Street Address: Jiyuan
City: Jiaozuo
Province: Henan
Country/Region: China
Oil Drilling
According to API Spec.7 and SY/T5144, drill collar is made of AISI 4145 modified chromium- molybdenum alloy steel. All threads are phosphated, copperized or cold rolled , and they are machined with CNC Lathes –Double –shoulderd, including some special threads. The maximum outer diameter of drill collars can amount to 14 inch.