Spontaneous Breaking of Thermally Toughened Safety Glass in Facades

Can we state if the Heat Soak Test (HST) was done according to EN14179-1:2005 or not ?


  • Philippe Letocart Saint-Gobain Research Germany
  • Francis Serruys Saint-Gobain BU Glass Facades, Belgium


Spontaneous glass breakage of thermally toughened glass due to NiS inclusions can be largely prevented by a Heat Soak Test (HST)1. This well-established test has been incorporated into the European standard EN 14179-1:2005. However, according to literature (Yousfi 2010b), there might be a theoretical probability, that a potentially dangerous inclusion could lead to a breakage after a well-conducted HST. Glass processors may neglect to conduct the test for a variety of reasons (sometimes furnaces are not calibrated, are overloaded, a wrong temperature profile is run etc.), even advising not to perform it at all, preferring to replace the glass should failure on a building occur. In this talk, we will show that, due to recent advances in microanalysis techniques, it is now possible to state after a failure on a building whether the heat soak test was correctly conducted according the EN standard or not.





Structural Glass Design & Standards