The casing bowl incorporates features to secure and seal the upper end of the casing string and frequently provides a port to enable communication with the annulus.

套管头四通包括固定和密封套管柱上端的部件，并经常提供一个用于与环形空间连通的开口。

youdao

Provide pin to avoid sealing at midway and protect seal part of packer, enhanced reliability of plugging string.

设计有防中途坐封的销钉，保护封隔器的密封件，提高了封堵管柱的可靠性。

youdao

Conventional connector for casing string can't meet the demand of seal and connection in solid expandable tubular and presented a new thread structure for an expandable casing connector.

传统的套管接头不能满足连接与密封要求，并设计出了一种新型的膨胀连接螺纹结构。

youdao

But Safin did not have to stretch himself much to seal the set, Lopez making a string of unforced errors to lose the tie-break 7-1 and fall 2-1 behind in sets.

BBC: Safin books meeting with Federer