Glass Cookware Failure Analysis: Pyrex Pie Plate Failure

Fracture Surface at One Failure Origin

Assembled Pie Plate Showing Several Failure Origins

Read Consulting Failure analysis lab performed a glass failure analysis. An annealed borosilicate glass Pyrex baking dish failed as a result “thermal shock”. There were multiple origins for the failure, and these all initiated at damage sites on the bottom of the Pyrex baking dish. Because the bottom of the pie plate was convex, setting the dish down and moving it on hard (abrasive) surfaces such as tile counter tops created a “rim” of damage. When the hot dish was placed on a cold surface,thermal shock created tensile stress  on the bottom of the dish, and this caused the failure to initiate at the several preexisting damage sites. This baking dish is appears old and shows signs of heavy use. 

"Scuff" Damage on the Pie Plate Bottom