A spare replacement sleeve should be placed on order when this valve is placed in service.
当阀门预备维修时应该订购备用更换套管。
2
The abrasion-resistant and rustproof sleeve is the only part exposed to the chain and the process, which results in a long service life minimal maintenance requirements.
这种耐研磨和不生锈套管是阀门中唯一与锚链接触的部件，因此阀门的使用寿命就更长，对维护的需求也更少。
3
Upon completion of the treatment, the service tool was repositioned to close the monitoring sleeve and the frac sleeve in one upward movement.