胀管为开口薄壁套管；

The expanded tube is thin wall casing with open mouth.

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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。

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.

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第一和第二套管针活门定位在套管主体端盖内，并且各自在其中间部分具有开口。

First and second trocar valves are positioned within the cannula body end housing and each having an opening in a medial portion thereof.

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