Borosilicate 3.3 glass is the preferred material of construction for reactors and process systems in chemical, pharmaceutical and allied industries due to its characteristic properties such as high chemical resistance, resistance to temperature, low coefficient of linear thermal expansion, high corrosion resistance, to name a few.
It complies with the full chemical and thermal properties mentioned in the standards such as ISO 3585 and DIN EN 1595. Additionally, it offers many benefits which distinguish glass from other corrosion resistant materials of construction such as

  • Smooth and non-porous
  • Perfectly transparent
  • Indifferent to catalysts
  • Corrosion resistance
  • Environmental friendly
  • Non-flammable
Chemical Properties
Chemical Properties
The approximate chemical composition of 3.3 borosilicate glass used by Ablaze is as follows:
Component Content (% by weight)
SiO2 80.6%
B2O3 12.8%
Al2O3 2.4%
Na2O + K2O 4.2%
Products made of Borosilicate glass 3.3 have chemical stability, are practically inert, and have a high resistance to the effects of water, water vapours, acids, salts solutions and a fair resistance to alkali. Exceptions are hydrogen fluoride and concentrated phosphoric acid, and concentrated hot alkaline solutions. Corrosion may be increased, if acid medium alternates with alkaline medium permanently.

Physical Properties
Physical Properties
3.3 borosilicate glass is an amorphous solid and is characterized by physical properties as indicated in ISO 3585 standard.
Mean linear thermal expansion coefficient – 3.3 X 10-6 K-1
Density 2.23 g cm-3
Thermal conductivity 1.2 W m-1 K-1
Transformation temperature 525°C

Thermal Properties
Thermal Properties
Borosilicate 3.3 glass has low coefficient of thermal expansion. This, coupled with low modulus of elasticity and high heat conductivity make the products made of this glass resistant to sudden temperature variations.
All glass components and plants can be safely operated up to a temperature of 200°C provided that there is no sudden thermal shock. This limit is set by the physical properties of accompanying components such as gaskets, bellows, etc made of PTFE and not by the glass part. The acceptable value of thermal shock varies in accordance with the wall thickness of the glass components but it is usually accepted that up to 120°C of thermal shock can be accommodated without damage to the glass.

Optical Properties
Optical Properties
Borosilicate glass 3.3 does not exhibit appreciable light absorption in the visible range of the spectrum. As a result, it is clear & colourless. In the middle spectrum, transmission of UV light is significant as compared to normal glass. Due to its optical properties, borosilicate glass 3.3 is ideally suited for photochemical reactions such as chlorination.