It is generally recommended that tempered glass with a thickness of ≥6mm should all undergo homogenization treatment.
Core principle: Why is thickness the key factor?
The self-explosion of tempered glass is mainly caused by nickel sulfide (NiS) impurities. During the production process of glass sheets, it is inevitable that extremely trace amounts of nickel sulfide will be mixed in.
Thickness and stress: The thicker the glass, the higher the required tempering strength (surface compressive stress), and the greater the tensile stress formed inside it.
Impurities and stress concentration: During the tempering process (phase transformation) of glass from high temperature to low temperature, the volume of nickel sulfide particles changes. When it is located in the high-tensile stress area of tempered glass, it will become a "stress concentration point".
Thick glass is more fragile: Under the action of greater internal tensile stress, nickel sulfide impurities in thick glass are more likely to cause self-explosion. That is to say, as the thickness increases, the risk of self-explosion also increases accordingly.
Industry standards and general recommendations.
Homogenization treatment (HST) is a "detonation" test: its purpose is to screen out potentially risky glass (i.e., glass containing NiS) by simulating a high-temperature environment and causing it to shatter prematurely in the factory.
It is recommended that tempered glass used for doors, Windows, curtain walls, etc. in buildings be homogenized, especially when they are used above crowds or in locations where personal injury is likely to occur.
Apart from thickness, what other factors determine the need for homogenization?
Small sheet materials, thin glass ,< 5mm,The internal stress is relatively small, and the risk of self-explosion is relatively low. It is commonly found in furniture, household appliances, small partitions, etc., and homogenization is usually not mandatory.
Architectural glass,≥ 6mm,Enter the high-risk thickness range. This is the "initial thickness" that the industry generally believes should be homogenized. For tempered glass used in doors, Windows and curtain walls, if the thickness reaches or exceeds 6mm, it is strongly recommended to undergo homogenization treatment.
Large size, thick glass ,≥ 8mm,It belongs to the high-risk category. This type of glass is typically used in large curtain walls, skylights, railings, etc. Once it explodes spontaneously, the consequences will be serious. Homogenization treatment must be carried out, which has become a standard requirement in architectural design and glass procurement.
Apart from thickness, the following factors are equally crucial and should even be given priority over thickness itself:
Application location and security requirements:
Above personnel: Skylights, canopies, suspended ceilings, skylights, etc., must be homogeneous.
Densely populated areas: large shopping mall facades, hotel lobbies, schools, hospitals and other public buildings.
High-rise building curtain walls: Broken and falling glass can cause serious secondary injuries.
Railings and stair railings: They are directly related to personal safety.
The processing procedure of glass
If glass is slightly damaged during processes such as cutting, edge grinding and drilling, the risk of self-explosion will increase. Tempered glass that has undergone deep processing is more recommended to be homogenized.
Conclusion and Final recommendation
To ensure absolute safety and avoid potential liability risks, the most reliable approach is:
In the field of architecture, for all tempered glass used in exterior envelope structures (doors, Windows, curtain walls) and parts involving personal safety (skylights, railings), if its thickness reaches or exceeds 6mm, it should be regarded as an object requiring homogenization treatment. For thicker (≥8mm), large-sized or glass used in critical positions, homogenization treatment should be a mandatory requirement.
When you purchase or specify tempered glass, directly and clearly inform the supplier: "This batch of glass requires homogenization treatment (HST)" and provide the corresponding homogenization treatment certificate. This is the best practice to ensure the absolute safety of the project.
