The steam trap is an automatic control device that automatically discharges condensate from a closed system in which steam is stored while keeping fresh steam from leaking. It also allows steam to pass through at a predetermined flow rate if necessary. In modern society, steam is widely used in industrial and agricultural production and living facilities, nuclear power plants are no exception. The condensate produced in the process of heating, drying, heat preservation, disinfection, cooking, concentration, heat transfer, heating, air conditioning and so on, whether in the steam transmission pipeline system or in the process of using steam for heating, drying, heat preservation, disinfection, cooking, condensation, heat exchange, heating, air conditioning, etc., needs to be removed through steam traps and is not allowed to leak out.

Steam traps can be divided into three types according to the driving mode of the opening and closing parts; mechanical steam traps driven by the change of condensate level; thermostatic steam traps driven by the change of condensate temperature; and thermodynamic steam traps driven by the dynamic characteristics of condensate.

Steam trap is an important accessory in the steam use system. Its performance plays an important role in the normal operation of the system, the improvement of equipment thermal efficiency and the rational use of energy.