3:1 Adhesive Heat Shrink Tubing – Dual-Wall Glue Lined, Φ1.6mm to Φ160mm

Select a diameter (unshrunk) that is at least 20–30% larger than the outer diameter of the object you are covering. After shrinking at 3:1 ratio, the tubing will typically reduce to about one-third of its listed unshrunk diameter. For example, Φ9.5mm (≈3/8") unshrunk shrinks to approximately Φ3.2mm (≈1/8") recovered. When in doubt, size up — you can always apply more heat, but you cannot reverse over-shrinkage.

A 3:1 shrink ratio means the tubing shrinks to one-third of its original diameter, compared to one-half for standard 2:1 tubing. This makes 3:1 tubing better suited for irregular shapes, stepped connectors, and applications where a tighter, more conforming fit is needed. The adhesive lining in this dual-wall tubing further enhances the seal compared to single-wall options.

The hot-melt adhesive lining generally flows and bonds to the substrate during shrinking, creating a mechanical and environmental seal. Pull-off strength varies by substrate material and surface preparation, but in most cases the bond is sufficient to resist vibration, moisture ingress, and moderate mechanical stress in automotive and marine environments. For critical structural applications, contact us to confirm suitability.

Yes. Polyolefin material is generally UV-resistant and rated for outdoor exposure. The adhesive lining creates a waterproof seal that helps prevent moisture, salt spray, and corrosion from reaching the underlying wire or connector — making it a common choice for marine wiring, outdoor electrical connections, and automotive underhood applications.

Polyolefin dual-wall heat shrink tubing typically begins to shrink at around 90°C (194°F) and the adhesive activates at approximately 120°C (248°F). A heat gun set to 150–200°C (300–390°F) is generally recommended for even shrinkage. Move the heat gun slowly along the length of the tubing from the center outward to avoid trapping air bubbles. Avoid open flames, which can cause uneven shrinkage or scorching.

Yes. Dual-wall adhesive heat shrink tubing is widely used on battery terminals, cable splices, and butt connectors. The adhesive lining flows around irregular surfaces to create a moisture-resistant seal, while the outer polyolefin layer provides electrical insulation and mechanical protection. Confirm the recovered diameter fits snugly over your terminal before ordering.

Measure the length of the area you need to cover and add at least 10–15mm (about 1/2") of overlap on each end to ensure a complete seal. For bulk wiring projects, ordering longer rolls (10M, 20M, or 50M) is generally more cost-effective than multiple short pieces. The tubing can be cut with standard scissors or a utility knife.