what is heat strengthened glass

Heat strengthened glass is a semi tempered glass, which 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. It is two times stronger than annealed glass. Though it is not considered to be a safety glass, it is widely used on building facades due to better optics.


Strong Clip Art 200x200

Heat Strengthened Glass is 2 times stronger than normal annealed glass.

Safe Breakage (Laminated Glass) 200x200

The fragments tends to remain in sashes and having less probability of fallout.

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Heat Strengthened Glass has flatter finish and has lesser optical distortions

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No Thermal Breakage

Heat Strengthened Glass will resist temperature difference of up to approximately 130°c.

Range Available

  • Maximum size : 3000 mm X  6000 mm or  3500 mm X 5000 mm
  • Minimum size : 220 mm diagonals
  • Thickness range : 3 mm to 19 mm
  • Colors : Clear, Bronze, Gray, Green, Blue, Reflective & Low-E
  • Bent Tempered: 2500 mm (width) X 3500 mm (straight edge)
  • Minimum radius : 1100 mm


Properties Tempered Glass Heat strengthened glass Annealed Glass
Thermal stress Upto 250°C Upto 130°C Upto 50°C
Strength 4 times of annealed 2 times of annealed Not strong
Bending strength 120 – 200 N/mm² 60 – 100 N/mm² 40 N/mm²
Design stress 50 Mpa 27 Mpa 17 Mpa
Surface compression >10000 psi (69 Mpa) 3500-7500psi (24-52 Mpa) Upto 2800 psi (19 MPa)
Safety Approved as safety
glazing for most
Not approved as safety
Not approved as safety
Site alterations Not possible Not possible Possible
Flatness Slight bow and
Bow and corrugation
lower than tempered
Very flat
Optics Reasonably good Good. Comparatively
better than tempered
Very good
Lamination Min 1.52 PVB Min 1.52 PVB Min 0.38mm PVB
NiS breakage Prone Extremely rare possibility Non existent
Heat Soaking Recommended Not necessary Not required

applicatons of heat strengthened glass

how is heat strengthened glass made

Heat Strengthened Glass is made on state of the art electrically heated horizontal furnace, which heats the glass to an uniform temperature of approximately 660ºC. Ceramic rolls convey the glass through these furnace at speeds regulated to ensure temperature uniformity and minimal optics distortions. The heat strengthened process parallels the traditional process of glass tempering, except that the heating temperature are lower and the cooling cycle is less rapid. During production, non-destructive verification of the range of stresses is done by using grazing angle surface polarimeter to ensure the right surface compression.

Why does heat strengthened glass have better optics

Heat Strengthened glass have better optics because of lower temperature at processing which leads to less distortion on the glass.

Is heat strengthened glass is safety glass

Heat-strengthened glass is not a safety glass product but it is suitable for security laminates.

Does heat strengthened glass breaks spontaneously

NO, heat strengthened glass does not breaks spontaneously.

Why heat strengthened glass is more suitable for security laminated glass

security-glassLaminated glass resists intrusion because the inter-layer continues to safeguard the building even after the glass itself is broken. Security glass cannot be cut from only one side, so ordinary glass cutters are useless as break-in tools. Laminated glass tends to resist impact. In multiple configurations, it can even resists bullets, heavy objects, or small explosions. In most cases, it takes many blows, all in the same spot, to penetrate the glass.

Is heat strengthened is suitable for glass doors

No, Heat Strengthened glass is not suitable for glass doors.