Stainless Steel Coil Tube (Coiltube) for Analytical Instrumentation

Product Overview

The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered wound stainless steel tubing designed primarily for use in high-precision analytical instrumentation, including amino acid analyzers (e.g., Hitachi L-8350 series), HPLC systems, and other laboratory chromatography platforms. The coil tube serves as a critical reaction vessel and flow channel where chemical derivatization reactions, sample conditioning, and pressure regulation occur prior to chromatographic separation and detection.

This product is specifically engineered to meet the stringent requirements of amino acid analysis workflows, where the coil tube functions as the reaction coil in which ninhydrin or other derivatization reagents interact with amino acid samples under controlled temperature and pressure conditions. The consistent internal geometry and chemical inertness of the coil tube ensure reproducible reaction kinetics and minimal carryover between analytical runs.

Material & Properties

The coil tube is fabricated from high-purity austenitic stainless steel, typically conforming to ASTM A269 / ASTM A270 specifications. The following material properties are maintained to ensure long-term chemical compatibility and mechanical integrity:

Specifications

Parameter Specification Measurement / Tolerance
Inner Diameter (ID) 0.10 mm, 0.15 mm, 0.25 mm, 0.32 mm, 0.40 mm, 0.50 mm, 0.80 mm, 1.00 mm, 1.60 mm, 2.00 mm ± 0.01 mm
Outer Diameter (OD) 0.25 mm, 0.32 mm, 0.40 mm, 0.50 mm, 0.63 mm, 0.80 mm, 1.00 mm, 1.60 mm, 2.00 mm, 3.00 mm ± 0.01 mm
Coil Length Up to 150 meters (custom lengths available) ± 0.5%
Coil Winding Diameter 6 mm – 25 mm (configurable per instrument OEM requirements) ± 0.1 mm
Number of Turns Up to 500 turns (instrument-dependent) Uniform winding, no cross-over
Maximum Operating Pressure Up to 50 MPa (7,250 psi) for sealed coil configurations Pressure-tested to 1.5× working pressure
Operating Temperature Range -40°C to +250°C (continuous); up to 300°C (short-term) Thermally stable austenitic structure
Flow Rate Compatibility 0.01 mL/min to 50 mL/min (instrument-dependent) Laminar and turbulent flow regimes
Wall Thickness 0.05 mm – 0.50 mm (selected per pressure and ID requirements) Uniform ± 0.01 mm
End Configuration Plain cut, flared, swaged, or fitted with precision compression fittings Per instrument interface specification
Surface Roughness (Interior) Ra ≤ 0.25 μm (electropolished); Ra ≤ 0.10 μm (mirror-polished, upon request) Verified via profilometry
Particle Contamination < 10 particles ≥ 5 μm per meter (ultra-clean grade) ISO 16232 compliant
Compliance ASTM A269, ASTM A270, ISO 15530, ISO 15531, GB/T 12771, GB/T 14976 Third-party certified

Manufacturing Process

The production of precision stainless steel coil tubes for analytical instrumentation follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, chemical purity, and mechanical reliability:

  1. Raw Material Selection and Verification: High-purity stainless steel bar stock (316L or 304L grade) is procured from certified mills. Each heat lot undergoes spectroscopic analysis (Optical Emission Spectrometry, OES) to verify alloy composition within specification tolerances. Certificates of Analysis (CoA) are maintained for traceability.
  2. Tubing Extrusion and Cold Drawing: Solid bar stock is hot-extruded to form seamless hollow tubes, followed by multiple passes of cold drawing through precision dies to achieve the target inner and outer diameters with uniform wall thickness. Cold working induces beneficial work hardening while maintaining the austenitic crystal structure.
  3. Precision Coiling (Winding): The drawn tubing is wound onto calibrated mandrels using CNC-controlled coiling equipment. Winding parameters — including coil diameter, number of turns, winding pitch, and tension — are precisely controlled to ensure uniform geometry, eliminate kinking or flattening, and achieve the required dead volume and pressure drop characteristics for the target analytical application.
  4. Heat Treatment (Annealing): Coiled tubes undergo stress-relief annealing at temperatures between 1050°C and 1150°C followed by controlled cooling (air or furnace cool) to restore full austenitic microstructure, relieve residual stresses introduced during cold drawing and coiling, and ensure dimensional stability during subsequent use.
  5. Surface Treatment — Electropolishing: The interior surface of the tubing undergoes electropolishing (electrochemical polishing) to remove surface contaminants, decarburized layers, and micro-roughness. This process produces a passive, corrosion-resistant chromium-rich oxide layer and achieves surface roughness Ra ≤ 0.25 μm. The electropolished surface is critical for minimizing protein adsorption, reducing non-specific retention of analytes, and facilitating complete cleaning and sanitization between analytical runs.
  6. End Finishing and Fitting Installation: Tube ends are precision-cut, deburred, and may be flared, swaged, or fitted with compression fittings (Viton® or PTFE-sealed) compatible with standard analytical instrument tubing interfaces (e.g., 1/16" UNF, 1/8" UNF, or metric equivalents).
  7. Final Cleaning and Packaging: Completed coil tubes undergo final ultrasonic cleaning in deionized water (DI water, ≥ 18.2 MΩ·cm), followed by drying under controlled atmosphere. Each unit is individually packaged in anti-static, moisture-barrier packaging with accompanying documentation including CoA, dimensional inspection report, and surface finish verification data.

Applications

The stainless steel coil tube is a mission-critical component across a broad spectrum of analytical and process instrumentation applications:

Quality Certifications and Compliance

Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality management systems and product certifications to assure international customers of product conformity and reliability:

Each production batch undergoes rigorous inspection including:

Unique Selling Points