Cause Analysis of Crack Defects on ZG15Cr1Mo1V Casting Water Pressure Plug Valve of Steam Pipeline in Thermal Power Plant
The crack defect of casting water pressure plug valve is one of the typical problems in the metal supervision and inspection of thermal power.In order to explore the causes of crack defects and guide on-site inspection and defect treatment,the large-scale crack defects of ZG15Cr1Mo1V main steam and reheat hot section plug valve are studied from the aspects of material characteristics,structural characteristics,manufacturing process and service characteristics etc.The analysis shows that small original defects in the manufacturing stage expand to crack defects along with operation and service.The material characteristics and manufacturing process determine the tendency of original defects.Parting casting method leads to obvious difference of defects on both sides of valve body.The difference of crack defects in front and back of the valve body is caused by unilateral force in the hydraulic test.The transition region of the intersecting line and the mouth ring connection are easy to form shrinkage and micro-cracks.In addition,the transition area is mostly the stress concentration area,which leads to the enrichment and propagation of crack defects.The effect of temperature and pressure during manufacturing heat treatment and service stage promotes the formation and expansion of crack defects.
water pressure plug valveZG15Cr1Mo1Vcastingcrack defectscause analysis
万方数据
维普
