Image Credit: Technical Glass Products, Inc. - OH

Glass tube and rod are hollow or solid stock shapes of fused silicate materials. They are used in laboratory, sight glass, level gage, X-ray tube, optical, lamp, pharma, vacuum tube stem assembly, and industrial process applications.

Glass tube and rod is a raw or semi-finished stock material that is used to form other components or systems. Glass gobs are softened or melted and then formed (drawn) or extruded into tube or rod shapes. Rods or tubes can have round, square or specialized shapes. Multi-bore glass tube and rod is also available.

Types of Glass Tube and Rod

There are many different types of glass tube and rod. Silica-based glass is the most common type, but specialty glasses are also available. Choices include:

• Silica
• Amber
• Neutral
• Chemically-resistant
• Highly chemical-resistant
• Corrosion-resistant
• Environmentally-stable
• Leaded
• Lead-free
• Sealing
• Soft
• Alkaline
• Artistic
• Low-melting passivation
• Ultraviolet
• Gage
• Fused silica
• Borosilicate
• Aluminosilicate

Specifications

Selecting glass tube and rod requires an analysis of physical and optical properties, thermal characteristics, and electrical and mechanical parameters. Some of these specifications include:

• Density
• Index of refraction
• Amount of light transmitted
• Maximum use temperature
• Thermal conductivity
• Coefficient of thermal expansion (CTE)
• Dielectric strength
• Dielectric constant
• Loss tangent
• Electrical resistivity
• Modulus of rupture (MOR)
• Compressive or crushing strength
• Modulus of elasticity

Glass tube and rod differ in terms of features. Most glass has an amorphous or non-crystalline structure, which means that no grain boundaries are present for corrosive or environmental attack. Glass ceramics are a special class of glasses or ceramics that start-out and are initially processed using common glass-forming techniques. Then they are crystallized to convert the material into a ceramic. Typically, such glass tube and rod is made of phosphates, borates, chalcogenides, fluorides and other networked formers.

Standards

KS L 2306 - GLASS TUBES