Mysterious breakage, fulyy tempered glass doors

My client has a number of fully tempered glass doors mysteriously shattered in the middle of nights. A total of 6 doors out of about 200 doors shattered in about 21/2 years. All but one shattered at night when there was no one around. However, the latest one happened in the middle of a day when the occupant was still in the office. Apparently when the glass popped, it stayed in place and the occupant needed assistance to break it open before getting out of the office. We were advised that the door just popped without being touched in anyway.
These are fully tempered glass doors measuring 8'-6"h x 3'-0"w x 1/2" t. All have patch panels at the pivot points but no continuous top and bottom rail.
About 4 months ago, the contractor re-inspected the headers and found some movement in some of the glass doors, including the latest broken one which by the way had been broken for the second time. The contractor had since reinforced the header so presumably it is not the course for the latest breakage.
Here are my questions:
1. The size of tempered doors for this project appeared to fall within the GANA selection chart sizing guideline so it should not be the problem of improper door size that cause the breakage. Does anyone know of the actual performance specifications and limitations for these type of glass doors?
2. Does anyone know of an agency that can test these doors for conformance with industry standards? If so, what are the standards?
3. Isn't it true that when shattered, a fully tempered glass is supposed to fall into small shards and not stay up by itself. When the last door broke, the shattered glass door actually stayed up! And when it was finally pushed down to the floor to let out the occupant, a number of the glass shards remain in large pieces of about 6

Guest User
Fri, 14/11/2003 - 16:43

Dear sir;

You may have one or some reasons for this breakage.

I-Spontaneous brekage of tempered glass , because NI inclusions in float glass.
In some cases if the primary glass supplier is not nikel free certificate you might make a heat soak test to tempered glass to avoid spontaneous breakage.
II-The building is moving , how is the gap between glass and door.
we recommend 3mm per side and 5mm in top and 10 mm in bottom side, if this gap is less you may have problems with this, I think if in one case the door do not fall in brekage it might be tigheten by the sides.
III-the fittings are not properly fixed ,only in the case the floor is of marble or ceramics , in carpet or woor the door will release trapped not break.
IV-Look the pieces carefully , we have a case in a building that one emplee break the doors with an air gun only for fun ....
sorry for my english
metalglass s.a.
ing.pablo cassani

Guest User
Tue, 18/11/2003 - 03:41

Thank you so much for the reply. Your English is fine. I really appreciate your taking the time to share your experience.

I. Spontaneous breakage is the one explanation I could come up in the absence of any other reasons for breaking the glass at this point.
It has been suggested that perhaps the glass is substandard in that it contains unacceptable amount of nickel sulfide. I understand that nickel sulfide has a tendency to expand when temperature is rising which may eventually causes the glass to expand out of shape and break in pieces. This seems like a probable explanation.
II. These glass doors are located in a Class A office building so I doubt that excessive structure movement could be the cause although loose pivot support fitting as result of operational movements could eventually push the door out of position and break.
III. The pivots supports are mostly mounted on carpet flooring so there is certain amount of trapping below. The owner does have a regular maintenance program going to minimize it. This is definitely a probable cause.
IV. Vandalism is definitely a possibility but since the Owner has denied it to be the case, such is not considered a reason.
The bottom line is the Owner is losing confidence in these doors and we can't seem to offer a good explanation or assurance that breakage we not happen again.
We'd like to know if there are testing procedures that can determine the content of the glass. Anyone who can offer suggestions is welcome.


Guest User
Wed, 19/11/2003 - 11:30

If there were 6"x6" particles on floor after breakage you can be sure that the door was not tempered glass.
According to ANSI Z 97.1, impact test, maximun
weight of 10 largest pieces shall be no more than weight of 10 square inches of original glass.
In local building code should be more precise
requirements for tempered glass doors used in public places.
To give confidence to your customer you should get
the doors measured for their tempering quality.
You can get necessary instruments and measuring service from STRAINOPTIC TECHNOLOGIES, INC.
www., email:

If you get heat soak test certificate from your supplier and you measure surface stress yourself
you can assure that the doors will be proper and there will be no further breakages assuming installation has been made properly.

Joel Feingold
Thu, 20/11/2003 - 21:21

Dear Highhook:

I hope that the following responses to your posting are of help to you.

1. The most common causes for spontaneous breakage are localized areas of excessive tensile stress which form around intrinsic defects, such as Nickel Sulfide inclusions. This condition most often results from overtempering the glass, and can be avoided by measuring surface stress according to ASTM C1279, and optimizing all process control parameters. ASTM C1279 is a non-destructive test method using an instrument called the GASP

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