... experience,OEM factory credit . 2.Approve ICQ inspection& obtain UKAS certification PDC core bit with (include any ... ( wireline core drilling and double-tube core drilling)1.Drill rod:BQ NQ HQ PQ 2.Core barrel: BQ ... NQ HQ PQ head assembly and core barrel parts 3. ... 160, φ170, φ219, φ27514. Chinese Standard Metric Core Bits for Double Tube Core Barrels: φ56, φ59, φ75, φ9115. ...