Originally Posted by jes
I see. So, it is around the rim of the pan to form a seal between the pan and the lid.
What would make it "expandable"?
If the pressure in the pan gets high enough, it will blow the gasket out instead of blowing the pan lid off.
The flying lid and hot liquid are what are the danger. When the gasket blows, it allows the pressure to escape without harming anyone.
If that happens, the gasket should NEVER be reused. buy another one and install it on the pan.