G11 Tube — IDs, ODs, Wall Thicknesses & Lengths
G11 tube is hollow cylindrical stock produced from NEMA G-11 glass-reinforced epoxy laminate, wound or compression-molded from woven fiberglass and high-temperature epoxy resin. Operating continuously to 180 °C (355 °F) with tensile strength of 63,000 psi, G11 tube provides the structural and dielectric performance needed for coil forms, insulating sleeves, conduit runs through high-temperature enclosures, and bearing liners where epoxy-glass durability at elevated temperatures is required.
At a glance:
- Wall thickness range: 0.062" to 0.500"+ (ID/OD combinations vary)
- Standard lengths: 12" to 48" nominal; longer cuts available
- Wall tolerance: ±0.010" typical
- Material: NEMA G-11, glass-fabric/epoxy thermoset
- Production method: Filament-wound or compression-molded tube
- Color: Natural yellow-green
Standard Tube Size Table
G11 tube is stocked in common ID/OD combinations at Ready Plastics:
| ID | OD | Wall | Standard Length | Notes |
|---|---|---|---|---|
| 0.500" | 0.750" | 0.125" | 24" & 48" | Insulating sleeve |
| 0.750" | 1.000" | 0.125" | 24" & 48" | |
| 1.000" | 1.375" | 0.187" | 24" & 48" | Coil form blank |
| 1.250" | 1.625" | 0.187" | 24" & 48" | |
| 1.500" | 2.000" | 0.250" | 24" & 48" | Conduit/sleeve |
| 2.000" | 2.500" | 0.250" | 24" & 48" | |
| 2.500" | 3.000" | 0.250" | 24" | Structural sleeve |
| 3.000" | 3.750" | 0.375" | 24" | Larger bore bearing liner |
Custom ID/OD combinations and non-standard wall thicknesses are available on request.
Mechanical & Electrical Properties
| Property | Value |
|---|---|
| Tensile strength | 63,000 psi (430 MPa) |
| Flexural strength (LW, 0.125") | 75,000 psi (515 MPa) |
| Compressive strength | 37,000 psi (255 MPa) |
| Shear strength | 22,000 psi (150 MPa) |
| Bond strength | 2,200 psi (15 MPa) |
| Hardness (Rockwell M) | 112 |
| Izod impact strength (49 °C, LW) | 12.00 ft·lb/in |
| Specific gravity | 1.82 |
| Water absorption (24 hr) | 0.20% |
| Flammability rating | UL 94HB |
| Maximum continuous service temp | 180 °C (355 °F) |
Typical Applications
G11 tube is used wherever a hollow insulating form must survive elevated temperatures:
- Coil forms and bobbin blanks — dimensionally stable under winding tension and heat cycling
- Insulating sleeves and conduit — protects conductors passing through high-temperature zones in switchgear or motor housings
- Bearing liners and journal bearings — compressive strength resists radial loads; low moisture absorption maintains fit
- Structural spacer tubes in power assemblies — substitutes for metal tubes where electrical isolation is required
- High-voltage test fixtures and probe guides
- Transformer bobbin cores — compatible with varnish impregnation processes
Machining G11 Tube
G11 tube can be cut to length on a band saw or chop saw with carbide blades. For tight-tolerance facing and ID/OD turning, a lathe with carbide inserts at moderate surface speeds produces clean finishes with minimal delamination. Drilling and tapping through the wall is straightforward with sharp carbide drills; use a backing block when breaking through to prevent edge breakout. Bonding flanges or fittings to tube ends is readily accomplished with structural epoxy adhesive. Avoid excessive heat input during extended machining operations to preserve resin integrity at the cut surface.
Related
- G11 Glass Epoxy — Line Card
- G11 Rod — solid round bar for machined standoffs and insulators
- G11 Sheet — flat stock for panels, barriers, and slot liners
- G10 Tube — standard-temperature glass-epoxy tube for moderate-temperature service
- FR5 Tube — flame-retardant epoxy-glass tube, same thermal class