Definition - What does Annealed Glass mean?
Annealed Glass is a type of glass produced when a hot glass is slowly cooled so that internal stresses inside it can be relieved once it is formed. The process is called Annealing and is carried out in lehr, which is a temperature controlled kiln. This type of glass is usually used in industrial processes such as oil and gas, petroleum, power generation because it has the property of absorbing mechanical shocks and can absorb thermal stresses because of quenching.
Petropedia explains Annealed Glass
Annealed Glass has very high durability as compared to a non annealed glass, which makes it suitable for use in the industries that undergo high temperatures, high pressure, produce thermal stresses and mechanical shocks. In the manufacture of Annealed Glass, the glass is heated up to the annealing temperature (annealing point) until the stress relief point is reached. The viscosity of 10^13 Poise is maintained in the annealing process which makes the hot glass very hard to deform but it remains soft enough so that internal stresses get relaxed. This hot piece is then heat soaked until the temperature evens throughout. After this process, the glass is allowed to cool slowly until its temperature reaches below the strain point where viscosity is 10^14.5 Poise. Following this procedure makes the Annealed Glass achieve thermal conductivity, thickness and durability.