出生地 |
Heilongjiang China (Mainland) |
01 Design & working procedure Conform to the requirment of API Spec 7 02 Non-API standard type of drill collars are also available as per client'request 03 Cold-rolled thread roots 04 Thread connections are performed with stress relief grooves 05 phosphated threads applied 06 with elevator recess & slip recess and Sprial grooves