Assertion: furnace's hearth | /r/HasProperty | locked
Facets:
Source sentences:
text: If the skewback does not move upward during hot operation of the furnace, or if it wedges after rising and does not settle back when the furnace cools, the hearth is said to be "locked in".
text: If the hearth is "locked in" and does not slip, the skewback bricks will rotate, flattening the arch.