Read Consulting, a California failure analysis laboratory, was asked to determine the root cause of the failure of tempered glass patio doors. Installed in 2019–2020-time frame. A year after installation several glass doors spontaneously failed. Read Consulting performed a root cause failure analysis on representative doors. The results indicate that the plate glass (i.e., the float glass) was contaminated with (NiS). During the tempering the NiS changes phases and is frozen in the high temperature structure. Over time, the NiS reverts to the stable room temperature phase, expands and initiates the failure.
Cause was Nickel Sulfide Contamination from the glass melt.