Definition - What does Barrel Reamer mean?
Barrel reamers are barrel-shaped reamers that are used to expand the pilot bore in a horizontal directional drilling (HDD) operation in order to allow the required diameter of the pipe to be pulled in.
These reamers have tapered closings that are edged with chisels on the conical surface that enlarge the hole for the body of the barrel reamer to pass through. HDD operations are carried out by drilling a pilot bore from the entry to the exit point. Once the pilot bore is complete, reamers are used to upsize the diameter of the borehole.
Trenchlesspedia explains Barrel Reamer
Barrel reamers are used in soft ground and help to compress the surrounding soil to leave a clean hole for the pipe to be pulled in. The reaming process with a barrel reamer can be slow because of the compression process. The mud slurry flows to the rig's side because the reamer acts as a plug right behind the cutting nozzles. The central mandrel of the reamer carries pipe connections and the face of the reamer is fitted with jet nozzles and teeth to facilitate cutting.
The barrel reamers are also provided with nozzles and teeth on the back in case of the necessity to back out of the hole due to blockage in the progress of the reamer. Sometimes, this reamer is also used as a leading tool while pulling the pipe through a hole that has already been reamed.