Dual-Wall Adhesive Heat Shrink Tubing 3:1/4:1
Dual-Wall Adhesive Heat Shrink Tubing 3:1/4:1 pairs a cross-linked PE outer wall with a hot-melt adhesive inner layer, rated to 600V for sealing joints where the object diameter changes sharply: connector backs, splices, sensor cable entries. The 3:1 and 4:1 ratios let one tube clear a bulky fitting and still close on the cable behind it, while the adhesive flows during recovery to fill gaps and block water. Service range is -45℃~+125℃ in black, built to UL224. The specification is below; send the largest and smallest diameters and we size the tube.
Specification
| Material | PE outer wall + hot-melt adhesive inner wall |
|---|---|
| Operating temperature | -45℃~+125℃ |
| Shrink ratio | 3:1 / 4:1 |
| Voltage rating | ≤600V |
| Wall type | Extra-thick dual wall |
| Colors | Black |
| Standards | UL224 |
| Size range | Ultra-high ratio, for large-dia-difference sealing |
Cross-Reference & Industry Standard Mapping
Looking to replace a competitor part number? Wellele equivalent models match or exceed key dimensions and performance standards:
| Wellele Series | Shrink Ratio | Raychem / TE | 3M Equivalent | Sumitomo | Alpha Wire | Reference Standards |
|---|---|---|---|---|---|---|
| WLL-DW-3X | 3:1 | ATUM | EPS-300 | Sumitube W3B2 | FIT-300 | UL 224, MIL-DTL-23053/4 Class 3 |
| WLL-DW-4X | 4:1 | ATUM (4:1) | EPS-400 | Sumitube SA3 | FIT-400 | UL 224 VW-1, RoHS / REACH |
| WLL-DW-HT | 3:1 (High Temp) | DSQC / SCL | MW / TFW | Sumitube W3F3 | - | SAE-AMS-DTL-23053/4 |
* Note: All competitor part numbers are registered trademarks of their respective owners and are listed for engineering reference and cross-identification only.
What it is and how it recovers
The tube is co-extruded: a radiation cross-linked PE jacket over a hot-melt adhesive liner. The jacket is expanded onto a mandrel and cooled in the expanded state; the adhesive is solid at room temperature. Under recovery heat the cross-linked PE contracts onto the part while the adhesive melts and flows into the gaps between the tube and the substrate, then sets as it cools into a seal that blocks capillary water paths. The high ratio versions recover enough to seal from a connector back down to cable diameter in one piece: which single-wall tubing cannot do, since it seals by fit alone.
Where Dual-Wall Adhesive Heat Shrink Tubing 3:1/4:1 is used
Primary applications: Large-diameter-difference joint sealing.
How to select the right size
The two diameters decide the ratio:
- Largest and smallest diameter. The expanded ID must clear the connector back; the recovered ID must close on the cable. Send both : if the spread exceeds 2:1, you need the 3:1 or 4:1 grade.
- Sealing duty. Confirm the environment is wet, buried or marine : that is what the adhesive layer is for; dry indoor runs can use single-wall.
- Recovery temperature. Plan enough heat to melt the adhesive, not just shrink the jacket : underheated dual-wall looks shrunk but has not sealed.
- Voltage. This range is rated to 600V; above that use the cable-accessory kits.
Common Failure Modes & How to Prevent Them
These are the issues most often seen when installing or specifying Dual-Wall Adhesive Heat Shrink Tubing 3:1/4:1, with the root cause and the prevention or fix for each.
The seal looked right but failed months later
Root cause: The outer polyolefin recovers around 90 C and looks done. The inner adhesive needs 110-140 C to fully melt. Stop early and the glue never flowed.
Fix: Heat until you see a bead of adhesive at both ends - that is the proof it flowed. Hold 120-140 C and keep the gun moving so the whole length activates.
The tube still turns on the wire
Root cause: Dirty surface, or a low-surface-energy insulation (silicone, PTFE) the adhesive can't bond to, or a material mismatch between the glue and the jacket.
Fix: Clean with isopropyl alcohol first. On silicone or fluoropolymer, abrade the surface or use a tube formulated for difficult substrates. Keep at least 25 mm of overlap onto clean wire insulation.
Cheap glue opened up
Root cause: Low-grade adhesive, or excessive longitudinal shrink pushing the glue out where nothing holds it.
Fix: Buy spec-grade dual-wall with a named adhesive (EVA or polyamide). After install, a continuous ring of cured adhesive at each end is the check; if it opened, re-heat, and if it opens again, the tube is the problem.
Too much heat pushed the glue away
Root cause: Overheating drives the melt beyond the joint and leaves thin coverage.
Fix: Lower the gun temperature or shorten the dwell. Some flow-out is normal and wanted; a clean bead at the ends is the target, not a puddle.
Frequently asked questions
How do I know the adhesive actually seals out water and moisture?
The inner hot-melt adhesive in Dual-Wall Adhesive Heat Shrink Tubing 3:1/4:1 softens and flows at 150–250 °C, filling voids around the conductor, crimp and jacket as the PE outer wall + hot-melt adhesive inner wall outer wall recovers. Once cooled it forms a continuous moisture barrier: a watertight seal at the splice. For a documented IP67/IP68 rating on your assembly, tell us the cable and joint type and we confirm the grade.
How do I size it when the connector is much larger than the wire?
Pick the supplied (expanded) ID at least 3:1 / 4:1× the largest object. This product's 3:1 / 4:1 ratio recovers to roughly one-third of its supplied ID, so one sleeve covers both a bare conductor and a bulky barrel. If the crimp exceeds 3× the wire, step up to 4:1; we stock 3:1 and can source 4:1.
Will it hold up under the bonnet or in marine / salt-spray environments?
The PE outer wall + hot-melt adhesive inner wall outer wall runs -45℃~+125℃ continuous and resists automotive fluids, mild solvents and salt spray once sealed. For sustained under-bonnet heat above the ceiling or fuel immersion, tell us and we steer you to a fluoropolymer or silicone-fibreglass grade.
Is it flame retardant and compliant with UL / MIL for tenders?
Built to UL224; certificates issued per batch. Flame class (e.g. VW-1) and the specific MIL class depend on grade: name your market (US / EU / Asia) and we align the documentation.
Can I use it on a soldered or crimped splice without blocking the terminal?
Slide the sleeve over the wire before making the joint, centre on the splice, then shrink. The adhesive flows outward toward the wire ends and seals the crimp, not the open terminal, so the contact face stays clear. Leave a few mm of bare conductor outside the sleeve for a terminated lead.
Can it be used outdoors or buried?
Being adhesive-lined it seals out moisture and resists tracking, suiting outdoor and damp locations; black PE also carries UV stability for exposed runs. For direct burial or permanent sun, confirm the UV/black grade with us so the wall does not embrittle.
How do I know the adhesive actually sealed?
A bead of adhesive at both ends is the proof it flowed. If you see none, the glue never melted - keep heating at 120-140 C.
Why does the tube still turn on the wire?
Dirty surface or a low-surface-energy jacket (silicone, PTFE) the adhesive can't bond to. Clean with isopropyol, abrade difficult surfaces, keep 25 mm overlap.
Cheap dual-wall opened up - why?
Low-grade or recycled adhesive, or glue pushed out by excess longitudinal shrink. Buy spec-grade and look for a continuous cured ring at each end.
Can I overheat dual-wall?
Yes - too much heat drives the melt beyond the joint. Lower the temperature or shorten the dwell; aim for a clean bead, not a puddle.
Request a quote for Dual-Wall Adhesive Heat Shrink Tubing 3:1/4:1
Send the largest and smallest diameters, wall preference, length and quantity. We return the size code, stock status and lead time.
Certifications & Compliance
Dual-Wall Adhesive Heat Shrink Tubing 3:1/4:1 is built to the following standards and directives. Certificates are supplied per batch on request.
- UL224
Tell us your target market (EU / US / Asia) and we align the documentation to your filing.
View our verified UL / SGS / RoHS certificates →
Size range & specification notes
Ultra-high shrink ratio for sealing large diameter differences.