The liner is to be molded in or captive boot design. Top and bottom stem bushings of dissimilar material are required with a positive retention mechanism for the stem.

• 衬垫材料采用模压进技术或捕获罩设计技术。如果阀杆存在机械阻力时,就需要对阀杆的顶部和底部采用不同的衬套。