Tempered glass is known for its remarkable strength, durability, and safety features. Surprisingly, it is five times stronger than the usual annealed glass. One of the most remarkable qualities of tempered glass is that when it breaks, it shatters into small yet blunt pieces, reducing the risk of injury. From shower doors and office partitions to car windows and architectural facades, tempered glass is found in almost everything.
However, as with everything, tempered glass can sometimes shatter unexpectedly. This phenomenon puzzles many people. Therefore, we have created this comprehensive guide to help you explore the top five causes of spontaneous breakage of tempered glass. Moreover, this guide will also help you examine the science behind each factor and offer practical prevention tips for manufacturers and end-customers alike.
1. Nickel Sulfide (NiS) Inclusions:
When a non-professional or ill-experienced manufacturer produces tempered glass, it faces major problems. One of the most common is the unintentional inclusion of Nickel Sulfide within the glass material. These are microscopic impurities unintentionally introduced during a specific process. In short, when nickel-bearing materials are in contact with sulfur-containing elements, the risk of impurity inclusion largely increases.
How It Happens:
- During the tempering process, Nickel sulfide particles undergo a phase through which they transform into smaller formations.
- Sometimes, these small particles revert themselves into their larger forms.
- This delayed expansion ultimately creates internal pressure within the glass sheet. Thus, it can lead to sudden breakage.
Risk Level:
Although NiS inclusions are rare, these are almost impossible to detect with the usual apparatus. Even it becomes challenging to detect them through the naked eye or standardized inspection equipment.
Prevention:
- You should always choose a high-class tempered glass manufacturer such as Shenxun.
- During the process of float or base glass production, you should always use high-purity raw materials because they impact a lot of quality.
- One of the most crucial tests to check is called Heat Soak Testing (HST). A reliable manufacturer should always conduct this by reheating the tempered glass up to 290°c. It will accelerate the projected expansion of Nickel Sulfide.
- Source or base glass should always be used from certified suppliers with strict quality assurance systems.
2. Edge Damage and Poor Handling:
Although tempered glass is robust under normal pressure, its edges are mostly vulnerable. Even then, catastrophic failures can occur due to minor chips or microcracks around the perimeter. Resultantly, entire tempered safety can be compromised in seconds.
How It Happens:
- The most common cause of this vulnerability can be some mishandling during the installation or fabrication of tempered glass.
- When the temperature changes, these edge flaws can aggravate into something serious for tempered glass sheets.
- Mishandled edges can sometimes be stress concentrators, which could propagate further damages under internal or external load.
Risk Level:
Imagine developing a tempered glass product for a high-rise building, but due to its vulnerable edges, it shatters. The primary concern is that this type of tempered glass damage often goes unnoticed until it’s too late.
Prevention:
- Firstly, you need to use proper glass lifters for installing tempered glass in critical applications.
- Secondly, the management and handling of tempered glass is the most significant step. You should use gloves and reliable edge protection during all installation techniques.
- The transportation of tempered glass should be conducted using standardised safety methods. Training personnel and opting for adequate installation procedures should also be encouraged.
- Quality assurance plays a key role in assuring edge vulnerabilities. You must ensure to inspect all edges post-fabrication and, most importantly, before installation.
3. Thermal Stress and Temperature Gradients:
In unbearable weather conditions, when tempered glass is exposed to uneven heating or cooling, it becomes vulnerable to breakage. Although it is manufactured through a proper heat treatment than standard glass, tempered glass can withstand a specific high or low temperature.
How It Happens:
- In this phenomenon, one part or side of the tempered glass heats up through factors like exposure to direct sunlight. On the other hand, the other part or side of it stays cooler, either shaded by a frame or an indoor environment.
- This critical difference between layers of tempered glass creates significant tension between zones. Ultimately, it triggers huge breakages.
- Sometimes, extremely low temperatures can also impact the impact resistance of tempered glass.
Risk Level:
The risk level of thermal stress remains moderate to high, particularly in tempered glass applications such as facades, skylights, or other external products.
Prevention:
- To improve the heat-absorption capabilities of tempered glass, you should use fritted, tinted or low-emissivity coatings.
- Ensuring reliable ventilation and proper airflow also plays a huge role in defending the structure of tempered glass. You should ensure that both sides of the tempered glass are ventilated, not just one side.
- While designing glazing systems, allow for thermal expansion as much as possible.
- Your reliable tempered glass manufacturer, such as Shenxun, will take care of these elements beforehand.
4. Improper Installation or Framing Pressure:
The unprofessional installation of tempered glass can introduce unintended mechanical stress to its surface. This can be a result of an inadequate glass frame or no room for glass movement or other tolerances. Still, a manufacturer with expertise doesn’t neglect these points during the entire process.
How It Happens:
- This can happen due to over-tightened bolts, uneven gaskets as well as rigid frames. Point pressure can sometimes pose a danger to glass safety.
- It can also happen when stress gradually builds up either due to temperature variations or building movements.
Risk Level:
There is a high risk of tempered glass shattering, particularly due to improper installation or external forces. Most notably, it becomes risky for curtain wall systems, doors, and balustrades with insufficient tolerances.
Prevention:
- An experienced glass maker like Shenxun always assures edge clearance and gasket flexibility, which are essential steps for breakage prevention.
- Always choose high-performance glazing systems that can accommodate expansion and contraction alike.
- Avoid any drilling or making changes after the tempering process.
5. High Impact from External Objects:
Every glass is prone to some defects, but tempered glass has less probability of damage or shattering. However, if there is a sudden blow from some hard or sharp object over a tempered glass surface, the strength threshold can be exceeded. Especially the edges or corners of tempered glass are more vulnerable to these foreign pressures.
How It Happens:
- There could be some accidental impact with different tools, ladders, furniture, or other construction materials.
- Tempered glass is installed in safety-critical areas, but sometimes acts of vandalism and forced entry can make it vulnerable.
- Powerful climatic conditions can also pose external impacts on the surface of tempered glass, resulting in shattering.
Risk Level:
The shattering risk level of tempered glass due to external object pressure varies based on the application and the object itself. The risk primarily prevails in commercial settings or public spaces. The more the external impact, the higher the risk level of tempered glass shattering.
Prevention:
- In vulnerable areas, installing protective barriers or railings proves to be highly effective.
- To get enhanced protection from breakage, you should use laminated tempered glass. It provides enhanced impact resistance and more strength to the glass due to multiple layers.
- Educate your maintenance and facility staff on handling tempered glass in accordance with best international practices.
What are Some Additional Causes of Tempered Glass Shattering?
In addition to the top five primary causes mentioned above, there are a few other minor causes of tempered glass breakage. The most common ones are underlined as follows:
Tempered Glass Thickness:
Your tempered glass should be made with adequate thickness to withstand breakage reasons. The thinner the tempered glass is, the more susceptible it is to stress. Therefore, a high-standard manufacturer like Shenxun always prioritises these crucial aspects.
Improper Glass Drilling:
It is advised to present every requirement before the tempered glass is out for the production phase. This is because all the procedures and modifications applied during the manufacturing process ensure flawless tempered glass quality. Otherwise, if you attempt to modify the glass in any way after the manufacturing process, it can introduce flaws.
Building Movement:
Structural and architectural shifts due to factors such as earthquakes can stress fixed-tempered glass panels. It will ultimately make tempered glass weaker and prone to further deformations in the long run.
Poor Quality Control:
Quality control is proven to be the most crucial aspect of a reliable tempered glass manufacturer. Whether heat treatment remains inconsistent or the tempering cycle is insufficient, a good quality control team always assures quality production. This is why Shenxun doesn’t compromise on its quality control parameters. Moreover, international quality control standards for tempered glass are strictly followed.
Chemical Corrosion:
Extended exposure to harsh chemicals or environmental pollutants can significantly degrade tempered glass. This is because numerous chemicals gradually degrade their surface integrity.
Ageing and Wear:
Especially in high-traffic zones, like most other glass types, tempered glass also becomes vulnerable to breakage due to ageing. Even if it’s installed properly and professionally, tempered glass may experience microstructural fatigue.
Understanding Breakage Patterns of Tempered Glass
The most common breakage pattern of tempered glass is that it shatters into tiny, cube-like fragments rather than sharp shards. However, it is crucial to identify the origin behind its breakage:
- Starburst Pattern: It often corresponds to either the point impact or NiS inclusions.
- Edge-Origin Cracks: This suggests typical edge damage or framing stress, as mentioned earlier.
- Thermal Break Lines: These lines only appear in areas exposed to uneven heat.
Additionally, a forensic glass analysis is conducted to break down the entire pattern by which your tempered glass breaks.
How to Minimize Breakage Risk in Tempered Glass Design and Procurement?
To safeguard tempered glass from unexpected shattering, industry professionals should do the following:
- Specifying heat-soak tested tempered glass separately for overhead, façade or other architectural applications.
- Where you need safety with protection from harsh sun rays, you should always prefer laminated tempered glass instead of simple glass. This ensures you get the ultimate soundproofing and UV protection at their best.
- Sometimes, demanding third-party certification and analysis results becomes a safer option for suppliers.
- Flexibility is the key to tempered glass design, especially in glazing systems. In turn, I will effectively accommodate any thermal movement or external pressures. That is why tempered glass design should be created under the supervision of an experienced glass producer, such as Shenxun.
- Periodic inspections should always be preferred for existing tempered glass installations. Places that are accessible and critical, such as public, commercial, or coastal areas, should be inspected monthly.
When you combine innovative tempered glass design practices with the best procurement procedures, you significantly reduce the risk of breakage.
Is Tempered Glass Still Safe?
Yes, tempered glass is a highly safe option compared to most other types of glass. It is one of the safest glazing materials available. The chances of spontaneous breakage of tempered glass are reduced mainly if it is manufactured and installed correctly. Moreover, it has a predictable fragmentation pattern.
In a nutshell, tempered glass should not be perceived as invincible but rather as a high-performance safety glass that requires sufficient handling, installation, and specification. When selecting a manufacturer for tempered glass, ensure that they follow rigorous quality controls. Shenxun is a top-quality tempered glass manufacturer that adheres to international quality standards. Furthermore, users should also be aware of the limitations of glass products.
Final Thoughts
By understanding the top five causes of failure in tempered glass, you can effectively minimise the risk. These causes include Nickel Sulfide inclusions, edge damage, thermal stress, and other installation errors, which can have an external impact on its quality and durability. Understanding the breakage pattern is just as important as selecting the best-tempered glass.
Whether you are an architect, contractor, supplier, or customer, you are likely familiar with the science behind tempered glass and its working structure. Although the process starts with a float glass, tempering it adds extra trust of safety and protection. Most importantly, the right design, manufacturing, inspection and handling play a vital role in the health of tempered glass.
If you need customised tempered glass that does not shatter spontaneously with high quality, contact the experts at Shenxun.