PRODUCT OVERVIEW
Our 3:1 ratio dual-wall adhesive-lined heat shrink tubing is engineered for demanding electrical and environmental sealing applications where standard 2:1 tubing fails to deliver adequate coverage. Constructed with a cross-linked polyolefin outer jacket (UL VW-1 flame-retardant) and a thermoplastic hot-melt adhesive inner liner, this tubing provides a 3-to-1 shrink ratio, enabling it to conform tightly around large connectors, splices, and irregular cable geometries while delivering a hermetic, moisture-proof seal.
Upon heat activation, the outer wall shrinks uniformly while the inner adhesive melts and flows, encapsulating the substrate and forming a durable, strain-relieved bond that resists water ingress, corrosion, vibration, and mechanical abrasion. Rated for continuous operation from -55°C to +125°C, the polyolefin outer wall meets UL 224 VW-1 flammability requirements and the assembly is fully RoHS and REACH compliant — making it suitable for marine, automotive, industrial control, and renewable energy installations.
Important Note: The UL 224 VW-1 flammability rating applies specifically to the outer polyolefin wall. The inner hot-melt adhesive layer is not flame-retardant and is designed primarily for environmental sealing and mechanical bonding. In applications requiring full assembly flame resistance, please verify suitability for your specific use case.
KEY TECHNICAL SPECIFICATIONS
• Shrink Ratio: 3:1 (recovers to 1/3 of original diameter)
• Wall Construction: Dual-wall structure
- Outer Wall: Cross-linked flame-retardant polyolefin (UL VW-1)
- Inner Liner: Hot-melt thermoplastic adhesive (non-flame-retardant)
• Operating Temperature Range: -55°C to +125°C (continuous)
• Shrink Initiation Temperature: ≥ 70°C
• Full Recovery Temperature: 125°C
• Dielectric Strength: ≥ 15 kV/mm (ASTM D2671)
• Dielectric Constant: ≤ 2.8 @ 1 MHz
• Volume Resistivity: ≥ 1×10¹⁴ Ω·cm
• Outer Wall Flammability: UL 224 VW-1 (vertical burn) — outer polyolefin layer only
• Tensile Strength: ≥ 10.4 MPa (ASTM D2671)
• Elongation at Break: ≥ 200%
• Water Absorption: ≤ 0.5%
• Copper Corrosion: Passes ASTM D2671
• Fluid Resistance: Resistant to diesel, gasoline, hydraulic fluids, and mild acids
• Certifications: UL Recognized (outer wall), RoHS 3.0, REACH SVHC Compliant
PERFORMANCE ADVANTAGES
► Superior Conformability with 3:1 Recovery
The 3-to-1 shrink ratio allows a single tubing size to cover a wider range of cable diameters and large-diameter connectors — reducing SKU count and simplifying inventory management. Ideal for transition splices, molded connectors, and irregularly shaped components where 2:1 tubing cannot achieve full recovery.
► Hermetic Environmental Sealing
The internal hot-melt adhesive liner melts at approximately 80°C and flows under shrink pressure, filling voids and bonding directly to the cable jacket and underlying substrate. The resulting seal provides IP67-equivalent moisture protection, preventing water intrusion, salt spray corrosion, and dust contamination in outdoor and submerged applications.
► Enhanced Mechanical Strain Relief
The bonded adhesive layer creates a unified structure between the tubing and the cable, distributing mechanical stress across the splice junction. This significantly improves pull-out resistance and flex fatigue performance compared to non-adhesive tubing, extending service life in high-vibration environments.
► Flame-Retardant Outer Layer
The polyolefin outer wall is formulated with flame-retardant additives and meets UL 224 VW-1 vertical burn requirements, ensuring compliance with NEC and international electrical safety standards for enclosed and industrial installations. Note: The inner adhesive layer is non-flame-retardant and contributes to sealing performance only.
► Long-Term Thermal Stability
The cross-linked molecular structure of the outer wall provides excellent resistance to thermal aging, UV degradation, and thermal cycling — maintaining dielectric and mechanical integrity throughout the product's service life across the full -55°C to +125°C operating range.
INDUSTRY APPLICATIONS
⚓ Marine & Offshore
• Boat wiring harnesses and navigation system splices
• Bilge pump and transducer cable sealing
• Saltwater-exposed electrical connections
• Dockside and offshore platform instrumentation
🚗 Automotive & Heavy-Duty Vehicles
• Engine bay wiring and sensor connections
• Trailer and towing harness repairs
• Battery cable splices and terminal insulation
• Off-road and agricultural equipment wiring
🏭 Industrial & Automation
• PLC and control cabinet wiring
• Motor lead and transformer connections
• Conveyor and sensor cable splicing
• Outdoor LED lighting and signage
☀️ Renewable Energy
• Solar panel string wiring and junction box connections
• Wind turbine cable terminations
• Inverter and charge controller wiring
📡 Telecom & Data Infrastructure
• Cell tower and base station cable sealing
• Fiber optic buffer tube protection
• Outdoor Ethernet and PoE cable splices
INSTALLATION INSTRUCTIONS
Required Tools: Heat gun (minimum 300°C output), heat-resistant gloves, utility knife or tubing cutter
Step 1 — Preparation
Cut tubing to length using a sharp blade or tubing cutter. Ensure a minimum overlap of 15–20 mm on each side of the splice or connector. Deburr cut edges to prevent tearing during recovery.
Step 2 — Placement
Slide the tubing over the cable and position it centrally over the splice, joint, or termination point before making the electrical connection.
Step 3 — Heat Application
Apply heat uniformly using a heat gun set to 300–350°C. Begin heating from the center of the tubing and work progressively outward toward each end. Maintain sufficient distance to avoid scorching while ensuring the adhesive reaches flow temperature.
Step 4 — Verification
Continue heating until a continuous bead of adhesive extrudes from both ends of the tubing, confirming complete adhesive flow and a circumferential seal. The tubing should conform smoothly to the underlying profile with no wrinkles or bridging.
Step 5 — Cooling & Inspection
Allow the assembly to cool naturally. Inspect for full recovery, uniform adhesive coverage, and absence of voids or air bubbles. A properly installed joint will be rigid at the adhesive bond line with no movement under lateral stress.
Note: Use of open-flame torches is not recommended for precision installations as localized overheating can degrade the adhesive and polyolefin material, compromising seal integrity.
QUALITY ASSURANCE & COMPLIANCE
• Manufactured under ISO 9001:2015 certified quality management systems
• Each production lot undergoes dimensional verification, shrink ratio testing, and dielectric breakdown testing
• Material traceability available upon request for qualified industrial customers
• Custom lengths, colors, and printed marking available for volume orders (MOQ applies)
PACKAGING OPTIONS
• Bulk Spools: 30m / 50m / 100m continuous lengths on plastic spools
• Cut Pieces: Pre-cut segments in assorted lengths (customizable)
• Kit Assortments: Multi-diameter organizer kits for service technicians
• Private Label: Custom branding and packaging available for OEM and resale partners
