Borosilicate Glass & Borosilicate Glassware

Borosilicate Glass 3.3

We fabricate precision-engineered glass components using premium raw materials sourced from globally recognized manufacturers, ensuring superior quality and performance. Upon request, we also manufacture components using leading European Borosilicate Glass 3.3 tubing that complies with DIN ISO 3585 and ASTM E438 Type I, Class A standards—delivering exceptional dimensional accuracy, outstanding chemical resistance, and superior optical clarity comparable to the world’s foremost producers.

Borosilicate Glass 3.3 is the most reliable and standardized material for constructing plant equipment and pipeline systems across the chemical, dyestuff, food processing, pharmaceutical, and petrochemical industries. Its expanding global adoption is driven by significant advantages over conventional materials, including high thermal shock resistance, excellent corrosion resistance, mechanical strength, and long service life—making it the ideal choice for demanding industrial applications.

Key Features & Advantages

Outstanding corrosion resistance against acids, alkalis, and chemical solvents
Excellent thermal shock resistance with low thermal expansion
Smooth, pore-free surface preventing contamination and residue buildup
High transparency for easy process monitoring
Catalytically inert – does not interfere with chemical reactions
No impact on taste or odor of processed materials
Physiologically inert and non-toxic
Long service life with minimal maintenance

Borosilicate glass is widely preferred in industrial applications due to its exceptional chemical durability and thermal stability. It is engineered using a carefully controlled composition of high-purity oxides, primarily Silica (SiO₂) and Boron Oxide (B₂O₃), along with selected modifiers that enhance strength, resistance, and performance under demanding conditions.

The chemical and physical characteristics of borosilicate glass are directly influenced by its precise composition, making it highly reliable for process industries, laboratories, and chemical handling systems.

Chemical Composition

The composition of borosilicate glass used for chemical plants has the following approximate composition:

SiO₂ (Silicon Dioxide) – 80.6%	B₂ O₂ (Boron Trioxide) – 12.5%
Na₂O (Sodium Oxide) – 4.2%	Al₂O₃ (Aluminium Oxide) – 2.2%

Borosilicate glass is an oxide glass primarily composed of silica and boron trioxide, with smaller amounts of alkali and alumina. This specific composition provides excellent chemical resistance, thermal stability, and mechanical strength, making it ideal for chemical process equipment, reactors, pipelines, and storage vessels.

Resistance to Chemicals

Borosilicate glass is highly resistant to most chemicals and remains inert when exposed to the majority of acids, alkalis, and organic substances. However, it is not resistant to hydrofluoric acid (HF), phosphoric acid (H₃PO₄), and hot, concentrated caustic solutions. Among these, hydrofluoric acid has the most severe effect and can attack borosilicate glass even at very low concentrations measured in parts per million (PPM).

Phosphoric acid and caustic solutions generally do not affect borosilicate glass at ambient temperatures. However, at elevated temperatures, corrosion may occur depending on concentration and operating conditions. Caustic solutions with concentrations up to 30% can typically be handled safely at normal room temperature.

Under actual process conditions, factors such as temperature, turbulence, pressure, and the presence of trace contaminants can influence the rate of chemical attack. Therefore, exact corrosion rates for caustic solutions cannot be universally defined and should be evaluated based on specific operating environments.

Thermal Properties

Linear Coefficient of Thermal Expansion

The coefficient of thermal expansion of borosilicate glass within the temperature range of 0–300°C is 3.3 × 10⁻⁶/°C. This exceptionally low expansion rate, compared to conventional glasses and metals, ensures excellent dimensional stability under temperature variations. Due to this characteristic, borosilicate glass is widely recognized as low-expansion borosilicate glass, making it ideal for applications involving thermal cycling and high temperature resistance.

Specific Heat

The average specific heat of borosilicate glass between 25°C and 300°C is approximately 0.233 Kcal/kg·°C. This property enables the material to absorb and retain heat efficiently while maintaining structural integrity, making it suitable for thermal processing and industrial applications.

Thermal Conductivity

Borosilicate glass has a thermal conductivity of approximately 1.0 Kcal/hr·m·°C within the permissible operating temperature range. This ensures uniform heat distribution and minimizes the risk of thermal stress, contributing to reliable performance in high-temperature environments.

Annealing

Annealing is a controlled heat treatment process in which the glass is heated to a specific temperature and held for a defined period to relieve internal stresses developed during manufacturing.

This is followed by gradual and carefully controlled cooling to prevent the formation of new stresses. Proper annealing enhances the mechanical strength, durability, and long-term performance of borosilicate glass.

Reshapeing

The following graph depicts the typical temperatures corresponding to specific viscosity levels required for reshaping borosilicate glass:

Lower cooling temperature	10²⁴ poise	515°C
Upper cooling temperature	10¹³ poise	565°C
Softening point	10⁷ poise	795°C
Reshapeing point	10⁴ poise	120° C

This data represents the standard thermal behavior of borosilicate glass during controlled heating and reshaping processes, ensuring precision and structural integrity.

Mechanical Properties of Borosilicate Glass

The lack of of ductility in glass reduces stress equalization at local abnormalities or faults, therefore the breakage strength varies significantly around a mean value. This latter occurs with a tensile strength of about 700 kg/cm2.

To account for the dispersion of breaking stress, a significant safety factor is utilized when estimating the wall thickness required to allow operation up to the working pressure values listed in the table.

Optical Properties of Borosilicate Glass

Borosilicate glass has no apparent resistance in the visible portion of the spectrum, therefore it appears clean and colorless. In photochemical processes, ultraviolet transparency is particularly important.

According to the transmittance of material in the ultraviolet area, photochemical reactions such as chlorination and sulpho chlorination can take place there.

Permissible Operating Conditions For Borosilicate Glass

The permitted internal operating pressure is determined by the nominal diameter of the glass components and the working temperature.

In the case of a unit having many combinations, such as vessels, filters, or heat exchangers, the overall permitted internal gauge pressure is always determined by the components with the lowest permissible operating gauge pressure. All components are acceptable for use in complete vacuum.

Bar is a unit of absolute pressure. The value for maximum recommended working pressure represents pressure above atmospheric.

Working Temperature

Borosilicate glass preserves its mechanical strength and will only deform when temperatures approach its strain point.

The practical upper limit for operating temperature is much lower, and it is controlled by temperature differentials in the glass, which are dependent on the relative temperature differentials in the glass, which are dependent on the relative temperature of the equipment's contents and the external surroundings.

Borosilicate glass can be safely used at temperatures up to 250 °C as long as it is not subjected to abrupt temperature changes that cause thermal shock.

It should be noted that in entire plants made not only of borosilicate glass, but also of other materials such as PTFE, the recommended max.

The operating temperature is 200°C. Operating temperatures may need to be adjusted to account for the impacts of other parameters such as pressure, thermal cycling, rapid heating and cooling, etc.

The degree of thermal shock (typically described as abrupt freezing or heating) that it can withstand is determined by a variety of parameters, including operating circumstances, forces imposed while supporting the equipment, and glass wall thickness.

It is therefore undesirable to introduce abrupt temperature fluctuations. However, temperatures up to 120 °C can be accommodated.

The tensile strength of borosilicate glass increases at sub-zero temperatures, allowing equipment to be utilized safely at temperatures as low as -50 °C for XTRONG and components.

Composite Material

Over the previous two decades, new or improved corrosion-resistant plant construction materials have been developed. PTFE, tantalum, titanium, graphite, and, of course, Borosilicate 3.3 glass are all common examples.

The use of various corrosion-resistant materials, as well as the individual benefits of each, allows for both safe and cost-effective construction.

Borosilicate Glass/PTFE

Borosilicate glass with PTFE is very important for the building of glass installations, for example. In seals, bellows, stirrers, pumps, heat exchangers, column inserts, and so on.

PTFE has been used with glass due to its outstanding mechanical and thermal qualities. They have near-universal fluid compatibility. In comparison to others, the wear life is extremely short. PTFE, in particular, is maintenance-free and has cryogenic stability as well as non-wetting properties.

The service temperature of PTFE is regarded to be -50°C to +200°C

Electrical Characteristics - Borosilicate Glass

Glass is a poor electrical conductor, therefore surface conductivity is negligible and fluctuates with the amount of water absorbed on the glass surface. At 200 degrees Celsius, the specific conductivity is 10 ohm/cm. The dielectric coefficient varies according to the current frequency.

Density Borosilicate Glass

Density of glass at 20°C(J)=2.23g/cc
Modulus of elasticity (E)=6.3 KN/mm2
Poissions ratio=0.2

With X Bonding

Without X Bonding

Extra Protection of Glass Components 'X Bonding'

X BONDING provides extra protection for common glass components. The primary benefit of X Bonding systems is that if the glass is accidentally broken, the bonded wrapping provides additional protection against the risk of injury, the discharge of corrosive fluids, or the loss of valuable products.

X BONDING is a glass bonded fibre coating that provides enhanced protection to glass components. This has a little negative influence on the transparency of the glass, making it translucent rather than transparent.

Permissible Operating Temperature

The maximum allowed operating temperature for X-Bonding is 130' C, unless limited by the component's unique operating temperature.

Permissible Operating Pressure

The permitted operating pressure for X Bonded components is the same as that for conventional glass components.

Thermal Shock

Despite the heating resulting from X Bonding, the thermal shock properties of normal glass components remain unchanged.

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