... credit . 2.Approve ICQ inspection& obtain UKAS certification PDC core bit with (include any size and oversize)China Drilling Geological ... exploration and hydrapower station grouting project ( wireline core drilling and double-tube core drilling)1.Drill rod:BQ NQ HQ PQ ... 130, φ160, φ170, φ219, φ27514. Chinese Standard Metric Core Bits for Double Tube Core Barrels: φ56, φ59, φ75, φ9115. Chinese Standard ...