High Borosilicate 3.3 Glass Discs used in High Temperature View
Window
Contents:
SiO2%: 80.10
B2O3%: 12.16
Al2O3%: 2.53
K2O%: 0.10
Na2O%: 4.50
Chemical Resistance
Borosilicate glass 3.3 is resistant to chemical attack by almost
any product, which makes its resistance much more comprehensive
than that of other well-known materials. It is highly resistant to
deionized water, saline solutions, organic substances, halogens
such as chlorine and bromine and most acids. There are only a few
chemicals which can cause noticeable corrosion of the glass surface
namely hydrofluoric acid, concentrated phosphoric acid and strong
caustic solutions at elevated temperatures. However, at ambient
temperatures caustic solutions up to 30% concentration can be
handled by borosilicate glass without difficulty.
Borosilicate glass 3.3 can be classified in accordance with the
relevant test methods as follows (see also ISO 3585 and EN 1595):
Hydrolytic resistance at 98 ºC Hydrolytic resist. grain class ISO
719-HGB 1
Hydrolytic resistance at 121º Hydrolytic resist. grain class ISO
720-HGA 1
Acid resistance Deposit of Na2O < 100 mg/dm² to ISO 1776
Alkali resistance Alkali resistance class ISO 695-A2
PHYSICAL PROPERTIES
Borosilicate glass 3.3 differs from other materials of construction
used for process plant not only because of its virtually universal
resistance to corrosion (see above) but also because of its very
low thermal expansion coefficient. There is, therefore, no need for
expensive measures to compensate for thermal expansion resulting
from changes in temperature. This becomes of particular
significance in the layout of long runs of glass pipeline.
