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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.
Trutuf heat
strengthened glass is made with the proven technology from Grenzebach
of Germany in a electrically heated horizontal furnace, which heats the
glass to a uniform temperature of approximately 660 C. Ceramic rolls
convey the glass through these furnaces at speeds regulated to ensure
temperature uniformity and minimal optical distortions. The heat
strengthening process parallels the traditional process of glass
tempering, except that the heating temperatures are lower and the
cooling cycle is less rapid. During production, non-destructive
verification of the range of stresses is done by the use of a grazing
angle surface polarimeter.
Characteristics of Trutuf Heat Strengthened Glass
Heat-strengthened
glass continues to gain popularity and is often the choice of the
design professional for vertical vision spendral areas and for
laminated sloped glazing. Heat-strengthened glass is valued for its
mechanical strength which is twice of normal annealed glass though half
of fully tempered glass.
With the exception
of strength and breakage characteristics, heat strengthened Laminated
glass as compared to Tempered Laminated glass, heat-strengthened glass
allows the interlayer of laminated glass to adhere more evenly because
of a flatter finish surface. heat-strengthened glass with its flatter
surface also results in the facade having less optical distortions.
Applications
Heat
Strengthened glass is best suited for spanderel and vision panels of
curtain walls and structural glazing as its safeguards against thermal
breakage's providing better optics than fully tempered glass provided
the calculations on wind loading are within safe limits.
It is ideal for making laminated glass panels for safety combined with strength.
It is also used in
complex glass combinations like double glazed with one life to
laminated glass, pool sides, pool bottoms, aquariums etc.
Precautions
- The glass cannot be cut or drilled after heat
strengthening. Any field alterations, including edge grinding, sand
blasting or acid etching may cause premature failure.
- Optics, As can be expected with any heat treated
glass, bow, warp and / or process roll distortion may be evident. This
is an inherent characteristic of the manufacturing process and is
within the limits set by ASTM Standard C 1048, or DIN 1249 Part 12
(See under 'Quality Control').
However,
there are many applications where heat-strengthened glass is not
sufficient, fully Tempered glass is still the only options.
Availability:
Maximum size: 2070 mm x 3660 mm 2440 x 3660 from July, 2001.
Minimum size: Dia. (diagonal) of 280mm (smaller sizes have to be heat-strengthened vertically.
Thickness range: 3 mm to 12 mm.
Colours: Clear, Green, Bronze, Grey, Blue, Reflective and Low-E.
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