Stainless Steel Coil Tube – Non-Standard & Extreme Specification Grade
Product Overview
The Stainless Steel Coil Tube (Coil Tube) produced by Wenzhou Jixing Metal Materials Co., Ltd. represents a specialized category of seamless stainless steel tubing supplied in continuous coil form. This product line addresses engineering applications that demand dimensions beyond standard commercial specifications — specifically ultra-thin wall thickness (below 0.5 mm), ultra-thick wall thickness (above 3.0 mm), and non-standard outer diameters (OD). Due to the inherent challenges associated with producing these extreme geometries, including significantly reduced material yield rates and frequent die-changeover requirements, a specification surcharge of 10%–30% is applied relative to standard-grade pricing.
Coil tube is distinct from straight-length tube in that it is delivered in a continuously wound coil configuration, enabling high-volume downstream processing without the need for individual cut-length handling. The non-standard and extreme specification variants are engineered for niche industrial applications where conventional tube dimensions are insufficient or impractical.
Material & Properties
Non-standard and extreme specification coil tubes are manufactured from austenitic and duplex stainless steel grades, selected according to the specific corrosion resistance, mechanical strength, and temperature tolerance requirements of the end application.
- Austenitic Grades (e.g., 304, 304L, 316, 316L, 321, 347): Provide excellent corrosion resistance, formability, and weldability across a wide range of environments.
- Duplex Grades (e.g., 2205, 2507): Offer superior yield strength (approximately 550–800 MPa) and enhanced resistance to chloride-induced stress corrosion cracking (SCC).
- Super-Austenitic Grades (e.g., 904L, Alloy 20): Engineered for aggressive chemical processing environments with elevated acid and halide concentrations.
For ultra-thin wall configurations (<0.5 mm), the material must exhibit exceptional surface finish quality and dimensional consistency to prevent deformation during downstream forming operations. For ultra-thick wall configurations (>3.0 mm), the steel must maintain uniform microstructure throughout the cross-section to avoid segregation and ensure consistent mechanical properties from core to surface.
Specifications
| Parameter | Standard Range | Non-Standard / Extreme Range | Surcharge Impact |
|---|---|---|---|
| Wall Thickness | 0.5 mm – 3.0 mm | Ultra-thin: <0.5 mm; Ultra-thick: >3.0 mm | 10%–30% premium |
| Outer Diameter (OD) | Standard commercial series (e.g., 6, 8, 10, 12, 16, 20, 25, 32, 38, 48, 57, 76, 89 mm) | Any OD outside the standard series | 10%–30% premium |
| Material Yield Rate (成材率) | 75%–85% (standard specifications) | 55%–70% (extreme specifications) | Primary cost driver |
| Die Changeover Frequency | Low (high-volume standard runs) | High (frequent tooling adjustments) | Secondary cost driver |
| Surface Finish | No.1, 2B, BA | No.1, 2B, BA, custom polished | May add additional surcharge |
| Coil Weight | 500 kg – 2,000 kg | Adjustable per order | — |
| Standard Length Equivalent | 3 m – 6 m (straight length equivalent) | Continuous coil | — |
Manufacturing Process
The production of non-standard and extreme specification coil tubes involves a multi-stage process that requires specialized equipment, extended production cycles, and rigorous in-process quality control.
- Raw Material Selection & Inspection: Virgin stainless steel billets or slabs are sourced from certified producers. Incoming material undergoes spectroscopic analysis (OES) to verify chemical composition within ASTM/EN specification tolerances.
- Hot Rolling & Piercing: Billets are heated to 1,150–1,250 °C and hot-rolled into hollow rounds. For ultra-thick wall tubes, the piercing reduction ratio is carefully controlled to prevent internal folding and ensure uniform wall thickness distribution.
- Cold Drawing / Cold Reduction: The hot-rolled blank is cold-drawn through precision dies to achieve the target OD and wall thickness. Ultra-thin wall tubes require multi-stage progressive drawing with intermediate annealing to prevent work hardening and dimensional drift.
- Intermediate Annealing: For multi-stage cold forming, intermediate annealing cycles are conducted at 1,000–1,150 °C followed by rapid quenching to restore ductility and relieve residual stresses accumulated during prior forming stages.
- Precision Sizing & Straightening: Final dimensional accuracy is achieved through precision rolling mills or sizing stands. Non-standard OD tubes require custom-rolled sizing stands or dedicated tooling.
- Surface Treatment: Pickling and passivation are performed to remove oxide scale and establish a protective chromium oxide layer. Custom surface finishes (e.g., mirror polish, matte) may be applied per customer specification.
- Coil Winding: The finished tube is wound into coil form on precision coil winders. Tension control is critical, especially for ultra-thin wall configurations, to prevent ovality and kinking.
- Final Inspection & Packaging: Each coil undergoes dimensional verification (OD, wall thickness via ultrasonic testing), surface inspection, and hydrostatic pressure testing. Coils are wrapped in protective film and palletized for shipment.
Applications
Non-standard and extreme specification stainless steel coil tubes serve demanding applications across multiple industries:
- Medical & Pharmaceutical Equipment: Ultra-thin wall coil tubes (<0.5 mm) are used in dialysis tubing, infusion devices, and precision pharmaceutical dosing systems where fluid dynamics and biocompatibility are critical.
- Oil & Gas / Petrochemical: Ultra-thick wall coil tubes (>3.0 mm) are employed in high-pressure heat exchanger bundles, wellhead piping, and subsea flowlines requiring enhanced mechanical integrity and corrosion resistance.
- Food & Beverage Processing: Non-standard OD tubes accommodate custom hygienic fittings and sanitary piping systems in breweries, dairy processing, and CIP (Clean-in-Place) systems.
- Chemical Processing: Specialty grades in extreme specifications are used for reactor internals, distillation column tubes, and chemical transfer lines exposed to aggressive media.
- Energy & Power Generation: Custom-diameter coil tubes are utilized in solar thermal collectors, geothermal heat exchangers, and nuclear-grade instrumentation tubing.
- Automotive & Aerospace: Precision ultra-thin coil tubes are used in fuel injection lines, brake hydraulic lines, and lightweight structural tubing where weight optimization is paramount.
Quality Certifications
Non-standard and extreme specification coil tubes produced by Wenzhou Jixing Metal Materials Co., Ltd. adhere to internationally recognized quality management and product standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and process control.
- ISO 14001 — Environmental Management System certification for sustainable manufacturing practices.
- ISO 45001 — Occupational Health and Safety Management System certification.
- EN 10204 3.1 — Material Inspection Certificate Type 3.1, providing independent third-party verification of chemical composition and mechanical properties.
- ASTM / ASME Compliance — Product specifications aligned with ASTM A213, ASTM A269, and ASME B36.19/B36.19M standards as applicable.
- EN 10217-7 — European standard for stainless steel tubes for pressure purposes.
Unique Selling Points
- Full-Spectrum Dimensional Capability: Production of coil tubes spanning wall thicknesses from below 0.5 mm to above 3.0 mm and any non-standard OD, eliminating the need for customers to source from multiple suppliers.
- Transparent Surcharge Structure: The 10%–30% specification surcharge is clearly communicated and justified by documented yield rate data and die-changeover frequency, ensuring procurement transparency.
- Low Minimum Order Quantity (MOQ) Flexibility: Non-standard specifications are produced with flexible MOQ terms, accommodating prototype and small-batch engineering requirements.
- End-to-End Traceability: Each coil is traceable from raw material heat number through all manufacturing stages to final shipment, supporting regulatory compliance in pharmaceutical, food, and nuclear applications.
- Technical Consultation Support: Dedicated metallurgical engineering support for specification optimization, material selection, and cost-performance trade-off analysis.
Note: The 10%–30% non-standard/extreme specification surcharge reflects the materially higher production costs associated with reduced material yield rates (55%–70% vs. 75%–85% for standard specifications) and increased die changeover frequency. This surcharge ensures that production economics remain sustainable while maintaining the stringent quality standards required for extreme-geometry stainless steel tubing.