
Product
Heavy Wall Gauge Glass Tube
Heavy Wall Gauge Glass Tube is a thick-walled borosilicate tube designed for direct liquid-level and flow observation in higher-pressure industrial service.
Technical Specifications
| Glass Material | Borosilicate Glass 3.3 |
|---|---|
| Linear Expansion Coefficient | 3.3 × 10⁻⁶ K⁻¹ at 20–300°C |
| Softening Point | Approx. 821°C |
| Annealing Point | Approx. 565°C |
| Maximum Reference Pressure | Up to 600 psi / 41 bar* |
| Reference Rating Temperature | Up to 150°F / 66°C* |
- Higher Pressure Capacity
- The thicker glass wall provides greater resistance to internal pressure than standard-wall gauge tubing. Selected sizes and lengths may be rated up to 600 psi under defined operating conditions.
- Clear Direct Observation
Gauge Glass Tubes
Product Description
Heavy Wall Gauge Glass Tube is manufactured from heat-resistant borosilicate glass with a substantially thicker wall than standard tubular gauge glass. It is installed in compatible liquid-level gauges, flowmeters and sight-flow assemblies to provide direct, power-free observation of liquids or gases.
The increased wall thickness improves the tube’s resistance to internal pressure and mechanical stress. Reference heavy-wall configurations can withstand pressures of up to 600 psi (approximately 41 bar) at temperatures up to 150°F (66°C). However, the allowable pressure decreases as tube length and operating temperature increase. The final rating must therefore be determined according to the tube’s outside diameter, wall thickness, length, end finish, medium and gauge assembly design.
Borosilicate glass 3.3 has a low linear thermal expansion coefficient of approximately 3.3 × 10⁻⁶ K⁻¹ between 20°C and 300°C. It also provides high resistance to water, most acids, salt solutions, halogens and organic solvents. These properties make the tube suitable for water tanks, oil reservoirs, flowmeters, process vessels and selected boiler applications.
Clear tubes are supplied for an unobstructed view of the process medium. A red-line heavy-wall version can also be produced when enhanced liquid-level visibility is required.

Key Features and Advantages
Higher Pressure Capacity
The thicker glass wall provides greater resistance to internal pressure than standard-wall gauge tubing. Selected sizes and lengths may be rated up to 600 psi under defined operating conditions.
Clear Direct Observation
High optical clarity allows operators to observe the liquid level, flow condition, color, contamination and phase boundary without electrical instruments.
Low Thermal Expansion
The approximate expansion coefficient of 3.3 × 10⁻⁶ K⁻¹ reduces thermal stress compared with ordinary soda-lime glass.
Chemical Resistance
Borosilicate glass resists water, most acids, saline solutions and many organic fluids. It is not recommended for hydrofluoric acid, hot concentrated phosphoric acid or strong hot alkaline solutions.
Custom Manufacturing
Outside diameter, inside diameter, wall thickness, tube length and end finish can be manufactured according to the customer’s gauge assembly.
Multiple End Finishes
Tube ends can be saw-cut, precision-ground or fire-polished, depending on sealing and installation requirements.
Technical Specifications
Sizes
Heavy Wall Gauge Glass Tubes Typical configurations include:
5/8-inch OD tube with a 3/16-inch (4.8 mm) wall,
3/4-inch OD tube with a 7/32-inch (5.6 mm) wall,
1-inch OD tube with a wall thickness from 1/4 to 5/16 inch (6.4–7.9 mm).
Common lengths include 8, 10, 12, 14, 16, 18, 20, 24, 30, 36 and 48 inches.
Custom diameters, wall thicknesses and cut lengths are available upon request.
CUSTOM MANUFACTURING
Need a Custom Size or Specification?
Send your drawing, sample, dimensions, material requirements, operating temperature, pressure and process medium. We will review the application and confirm the suitable product specification before production.
Standard products and OEM/ODM solutions available.
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- Product name or drawing/sample
- Required dimensions and quantity
- Material or applicable standard
- Operating temperature and pressure
- Process medium and installation details
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