Residual Risk of NiS Spontaneous Breakages after the Heat Soak Test

Abstract

Spontaneous glass breakage of thermally toughened glass due to Nickel Sulphide (NiS) inclusions can be largely prevented by a preliminary Heat Soak Test (HST) (Kasper 2018a). This well-established test has been standardised in the EU Norm EN 14179-1:2005. However, according to literature (Kasper – Rubbert 2020), there is a small theoretical probability, that a potentially dangerous inclusion could lead to a breakage even after a well-conducted HST-test. In this paper, a statistical approach will be used to explain the level of residual risk of having a spontaneous breakage of heat soaked, thermally toughened, soda lime silicate safety glass due to the presence of critical nickel sulphide inclusions.