Heat Soaked Toughened Glass
Heat soaking is an extra process that can be carried out on toughened glass to reduce the risk of spontaneous breakage through Nichol Sulphide (NiS) inclusions when the glass is in use.
What is Heat Soaked Glass?
Float glass can contain slight imperfections, one of which are nickel sulfide (NiS) inclusions. On the whole NiS inclusions do not cause a problem. However, there is a rare occasion on which NiS inclusions may potentially cause spontaneous breakage in toughened glass without any load or thermal stress being applied. Heat soaking can help to identify and avoid this occurrence. The test simulates actual glazing conditions.
Heat soak testing is recommended for safety critical work such as atrium glazing and balustrades as well as for any overhead glazing and highly trafficked areas, such as airports and other high profile projects where breakage could have a significantly adverse effect.
How does Heat Soak testing work?
Heat soaking is a process that can be undertaken to expose if there are any NiS inclusions in toughened glass. The process involves placing glass inside a sealed chamber and raising the temperature. This process accelerates nickel sulfide expansion and results in any glass containing nickel sulfide inclusions breaking within the heat soak chamber. By identifying this potential problem during heat soak testing, we can therefore reduce the risk of potential breakage once installed.
Heat soaking is a destructive test designed to break glass that is at risk, generally achieving a conversion rate of 90 to 95%. Heat soaking will not detect other inclusions such as silica that can also cause breakage.
Testing to standard EN 14179-1
Individual toughened glass panels are positioned on special racks and placed within a calibrated oven. The glass is then heated in a controlled manner until the last piece of glass reaches 250˚C The glass is then held at 260˚C ± 10 ˚C for a minimum of 2 hours then cooled in a controlled manner to minimise the risk of glass breakage due to thermal shock. Any breakages at this stage are replaced and the sequence is run all over again.
Please speak to one of our Technical Specialists if you have any queries
Available on glass thicknesses 6 to 19mm