What are the symptoms before the intermediate frequency furnace is worn?

1. Observe the thickness distribution of the inner wall of the furnace, and probably understand the part that will be perforated.

2. After pouring out each furnace of molten iron, observe whether there are any black marks on the inner wall.

3. Apply sand patch to the black spotted area before using it.

4. For safety, stop using the intermediate frequency furnace if you are not sure.