液压密封 meaning in Chinese

hydraulic seal
hydroseal

Researching to hydraulic seal device
液压密封装置的探索
Specification for dimensions of housings for hydraulic seals for reciprocating applications
往复运动的液压密封件壳体尺寸规范
Non destructive testing of steels tubes . part 1 : automatic electromagnetic testing of seamless and welded except submerged arc welded ferromagnetic steel tubes for verification of hydraulic leak - tightness
钢管的无损检验.第1部分:检验液压密封性用无缝和焊接铁磁钢管