Overhead glazing failures….
The occurence of overhead glazing breakages is becoming more prevalent and the risk to public safety remains high, with many glazed roof areas being found in shopping malls, public buildings and offices.The risk comes from toughened safety glass, which is the most common glazing found in glazed roof or structurally glazed areas, suffering a break failure due to Nickel Sulphide Inclusion.
This is a process whereby the individual toughened glass panes are heated and then allowed to cool for a specific period of time to ensure that any nickel sulphide inclusions (NIS) within the glass can expand and cause the glass to break. Heat soak testing significantly reduces the risk of toughened glass failure from nickel sulphide inclusions when the glass is in service. The generally accepted view is that the risk is reduced by approximately 90%, so there is still a residual risk of toughened glass failure from NIS inclusions.
The toughened glass process aligns the molecules into a much more rigid form, increasing its strength and ability to withstand an impact. This type of glass is tested to BS 6202 Clas A or EN12600 1b1 standard, allowing it to ‘break safe’. Toughened glass fragments into many small particles, typically 10-12mm in diameter, and as such it is considered to be as a safety glass. In terms of risk, there is still a 10% residual risk that a glass panel may fail due to a nickel sulphide inclusion.
Affordable solution….
HanitaUK’s specialist safety films are a good way of combatting the problem. Their 175micron clear Anti Shatter Film (ASF) is a retro installed solution which, in combiination with a suitable ‘edge retention’ system will hold any broken pieces in stiu, until the panel can be replaced. This eliminates the risk of glass falling and causing injury.
Another reason why overhead glazing should be filmed is that unfortunately, there is no time limit from the date of toughening to when a glass pane could fail due to a NIS inclusion.
For more detailed information on how Bonwyke Ltd can assist you in making overhead glazing safer, please call us on 01329 289621 or email us at sales@bonwyke.co.uk
