Wear Tests Approximating to Practical Experience on Materials Used for High-Pressure Control Valves in Contact with Water in Power Stations

摘要

The relative wear behavior of 14 possible materials for heavily loaded injection control valves is determined with the aid of a nozzle plate exposed to rapidly flowing water (about 200 m/s) in the feedwater system. The aim of the investigations was to find a replacement material for the previously used three-stage valves made of precision stellite 6 casting. Precision stellite 6 casting exhibits the greatest material erosion with both alkaline and combined operation. The hardness or strength of a material usually determines its wear behavior. In the case of heavy flow stressing material inhomogeneities have a marked effect on the erosion. The corrosive properties of the medium, oxygen concentration and pH are of secondary importance. Hence it is important to pay special attention to the homogeneity of the material of control valves contacted by water and subject to high loads ( delta /sub p/ > 40 bar). (ERA citation 11:013687)