Spiral Fiberglass Bellows Tube — Harness Conduit
A conduit, not a braid: fiberglass tape wound in a helix with adhesive-bonded overlaps forms a corrugated bellows wall. The concertina geometry bends tightly without collapsing the bore and springs back instead of taking a set. The reason this construction is chosen for routed harness runs with tight bends. Sizes 008–037 (ID Φ8–Φ37 mm), black finish, non-shrink. The -40 °C to +350 °C figure previously published for this tube is being re-verified against the actual adhesive system before it returns to the spec table.
Specification
| Material | Fiberglass spiral wrap + adhesive bond |
|---|---|
| Shrink behavior | Non-shrink spiral-wound tube |
| Wall type | Spiral corrugated (bellows) |
| Color | Black |
| Size range | Sizes 008–037; ID Φ8–Φ37 mm (full size table pending) |
| Operating temperature | -40 °C to +350 °C claim under verification |
How the spiral is built and bonded
Three construction facts matter when you specify this tube:
- Spiral winding. Fiberglass tape is wound in a helix, so every point on the wall is an overlap of the previous turn. The pitch of the wind sets how far each corrugation can open and close.
- Adhesive-bonded overlaps. The turns are glued, which is what makes the wall closed and the tube a true conduit : nothing passes through, and the bore holds its size. It also means the adhesive, not the glass, is the system's thermal weak link; that is exactly what our verification will pin down.
- Fixed bore. Unlike a braid, the bore does not expand. Dress the harness accordingly: either thread components before sleeving or size the bore for the largest object that must pass.
Bend accommodation, kink resistance, vibration
On a bend, the corrugated wall does what a smooth tube cannot: corrugations compress inside the curve and stretch outside, so the bore stays open at radii that would collapse a smooth wall. Along a straight run under vibration, the same geometry absorbs small movements instead of passing them to the bundle. Both behaviours are properties of the bellows form: no heat, no recovery, no adjustment in service. For routing: check the minimum bend radius against the size (the size table in preparation will state it), and support long runs with clips so the tube's own weight does not work on the bonded seams.
Where it is used
Primary documented application: automotive and NEV battery wire harness runs. Segments between pack and body where routing is fixed, bends are frequent, and the zone runs hot. The application statement here covers the routing duty; any specific OEM test-standard compliance (LV-series or customer specs) is part of the pending verification and is confirmed per order, not assumed.
Common failure modes, and prevention
Bore collapsed at a too-tight bend
Cause: The routing forced a radius below what that size's corrugation pitch accepts.
Prevention: Match the bend radius in the drawing against the size table; where the route is fixed and tight, step one size up so the corrugations have room to work.
Overlap seams opened near a heat source
Cause: Local surface temperature above what the adhesive system tolerates: even if the glass is comfortable.
Prevention: Measure the worst-point temperature on the actual route. Until this is confirmed, confirm suitability with us against the real build instead of assuming the published range.
Harness scuffed during pull-through
Cause: Bore sized too close to the bundle, so the harness dragged on the spiral wall during assembly.
Prevention: Add assembly clearance and dress the harness ends; on long runs, pull with a leader, not the connector.
Tube rubbed through at a bracket edge
Cause: The route let the tube bear on a hard edge under vibration.
Prevention: Add an edge guard or clip liner at the contact point and secure the run so the contact does not move.
Frequently asked questions
What does the spiral bellows geometry do?
The tube is wound from fiberglass tape in a helix with adhesive-bonded overlaps, so the wall is corrugated like a concertina. That geometry does two jobs at once: at a bend, the corrugations compress on the inside of the curve and open on the outside, so the bore keeps its shape instead of kinking flat; along the run, the same corrugation lets the tube flex a little under vibration instead of transmitting every movement to the harness inside. The bellows form is about bend accommodation and vibration, not about added thermal performance.
How should ID be selected for a routed harness?
Size on the largest object that must travel through the tube. Connectors and splices if the harness is dressed after sleeving, the bundle OD if it is sleeved first. Then add assembly clearance: a bore that is exactly bundle-sized will scuff every time the harness is pulled through, and a bore far above the bundle size lets the harness rub side to side inside the tube. Sizes 008–037 cover an 8–37 mm bore; the full size code table with wall build is being prepared from the master workbook, so confirm the exact code with us at order stage.
What is the limiting temperature: fiberglass, adhesive, or the complete tube?
In a bonded spiral tube the adhesive is the likely limiting element, not the glass: fiberglass itself tolerates temperatures far above what a bonded overlap system may accept, so the rating of the complete tube is set by the adhesive system and how it was qualified. The -40 °C to +350 °C figure attached to this product is currently being verified against the actual adhesive system; until that confirmation, treat any published number as unproven and tell us your zone temperature so we can answer against the real build.
How is the tube cut and finished on the harness?
Cut square with a fine abrasive wheel or sharp shears; the bonded spiral holds together far better than a braid, but the cut line can shed glass slivers, so gloves are standard practice. Where the cut end sits near a connector or clamp, bind the last corrugation with tape or a tie so the end cannot creep. Unlike a braid there is no weave to unravel. The failure to prevent is fiber itch and slivers, not fraying.
Where does this product sit versus braided fiberglass sleeves?
Different geometry, different strengths. The bellows tube gives a closed, fixed-bore conduit: it keeps its diameter at bends, shields the bundle along a defined route, and does not change fit when handled. A braid expands over connectors and grips the run, which suits irregular shapes and retrofit. Choose the bellows tube for defined routed runs with bends; choose braid where the sleeve must pass lumps and conform. For radiant-facing work, a foil-faced construction adds reflection this product does not claim.
Request a quote for Spiral Fiberglass Bellows Tube
Send the harness OD with its largest component, the routing (bend radii, heat-source location and temperature) and quantity. We return the size code, the verification status of the temperature figure for your zone, and lead time.