... inspection& obtain UKAS certification PDC core bit with (include any size and oversize)China Drilling Geological Equipment ltd., is ... B76, B86, B101, B116, B131, B14613. Chinese Standard Metric Core Bits for Single Tube Core Barrels: φ36, φ46, φ56, φ59, ... Chinese Standard Metric Core Bits for Double Tube Core Barrels: φ56, φ59, φ75, φ9115. Chinese Standard Metric Core Bits for Wireline Core Barrels: ...