Stainless Steel Coil Tube — Second-Tier Domestic Supply (Industrial Grade)
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) supplied through the Second-Tier Domestic Supply Chain represents a critical segment of the industrial stainless steel pipe market in China. This tier comprises established domestic manufacturers — including Jiuli (久立), Wujin (武进), Huaxin Lihua (华新丽华), and Yongxing (永兴) — that collectively form the backbone of the nation's stainless steel coil tube production capacity. These suppliers are characterized as the "industrial workhorses" of the market, delivering a superior balance between material quality, dimensional accuracy, and cost-effectiveness.
Unlike the first-tier (imported or premium domestic) supply chain, the second-tier domestic suppliers offer products that meet or approach international standards at significantly reduced unit costs. This tier is the default choice for the majority of industrial applications where full compliance with international certifications is required but extreme performance margins are not necessary. Wenzhou Jixing Metal Materials Co., Ltd. serves as an aggregator and distributor for this tier, ensuring reliable sourcing, quality verification, and logistics for downstream customers.
2. Material & Properties
2.1 Grade Composition
The coil tubes in this tier are predominantly manufactured from the following austenitic and duplex stainless steel grades:
- AISI 304 / SUS304 / 06Cr19Ni10 — General-purpose austenitic grade with excellent corrosion resistance and formability. Chromium (Cr) content: 18–20%; Nickel (Ni) content: 8–10.5%.
- AISI 316 / SUS316 / 06Cr17Ni12Mo2 — Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion. Mo content: 2–3%.
- AISI 321 / SUS321 / 06Cr18Ni11Ti — Titanium-stabilized grade for elevated-temperature applications up to 870°C. Ti content: 4–6× C.
- AISI 316L / SUS316L / 022Cr17Ni12Mo2 — Low-carbon variant of 316 (C ≤ 0.03%) for welding-critical applications.
- AISI 304L / SUS304L / 022Cr19Ni10 — Low-carbon variant of 304 (C ≤ 0.03%) for enhanced weldability and post-weld corrosion resistance.
- AISI 310S / SUS310S / 06Cr25Ni20 — High-temperature austenitic grade with Cr: 24–26%; Ni: 19–22%.
- Duplex 2205 / UNS S32205 — Duplex phase (ferrite/austenite) grade with PREN ≥ 34, offering high strength and excellent chloride pitting resistance.
2.2 Mechanical Properties (Typical for 304 Coil Tube, Annealed Condition)
- Tensile Strength (UTS): ≥ 520 MPa
- Yield Strength (0.2% offset): ≥ 205 MPa
- Elongation at Break: ≥ 35%
- Hardness (Brinell): ≤ 201 HB
- Density: 7.93 g/cm³
- Thermal Expansion Coefficient (20–100°C): 16–18 × 10⁻⁶ /K
- Thermal Conductivity (100°C): ~16.3 W/(m·K)
- Specific Heat Capacity: ~500 J/(kg·K)
2.3 Corrosion Resistance
The austenitic grades in this tier exhibit excellent resistance to atmospheric corrosion, dilute organic and inorganic acids, and alkaline solutions. The 316/316L grades additionally demonstrate robust performance in chloride-containing environments (e.g., seawater, chemical processing streams) due to the presence of molybdenum. The duplex 2205 grade offers a PREN (Pitting Resistance Equivalent Number) of ≥ 34, making it suitable for aggressive chloride environments at elevated temperatures.
3. Specifications
| Parameter | Specification / Range | Applicable Standard |
|---|---|---|
| Outer Diameter (OD) | Φ6.0 mm – Φ108 mm (typical); up to Φ219 mm on request | ASTM A269 / GB/T 12771 |
| Wall Thickness (WT) | 0.3 mm – 6.0 mm (typical) | ASTM A269 / GB/T 12771 |
| Coil Length (per coil) | 3 m – 12 m (standard); custom lengths available | — |
| Coil Weight (per coil) | 500 kg – 2,000 kg (typical) | — |
| Surface Finish | 2B (Cold Rolled & Annealed), No.1 (Pickled), BA (Bright Annealed), Matte, Hairline | ASTM A480 / GB/T 3280 |
| Inner Surface Roughness (Ra) | 0.5 – 1.6 μm (2B); 0.2 – 0.5 μm (BA, polished) | GB/T 1031 |
| OD Tolerance | ±0.05 mm (precision); ±0.1 mm (standard) | ASTM A269 |
| Wall Thickness Tolerance | ±0.05 mm (precision); ±0.1 mm (standard) | ASTM A269 |
| Roundness | ≤ 0.1% of OD | — |
| Coil Straightness | ≤ 1 mm/m | — |
| Heat Treatment Condition | Annealed (Solution Annealed); optionally Cold Worked (1/4 Hard, 1/2 Hard, Full Hard) | ASTM A269 |
| End Treatment | Plain ends, beveled ends, or capped ends (as specified) | — |
| Coil Packaging | Wooden pallet or steel ring packaging; moisture-proof wrapping; seaworthy export packaging | ISO 4180 |
4. Manufacturing Process
The production of second-tier domestic stainless steel coil tubes follows a well-established cold-drawn and cold-rolled process route. The key stages are detailed below:
4.1 Steelmaking & Casting
Raw materials (ferrochrome, ferro-nickel, ferro-molybdenum, and recycled stainless scrap) are melted in a Basic Oxygen Furnace (BOF) or Electric Arc Furnace (EAF), followed by Argon Oxygen Decarburization (AOD) or Vacuum Induction Melting (VIM) for precise alloy composition control. The molten steel is cast into slabs via Continuous Casting (CC). For higher-purity requirements, Argon On Tap (AOT) or Vacuum Arc Remelting (VAR) may be employed.
4.2 Hot Rolling & Pickling
Cast slabs are reheated to ~1,200°C and hot-rolled into strip or tube blanks. The resulting hot-rolled product undergoes acid pickling (HNO₃/HF mixed acid) to remove the oxide scale, yielding the No.1 surface finish.
4.3 Cold Rolling & Annealing
The hot-rolled strip is cold-rolled to the target thickness, introducing work hardening and improving dimensional accuracy. The cold-rolled strip is then inter-rolled annealed (typically at 1,050–1,100°C in a protective atmosphere or vacuum furnace) to relieve residual stresses and restore ductility. This produces the 2B surface finish.
4.4 Tube Forming
The annealed strip is fed through a cold-drawn tube mill or seamless tube mill system. For welded coil tubes, the strip is formed into a tube shape and joined via TIG (Tungsten Inert Gas) welding or laser welding with argon shielding. For seamless coil tubes, the tube blank is pierced and drawn through a die set.
4.5 Final Annealing & Surface Treatment
The formed tubes undergo final solution annealing (1,050–1,150°C) followed by controlled cooling (air or water quench) to achieve the required microstructure and mechanical properties. Surface treatments (passivation, pickling, polishing) are applied as specified to enhance corrosion resistance and aesthetic finish.
4.6 Coiling & Quality Control
The finished tubes are wound into coils using a precision coiling head that controls tension and layer alignment to prevent deformation. Each coil undergoes non-destructive testing (NDT) including eddy current inspection (for wall thickness uniformity and seam integrity) and hydrostatic testing (typically at 2× working pressure for 10–30 seconds). Chemical composition is verified via OES (Optical Emission Spectroscopy) and ICP-OES. Mechanical properties are confirmed through tensile testing and hardness testing per ASTM E8/E10.
5. Applications
The second-tier domestic stainless steel coil tubes find extensive application across multiple industrial sectors:
- Food & Beverage Processing: Hygienic piping, CIP (Clean-In-Place) systems, milk and juice processing lines (304/316L grades).
- Pharmaceutical & Biotechnology: GMP-compliant process piping, sterilization circuits, and fluid transfer systems (316L, BA finish).
- Chemical Processing: Reactor cooling coils, heat exchanger tubes, chemical transfer lines (316, 310S, 2205 grades).
- Petrochemical & Oil & Gas: Downstream processing units, condensate handling, and instrumentation tubing.
- Power Generation: Boiler feedwater systems, steam lines, and condensate return systems (304, 321, 310S grades).
- Construction & Architecture: Structural tubing, handrails, decorative elements, and facade systems (2B or hairline finish).
- Automotive & Transportation: Exhaust systems, fuel lines, and hydraulic tubing.
- Medical Devices: Instrument tubing, endoscope channels, and implant-grade components (316L, high-purity grades).
6. Quality Certifications & Standards Compliance
Products from the second-tier domestic supply chain are certified against the following international and national standards:
- ASTM A269 / ASME SA269: Standard Specification for Welded Austenitic Stainless Steel Tube for Chemical and Similar Severe Service
- ASTM A213: Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Tubing for Heat-Exchanger and Similar Service
- GB/T 12771: Chinese National Standard for Stainless Steel Seamless Tubes for General Application
- GB/T 17898: Chinese National Standard for Stainless Steel Tubes for Food Industry
- ISO 9001:2015: Quality Management System certification (held by all tier-2 manufacturers)
- EN 10216-5: European Standard for Tubes for Heat Exchangers and Similar Uses
- JIS G3459: Japanese Industrial Standard for Austenitic Stainless Steel Tubes
- EN 10217-7: European Standard for Stainless Steel Tubes for Mechanical and Structural Purposes
6.1 Third-Party Inspection & Mill Test Reports
Each shipment is accompanied by a Mill Test Report (MTR) / En 10204 3.1 Certificate documenting chemical composition, mechanical test results, dimensional measurements, and heat treatment records. Independent third-party inspection by organizations such as SGS, BV (Bureau Veritas), CCIC, or DNV is available upon request to verify conformity with purchase specifications.
6.2 Traceability
Full traceability from the heat number to the final coil is maintained. Each coil is marked with the manufacturer's name, grade designation, heat number, OD × WT, coil weight, and date of manufacture, enabling complete supply chain traceability for quality assurance and regulatory compliance.
7. Unique Selling Points of the Second-Tier Domestic Supply
- Exceptional Cost-Performance Ratio: Second-tier domestic products typically offer 20–40% cost savings compared to first-tier imported equivalents, while maintaining compliance with major international standards. This makes them the optimal choice for high-volume industrial projects with budget constraints.
- Broad Industry Acceptance: Products from Jiuli, Wujin, Huaxin Lihua, and Yongxing are recognized and accepted by the vast majority of end-user industries, including food, pharmaceutical, chemical, and energy sectors, reducing the risk of qualification delays.
- Reliable Domestic Supply Chain: As a second-tier domestic supply, these products benefit from shorter lead times, reduced logistics costs, and lower exposure to international trade disruptions compared to imported alternatives.
- Customization Flexibility: Domestic manufacturers offer greater flexibility in custom dimensions, surface finishes, and packaging configurations compared to standardized import offerings.
- Established Quality Infrastructure: The named manufacturers operate state-of-the-art production facilities with comprehensive NDT capabilities, ensuring consistent product quality across large production volumes.
8. Supply Chain & Distribution
Wenzhou Jixing Metal Materials Co., Ltd. functions as an authorized distributor and quality assurance intermediary for