井式炉是周期式作业炉，适用于杆类，长轴类零件的热处理。井式炉的结构是：炉身是圆筒形的深井，工件由专用吊车垂直装入炉内加热。所使用的燃料通常为煤气和燃油。以电为热源时，称为井式电阻炉。井式炉一般安置在车间地平面以下，也有安置在地平面以上的，或地平面之上之下各一半的。井式炉的名称有：强迫对流井式炉，自然对流井式炉，井式气体渗碳炉等。

The pit furnace is a batch-type operational furnace suitable for the heat treatment of rod-like and long-shaft components. Its structure features a cylindrical, deep-well furnace body, into which workpieces are vertically loaded for heating using a specialized crane. The fuels commonly used are coal gas and fuel oil. When electricity serves as the heat source, it is referred to as an electric pit resistance furnace. Pit furnaces are generally installed below the workshop floor level, though some are positioned above it, or half above and half below. The types of pit furnaces include forced convection pit furnaces, natural convection pit furnaces, and pit-type gas carburizing furnaces, among others.