HEAT STRENGTHENED GLASS
The Heat Strengthened Glass is similar to tempered glass in many respects. It is approximately two (2) times as strong as annealed glass of the same size and thickness. Distortion is less evident than tempered. It does not qualify as a safety glazing material because its break pattern is like annealed glass. It does not have the tendency to break spontaneously like tempered glass. Once heat strengthened, the glass can not be cut or drilled.
During heat strengthening, annealed glass is reheated to a high temperature, then cooled Quickly in a process called “quenching” the resulting heat-strengthened glass is twice as strong as annealed glass of equal thickness and offers significantly greater resistance to wind loads, impacts, and thermal loads.
The first step in the heat- strengthening process is cleaning annealed glass and cutting to size. then it is placed in a furnace and heated to approximately 1150°F. The glass is then air- cooled to create a balanced condition of stress with in the glass itself, making it more resistant to external stresses.
Heat strengthening does not result in a “safety “glass product ; heat-strengthened glass breaks in a pattern similar to annealed glass. For applications where “safe” breakages is a concern, tempered glass should be used.
Heat-strengthened products form SIGTuff are perfect for many commercial applications include spandrels, windows in high wind load areas, and applications where the glass is expected to develop high thermal stresses.