Architectural Products

Heat Strength Glass

Heat strengthened glass is similar to tempered glass except that the cooling is done at a much slower pace. Annealed glass is heated to approximately 650-700 º C, but the cooling process is slower than that for tempered glass. Heat strengthened glass is about twice as strong as annealed glass of the same size and thickness. Heat strengthened glass is a semi tempered glass which retains the normal properties of ordinary float glass. Heat Strengthened glass has been strengthened thermally by inducing a surface compression of 6000 to 9000 psi as compared to a range of 11000 to 20000 psi in case of fully tempered glass. Heat strengthening adds strength to the glass while limiting the change in its breakage characteristics. The cooling process places the surfaces of the glass in a state of high compression and the central core in a state of compensating tension.

HS glass - in which heats the glass to a uniform temperature of approximately 650º C to 700 º C in an electrically heated horizontal furnace. Ceramic rolls convey the glass through these furnaces at speeds regulated to ensure temperature uniformity and minimal optical distortions. The heat strengthened process parallels the traditional process of glass tempering, except that the cooling cycle is less rapid. However, the heating temperature remains the same for both processes. The residual stress on the edge and the glass surface differ in both cases with tempered glass having a higher level of stress. Due to the relatively lower rate of cooling during the strengthening process, heat strengthened glass develops less stress as compared to fully tempered glass. The process increases the mechanical and thermal strength of heat strengthened glass, making it twice as tough as annealed glass.

Ø Max Size 2440mm X 4200mm
Ø Min. Size 300m X 300mm
Ø Thickness 4mm – 19mm
Ø Glass Type Clear, Tinted, Reflective, Low-E

Difference Between Breakage Pattern of Heat Strengthened Glass & Toughened Glass

Properties Heat-Strengthened Glass
Thermal Shock Resistance Up to 130°C
Mechanical Strength Two times stronger than annealed glass
Fragmentation Knife Edges
Tensile Strength 40-55 MPa
Bending Strength 40 N/mm2
Design Stress for Architectural Purpose 17 MPa


Substantially reduced visible distortion in comparison to Tempered Glass.
Heat strengthening glass can not be cut or drilled, sandblasted or etched, or edge polished or ground. Any fabrication or field alteration will weaken or break the glass.
Tempered glass is subject to rare spontaneous breakage caused by one or a combination of these causes: surface or edge damage, deep scratches or gouges, severe weld spatter, missile or windborne debris impact, glass to metal contact, wind/thermal loading or rare inclusions or impurities in the float glass that weaken the compression layer of the glass. Breakage may occur long after the damaging event, seemingly for no apparent cause due to thermal or wind cycling. Because heat strengthened glass is produced with a lower level of compressive stress, it is even less likely to experience "spontaneous breakage".
When tempered glass breaks, the resulting small pieces tend to vacate the framing system under lateral load. Heat strengthened glass are less likely to leave the framing system in the case of breakage and subsequent lateral load.
Heat strengthened glass is supplied with a permanent mark in one corner identifying the manufacturer, Kaenat and the words heat strengthened.

Applications & Specification
Heat-strengthened glass continues to gain popularity and is often the choice of the design professionals for vertical vision spandrel areas and for laminated sloped glazing. Heat-strengthened glass is valued for its mechanical strength which is twice of normal annealed though half of fully tempered glass. Heat strengthened glass has a comparatively flatter finish than fully tempered glass. It therefore has lesser optical distortions and so can be used in places where high optical quality is required. It can be used for general glazing where additional strength or resistance to mechanical/thermal loads caused by certain tinted or coated glass. The glass can also be used in high wind load areas, but IT CANNOT BE USED IN ANY SAFETY GLAZING APPLICATIONS. Heat-strengthened glass is widely used in laminated glass for additional strength, such as in overhead and sloped glazing.

For Commercial: Corners of tall building , Spandrel Glass , Glass façade/Curtain Walls
For Residential: Aquariums Walls, Interior Partitions, Window, Refrigerator

Maximum Size: 2440mm x 3660mm
Minimum Size: 300mm x 300mm Glass
Thickness: 3.5mm - 19mm
Glass Types: Clear, Tinted, Reflective, Low e, Figured

Home  |  About Us  |  Products  |  Glass For  |  Contact Us  |  Terms & Condition Copyright @ 2014, Kaenat Glass Industries