Inner Rubber Outside Glass Fiber Tubing
This tubing carries the two layers in the reverse order of coated-fiberglass sleeving: a silicone rubber core tube inside, a fiberglass braid outside. The rubber bore grips and cushions the line; the glass braid is the outer skin against radiant heat and mechanical wear. Rated -60℃~+200℃, non-shrink, it is positioned on hydraulic and fuel lines routed near hot surfaces: runs where the threat comes from outside the tubing, not from fluids wicking in. Send the measured line OD and the tightest bend on the route and we return the size and bend allowance.
Construction: rubber core, glass shield
The build is an extruded silicone rubber tube with a fiberglass braid applied over it, and each layer is doing a job the other cannot. The inner rubber layer is the compliant one: it grips the hose or cable so the tubing holds position, damps the vibration a hard outer wall would otherwise pass straight through, and keeps glass fibres from ever rubbing directly on the line surface. The outer fiberglass braid is the shield: glass tolerates radiant heat far beyond any rubber, and the woven structure takes sliding contact and abrasion that would scour a rubber skin away.
Why this differs from the inverse construction: the sleeving with glass inside and silicone outside is specified when fluids and dust meet the outer face; the silicone there is a sealing skin. Here the hazards are external: heat and wear. So the glass moves to the outside and the rubber takes the contact face. Same two materials, opposite exposure logic. The two pages (this one and inner fiber / outer silicone rubber sleeving) should be quoted against the drawing's hazard list, not interchangeably.
What each layer means for selection: the outer braid sets the minimum bend radius. Glass does not stretch, so a bend tighter than the tubing accepts bell-mouths the weave. The inner rubber sets the grip. The bore must match the line's measured OD, not its nominal size. And the rubber core carries the -60℃~+200℃ limit: the glass outside survives heat that the rubber inside does not, so sustained hot-surface contact defeats the construction from within.
Where Inner Rubber Outside Glass Fiber Tubing is used
Primary applications: high-temperature hydraulic line protection, hose and tube runs passing near exhausts, heating equipment and hot castings, plus fuel and lubrication lines in the same zones. It installs over assembled runs: no heat, no shrink step, no threading-before-termination constraint.
How to select: OD, ID and bend radius
- Line OD (the grip fit). Measure the actual hose or tube : the rubber bore does the holding, so size the ID to the measured OD with only working clearance. Nominal hose sizes do not survive tolerance stacking.
- Bend radius of the route. The tightest bend on the run must stay within the tubing's bend allowance; the outer braid cannot stretch around a tighter radius without opening up. State the tightest bend and we confirm it against the size.
- Heat geometry. Radiant heat and brief hot-surface contact are braid duty; sustained contact above the -60℃~+200℃ core rating is not : that needs standoff spacing or a different construction family.
- Movement in service. If the line flexes, the rubber core shears inside the braid and follows; tell us the motion and we confirm the braid flexibility grade.
Specification
| Material | Inner silicone rubber tube + outer fiberglass braid |
|---|---|
| Contact face (to line) | Silicone rubber bore : grip and cushioning |
| Outer face (to environment) | Fiberglass braid : heat shield and wear skin |
| Operating temperature | -60℃~+200℃ (rubber core governs) |
| Shrink behaviour | Non-shrink, slip-on |
Common Failure Modes & How to Prevent Them
These are the failures specific to a rubber-core / glass-outside tubing, with the root cause and the prevention for each.
The braid bell-mouthed at a tight bend
Root cause: The route bent tighter than the tubing's bend allowance. Glass braid cannot stretch like rubber, so the weave opened at the outside of the bend and the tubing lost wall integrity there.
Fix: Map the run's tightest bend before ordering and confirm it against the size's bend allowance. Where the route cannot be relaxed, split the protection into two lengths with a joint at the bend.
The tubing slid off the line section
Root cause: The ID was cut loose against the nominal hose size. The rubber bore grips by interference; with excess clearance there is no grip and vibration walks the tubing off the section it covers.
Fix: Order from the measured line OD, not nominal size, and secure both ends with a clamp or wrap over the braid. Mid-span clips on long runs keep the position true.
The core hardened beside a sustained hot surface
Root cause: The tubing was read as "glass = unlimited heat". The braid survived, but the line sat pressed against a surface above the -60℃~+200℃ core limit and the rubber inside cooked, lost elasticity and cracked.
Fix: Treat the core rating as the governing limit. Radiant heat and brief contact are braid duty; sustained hot-surface contact needs standoff spacing, a heat shield plate, or a different construction.
The braid loaded up with oil and grime
Root cause: Hydraulic mist settled into the open weave over months. A loaded braid insulates less, holds heat against the core and holds contaminants against the line.
Fix: Keep the outer braid clean, wipe at service intervals in misty zones. Where saturation is unavoidable, that zone needs a sealed-face construction instead of an open braid.
It was specified where silicone-outside was wanted
Root cause: The drawing showed a wet, dusty zone with edge-rub (the profile of the glass-inside / silicone-outside sleeving), but this tubing was quoted. The exposed braid wicked fluid and abraded on the edge; neither layer was on its intended hazard.
Fix: Match the construction to the hazard list at RFQ: external heat and wear go to this tubing; fluid sealing and outer-face wipe-down go to the inverse sleeving. Confirm the layer order line by line before order confirmation.
Frequently asked questions
Why place fiberglass on the outside instead of silicone?
Because this tubing is built for hazards that arrive from outside: radiant heat, hot-surface contact and mechanical wear. Glass fibre shrugs off heat that would cook a rubber skin, and a woven braid takes sliding contact far better than rubber. The silicone goes inside where its job is grip and cushioning, not weatherproofing. On the coated-sleeving construction the order is the other way round precisely because there the hazard list is fluid wicking and edge rub.
What does the inner rubber layer contribute?
Three things: it grips the hose or cable so the tubing does not migrate, it cushions the line against vibration transmitted through the braid, and it puts a compliant layer between a hard outer wall and the line's own surface: no glass rubs directly on the hose. It also decouples bending: the rubber core shears slightly inside the braid, which is why this tubing follows moving lines without kinking.
How should OD and ID be selected for a layered sleeve?
Work from two fits. The ID must match the line's measured OD closely. The rubber bore does the gripping, so excess clearance defeats it. The OD then follows from the braid and wall build, and it decides the minimum bend radius: the outer glass layer does not stretch, so a routed bend tighter than the tubing accepts will bell-mouth or crush the braid. Send the measured line OD, the run's tightest bend and the heat source, and we return the size and the bend allowance.
How is this tubing different from the inner-fiber / outer-silicone sleeving page?
The layer order is reversed and so is the job. That sleeving puts woven glass against the harness with silicone as the outer seal: built for harness runs where fluids and dust meet the outer face. This tubing puts rubber against the line with glass as the outer heat and wear shield: built for lines near hot surfaces. Specifying one when the drawing means the other puts the wrong material on every hazard.
What heat does the outer glass layer actually block?
Radiant heat from nearby hot surfaces and brief contact with flame or hot parts: that is braid duty. The -60℃~+200℃ rating still governs the rubber core: if the line itself runs hot, or the tubing sits in sustained contact with a surface above the rating, the core degrades regardless of the glass outside. Sustained hot-surface contact needs standoff or a different construction, not just this tubing.
How is it installed and secured on a hydraulic run?
Slip it over the line (no heat, no shrink step), and push it fully home over the section to be protected. Secure at both ends with a clamp or tape wrap over the braid so the rubber bore stays seated, and clip mid-span on long runs. Leave the braid free of paint and grease; a loaded weave loses its heat-shielding behaviour.
Request a quote for Inner Rubber Outside Glass Fiber Tubing
Send the measured line OD, the tightest bend on the route, the heat source and quantity. We return the size, the bend allowance and lead time.
Size range & specification notes
Sizes are issued against measured line ODs with a confirmed bend allowance per size; grade and test data are held in the data note above until verified.