Drill-stem sub is the essential part during the drilling operation of petroleum, natural gas and geology exploration. It is one of the main parts of drill stem. It performs the function of connection and switching in drills of different specifications.

We can produce diverse ranges of drill-stem subs which are linked with drill collars, drill pipes, kellys and taps. Besides, we can supply connection slip blank. Drill-stem Sub is made from AISI4145H chrome-molybdenum alloy steel. The content of microelement is effectively controlled. Special heat treatment and ultrasonic non-damage inspection are applied. Therefore, our Drill-stem Sub has the advantages of high strength, pretty toughness, long life, and so on. The surface of connector thread has been phosphorized or copperized, which makes its anti-buckle performance excellent. Its mechanical properties have met the standard of API Spec7.

There are three types according to its shapes and functions:

a (same diameter): one sub has only one OD size

b (different diameters): one sub has two OD sizes

c (left hand): sub's connecting thread is left-handed