304L Austenitic Stainless Steel Coil Tube — Low Carbon Welding-Grade Coiled Tubing
Wenzhou Jixing Metal Materials Co., Ltd. is a leading manufacturer and supplier of high-performance stainless steel coil tubes engineered for demanding industrial, chemical, food processing, and construction applications. The 304L Stainless Steel Coil Tube represents the pinnacle of the austenitic general-purpose family, distinguished by its ultra-low carbon composition that delivers exceptional weldability and resistance to intergranular corrosion without the need for post-weld heat treatment.
Product Overview
The 304L coil tube is a cold-worked, continuous-length stainless steel tubing product supplied in coiled form for ease of handling, storage, and on-site fabrication. Designed as an advanced upgrade over standard 304 grade, the 304L designation reflects a deliberate reduction of carbon content to 0.03% maximum — a critical threshold that fundamentally alters the material's behavior during and after welding operations.
This coil tube is specifically engineered for applications where welded assemblies must maintain full corrosion resistance without requiring subsequent solution annealing or pickling. Its austenitic crystal structure, combined with the low carbon matrix, makes it the material of choice for field-installed piping systems, welded structural components, and any fabrication scenario where post-weld heat treatment is impractical or impossible.
Material & Properties
Composition Highlights
- Carbon (C): ≤ 0.03% — Ultra-low carbon content minimizes chromium carbide precipitation at grain boundaries during welding, thereby preserving the full passivation layer and preventing intergranular corrosion in sensitized conditions.
- Chromium (Cr): 18.0–20.0% — Provides robust passive film formation and general corrosion resistance.
- Nickel (Ni): 8.0–11.0% — Stabilizes the austenitic structure, enhances ductility, and contributes to resistance in reducing environments.
- Manganese (Mn): ≤ 2.0% — Supports cold-formability and maintains mechanical integrity.
- Silicon (Si): ≤ 1.0% — Contributes to high-temperature oxidation resistance.
- Sulfur (S): ≤ 0.03% — Controlled to ensure weldability and surface quality.
Key Performance Characteristics
- Post-Weld Heat Treatment Exemption: The ultra-low carbon content eliminates the need for solution annealing after welding, significantly reducing fabrication costs and project timelines.
- Intergranular Corrosion Resistance: Even in sensitized states (exposed to temperatures in the 450–850°C range during welding), the material resists grain boundary attack due to minimal chromium depletion at grain boundaries.
- Superior Weldability: Compatible with all standard welding processes including GTAW (TIG), GMAW (MIG), SMAW (stick), and orbital welding.
- Excellent Formability: Austenitic structure permits extensive cold working, bending, and shaping without cracking.
- Non-Magnetic: Fully austenitic microstructure ensures non-magnetic properties in the cold-worked condition.
- Wide Temperature Range: Suitable for service from cryogenic temperatures up to approximately 870°C (1600°F) in non-oxidizing atmospheres.
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | ASTM A270 TP304L / AMS 5514 / EN 1.4307 |
| Carbon Content | ≤ 0.03% |
| Product Form | Coil Tube (Continuous Coiled Length) |
| Manufacturing Method | Cold-Drawn / Cold-Rolled Seamless |
| Outer Diameter Range | Φ 3.0 mm – Φ 32.0 mm (custom sizes available upon request) |
| Wall Thickness Range | 0.3 mm – 3.0 mm |
| Coil Length | Standard: 50 m – 300 m per coil; customizable |
| Surface Finish | Bright Annealed (BA), Pickled & Passivated, or Custom |
| Tolerance (OD) | ±0.05 mm – ±0.10 mm (per ASTM A213/A270) |
| Tolerance (Wall) | ±10% of nominal |
| Hardness | ≤ 92 HRB (Annealed Condition) |
| Tensile Strength | ≥ 515 MPa (75 ksi) minimum |
| Yield Strength | ≥ 205 MPa (30 ksi) minimum |
| Elongation | ≥ 40% (minimum, in 50 mm gauge length) |
| Applicable Standards | ASTM A270, ASTM A269, ASME SA-213, EN 10216-5, JIS G3446 |
| Packaging | Wooden pallet with moisture-proof wrapping; export-standard crating |
Manufacturing Process
The 304L coil tube is produced through a rigorously controlled multi-stage manufacturing process to ensure dimensional precision, metallurgical integrity, and surface quality:
- Raw Material Selection: Virgin 304L stainless steel wire rod or continuous casting billet is sourced from certified mills with verified chemical composition (C ≤ 0.03%).
- Hot Rolling & Annealing: The base strip or tube blank is hot-rolled to approximate dimensions and subsequently annealed to establish a uniform austenitic microstructure.
- Pickling & Passivation: The hot-rolled product undergoes acid pickling to remove oxide scale, followed by passivation to establish a chromium-rich passive film.
- Tube Forming: The flat strip is precision-formed into tubular cross-section through cold-rolled forming or seamless cold-drawing processes, depending on diameter specifications.
- Cold Drawing / Cold Rolling: The formed tube is cold-worked to achieve final dimensional tolerances, enhanced mechanical properties, and a smooth surface finish.
- Final Annealing & Passivation: A controlled bright annealing cycle in a protective atmosphere restores ductility while maintaining the low-carbon austenitic structure.
- Coiling & Inspection: The finished tube is coiled to specified lengths, subjected to 100% dimensional inspection, hydrostatic pressure testing, and surface quality verification.
- Packaging & Dispatch: Product is packaged in export-standard wooden pallets with moisture-barrier wrapping and accompanied by full material test certificates (MTC/EN 10204 3.1).
Applications
Primary Application Areas
- Welded Structural Components: The defining application for 304L coil tube — ideal for fabricating welded assemblies where post-weld solution treatment is not feasible. The low carbon content ensures that weld zones and heat-affected zones retain full corrosion resistance.
- Field-Installed Piping Systems: Piping networks installed on-site (e.g., offshore platforms, chemical plants, building services) where the ability to perform post-weld heat treatment is logistically impossible.
- Food & Beverage Processing Equipment: Hygienic tubing for dairy, brewing, pharmaceutical, and food processing lines requiring corrosion resistance and ease of welding.
- Chemical Processing: Transfer lines, heat exchangers, and reactor internals in mild to moderate corrosive environments.
- Architectural & Decorative Applications: Handrails, railings, structural supports, and architectural elements requiring both aesthetic finish and structural integrity.
- Automotive & Engineering: Exhaust systems, fuel lines, and structural tubing in automotive and heavy equipment manufacturing.
- Medical Equipment: Tubing for medical device fabrication, surgical instruments, and hospital fixtures.
- Energy & Power Generation: Boiler tubes, heat exchanger coils, and process piping in power plants and renewable energy installations.
Why 304L Over Standard 304?
For any application involving welding, the 304L grade provides a decisive advantage. Standard 304 (C ≤ 0.08%) is susceptible to intergranular corrosion when exposed to welding heat without subsequent annealing. The 304L grade, with its carbon content at or below 0.03%, virtually eliminates this risk — making it the industry standard for welded stainless steel assemblies where post-weld heat treatment cannot be performed.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality assurance protocols throughout the entire production chain:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control.
- EN 10204 3.1 — Full material test certificates (MTC) provided with every shipment, including chemical analysis, mechanical test results, and heat traceability.
- ASTM / ASME Compliance — Products manufactured and tested in accordance with ASTM A270, ASTM A269, and ASME SA-213 standards.
- 100% Hydrostatic Testing — Every coil tube undergoes hydrostatic pressure testing to verify structural integrity and absence of porosity.
- Third-Party Inspection Available — Customers may appoint independent inspection agencies (SGS, Bureau Veritas, etc.) for on-site verification.
- Full Heat Traceability — Each coil is traceable back to its original mill heat number for complete supply chain accountability.
- Non-Destructive Testing (NDT) — Eddy current and ultrasonic testing available upon request for critical applications.
Unique Selling Points
- Zero Post-Weld Heat Treatment Required: Drastically reduces fabrication costs, project schedules, and field logistics complexity.
- Guaranteed C ≤ 0.03%: Verified ultra-low carbon content eliminates intergranular corrosion risk in sensitized weld zones.
- Coiled for Maximum Fabrication Efficiency: Continuous coiled supply minimizes butt welds, reduces material waste, and accelerates production throughput.
- Full Traceability & Certification: EN 10204 3.1 material certificates with complete chemical and mechanical data for every batch.
- Custom Sizing & Surface Options: Flexible manufacturing capability to accommodate bespoke OD, wall thickness, coil length, and surface finish requirements.
- Proven Supplier Track Record: Wenzhou Jixing Metal Materials Co., Ltd. delivers globally to OEMs, EPC contractors, and end-users across multiple industries.
For detailed quotations, technical datasheets, sample requests, or custom specifications, contact Wenzhou Jixing Metal Materials Co., Ltd. to discuss your 304L stainless steel coil tube requirements.