Heat Soak Test
Heat soak testing guarantees the safety and durability of tempered glass by eliminating the risk of spontaneous breakage due to nickel sulfide inclusions. Ideal for projects requiring increased protection, such as building facades and glazing installed at height.
HST secondary thermal test
Heat Soak tested glass undergoes a high-temperature heating process to detect nickel sulfide inclusions responsible for spontaneous breakage. This treatment is indispensable for complex architectural applications and hard-to-reach installations, offering additional peace of mind.
The secondary heat test identifies and eliminates nickel sulfide inclusions in tempered glass. This in-plant process heats the glass to around 265°C, causing the breakage of glass likely to break spontaneously. This method is essential for structural glass, skylight glazing and other complex installations requiring enhanced durability and safety. Chronoglass supports you in your demanding projects, guaranteeing reliable and safe solutions.
The Heat Soak Test (HST) is a controlled thermal process applied to tempered glass to minimize the risk of spontaneous breakage caused by nickel sulfide (NiS) inclusions. During manufacturing, microscopic NiS particles can become trapped within the glass. Over time, these inclusions may expand, leading to unexpected fractures. By subjecting tempered glass to elevated temperatures of approximately 290°C (554°F) for a specified duration, HST accelerates the expansion of NiS inclusions, causing susceptible panes to break in a controlled environment rather than during service.
HST is highly recommended in applications where glass breakage poses significant safety risks or where replacement would be challenging and costly. Key sectors include:
- Architectural facades and curtain walls: High-rise buildings and structures with extensive glass exteriors benefit from HST to ensure safety and durability.
- Balustrades and railings: Glass used in barriers and railings, especially in public spaces, should undergo HST to prevent spontaneous breakage.
- Overhead glazing and skylights: Glass installed above areas with foot traffic requires HST to mitigate risks associated with falling glass.
- High-traffic commercial environments: Shopping malls, airports, and other public venues where glass is exposed to varying temperatures and mechanical stresses.
The HST procedure involves several key steps:
- Loading: Tempered glass panes are placed inside a specialized heat soak oven, ensuring adequate spacing for uniform heat distribution.
- Heating: The oven temperature is gradually increased to approximately 290°C (554°F) and maintained for a duration of 2 to 4 hours, as specified by standards such as EN 14179-1.
- Cooling: After the soak period, the glass is slowly cooled to room temperature to prevent thermal shock.
- Inspection: Any panes that have fractured during the test are removed, and the remaining glass is deemed less likely to experience spontaneous breakage.
Incorporating HST into industrial projects offers several advantages:
- Enhanced safety: Reduces the likelihood of spontaneous glass breakage, thereby protecting occupants and passersby.
- Cost savings: Minimizes expenses related to glass replacement, potential legal liabilities, and associated downtime.
- Compliance: Meets industry standards and building codes that mandate additional safety measures for glass installations.
- Reputation: Demonstrates a commitment to quality and safety, enhancing the credibility of manufacturers and contractors.
While HST is not universally mandated, it is strongly recommended for applications where the consequences of glass breakage are severe. Certain building codes and project specifications may require HST for specific installations, particularly in critical safety areas. It is advisable for project stakeholders to assess the potential risks and consult with glass manufacturers or industry experts to determine the necessity of HST for their specific applications.
