Silicone Coated Fiberglass Sleeving
A braided fiberglass sleeve with the silicone rubber coating applied on the outside — glass textile for structure and flexibility, rubber face for sealing and wear. Non-shrink, slip-on, rated -60℃~+200℃ for motor leads and high-temperature harness runs. What each layer does is fixed by the construction: the braid carries load and resists cut-through, the coating stops fluid wicking and fraying. UL1441 recognition scope and dielectric values are pending batch documentation (data note below); send the lead OD and environment and we return the size.
Construction: braid outside-in
The wall is a woven fiberglass braid that has been passed through silicone rubber and cured, leaving the rubber bonded into the braid interstices as a continuous outer face. Layer by layer, the jobs divide like this:
- The fiberglass braid — structure and flexibility. The woven glass carries the mechanical load, holds the bore round, resists cut-through from edges and vibration, and lets the wall flex with the harness. Glass itself tolerates temperature far above any rubber; in this construction it is the backbone, not the limiting layer.
- The silicone coating — the sealing and wear face. On the outside the rubber does three jobs: it stops oil and moisture wicking along the glass fibres, it locks the braid into a continuous film so cut ends do not fray, and it takes the surface rubbing of routing through enclosures.
- Consequence for temperature. The working limit of the coated sleeve is set by the rubber face, not the glass. That is why the rating is read off the coated construction — see the specification and the data note.
- Consequence for electrical use. Glass braid composite is used around live conductors, but the voltage behaviour of the sleeve belongs to the ordered grade and its test data. Until that documentation is supplied, this page claims no dielectric value and the conductor's own insulation stays the primary dielectric.
For contrast: the range also covers the inverse construction — silicone rubber on the inside, fiberglass braid outside — which behaves differently in abrasion and flexibility trade-offs. That product has its own page (inner fiber / outer silicone rubber sleeving); the two are not interchangeable specs.
Where Silicone Coated Fiberglass Sleeving is used
Primary applications: motor lead and winding exit protection, high-temperature harness runs near engines and heating equipment, and any routed loom where fluid contact and edge abrasion are combined with elevated temperature. It installs over assembled looms because nothing shrinks — push it on and clip it.
How to select: diameter, grade, documentation
- ID versus lead OD. Size the bore close to the conductor-insulation OD of the lead: tight enough to hold position under vibration, loose enough to push on without tearing the coating at the mouth.
- Temperature zone. Read the surface temperature where the sleeve sits, continuous and peak, against the -60℃~+200℃ coated rating. Hotter zones need a different construction, not a heavier wall of this one.
- Fluid exposure. Oil, coolant and solvent contact go to the coating grade — state the fluid and we confirm the rubber against it.
- Coating thickness and wall data. Coating thickness per size and the size table (ID / wall per code) are part of the pending documentation listed below.
- Documentation. If a filing or bid needs UL documentation, tell us the market; the recognition scope is confirmed with the batch paperwork once verified.
Specification
| Material | Fiberglass braid + external silicone coating |
|---|---|
| Construction | Coating on the outer surface; braid is the structural wall |
| Operating temperature | -60℃~+200℃ (coated construction) |
| Shrink behaviour | Non-shrink, slip-on |
| Installation | Push-over assembled looms; clip at intervals |
Cross-Reference & Industry Standard Mapping
Insulation fiberglass & silicone sleeving cross-reference chart for high temperature motor & transformer leads:
| Wellele Series | Coating & Structure | Bentley-Harris | Federal-Mogul | Suflex | Reference Standards |
|---|---|---|---|---|---|
| WLL-FG-SIL | Silicone Coated Fiberglass | Ben-Har 1151 XL | Acryl-Flex / Pyro-Jacket | Silicone Sleeving 7000 | UL 1441 (VW-1), IEC 60684-3-400 |
| WLL-FG-ACR | Acrylic Coated Fiberglass | Ben-Har Acryl-10 | Pyrotube | Acrylex | NEMA TF-1 Type 6 |
* Note: All competitor part numbers are registered trademarks of their respective owners and are listed for engineering reference and cross-identification only.
Common Failure Modes & How to Prevent Them
These are the failures specific to an outer-coated fiberglass braid sleeve, with the root cause and the prevention for each.
The coating wore through at a routing edge
Root cause: The rubber face is the wear layer. Where the sleeve bears hard against a sheet-metal edge or a casting line, the coating thins first, and once it is through, the exposed glass braid frays and loses the fluid seal.
Fix: Route clear of edges where possible, add an edge grommet or an abrasion guard at unavoidable contact points, and clip the run so vibration does not drive the sleeve into the edge.
The wall was cut pushing it onto a sharp bundle
Root cause: Installation damage — the sleeve mouth snagged a connector pin or a burred clip while being pushed on, tearing the coating before the sleeve ever saw service.
Fix: Push from the mouth with a blunted guide, trim sharp features first, and inspect the coating at both ends after install. A torn mouth keeps tearing under vibration.
Fluids attacked the rubber face
Root cause: The coating grade was not matched to the fluid in the zone — a silicone face that shrugs off one coolant can swell in another fluid, and the sealed wall turns tacky or cracks.
Fix: Name every fluid the run touches at enquiry stage. Grade confirmation against the fluid list is part of order confirmation, not an afterthought.
It was speced from the glass rating, not the coated rating
Root cause: Bare fiberglass tolerates several hundred degrees, so the sleeve was placed against a heat source far above what the silicone face accepts. The glass survived; the rubber face cooked, hardened and cracked.
Fix: Always read the -60℃~+200℃ coated-construction limit against the actual surface temperature. Beyond that range, move to a high-temperature uncoated or mineral-coated construction — that is a different product family.
Dielectric duty was assumed from the datasheet category
Root cause: The sleeve was treated as primary insulation because it is used near live parts. Construction and test data are different things: without the grade's dielectric test values, the voltage behaviour is unverified.
Fix: Keep the conductor's own insulation as the primary dielectric and treat this sleeve as heat, fluid and abrasion protection. If a voltage classification is required for the job, it must come from the pending test documentation — request it before the design is frozen.
Frequently asked questions
What does the silicone coating add to the fiberglass braid?
Three things the bare braid cannot do: it seals the wall so oil and moisture do not wick along the glass fibres, it keeps cut ends from fraying because the coating bonds the braid into a continuous film, and it adds surface toughness for routing through enclosures. The braid contributes the structure, the temperature backbone and the flexibility; the coating is the sealing and wear face.
How is this different from silicone tubing?
Silicone tubing is rubber through the whole wall; this sleeve is a glass textile carrying a much thinner rubber face. The practical differences: the fiberglass wall holds shape and resists cut-through better than an all-rubber wall of the same diameter, while the all-rubber tube seals and grips better. Where abrasion from routing is the main hazard, the coated braid usually wins; where a soft sealing wall matters, the tubing does.
Which diameter and coating grade should be specified?
Spec the ID against the conductor-insulation OD of the lead being covered — close enough to hold position, loose enough to push on without wall damage. Then state the fluid contact (oil, coolant, solvent) and the temperature zone, because the coating grade is confirmed against the fluid. Send the lead OD, environment and quantity and we return the size code and grade.
Is the dielectric strength of this sleeve a rated value?
It is not published on this page. Glass-braid construction is used in electrical applications, and a dielectric classification per the ordered grade is exactly what the pending documentation covers — until the batch test data is supplied, no voltage value is claimed here. Keep the conductor's own insulation as the primary dielectric and treat this sleeve as heat, fluid and abrasion protection over it.
How does it install without taking the harness apart?
It is a slip-on sleeving with no shrink step: push it over connectors and assembled looms as routed. That is the practical advantage over heat-shrink tubing, which must be threaded on before termination. Secure long runs with clips at intervals so the sleeve does not migrate under vibration.
What does the -60℃~+200℃ rating describe?
The rating belongs to the coated construction, not to the glass fibre alone. Bare glass tolerates far higher temperature than any rubber, so once silicone is on the surface the rubber face sets the limit. Size against the actual surface temperature at the sleeve location, and if a zone exceeds the rating the answer is a different construction, not a thicker wall of this one.
Request a quote for Silicone Coated Fiberglass Sleeving
Send the lead OD, the temperature zone and every fluid the run touches, plus quantity. We return the size code, the confirmed coating grade and lead time.
Certifications & Compliance
UL1441 recognition scope for this sleeving is being confirmed with batch documentation; details are held in the data note above until verified. Certificates for the ordered grade are issued per batch on request. 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
Slip-on ID range per the size table; coating thickness per size is part of the pending documentation above.