Stainless Steel Coil Tube (Coiltube) with Compression Fitting Two-Step Tightening System

Product Code: No. 219 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Category: Installation & Maintenance — Connection Technology — Compression Fittings

1. Product Overview

The Stainless Steel Coil Tube (Coiltube) is a precision-engineered flexible tubing solution designed for demanding industrial and commercial piping applications. This product is supplied in coiled form to facilitate easy routing, bending, and installation in complex configurations without the need for additional forming equipment. The coil tube is specifically engineered for use with compression fittings (compression joints), employing a proprietary Two-Step Tightening Method (Pre-Assembly + Final Assembly) to ensure leak-free, reliable connections.

The Two-Step Tightening Method is a critical installation protocol that ensures optimal sealing integrity at the tube-fitting interface. This method involves three sequential steps: (1) inserting the tube fully to the bottom of the fitting body, (2) hand-tightening the nut to achieve initial engagement, and (3) using a wrench to rotate an additional 1.25 turns past hand-tight. This precise procedure ensures uniform compression of the ferrule (compression nut) against the tube wall, creating a permanent metal-to-metal seal without over-compression that could compromise the tubing integrity.

2. Material & Properties

The coil tube is manufactured from high-grade austenitic stainless steel, offering exceptional corrosion resistance, mechanical strength, and formability. Key material properties include:

3. Specifications

Parameter Specification Remarks
Product Name Stainless Steel Coil Tube (Coiltube) Product Code No. 219
Material Grade SUS304 / SUS316 / SUS316L Custom grades available upon request
Outer Diameter (OD) 3 mm – 32 mm Multiple sizes available
Wall Thickness 0.3 mm – 1.5 mm Varies by OD and application
Coil Length Standard / Custom Typically 15 m – 100 m per coil
Surface Finish Mirror / Electropolished / Passivated / Matte Up to Ra 0.2 μm for sanitary use
Connection Type Compression Fitting (Ferrule Type) Two-Step Tightening Method
Installation Procedure Insert to bottom → Hand-tighten → Wrench 1.25 turns Strict adherence required
Pressure Rating Up to 1.0 MPa (typical) Depends on OD, wall thickness, and fitting grade
Applicable Standards ASTM A269 / ASTM A270 / GB/T 12771 / EN 10217 Compliant with international specifications

4. Manufacturing Process

4.1 Tube Production Process

  1. Raw Material Selection: High-purity stainless steel strip is sourced from certified mills with full material traceability.
  2. Slitting & Leveling: The strip is slit to precise width and leveled to eliminate residual stresses.
  3. Forming & Welding: The strip is rolled into a tube shape and welded using Argon Shielded TIG (Tungsten Inert Gas) welding to produce a smooth, high-integrity weld seam.
  4. Heat Treatment: Solution annealing and pickling to restore full austenitic microstructure and corrosion resistance.
  5. Surface Finishing: Electropolishing, passivation, or mechanical polishing to achieve the required surface roughness.
  6. Coiling: The finished tube is wound onto precision steel reels to form the coil configuration, with protective end caps to prevent damage during transport.
  7. Quality Inspection: 100% visual inspection, dimensional verification, pressure testing, and material certification (MTC — Material Test Certificate).

4.2 Two-Step Tightening Installation Protocol

The Pre-Assembly + Final Assembly Two-Step Tightening Method is the proprietary connection technology for this coil tube system. This method is critical to achieving a reliable, leak-free joint:

  1. Step 1 — Tube Insertion: The tube end must be cut squarely (perpendicular to the axis), deburred, and inserted fully into the compression fitting body until it seats at the bottom. Incomplete insertion is a primary cause of connection failure.
  2. Step 2 — Hand-Tightening (Pre-Assembly): The compression nut is tightened by hand until initial resistance is felt. This ensures proper alignment of the ferrule and prevents cross-threading.
  3. Step 3 — Final Assembly (Wrench Tightening): Using an appropriate wrench, rotate the nut an additional 1.25 turns past the hand-tight position. This controlled over-torque compresses the ferrule uniformly against the tube wall, creating the permanent metal-to-metal seal.
Critical Warning: The Three Primary Causes of Leakage in Compression Fitting Connections Are: (1) Scratches or Surface Damage on the tube end — any scoring or gouging compromises the seal; (2) Ovality — deformation of the tube cross-section due to improper bending or tooling; (3) Dimensional Tolerance Exceedance — OD or wall thickness outside specified limits prevents proper ferrule engagement. All three must be eliminated to ensure leak-free performance.

5. Applications

The Stainless Steel Coil Tube with Compression Fitting System is widely used across multiple industries:

6. Quality Certifications & Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems to ensure product reliability and regulatory compliance:

7. Unique Selling Points