What is heat soaking?
Heat soaking is a process used in glass manufacture to reduce the risk of a glass breakage. To understand the process, you should be familiar with nickel sulphide inclusion, a rare but unwelcome occurrence for glass.
To give a brief explanation, nickel sulphide inclusion (NSI) is a naturally occurring phenomenon whereby small particles of nickel sulphide are still present in glass after the manufacturing and toughening process and at the point of installation. The tiny impurities are not visible to the human eye but there is an estimated risk of 1m2 in every 10,000m2 of glass containing a NSI (estimation by the GGF) and this can cause breakages in glass when aggravated by sudden or extreme temperature changes.
When glass is heat soaked, it is thermally treated after any toughening or laminating process. The glass is put in large heat soaking ovens and heated up to temperatures of 555 degrees for approximately 2 hours. This creates a process of elimination in an effort to force panels with a NSI to break. You can then be sure the remaining glass has a lower chance of having a NSI within it.
When is heat soaking recommended?
In commercial properties it is common for glass to be placed in inaccessible places, making it more complex and inconvenient to replace if needed. This is why specifying heat soaked glass in panels that are inaccessible on completion of construction is sensible, reducing chances of having to plan access if a breakage occurs. In a lot of cases, replacing glass panes would require a crane to revisit after installation, incurring additional costs.
We would recommend specifying heat soaked glass to help minimise risk when planning a project, particularly in commercial properties such as offices where disruption would be major if a breakage occurred. An architect can specify heat soaked on any glass unit. Specifying heat soaked glass would ensure the glass has been tested as thoroughly as possible before installation, offering the architects piece of mind.
Generally speaking, risk is not a word we take lightly at IQ and we haven’t met an architect that doesn’t agree. Although this finishing process will increase glass cost and lead times, the risk of a Nickel Sulphide Implosion after heat soaking is lowered down to 1m2 in every 1 million m2 of glass.
If you want to know more about the heat soaking process or speak to someone about specifying this in your project, give our offices a call on 01494722880 and someone will be happy to help.
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