Usage patterns
釜でご飯を炊くto cook rice in an iron pot
In the old days, people used to cook rice in an iron pot.
釜に火をかけるto put the pot on the fire
My mother put the pot on the fire and boiled water.
釜の蓋を開けるto open the lid of the pot
Once the rice is done, you open the pot's lid to let the steam out.
Expressions
同じ釜の飯を食うto be close friends; to have lived together; to share a deep bond