ASTM E45 Certified Stainless Steel Coil Tube with Ultra-Low Non-Metallic Inclusion Ratings
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. delivers premium-grade stainless steel coil tubes engineered for applications where metallurgical purity is critical. These coil tubes are manufactured with rigorous control over non-metallic inclusion content, evaluated and certified to ASTM E45 Class A through E standards. By minimizing oxide and sulfide inclusions within the steel matrix, these coil tubes achieve superior flareability, enhanced fatigue resistance, and extended service life in demanding industrial environments.
Coil tubes—supplied in continuous coil form for maximum processing efficiency—are ideal for automated forming, flaring, and fabrication lines. Wenzhou Jixing's coil tubes represent the pinnacle of metallurgical quality control, ensuring that every coil meets exacting inclusion limits that directly correlate to downstream mechanical performance.
Material & Properties
Non-Metallic Inclusion Classification (ASTM E45)
ASTM E45 is the internationally recognized standard for determining the type and size of non-metallic inclusions in steel. Wenzhou Jixing classifies and controls inclusions across five categories, each with direct implications for product performance:
- Class A — Stringer Oxides (Linear Oxide Inclusions): Elongated oxide particles formed during hot working. High Class A ratings indicate significant oxide stringers that act as stress concentrators, directly degrading fatigue performance in cyclic-loading applications.
- Class B — Sulfide Stringers (Linear Sulfide Inclusions): Elongated manganese sulfide (MnS) inclusions that reduce transverse ductility and severely impair flareability and cold forming characteristics.
- Class C — Circular Oxides (Spherical Oxide Inclusions): Round oxide particles that compromise fatigue endurance and crack resistance. Elevated Class C ratings lead to premature fatigue failure under repeated stress cycles.
- Class D — Circular Sulfides (Spherical Sulfide Inclusions): Spherical sulfide particles that reduce ductility and negatively affect flareability and bending performance during cold working operations.
- Class E — Slag Inclusions: Non-metallic slag particles (silicates, aluminates) that act as internal defects, reducing overall toughness and surface integrity.
Performance Correlation
| Inclusion Class | Type | Primary Performance Impact | Wenzhou Jixing Target Rating |
|---|---|---|---|
| Class A | Stringer Oxides | Fatigue life degradation | ≤ 3 (excellent) |
| Class B | Sulfide Stringers | Flareability / forming limit | ≤ 3 (excellent) |
| Class C | Circular Oxides | Fatigue endurance | ≤ 3 (excellent) |
| Class D | Circular Sulfides | Flareability / ductility | ≤ 3 (excellent) |
| Class E | Slag Inclusions | Toughness / surface quality | ≤ 3 (excellent) |
Mechanical Properties
- Material Grades: 304, 304L, 316, 316L, 321, 310S, 904L, and custom alloys
- Tensile Strength: 515–720 MPa (75,000–104,000 psi), depending on grade
- Yield Strength (0.2% offset): 205–310 MPa (30,000–45,000 psi)
- Elongation at Break: ≥ 40% (superior ductility from low inclusion content)
- Flareability: Verified at 90° flare angle with no cracking (enabled by low Class B/D sulfides)
- Fatigue Endurance Limit: Enhanced by ≥ 15–25% compared to standard inclusion-rated tubes
Specifications
| Parameter | Specification | Notes |
|---|---|---|
| Outer Diameter (OD) | 3.175 mm (1/8") – 152.4 mm (6") | Custom sizes available upon request |
| Wall Thickness | 0.3 mm (0.012") – 6.35 mm (1/4") | Tight tolerance: ±0.05 mm (±0.002") |
| Coil Length | 500 m – 5,000 m (1,640 – 16,404 ft) per coil | Custom coil lengths available |
| Coil Inner Diameter | 250 mm (9.8") – 500 mm (19.7") | Standard shipping coil size |
| Surface Finish | Ba&P, 2B, No. 4, Satin, or Mirror (Ra ≤ 0.4 μm) | Low slag inclusions (Class E) ensure superior surface quality |
| Temper Condition | Annealed (soft), Half-Hard, Full-Hard, or Custom | Inclusion control maintained across all tempers |
| ASTM E45 Inclusion Rating | A/B/C/D/E all ≤ 3 | Verified by certified metallurgical testing |
| Flareability | 90° flare without cracking | Enabled by low Class B/D sulfide content |
| Fatigue Performance | Enhanced ≥ 15–25% vs. standard | Enabled by low Class A/C oxide content |
| Temperature Range | −196 °C (−321 °F) to 870 °C (1,598 °F) | Depends on alloy grade |
| Corrosion Resistance | Superior to standard inclusion-rated tubes | Reduced internal defect sites inhibit crevice corrosion |
Manufacturing Process
Wenzhou Jixing's coil tube production integrates advanced metallurgical practices from raw material selection through final finishing, ensuring inclusion levels remain at the lowest achievable levels:
- Ultra-Pure Raw Material Selection: Virgin stainless steel feedstock (billet and ingot) is sourced from certified suppliers with guaranteed low sulfur (≤ 0.015%) and low oxygen (≤ 20 ppm) content. Incoming material is spectroscopically verified before processing.
- Secondary Metallurgy & Refining: Steel is processed through Argon Oxygen Decarburization (AOD) and Vacuum Arc Remelting (VAR) or Vacuum Induction Melting (VIM) to remove dissolved gases and non-metallic inclusions at the molten stage.
- Continuous Casting: Billets are produced via controlled continuous casting with optimized cooling rates to minimize oxide formation during solidification.
- Hot Rolling & Annealing: Billets are hot-rolled into seamless tube blanks with controlled deformation to prevent oxide inclusion elongation (maintaining low Class A ratings). Intermediate annealing cycles dissolve and spheroidize any residual inclusions.
- Cold Drawing & Coiling: Tubes are cold-drawn to final dimensions on precision dies, then coiled. The cold drawing process is performed with controlled strain rates to prevent sulfide stringer elongation (maintaining low Class B ratings).
- Final Annealing & Pickling: Coils are solution-annealed to relieve residual stresses, followed by acid pickling and passivation to remove surface contamination and restore corrosion resistance.
- Metallurgical Certification Testing: Every coil lot undergoes ASTM E45 inclusion testing on certified cross-section samples. Only coils meeting the specified A/B/C/D/E ≤ 3 ratings are released for shipment.
Applications
Coil tubes with ultra-low non-metallic inclusion content are indispensable in applications where flareability, fatigue resistance, and long-term structural integrity are paramount:
High-Demand Applications
- Automotive & Aerospace Fuel Systems: Low Class A/C oxide content ensures exceptional fatigue life in fuel lines and hydraulic circuits subjected to cyclic pressure loading.
- Cryogenic Piping: Flareability (low Class B/D sulfides) enables reliable 90° flare joint fabrication for liquid natural gas (LNG) and liquid oxygen (LOX) transfer lines.
- Medical & Pharmaceutical Equipment: Clean surface integrity (low Class E slag) and fatigue resistance support use in tubing for medical gas delivery and sterile processing equipment.
- Food & Beverage Processing: Flareability enables sanitary flared joint connections; low inclusion content prevents surface defects that could harbor bacterial growth.
- Hydraulic & Pneumatic Systems: Enhanced fatigue endurance (low Class A/C oxides) extends service life in high-pressure hydraulic lines and pneumatic actuator circuits.
- Pressure Vessels & Heat Exchangers: Superior fatigue performance and corrosion resistance from minimal internal inclusions ensure reliable performance under thermal cycling.
- Oil & Gas Downhole Tubing: Resistance to fatigue and sulfide stress cracking in corrosive well environments.
- Construction & Architectural Applications: Reliable cold forming and flaring for structural tubing and decorative applications.
Quality Certifications & Testing
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality assurance systems to guarantee product conformity:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing processes
- ISO 14001 — Environmental Management System certification
- ISO/TS 22163 — Automotive quality management for IATF compliance
- ASTM E45 — Non-metallic inclusion testing performed on certified cross-sections per ASTM E45 standard
- ASTM A213 / A269 — Seamless stainless steel tube standards compliance
- EN 10216-5 / EN 10217-7 — European standard compliance for stainless steel tubes
- JIS G3446 / G3459 — Japanese Industrial Standard compliance
- Mill Test Certificates (MTC/EN 10204 3.1) — Full chemical and mechanical analysis with inclusion rating data provided with every shipment
- Third-Party Inspection — Independent verification available through SGS, Bureau Veritas, or Lloyd's Register
Unique Selling Points
1. Industry-Leading Inclusion Control: Wenzhou Jixing achieves ASTM E45 A/B/C/D/E ratings of ≤ 3 across all five inclusion categories—significantly outperforming the industry average of 4–5 for comparable grades. This translates directly to measurable gains in flareability and fatigue life.
2. Direct Performance Correlation: Unlike generic coil tube suppliers, Wenzhou Jixing explicitly links inclusion ratings to end-use performance. Low Class B/D sulfides guarantee reliable 90° flaring without cracking; low Class A/C oxides deliver 15–25% enhanced fatigue endurance. Customers receive quantified performance advantages, not just material specifications.
3. Continuous Coil Supply: Tubes are supplied in continuous coils up to 5,000 m (16,404 ft), enabling uninterrupted automated forming and fabrication lines. This eliminates butt-weld joints, reduces material waste, and improves production throughput—while maintaining inclusion integrity throughout the entire coil length.
4. Full Traceability & Certification: Every coil is individually heat-numbered and accompanied by a comprehensive mill test certificate including chemical composition, mechanical properties, dimensional compliance, and full ASTM E45 inclusion test results. Complete traceability from raw material to finished product ensures accountability at every stage.
5. Custom Alloy & Specification Capability: Wenzhou Jixing supports custom alloy compositions and inclusion specification requirements tailored to specific end-use applications. Whether requiring ultra-low sulfur (< 0.005%) for cryogenic service or controlled inclusion elongation for aerospace fatigue-critical components, custom metallurgical programs are available.
Technical Summary
| Key Advantage | Technical Basis | Customer Benefit |
|---|---|---|
| Superior Flareability | Low Class B/D sulfide inclusions (≤ 3) | Reliable 90° flaring without cracking; reduced scrap rates |
| Enhanced Fatigue Life | Low Class A/C oxide inclusions (≤ 3) | 15–25% longer service life in cyclic-loading applications |
| Premium Surface Quality | Low Class E slag inclusions (≤ 3) | Superior cosmetic finish; reduced surface defect risk |
| Process Efficiency | Continuous coil supply up to 5,000 m | Eliminated butt-weld joints; reduced material waste |
| Full Traceability | Heat-numbered coils with ASTM E45 test data | Complete quality documentation for regulatory compliance |
Wenzhou Jixing Metal Materials Co., Ltd. stands as a trusted partner for engineers and manufacturers who demand the highest metallurgical purity in stainless steel coil tubing. By controlling non-metallic inclusions to the lowest achievable levels across all ASTM E45 categories, every coil tube delivers quantifiable advantages in flareability, fatigue endurance, and long-term reliability.