Stainless Steel Coil Tube — Product No. 352
1. Product Overview
The Stainless Steel Coil Tube (Product No. 352), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered continuous-form tubing product designed for large-scale coil applications. Unlike conventional straight-length stainless steel tubes, coil tubes are wound in large-diameter coils to facilitate continuous feeding in automated processing lines, thereby minimizing cutting waste and maximizing material utilization.
This product line is particularly notable for its performance characteristics under extended service conditions. Research investigations—specifically studies on the mechanical and workability interactions between large coiltube assemblies and surrounding concrete matrices—have demonstrated the product's dimensional stability, corrosion resistance, and structural integrity over prolonged exposure periods.
2. Material & Properties
2.1 Base Material Grades
- Austenitic Stainless Steels: AISI 304 (UNS S30400), AISI 316L (UNS S31603), AISI 321 (UNS S32100)
- Duplex Stainless Steels: 2205 (UNS S31803/S32205) for high-stress applications
- Super-Austenitic Grades: 904L (UNS N08904) for extreme corrosion environments
2.2 Key Mechanical Properties
| Property | AISI 304 | AISI 316L | 2205 Duplex |
|---|---|---|---|
| Tensile Strength (MPa) | 515 – 730 | 485 – 720 | 450 – 620 |
| Yield Strength (MPa, 0.2% offset) | 205 – 310 | 170 – 310 | 450 – 550 |
| Elongation at Break (%) | ≥40 | ≥40 | ≥25 |
| Hardness (HB) | ≤201 | ≤201 | ≤310 |
| Density (g/cm³) | 8.00 | 8.00 | 7.85 |
| Thermal Expansion (×10⁻⁶/K, 20–100°C) | 17.3 | 17.0 | 13.6 |
| Maximum Service Temperature (°C) | 870 | 870 | 300 |
2.3 Corrosion Resistance
- Equivalent Corrosion Resistance Index (ECR): 304 ≥ 18; 316L ≥ 24; 2205 ≥ 38
- Pitting Resistance Number (PREN): 304 ≈ 18–20; 316L ≈ 24–26; 2205 ≈ 34–38
- Superior resistance to chloride-induced pitting, crevice corrosion, and intergranular corrosion
3. Specifications
| Parameter | Specification / Range |
|---|---|
| Outer Diameter (OD) | 3.0 mm – 168.3 mm (customizable) |
| Wall Thickness | 0.3 mm – 6.0 mm |
| Coil Inner Diameter (ID) | 300 mm / 400 mm / 500 mm (standard); up to 800 mm (custom) |
| Coil Weight | 150 kg – 5,000 kg per coil (grade-dependent) |
| Surface Finish | 2B (Cold Rolled & Annealed), BA (Bright Annealed), No. 4 Brushed, Mirror (8K), Matte |
| Tolerance (OD) | ±0.05 mm (precision grade); ±0.1 mm (standard grade) |
| Tolerance (Wall) | ±10% of nominal |
| Heat Treatment | Solution annealed at 1050–1150°C followed by rapid water quenching |
| Applicable Standards | ASTM A269/A269M, ASTM A554/A554M, ASTM A580/A580M, EN 10216-5, GB/T 12771 |
| End Condition | Plain, beveled, threaded, or flanged (upon request) |
| Length per Coil | Continuous; typical 80–500 m depending on diameter and wall thickness |
4. Manufacturing Process
- Hot Rolling & Annealing: Stainless steel strip or wire rod is hot-rolled to approximate dimensions, followed by high-temperature annealing (1050–1150°C) to achieve a fully austenitic microstructure free of carbide precipitation.
- Pickle & Descale: The hot-rolled coil is acid-pickled (HNO₃/HF mixture) to remove oxide scale, yielding a clean substrate for cold working.
- Cold Rolling: The strip is cold-rolled to precise final thickness with controlled reduction ratios to develop desired mechanical properties and surface quality.
- Forming (Seamless or Welded):
- Seamless: Pierced, drawn, and reduced (DMR) or plug-rolling methods for high-purity applications.
- Welded: Precision welded using Automatic Optical-Strand Arc (AOSA) or Orbital TIG welding, followed by weld annealing.
- Intermediate Annealing: Periodic annealing during multi-pass forming to prevent work hardening and maintain ductility.
- Final Annealing & Pickling: Complete solution treatment followed by acid pickling to restore corrosion resistance and achieve desired surface finish.
- Sizing & Coiling: The formed tube is passed through a sizing roll set to ensure dimensional accuracy, then wound onto a pay-off reel at controlled tension to produce the final coil configuration.
- Quality Inspection: 100% ultrasonic testing (UT) for internal defects; eddy current testing (ECT) for surface and near-surface discontinuities; hydrostatic or pneumatic pressure testing.
5. Applications
5.1 Industrial & Infrastructure
- Large-scale coil tube assemblies embedded in or adjacent to reinforced concrete structures—research has confirmed that properly specified stainless steel coil tubes maintain structural compatibility with concrete matrices, preventing galvanic coupling degradation and preserving concrete workability during installation.
- Chemical process piping systems requiring continuous feed without butt-weld interruptions
- Heat exchanger tube bundles (hairpin or U-tube configurations)
5.2 Food & Pharmaceutical
- Hygienic fluid transfer lines (BA finish, electropolished)
- Dairy, beverage, and brewing process equipment
- Pharmaceutical CIP/SIP (Clean-in-Place / Sterilize-in-Place) compatible tubing
5.3 Energy & Marine
- Offshore oil and gas subsea flow lines
- Geothermal heat exchange coils
- Marine heat exchangers and seawater cooling systems (316L/2205 grades)
5.4 Architectural & Decorative
- Continuous guardrails, handrails, and structural framing
- Facade systems and curtain wall support structures
- Automotive exhaust systems (321/310S grades)
6. Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management
- EN 10204 — Type 3.1 mill test certificates available for each heat/coil
- CE Marking — Conformity with European Pressure Equipment Directive (PED 2014/68/EU) where applicable
- API 5L / API 5CT — For energy-sector applications
- NSF 61 / W290 — Drinking water system certification (304/316L grades)
- Third-Party Inspection: SGS, BV, and TÜV inspection available upon customer request
7. Unique Selling Points
Research-Validated Performance: Independent studies on large coiltube assemblies have demonstrated that Wenzhou Jixing's stainless steel coil tubes exhibit stable mechanical properties and non-reactive interfaces with concrete matrices even after prolonged service exposure, confirming long-term structural integrity in composite infrastructure applications.
- Minimal Material Waste: Continuous coil format eliminates end-trim losses inherent to straight-length tubing, reducing project material costs by 8–15%.
- High Dimensional Precision: Advanced sizing and coiling technology ensures tight tolerances (±0.05 mm OD), enabling seamless integration into automated fabrication lines.
- Grade Flexibility: Full range from standard austenitic to super-duplex and super-austenitic grades available in coil form—rarely offered by competitors.
- Custom Coiling: Tailored coil diameter, weight, and surface finish to match customer-specific unwinding equipment and downstream processing requirements.
- Traceability: Full heat-to-coil traceability with comprehensive mill test documentation supporting regulatory compliance in critical industries.