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Operating Procedures For Roller Cone Bits

running roller cone bit
  • New bits should be ordered without nozzles and stored in their boxes. Serial numbers and date of arrival should be recorded. Re-run bits should be cleaned and stored with pipe coating on the threads.
  • Before a new bit is run in the hole, the drilling representative should check the bit and confirm it is of the correct type and size and has no missing inserts or protruding seals.
  • Grease reservoir equalization ports should not be clogged.
  • The drilling representative should witness the installation of new nozzles. Never force a nozzle into the bit.
  • Measure nozzle size with a nozzle gauge.
  • The bit should be made up using a properly sized bit breaker.
  • The threads should be cleaned, greased and properly torqued.


  • The bit should be run slowly in the hole to get through ledges or restrictions which may be present in blow out preventers, casing leaks, whipstocks, liner hangers, casing patches and casing shoes. Hitting obstructions at high running speed can break teeth and damage bearings.
  • Bits should not be used to ream obstructions in casing and liner hangers or drill on junk.
  • When in the open hole the bit should be run with care in areas which were tight in the previous bit run. Tight holes may be reamed at low bit weight and high RPM and pumping rate. Excessive reaming can damage teeth on the outer row where all the bit weight is applied during reaming.
  • When the bit is on bottom, wash the last two joints and avoid running into fill which may plug the bit. Start the pump slowly and avoid pressure surges which could blow the nozzles out of the bit.
  • Start drilling with low weight and rpm for few feet to enable the bit establish a bottomhole pattern. Do not exceed the rpm and weight recommended by bit manufacturer.