Stainless Steel Coil Tube — Precision Ovality-Controlled Coil Tubing
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. delivers premium-grade stainless steel coil tubes engineered for demanding industrial and commercial applications. Our coil tubing is manufactured with rigorous dimensional control, placing particular emphasis on ovality (ellipticity) tolerance — a critical geometric parameter that directly governs seal integrity, flow performance, and long-term reliability in cartridge, crimp, and compression-fitting systems.
Ovality is defined as the deviation of the tube's cross-section from a perfect circle and is quantified by the industry-standard formula:
Ovality (%) = (Dmax − Dmin) / Dnom × 100%
Where Dmax and Dmin represent the maximum and minimum outer diameters measured across the tube cross-section, and Dnom is the nominal outer diameter. Excessive ovality is the primary geometric root cause of cartridge seal failure, leading to leakage, premature fitting wear, and costly system downtime.
Material & Properties
- Available Grades: 304, 304L, 316, 316L, 321, 310S, 904L, and custom alloy specifications upon request
- Corrosion Resistance: Exceptional resistance to pitting, crevice corrosion, and intergranular attack in aggressive chemical and marine environments
- Mechanical Properties: High tensile strength and ductility ensuring reliable cold-formability during coil winding and downstream processing
- Hygienic Surface: Passivated and pickled finish with Ra ≤ 0.4 μm available for food-grade and pharmaceutical applications
- Temperature Range: Suitable for continuous operation from cryogenic temperatures up to 870°C (grade-dependent)
Specifications
| Parameter | Precision Grade | Ordinary Grade | Measurement Standard |
|---|---|---|---|
| Ovality (Ellipticity) | ≤ 3% | ≤ 5% | (Dmax − Dmin) / Dnom × 100% |
| Outer Diameter Tolerance | ±0.05 mm | ±0.10 mm | ISO 285 / ASTM A213 |
| Wall Thickness Tolerance | ±0.025 mm | ±0.05 mm | ASTM A269 |
| Coil Diameter | 500 mm – 2,000 mm (customizable) | — | |
| OD Range | 3 mm – 50 mm | — | |
| Wall Thickness Range | 0.5 mm – 5.0 mm | — | |
| Length per Coil | Up to 300 m (continuous) | — | |
| Surface Finish | Polished / Passivated / Sandblasted | — | |
Manufacturing Process
- Raw Material Inspection: Ingot certification and spectroscopic analysis of incoming steel to verify alloy composition and purity.
- Piercing & Hot Rolling: Billet piercing followed by controlled hot rolling to establish initial tube geometry and microstructure.
- Cold Drawing / Cold Rolling: Multi-pass cold reduction to achieve precise OD and wall thickness tolerances with minimized residual stress.
- Ovality Control & Calibration: Precision mandrel-guided drawing and in-line laser diameter measurement systems ensure ovality remains within specified limits — ≤ 3% for precision grade and ≤ 5% for ordinary grade.
- Coil Winding: Automated coil winding with tension-controlled spooling to prevent cross-sectional deformation during forming.
- Heat Treatment & Annealing: Solution annealing to relieve cold-work stresses, restore ductility, and achieve the desired microstructural properties.
- Pickling & Passivation: Chemical cleaning and passivation to remove surface oxides and establish a protective chromium-oxide layer.
- Final Dimensional Inspection: 100% ovality verification using calibrated bore gauges and ultrasonic thickness gauges; sampling per lot for spectroscopic and mechanical property confirmation.
Applications
- Heat Exchangers & Cooling Systems: Precision ovality ensures uniform gap clearance in shell-and-tube heat exchangers, maximizing thermal transfer efficiency and preventing vibration-induced fatigue.
- Hydraulic & Pneumatic Systems: Tight ovality tolerances are essential for cartridge seal integrity — preventing the leakage failures that result from geometric deviation at fitting interfaces.
- Automotive Fuel & Turbocharger Lines: Corrosion-resistant coil tubing with controlled roundness withstands high-temperature exhaust environments and aggressive fuel chemistry.
- Food & Beverage Processing: Hygienic-grade tubing meets FDA and EHEDG requirements for sanitary fluid handling and CIP/SIP compatibility.
- Pharmaceutical & Biotech: Passivated surfaces prevent product contamination and support rigorous sterilization protocols.
- Chemical & Petrochemical Processing: Grade 316L and 904L coil tubes resist chloride-induced pitting and acid corrosion in severe service conditions.
- Medical Device Fabrication: Biocompatible tubing for endoscopes, dialysis systems, and surgical instrument channels.
- CAP (Cathodic Arc Propulsion) & Aerospace: High-temperature alloy coil tubing for rocket engine feed lines and thermal management systems.
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System certification ensuring consistent process control and continuous improvement.
- ISO 14001:2015 — Environmental Management System demonstrating commitment to sustainable manufacturing practices.
- ASME SA-213 / SA-269 — Compliance with American Society of Mechanical Engineers specifications for seamless austenitic stainless steel tubing.
- ASTM A213 / A269 — Conformance to ASTM International standards for seamless stainless steel tube dimensions, chemistry, and mechanical properties.
- EN 10216-5 — European standard compliance for cold-drawn seamless stainless steel tubes.
- GB/T 12771 — Chinese national standard compliance for stainless steel tubing.
- Material Test Reports (MTR): Full chemical analysis, tensile test data, and dimensional inspection certificates provided with every shipment.
- Third-Party Inspection: Available upon customer request through SGS, TÜV, or BV.
Key Differentiators
- Industry-Leading Ovality Control: With precision grade ovality held to ≤ 3% — significantly tighter than the general industry norm — our coil tubes deliver superior seal performance and extended service life in critical applications.
- Root-Cause Engineering Focus: By identifying and controlling ovality as the primary geometric cause of cartridge seal failure, we provide customers with a proactive solution to one of the most common and costly failure modes in tubing systems.
- End-to-End Traceability: Every coil is traceable from raw material ingot through final inspection, with complete documentation at each manufacturing stage.
- Customization Capability: Flexible ordering for non-standard OD, wall thickness, coil diameter, and surface finish requirements.