Stainless Steel Coil Tube with Cartridge Fitting Connection System

Product Overview

The Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubing solution designed for reliable fluid transfer, heat exchange, and instrument process connections. This product integrates high-grade stainless steel coil tubing with a cartridge fitting (compression fitting) connection system, offering a leak-free, reusable, and maintenance-friendly assembly method suitable for demanding industrial environments.

Unlike traditional soldering, brazing, or welding connections, the cartridge fitting system enables field-installable, tool-free disassembly and reassembly—making it ideal for applications requiring periodic maintenance, cleaning, or system modification without compromising structural integrity or leak performance.

Material & Properties

Specifications

Parameter Specification
Tube Outer Diameter (OD) 3.0 mm – 38.1 mm (1/8" – 1-1/4")
Wall Thickness 0.5 mm – 3.0 mm (0.020" – 0.118")
Coil Diameter 150 mm – 1200 mm (configurable)
Coil Length Up to 500 m per coil (custom lengths available)
Connection Type Cartridge Fitting (Compression / Ferrule Type)
Thread Standards BSPP (G), NPT, BSPT, Metric (M), DIN 2353, ASME B1.20.1
Pressure Class PN 16 / PN 25 / PN 40 / PN 63 / PN 100 / PN 160 / PN 250 / PN 320
Temperature Range −196 °C to +870 °C
Material Grades 304, 304L, 316, 316L, 321, 310S, Duplex 2205
Surface Finish Bright annealed / Polished / Electropolished (Ra ≤ 0.4 μm)
Standards Compliance ASTM A269, ASTM A270, EN 10217, ISO 2852, DIN 2353
Coating / Passivation Optional citric acid or nitric acid passivation

Manufacturing Process

Tube Production

  1. Raw Material Selection: Certified stainless steel wire rod or strip sourced from accredited mills, verified for chemical composition and mechanical properties via spectroscopic analysis.
  2. Forming: Precision cold-forming or seamless drawing processes to produce coil tubing with tight dimensional tolerances (±0.05 mm on OD, ±10% on wall thickness).
  3. Heat Treatment: Solution annealing and controlled cooling to achieve optimal grain structure, eliminate residual stresses, and ensure uniform mechanical properties.
  4. Surface Treatment: Bright annealing in a protective atmosphere, followed by optional electropolishing or mechanical polishing to achieve required surface finish specifications.
  5. Coiling: Computer-controlled coiling to produce uniform coil diameters with minimal kinking, distortion, or surface damage.
  6. Quality Inspection: 100% inline inspection for OD, wall thickness, roundness (ovality), and surface defects; random sampling for hydrostatic pressure testing and chemical composition verification.

Cartridge Fitting Assembly & Installation Procedure

The cartridge fitting connection system is engineered for a controlled, repeatable two-step tightening procedure that ensures optimal sealing performance and leak-free operation. This method is critical to achieving the design pressure rating of the system.

Two-Step Tightening Procedure (Pre-Installation + Final Installation)

  1. Step 1 — Tube Insertion: Insert the tube end fully into the fitting body until it seats against the bottom stop. Ensure the tube end is clean, deburred, and free of contaminants. Any burr or internal obstruction can compromise the seal.
  2. Step 2 — Hand Tightening (Pre-Installation): Hand-tighten the nut until it makes initial contact with the tube fitting body. This ensures proper alignment of the ferrule (compression sleeve) and eliminates cross-threading risk.
  3. Step 3 — Final Tightening (Wrench Turn): Using a calibrated wrench, rotate the nut an additional 1.25 turns (approximately 450°) beyond hand-tight. This controlled over-torque compresses the ferrule against the tube OD, creating a metallurgical interference fit that provides a permanent, leak-free seal.
Engineering Note: The 1.25-turn specification is calibrated to the specific ferrule geometry and tube OD. Over-tightening beyond 1.5 turns risks ferrule deformation and tube ovality; under-tightening below 1.0 turn risks incomplete compression and leak paths. Adherence to this specification is mandatory for achieving rated pressure performance.

Key Quality Control Indicators — Leak Prevention

Leakage in cartridge fitting systems is predominantly caused by three categories of defects. Wenzhou Jixing Metal Materials implements rigorous controls at every production stage to eliminate these failure modes:

Failure Mode Description Control Measures
Surface Scratches / Gouges External or internal surface damage on the tube OD where the ferrule contacts the tube creates direct leak paths through the compression zone. Protective coiling, controlled handling, 100% visual and automated surface inspection; optional protective end caps on finished coils.
Ovality / Roundness Deviation Non-circular cross-section (ovality) prevents uniform ferrule compression, resulting in incomplete sealing on the minor axis. Inline roundness monitoring (target: ≤ 1% of nominal OD); precision forming dies with calibrated tolerances; post-forming stress relief.
Dimensional Tolerance Exceedance OD or wall thickness outside specified tolerance prevents proper ferrule-to-tube engagement, causing either insufficient compression (leak) or over-compression (tube damage). CNC-controlled forming with ±0.05 mm OD tolerance; ultrasonic wall thickness gauging; SPC (Statistical Process Control) on all production runs.

Applications

Quality Certifications & Compliance

Unique Selling Points