The landing is thread connected with stop ring and tightened on and put into downhole with drill string. The landing sub is used as a sub above drill string before check valve is run in downhole.

就位接头与止动环用螺纹联结并上紧扣和钻柱连接下入井内，在未投入止回阀时作为钻柱上的一个接头。

youdao

The landing is thread connected with stop ring and tightened on and put into downhole with drill string. The landing sub is used as a sub above drill string before check valve is run in downhole.

就位接头与止动环用螺纹联结并上紧扣和钻柱连接下入井内，在未投入止回阀时作为钻柱上的一个接头。

youdao