Heat Treatment of ZJSB drill collar adopts unique medium frequency inductance heating method for hardening and tempering,during which steel parts rotate continuously to get even heating.In the course of hardening,it adopts anular internal and external injection water cooling method to get even and high strength.Drilling collar material after whole length heat treatment could guarantee 285-341 Brinell hardness 1” below the surface of the pipe body.
ZJSB drill collar includes open faced,spiral groove,square,lopsided and pipe slips,elevator groove,wearing ring drill collar.The length of the drill collar could be 10 feet to 30 feet with 3-1/20’’ to 11” external diameter.Data information of common size refers to diagram.
NNCTM thread is the know-how of ZJSB and its thread could exchange with APIN thread reduces stress concentration of thread tooth base more obviously than NC thread so as to make distribution of ridge loaded on each circle evenly.NNC could effectively improve sub fatigue life and reduce fatigue failure of drilling tool.
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