On Safety of Heat-Soaked Thermally Toughened Glass Panes

Using a newly developed detection method, a variety of even small inclusions was identified in a relatively big batch of annealed glass. This allowed us to collect a high number of nickel sulphide inclusions for statistical evaluation. The respective NiS containing samples were thermally toughened and subject to Heat-Soak Test (HST) following EN 14179-1 (2 hours holding-time). Not all of them broke, we investigated why.

Additionally, over years, we collected two data sets of position, size and composition measurements in breakage departure points of thermally toughened glass. One comprises breakages of un-soaked glass from buildings, the other exclusively breakages in HST’s. Both data sets were evaluated and characterized statistically. The respective comparison shows significant trends in size and position distributions, allowing interesting conclusions on the differences in breakage behavior between HS-tested and un-soaked glass panes. Through this, for the first time ever, we were able to quantify the proportion of breakages in Heat Soak Test that would never have led to breakages on buildings even without HST. This confirms the very high safety of the HS-tested glass, also under the aspect that HST temperature range shall soon be reduced by 30 degrees.