Borosilicate glass tubes are precision-engineered, low-expansion glass products designed for demanding applications that require excellent thermal resistance, chemical durability, and optical clarity. These tubes are widely used in laboratory, industrial, and electrical heating applications. Composed primarily of silica and boron trioxide, borosilicate glass combines high mechanical strength, low thermal expansion, and exceptional resistance to chemical corrosion and temperature shocks.
| Constituent | Typical Content (% by weight) | Function |
| SiO₂ (Silica) | 78 – 81 | Main network former providing strength and thermal resistance |
| B₂O₃ (Boron Trioxide) | 12 – 13 | Improves chemical resistance and lowers expansion |
| Na₂O + K₂O (Alkalis) | 4 – 5 | Reduces melting temperature for manufacturability |
| Al₂O₃ (Alumina) | 2 – 3 | Enhances strength and scratch resistance |
| Trace Oxides (Fe₂O₃, CaO, MgO) | ≤ 0.5 | Minor modifiers to adjust color and viscosity |
| Property | Typical Value | Remarks |
| Density | 2.23 g/cm³ | At 25 °C |
| Coefficient of Linear Expansion (CTE) | 3.3 × 10⁻⁶ /K | Between 20 °C–300 °C |
| Softening Point | 820 °C | Stable for continuous use |
| Annealing Point | 560 °C | For stress relief during forming |
| Thermal Conductivity | 1.2 W/m·K | Moderate for glass materials |
| Max Working Temperature | 500 °C continuous / 550 °C intermittent | For industrial operation |
| Light Transmission | > 92% (Visible range) | Excellent optical clarity |
| Property | Value | Standard Reference |
| Modulus of Elasticity (E) | 64 GPa | ASTM D790 |
| Modulus of Rupture | 70 MPa | ASTM C158 |
| Compressive Strength | 1000 MPa | ASTM C773 |
| Poisson’s Ratio | 0.20 | — |
| Hardness (Knoop) | 480 kg/mm² | ASTM E384 |
| Tubes – outside diameter | Length | End treatment |
| 4 mm ≤ Ø < 30 mm | 1500 ± 20 mm | cut only |
| 30 mm ≤ Ø < 100 mm | 1500 ± 10 mm | trimmed and glazed or only trimmed |
| 100 mm ≤ Ø ≤ 315 mm | 1500 ± 5 mm | trimmed |
Capillary tubes and rods |
Length |
End treatment |
3 mm ≤ Ø < 7 mm |
1500 ± 20 mm |
cut only |
8 mm ≤ Ø < 17 mm |
1500 ± 10 mm |
cut only |
18 mm ≤ Ø < 30 mm |
1500 ± 30 mm |
cut only |
✔ Excellent thermal shock resistance up to 165 °C differential.
✔ High optical transparency and clarity across visible and UV spectrum.
✔ Chemically inert to acids, saline solutions, and organic solvents.
✔ Stable mechanical integrity at elevated temperatures.
✔ Non-porous, clean, and environmentally safe surface.
✔ Fire-polishable, machinable, and easily sealable.
✔ Heating Elements: Protection for thermocouples and resistance wires.
✔ Laboratory Equipment: Beakers, condensers, reactors, sight glasses.
✔ Industrial: Flow meters, gauge tubes, boiler sight glasses.
✔ Lighting: Halogen and LED lamp housings, UV protection tubes.
✔ Medical: Syringes, vials, and analytical glass components.
✔ Automotive: Enclosures for sensors and precision fluid tubes.
✔ Raw Materials: High-purity silica, boric acid, soda ash, and alumina.
✔ Melting: Continuous or tank furnaces at ~1650 °C.
✔ Forming: Danner or Vello process for precision tube drawing.
✔ Annealing: Controlled cooling at 560 °C to remove internal stresses.
✔ Finishing: Cutting, polishing, and inspection for optical and dimensional accuracy.
✔ Quality Control: ISO 3585, ASTM E438, DIN ISO 3586 compliance.
✔ Complies with ISO 3585, ASTM E438, DIN 12111 standards.
✔ RoHS & REACH compliant (lead- and arsenic-free formulations).
✔ Each batch traceable with chemical and dimensional certificates.
✔ Tubes packed in shock-resistant crates or HDPE bundles with foam separators.
✔ Ends capped to prevent breakage and contamination.
✔ Store in a dry, shaded area; avoid sudden thermal exposure.
✔ Indefinite shelf life when handled properly.
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