HEAT STRENGTHENED GLASS
Heat strengthened safety glass differs from tempered glass in the fracture pattern and size of the pieces it breaks into. Heat strengthened glass breaks from the fracture center outwards in larger shards and islands, whereas tempered glass breaks into very small, blunt glass dice. Due to the size of the shards, the pane remains within the frame avoiding collapse, as is the case with tempered glass, leading to achieving a certain level of protection against injury. Due to the lower surface compression compared to tempered glass, heat strengthened glass characteristic minimum strength is approximately double that of annealed glass of the same width, while heat strengthened safety glass being impervious to thermal sock breakage (not artificially induced, for temperature variations up to 100°C).
Consequently, heat strengthened glass represents a plausible alternative for structural applications, e.g. staircases, balconies and balustrades, however always in a laminate format.
Heat strengthened glass is not considered safety glass, unless it is laminated into a multilayered format. Thermally treated glass (either heat strengthened or toughened) requires that some conditions/restrictions are taken into consideration before its treatment, regarding the size of incisions and the radius of holes with respect to the width of the pane. Further information with respect to such restrictions can be provided upon request, by contacting VAS GLASS.
At VAS GLASS, the safety glass heat strengthening process is offered certified (CE marked) according to the European Norm EN 1863, under the brand-name VAS-HS..