{"id":84143,"date":"2019-03-21T13:41:16","date_gmt":"2019-03-21T17:41:16","guid":{"rendered":"https:\/\/www.constructionspecifier.com\/?p=84143"},"modified":"2019-05-01T10:31:34","modified_gmt":"2019-05-01T14:31:34","slug":"spontaneous-glass-breakage-or-not","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/spontaneous-glass-breakage-or-not\/","title":{"rendered":"Spontaneous glass breakage (or not)"},"content":{"rendered":"

\"slaton\" \"patterson\" FAILURES<\/span><\/strong><\/span>
\nDeborah Slaton and David S. Patterson, AIA<\/strong><\/p>\n

The use of fully tempered (FT) glass is common in the building industry. While its increased strength (approximately four times stronger than annealed glass and twice as strong as heat strengthened) and distinctive breakage pattern that can reduce the potential for injury are regarded as benefits, its use should be carefully considered. A primary concern is FT glass may break without warning due to the presence of certain expansive inclusions, introduced to the material during initial fabrication. While the occurrences of \u2018spontaneous breakage\u2019 appeared to be waning over the past 20 years or so, an apparent escalation in the incidence of breakage attributed to this phenomenon has recently been noted, an upturn that may be the result of an increase in the use of nondomestic glass.<\/p>\n

Breakage of FT glass from impact is often difficult to differentiate from spontaneous breakage attributed to an inclusion, as inclusions contributing to the latter are often too small to detect visually without the use of magnification. A distinguishing characteristic often used as an initial visual indication of spontaneous breakage is the \u2018figure-eight\u2019 or \u2018cat\u2019s eye\u2019 pattern that is formed at the point of fracture origin. However, confirmation of the presence of an inclusion most often requires laboratory study.<\/p>\n

\"Illustration<\/a>
Illustration of glass following breakage attributed to nickel sulfide (NiS) inclusion and exhibiting the classic \u2018cat\u2019s eye\u2019 or \u2018figure eight\u2019 fracture pattern at the origin.<\/span>
Photo courtesy WJE<\/span><\/em><\/figcaption><\/figure>\n

Nickel sulfide (NiS) is the most common type of inclusion associated with spontaneous glass breakage. The NiS inclusion, which can be as large as 20 mils (0.020 in.) in diameter, exists in two crystalline forms:<\/p>\n