Dennis High-Density Thermal Insulation Sleeve
Dennis High-Density Thermal Insulation Sleeve is built from High-density fiberglass braid + vermiculite coating. It is a non-shrink sleeve you slip over the part; it stays in place by fit and friction, with no heating step. On the shelf it is held to working range -60℃~+550℃. Buyers spec it for High-temp pipe insulation, engine-bay, industrial furnace — the typical call is a sized part that stays put through vibration, thermal cycling and field handling. Below is the spec table, the size matrix we keep in stock, and the selection notes our engineering team uses when a purchaser sends a cable or component drawing.
Specification
| Material | High-density fiberglass braid + vermiculite coating |
|---|---|
| Operating temperature | -60℃~+550℃ |
| Shrink ratio | Non-shrink (braid) |
| Wall type | Thick-wall braid |
| Colors | Brown |
| Standards | UL94 V0 |
| Size range | ID Φ6~Φ75mm; continuous 550°C; fire/heat barrier |
What it is and how it recovers
Dennis High-Density Thermal Insulation Sleeve is a braided or wrapped sleeve that goes on by sliding. It holds by friction and the spring of the weave, so there is no recovery step and no heat. Because the body is High-density fiberglass braid + vermiculite coating, it keeps its insulation and protection through handling and thermal cycling. For procurement this matters: the part you receive is reusable on the bench, but once installed it stays put for the life of the assembly.
Where Dennis High-Density Thermal Insulation Sleeve is used
Primary applications: High-temp pipe insulation, engine-bay, industrial furnace.
How to select the right size
Specifying Dennis High-Density Thermal Insulation Sleeve is mostly about matching three numbers to the part you are covering:
- Recovered vs. supplied diameter. Pick the supplied (expanded) ID at least Non-shrink (braid)× the object's largest diameter so the sleeve slides on, then confirm the recovered ID grips it. When in doubt, size up one step rather than forcing a tight fit.
- Temperature class. The continuous range is -60℃~+550℃. If the assembly sees brief excursions beyond that, tell us — we will flag a high-temp grade instead of letting the wall soften in service.
- Wall and adhesive. Thin wall for tight harness bundles; medium/thick wall or adhesive-lined (dual-wall) where you need environmental sealing or abrasion resistance. We keep both in stock.
Common Failure Modes & How to Prevent Them
Drawing on field reports and our engineering team's experience, these are the most common issues installers and buyers report when working with Dennis High-Density Thermal Insulation Sleeve. Each entry shows the symptom, the root cause, and the fix we recommend on the bench and in the field.
It wore through at a sharp corner
An automotive note: "mounted at sharp edges in the engine bay, constant friction - cracking in a short time."
Root cause: A thin, uncoated braid has little abrasion resistance and vibration rubs it through.
Fix: Use a silicone-coated or double-layer braided sleeve, route it clear of edges, and clip it down. For hot zones, vermiculite-coated glass fibre takes molten splash that plain braid won't.
Molten splash burned a hole
A plant reported: "a spark of molten metal went straight through the sleeve."
Root cause: Plain glass fibre without a high-temp coating fails under molten splash.
Fix: Use a vermiculite-coated or high-density sleeve (the Dennis-type thermal sleeve) where weld splatter or molten metal is present. That coating is what stops the burn-through.
The cut end unravelled
"We cut it and the braid opened up along the harness."
Root cause: Braided glass fibre has no self-edge; a cut end frays.
Fix: Cut with a hot knife or melt-seal the end, or use a pre-expanded, bound-end sleeve. A sealed end stays put through vibration.
The rating on the box didn't match the job
A buyer found: "the silicone coat is rated lower than the base glass, so the sleeve isn't as hot as I thought."
Root cause: The coating, not the glass, often sets the working limit; base glass can take ~500 C but the coating lowers it.
Fix: Read the coated rating, not the fibre rating. Size the sleeve to the actual surface temperature plus margin, and pair it with primary insulation where voltage is present.
It is not the insulation
"I treated the sleeve as the insulation and the tester failed."
Root cause: A textile or braided sleeve is mechanical protection, not a primary dielectric.
Fix: Keep the wire's own insulation intact and use the sleeve for heat and abrasion on top. Don't rely on a sleeve alone for low- or high-voltage isolation.
Kapton is brilliant but edge-fragile
"Polyimide-fiberglass is great until the edge nicks."
Root cause: Polyimide film cuts cleanly but a nick can propagate.
Fix: Use polyimide-fiberglass where its temperature and dielectric shine, and protect the cut edges. It earns its cost in tight, hot, high-dielectric spots.
Common Failure Modes & How to Prevent Them
Drawing on field reports and our engineering team's experience, these are the most common issues installers and buyers report when working with Dennis High-Density Thermal Insulation Sleeve. Each entry shows the symptom, the root cause, and the fix we recommend on the bench and in the field.
It wore through at a sharp corner
An automotive note: "mounted at sharp edges in the engine bay, constant friction - cracking in a short time."
Root cause: A thin, uncoated braid has little abrasion resistance and vibration rubs it through.
Fix: Use a silicone-coated or double-layer braided sleeve, route it clear of edges, and clip it down. For hot zones, vermiculite-coated glass fibre takes molten splash that plain braid won't.
Molten splash burned a hole
A plant reported: "a spark of molten metal went straight through the sleeve."
Root cause: Plain glass fibre without a high-temp coating fails under molten splash.
Fix: Use a vermiculite-coated or high-density sleeve (the Dennis-type thermal sleeve) where weld splatter or molten metal is present. That coating is what stops the burn-through.
The cut end unravelled
"We cut it and the braid opened up along the harness."
Root cause: Braided glass fibre has no self-edge; a cut end frays.
Fix: Cut with a hot knife or melt-seal the end, or use a pre-expanded, bound-end sleeve. A sealed end stays put through vibration.
The rating on the box didn't match the job
A buyer found: "the silicone coat is rated lower than the base glass, so the sleeve isn't as hot as I thought."
Root cause: The coating, not the glass, often sets the working limit; base glass can take ~500 C but the coating lowers it.
Fix: Read the coated rating, not the fibre rating. Size the sleeve to the actual surface temperature plus margin, and pair it with primary insulation where voltage is present.
It is not the insulation
"I treated the sleeve as the insulation and the tester failed."
Root cause: A textile or braided sleeve is mechanical protection, not a primary dielectric.
Fix: Keep the wire's own insulation intact and use the sleeve for heat and abrasion on top. Don't rely on a sleeve alone for low- or high-voltage isolation.
Kapton is brilliant but edge-fragile
"Polyimide-fiberglass is great until the edge nicks."
Root cause: Polyimide film cuts cleanly but a nick can propagate.
Fix: Use polyimide-fiberglass where its temperature and dielectric shine, and protect the cut edges. It earns its cost in tight, hot, high-dielectric spots.
Frequently asked questions
What is this sleeve for — bundling, abrasion or both?
Dennis High-Density Thermal Insulation Sleeve (High-density fiberglass braid + vermiculite coating) is a flexible protective sleeve for wire harnesses and hose bundles: it tames rat's-nests, hides mismatched wires and adds a cut/abration layer without stiffening the loom.
Expandable or wrap — which do I need?
Expandable braid slides over a pre-assembled harness (no unplugging); wrap/velcro styles open along the length for mid-run additions. Tell us whether you fit it before or after termination.
What temperature can it take (-60℃~+550℃)?
Continuous service is -60℃~+550℃. For engine-bay or exhaust-zone heat, step up to a fiberglass/silicone construction — we keep both.
How is it better than heat-shrink for a harness?
Heat shrink must be threaded on before connectors are fitted and stiffens the run; a sleeve installs afterwards, stays flexible and covers long runs cheaply. Heat shrink is better only where you need a sealed, tight-moulded fit.
Can I get custom cut length and colour?
Yes — custom lengths, colours (including high-vis and zip/velcro closures) are standard for production. Send the bundle OD and run length and we quote.
Does it meet flammability or industry specs?
We supply grades with the relevant flame/smoke ratings on request; tell us the standard your program requires and we match it.
Will a plain glass sleeve take molten splash?
No - use a vermiculite-coated or high-density sleeve where weld splatter or molten metal is present.
How do I stop the cut end fraying?
Cut with a hot knife or melt-seal the end, or use a bound-end pre-expanded sleeve.
Is the sleeve the insulation?
No - it is mechanical and heat protection. Keep the wire's own insulation and add heat shrink at joints for isolation.
What temperature can it take?
Read the coated rating, not the glass rating. The coating usually sets the working limit.
Request a quote for Dennis High-Density Thermal Insulation Sleeve
Tell us the inner diameter, wall type, length and quantity you need, plus the voltage class and environment. We return a sized part number, stock status and lead time — no price guessing, no minimum-order surprises.
Certifications & Compliance
Dennis High-Density Thermal Insulation Sleeve is built to the following standards and directives. Certificates are supplied per batch on request.
- UL94 V0
Tell us your target market (EU / US / Asia) and we align the documentation to your filing.
Size range & specification notes
内径Φ6~Φ75mm；连续耐温550℃；防火隔热