The pipe supports surrounding the valve must be loose and the adjoining piping must be well aligned with the valve.
环绕阀门的管道的支架必须放松，毗连的管道必须要很好的对准阀门。
2
Blow out lines to remove all loose scale and other foreign matter that can damage valve seat.
向管道吹气，清除所有疏松鳞锈和可能损害阀门阀座的其他外部杂质。
3
The reasons are: different top heights of valve rods having the same names; loose adjustment nuts or adjustment screws moving; and big clearances between valve guides and valve rods.