|
When glass breaks it can be both frustrating and mystifying , particularly when it appears at first to be for no reason .
Diagnosing the cause of fracture can be a difficult job for an installer , but is often necessary to ensure a solution can be found and to prevent a similar break happening again .
Glass can break for a number of reasons , from edge damage to poor installation or thermal stress .
Here are some helpful pointers to bear in mind when called to investigate a breakage .
1 . Get kitted out . Having the right equipment is vital for inspecting glass . An eyepiece ( or magnifying glass ) and a torch are the bare essentials .
|
2 . Know the history . Ask questions about activities that were taking place near the glass and check the weather conditions at the time of fracture . Building up a history of the glass can be a quick way to determine the reason behind its breakage .
3 . Keep things in perspective . Viewing the glass surface can be useful , but the most conclusive assessment is often gained by examining the fracture origin from the edge .
4 . Branch out . Following the cracks , or branch lines , in the glass can point to where the break originated from . Apply tape to the pane to retain the pieces . If the fragments are on the floor , don ’ t sweep them away – they ’ re evidence !
|
5 . Say cheese . Photograph the fracture pattern for further examination or for seeking a second opinion from a colleague or professional expert .
‘ The smaller the mirror radius , the higher the stress
’ 6 . Mirror image . The size of the highly polished area – known as the mirror – around the origin of the fracture can be used to estimate the stress at failure . The smaller the mirror radius , the higher the stress . If the stress was high at time of breakage , this could indicate the glass was overloaded .
|
7 . Closer to the edge . Damaged or poor-quality edges are often prime reasons for a breakage . Inspect the edges closely .
8 . Check the glazing method . How glass is installed can give rise to a range of loadings that can drive failure . For example , protruding screw-heads , non-flat rebates or excessive fixing pressure can all lead to fracture .
9 . Getting warmer . Do you suspect the glass was at risk of thermal fracture ? This occurs when sufficient temperature differential is created across the glass , particularly in spring and autumn when the sun ’ s angles are low and the nights are cold . Thermal breaks typically run from an edge and are perpendicular to the edge .
|
10 . Don ’ t jump to conclusions . The presence of butterfly wings – two larger pieces of glass – around the fracture origin of the breakage does not necessarily indicate a nickel sulphide inclusion . These can be present for a wide range of fractures in toughened glass .
Follow these tips to ensure you ’ re able to properly diagnose the reason behind a glass fracture and offer
|
the correct solution to fix it .
Pilkington customers can find out more about diagnosing a glass breakage by registering to take part in a fractography training course : http :// www . pilkington . com / engb / uk / trade-customers / technical-help-andadvice / productknowledge-trainingcourses
|