The mechanical properties and lifespan of products made of SIMAX glass depend partly on the level of their finishing, especially as a whole, i.e. deep damage on the surface by handly and subsequent thermal load deteriorated the lifespan.
cooling SIMAX glass
Cooling is a thermal process with the purpose of preventing the generation of undesirable and inadmissibly high thermal stress in the glass that would decrease the product resistance and/or remove any existing stress.
The cooling cycle involves three stages:
I. Temperaure growth (product heating) with heating rate from feeding temperature to the upper cooling temperature.
II. Persistence for a certain period (lag, temper, stabilization) of products on the upper cooling temperature, with the temperature differences in the product need to be balanced out, including a decrease in the stress to a permissible limit.
III. Temperature decrease (cooling and after-cooling) with the cooling rate from the upper to the lower cooling temperature (this stage is important because permanent stress might be generated), and from the lower cooling temperature to the final temperature or ambient temperature (important for subsequent practical manipulation with the product).
permissible stress with inner overpressure
Permissible inner overpressure in glas pipping and equipement depends on nominal inner diameter, shape, operating temperature, material of connecting parts, and type of gasket used. In case of an apparatus assembled from parts of different inner diameters and shapes, the permissble stress by inner overpressure is always givven by the part of the lowest permissble stress.
The operating values of liquid overpressure at a temperature difference between the inner ans outer wall t = 5°C ( and temperatures up to 120°C) are:
table of the permissble overpressures for "T"-pieces and crosses
The pressure shocks caused by running pumps or fittings should not exceed the maximum operating pressure of the piping, the piping must be protected (safety valves, receivers, etc.)
permissble stress by inner underpressure
Permissble stress of the apparatus by vacuum depends on shape stability of large glass parts, operating temperature, material of connecting parts and type of gasket used. Long-term process experience has proven that an appratus can be safely operated with the underpressure corresponding to the absolute pressure of 0.0015-0.0020 MPa.