它是个上端为钻杆母扣或者由壬，下端为套管公扣，内空心的转换接头。

Its upper end is drill pipe box or union, the nether end is casing pin. It is a crossover with hollow inside.

youdao

它是个上端为钻杆母扣或者由壬，下端为套管公扣，内空心的转换接头。

Its upper end is drill pipe box or union, the nether end is casing pin. It is a crossover with hollow inside.

youdao