Possible failure reasons of the failure of flange connection part of the leakage of flange connection bolts eliminate method not tight or slack uneven. Tighten bolts evenly gasket failure to replace gasket between the flange sealing surface is clean dirt off the flange leakage gland packing deviation should be no loose or gland pressure tight packing gland evenly on failure to replace the new packing sealing surface leakage between the sealing surface with dirt cleaning the sealing surface sealing surface damage to grinding stem rotation is not flexible packing gland packing too tight and adjustment of looseness between stem and stem nut have sundry jam, threaded parts damaged pieces clean or repair damaged thread electric actuator failure according to instruction manual check and repair