According to actual needs. there are circulating sub with casing thread and circulating sub with union thread.
根据需要可分为套管螺纹循环接头和油壬螺纹循环接头(全规格)。
2
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。
3
Taking the conical thread as the object of study, a sub-pixel image detection method for the mechanical part linear edge based on the support vector regression was proposed.