Drill Stem Sub
Drill stem sub is made from AISI4145H chrome-molybdenum alloy steel, the content of microelement is effectively controlled, the surface of connector thread has been phosphatized or copperized.
There are three types according to the 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
　
Function: Connecting and switching different drilling tools.
Features：The different size drill subs with standard SY5200－93 《Drill-stem Sub》and API Spec7 are available.
All products have been checked through ultrasonic non-damage inspection and the surface of connector thread has been copper coated, we can produce various specifications of Drill-stem Sub according to client’s request.