Glass failure in high-rise buildings and regulations aiming to combat it have been in the spotlight in recent months, and for good reason.
Nickle Sulphide (NiS) is a substance which can form within glass during manufacture due to the presence of minute impurities in the batch ingredients or manufacturing process.
This rarely occurs, however, when present it can form tiny "inclusions" in the glass, which doesn't present a problem to ordinary annealed glass, but does to toughened or strenghtened glass. Under certain load and temperature conditions, NiS particles can go through a transformation phase, which if the particle is within the glass's tensile zone, can lead to a crack, which could then cause the glass to shatter.
While no glass manufacturing process is immune from the possibility of NiS, manufacturers with good controls in place are less at risk than others.
Paying close attention to where you source your glass from and considering manufacturing alternatives like heat soaking, using heat strengthened glass or using custom laminated glass could help to ensure the safety of your glass.
Viridian is Australia's only manufacturer of float glass, which is made by floating molten glass on a bed of molten metal, giving the glass sheet uniform thickness and very flat surfaces. Each year Viridian makes over half of the float glass consumed by the local market here in Australia and in New Zealand. The rest of the glass is imported, mostly from Asia.
Many high-rise construction projects import their glass because it seems to be an economically attractive option. However, such glass may or may not have been heat-soaked or otherwise treated to mitigate the risk of NiS failure.
