排水管套环 grommet-drain hose

气门导管套环 valve guide sleeve

热水管套环 grommet-hot tube

套管底环 casing shoe

套管环空 casing annulus

套管压紧环 casing hold-down ring ; down ring

套管-井壁环空 casing-hole annulus ; casing-to-hole annulus

筛管-套管环空 screen casing annulus

套管柱外环隙 casing clearance