This specification covers a limit for thermal residual stress in reusable annealed glass laboratory apparatus as determined by prescribed photoelastic measurement procedures. This specification recognizes that photoelastic measurements are proportional to the difference of the principal stresses. The stress limit shall be measured and calculated to meet the specified requirements.
1.1 Thisspecification covers a limit for thermal residual stress inreusable annealed glass laboratory apparatus as determined byprescribed photoelastic measurement procedures.
1.2 Inbroad classification, the laboratory glassware items covered bythis specification, but not limited to, are:
joints, balland socket or standard taper
tubes, colorcomparison (turbidity)
tubes,connecting and adapter
tubes,thistle (spray traps)
1.3 Thisspecification recognizes that photoelastic measurements areproportional to the difference of the principal stresses. The limitimposed represents a safety factor to cover a situation in whichone of the principal stresses may be larger than the apparentstress.
1.4 Thisspecification applies only to annealed glassware that is intendedfor sale as such. It excludes glassware that has been thermallytempered, ion-exchanged, or laminated with glass layers ofdiffering expansion. The intent of this specification is to limitthe residual stresses for safe consumer use in annealed glass, asit leaves the manufacturer.
1.5Stresses introduced by thermal expansion differences within theglassware are covered by this specification. Graded andglass-to-metal seals are excluded.