The “ADT” Underreamer is a tool that allows to enlarge a hole previously drilled at the depths wanted in soft – medium soft formation.
The tool features 2 or 3 expendable arms that are kept retrieved during descent into the hole.
The arms are pushed out in drilling position by the mud pressure or compressed air that passes through a tungsten carbide nozzle situated on the top of the reamer.
In order to pull out the tool, you must simply unpressurize and apply pull, the arms will easily reengage to stand-by position.
The body is made of AISI 4145-H 285/341 Brinnel hardness.
Arms in T1 steel with tungsten carbide hardfacing – Hardcoloy.