The valve stem mainly has the a是鐵dvantages of being relatively照腦 compressible, capable of good heat但街 preservation, and less prone 哥下to corrosion and rust. It has 什購the sealing function of both sides, 拍近is relatively resistant to wear醫鐵, and its service life is relatively l又可ong. Then there are several reasons why間月 the valve stem is broken or 長錯deformed:
1. Area
The broken part of the valve stem i美秒s usually at the bottom 子這of its upper and lower thre短時ads, because the area of ​​that place筆月 is relatively small, an光北d the corresponding force conc好鄉entration and exceeding the st家內andard are prone to occur.北可
2. It breaks when openin家能g
Generally speaking, the mos跳短t likely occurrence of a broken va分化lve stem is the moment it is作東 opened. The main reason is tha分商t the gate has not separ湖關ated from the valve seat, an北子d the stem is broken at the西黃 root of the upper or lower thr喝懂ead. Under normal circumstan志快ces, it is considered that t輛刀he gate is stuck. This is not the whole書了 reason, and it is n票站ot the most importan西通t reason. .
3. Valve body
After the valve body is closed, abnorma近信l temperature rise and press銀錢ure drop occur, that is, after the 離綠valve is closed, the fluid press西鐵ure in the middle cavity機飛 enclosed between the upstream吧術 and downstream sealing surfaces is友自 much higher than the upstrea草科m pressure. The reasons are a分舞s follows:
(1) Expansion
(2) closed