HHF's drill collars are manufactured from 4145H mod steel. Drill collars are bored and drifted to API Spec 7-1 and fully heated to meet or exceed the mechanical property requirements of API Spec 7-1. Hardness range of 285-341HB and a sharp 'V' notch impact value of 54Joules are guaranteed one inch below the surface.
1. We adopts steel ingot from famous steel facotory in China, EAF or ESR steel.
2.Upon receipt of raw material, HHF's QC employees will die-stamp the exclusive serial number on both ends of material.
3. After each process, QC department will perform inspection, they will record the inspection result and keep the record according to the requirements of QMS.
4.We provide Mill certificate, includes Chemical compostition, Mechnical properties, UT test, MPI test etc
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