The valve stem is used to open and close the closing member and transmit the sealing force. The opening and closing action of the valve is realized by the power device, the valve stem and the stem nut. In addition to the axial force, the valve stem also bears the torque of the transmission mechanism, and its force situation is more complicated.

Cause and treatment of valve stem head bending

Stemthreadsaremainlydividedintotrapezoidalthreadsandordinarythreads.Thethreadedfastenersonthevalvedirectlybearthepressureofthemedium,whichplaysanimportantroleinpreventingtheleakageofthemedium.Therefore,theselectedmaterialsmustensuresufficientstrengthandimpacttoughnessunderthevalve'soperatingtemperatureandpressure.Thesetwotypesofthreaddamagemainlyincludecorrosion,breakage,over-tighteningofthethreadpair.Inordertoensurethenormaluseofthevalvestem,thethreadofthevalvestemmustberepaired.Thesurfaceofthetrapezoidalthreadcanberepairedwithafileandsandedwithabrasivecloth;thethreadpaircanbecoatedwithabrasivepasteformutualresearchifthethreadpairistootight;andthecirclecanbetrimmedwithasmallfile.Forthedamagetothecommonthreadofthevalvestem,thereareseveralwaystorepairit.