Drill collar is Gread 4145H
API standard
3-1/8 3-1/2 4-1/2 4-3/4 etc
Length from 9.15m-9.5m
Hot rolling or forging

Drill collar provide bitpressure for drill to makesure the drill pipe in tension, being the important tool to supporting drill and keep well trajectory with its greater stifness. The production of the drill collar adopt API Spec7-1 specification and SY5144 standard.

We could supply below collars.

3-1/8   3-1/2  4-1/2  4-3/4  5  6  6-1/2  7  8-1/2  9  10