Tempered Glass Saves Lives

June 1, 2020 in Glass, Injury, Safety, Tempered Glass

This past Sunday, May 31, 2020, marks another day in United States history where peaceful demonstrations and orderly civil disobedience were highjacked by unlawful activity leading to property destruction and theft. The author’s Bixby Knolls, Long Beach, California neighborhood was thankfully sparred wide-spread damage.

Tempered Glass

Tempered Glass Saves Lives

This article is not about the political reasons for the nationwide demonstrations.  Instead it concentrates on something that television coverage and social media have not reported. Specifically, how advancement in glass safety has reduced the number of people being injured due to broken glass.In fact, we will never know how many of the looters and bystanders, including police and national guardsman, were able to escape what could have easily been a significant number of bodily injuries from glass shards and glass debris used as weapons.

In the television broadcasts viewed by this author none of the glass storefronts being damaged or destroyed showed human blood from cuts by broken glass.  This is due to the major change in building codes decades ago requiring all commercial glass to be either of the wire safety type or tempered.  Again, from television broadcasts the evidence indicates that all the broken glass shown was of the tempered type.

Here is a short tutorial regarding tempered glass:

Tempered glass is also referred to as toughened or sometimes as fully tempered glass.  The glass sheets are heated to around 1,148℉. They then undergo a high-pressure cooling process called quenching.  This process, which only lasts between 6 to 10 seconds, blasts cool air from various positioned nozzles onto the glass surfaces which cools the outer surfaces of the glass much quicker than the center. As the center cools down it tries to pull back from the outer surfaces resulting in the center remaining in tension while the outer surfaces go into compression which gives tempered glass its high strength. Tempering can also be achieved with chemical treatment but it is far more expensive than quenching and not widely used commercially.

When damaged tempered glass breaks into smaller granular pieces (as can be seen in the image taken of one of the targeted stores near the author’s home) as opposed to large jagged shards of non-tempered glass.  These smaller granular pieces are less likely to cause bodily harm.  The high strength of tempered glass and its high safety record is why you also see it being used in shower and tub glass enclosures, microwave ovens, refrigerator trays, glass table tops, and more.

We can all be thankful to the scientists, engineers, and the many manufacturers of glass products for making our communities safer.

Injury By Glass and Building Codes Yesterday and Today

December 8, 2018 in Falls, Glass, Glass and Gazing, Injury, OSHA

            From time to time we have been called upon to investigate personal injuries due to glass breakage.  These types of accidents can vary from minor to major injuries including fatalities.

            There are various causes for such incidents including people walking into and through glass walls and doors, shattering of glass due to direct strikes by blunt objects, defective glass, failure of glass systems such as shower doors falling off their tracks, and sometimes plain old bad luck.

            Regardless of the cause there are two distinct differences between the incidents, those that involve untempered glass and those that involve tempered glass.

            Without going too deeply into the technical aspects of glass manufacturing the differences between tempered and untempered glass are stark and significant.

            When untempered glass breaks it does so in chunks typically referred to as shards.  Often the shards are broken into triangle shapes resembling knifes. Depending on the cause of the glass breakage the shards can impel, cut, or both any part of a soft tissue, human or animal.

            Tempered glass when broken is designed to shatter into very small pieces of glass. They too can cause injury but are less likely to become life threatening.

            There are circumstances when even tempered glass becomes dangerous.  One such occasion is when glass panes become dislodged from their frames in low and high rise buildings. The glass becomes airborne and transforms into a flying missile. Obviously in such a case it makes no difference whether the glass is tempered or not.

           As of the 1961 Uniform Building Code untempered glass was in wide and legal use. Starting with the 1964 Uniform Building Code we see where mandatory use of tempted glass [and other safety glazing] first becomes law under Section 5406 as follows:

 Glass lights subject to impact hazards and in the following locations shall  comply with Table No. 54-D:

 1. Glass doors and wall panels of bathtub and shower enclosures. For Plastics, see Section 1711 (e).

2. Where bottom of glass light is within eighteen inches (18”) of floor or walking surface.

3. Glass lights of glass panel doors.

            By the time this article was written in December of 2018, the codes and regulations governing the installation of glass become more strict. Under the 2015 International Building Code, which is the cornerstone of most building codes in the United States, Sections 2406.4, 2407, 2408, and 2409 require safety glazing, with minimal exceptions, in all hazardous locations including doors, windows, glass guard railings, wet surfaces, areas adjacent to stairways and ramps, fire department access panels, glazing in athletic facilities, and glazing in walkways, elevator hoist ways, and elevator cars.

            We do not anticipate any reductions in the current building codes and may see even more stringent requirements if future environmental and safety concerns dictate the need to provide even more protection.

            The author has investigated scores of incidents relating to glazing injuries and has qualified in court to testify as an expert in this field.