration.

Step 3 — Online Solution Treatment (Critical Process Step)

This is the defining process that differentiates this product from standard welded coil tubes. Immediately upon completion of the welding operation, while the tube is still at or near the solution treatment temperature range (1050 °C – 1150 °C), the tube is subjected to rapid quenching:

The timing of the quench is critical — it must occur before the tube temperature drops below the sensitization range (approximately 450 °C – 850 °C), ensuring that chromium carbides (Cr₂₃C₆) do not form at grain boundaries. This immediate quenching effectively "freezes" the austenitic structure in a fully solution-treated state.

Step 4 — Pickling & Passivation

Following solution treatment, the tube surface is cleaned through pickling to remove any oxide scale, followed by passivation treatment to establish a protective chromium oxide film on the entire surface, including the weld zone.

Step 5 — Quality Inspection & Coiling

The finished tube undergoes comprehensive non-destructive testing (eddy current, ultrasonic, and hydrostatic pressure testing) before being coiled to the specified length and packaged for shipment.

Unique Selling Points

Applications

Quality Certifications & Compliance

Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems to ensure every coil tube meets international standards:

Each production batch undergoes intergranular corrosion testing (ASTM A262 Practice E) to verify that the online solution treatment has effectively prevented sensitization in the weld zone, providing customers with documented proof of corrosion performance.

Technical Note: The online solution treatment process represents a significant advancement over traditional post-weld batch annealing. By quenching the tube immediately after welding — before the material cools into the sensitization temperature range — this process ensures that chromium remains fully dissolved in the austenitic matrix, preserving maximum corrosion resistance. This is particularly critical for low-carbon grades (304L, 316L) and duplex stainless steels where weld zone sensitization can lead to premature intergranular corrosion failure in aggressive environments.