Description: It's made from rolled or forged AISI4145H chrome-molybdenum steel. The content of chemical composition and microelement is controlled efficiently throughout the whole process.

According to its different figures and materials, it can be divided into three types:

Type A (columnar) : made from ordinary alloy steel, both inside and outside of the cross section of the pipe are cyclical.

Type B (spiral): made from ordinary ally steel, with a spiral chute on the outer surface of the pipe.

Type C (non-magnetic): made from stainless alloy-steel of low magnetic permeability, both inside and outside of the cross section of the pipe are rounded.

Main Functions: it's one of the most important components of drill stem. It can provide the bit with bit weight and improve the rigidity of drill stem.

It's in accordance with the standard of SY/T5144-1997 or API SPEC.7-1.