HDD Hammer Reamers
SPM HDD hammer reamers are used after the pilot bore has been established to enlarge the hole through hard rock formations. The reaming hammer combines down-the-hole impact energy with drill-string rotation, allowing the bore to be opened progressively while reducing the rotational load required for rock breaking.
The current HDD hammer reamer covers 254-457 mm reaming diameters with a 185 mm hammer OD, API 3 1/2 REG pin top sub connection and a minimum pilot bit diameter of 140 mm.
HDD hammer reamers are used for bore enlargement in hard-rock trenchless drilling after the pilot hole is completed. They are suited to directional crossings for underground pipelines, utilities and other infrastructure where the bore must be enlarged through competent or abrasive rock before installation.
During reaming, compressed air powers the hammer at the bottom of the bore while the drill rig rotates and pulls the reaming assembly through the pilot path. Percussive impact breaks the rock at the cutting face and rotation distributes the cutting action around the bore, allowing the hole diameter to be enlarged with lower rotational demand than rotary cutting alone.
The current reamer configuration is designed around a 185 mm hammer body and supports bore enlargement from 254 mm to 457 mm. Confirm the required final bore diameter, pilot-hole size, drill-string connection and compressor output before selection.
| Reaming Diameter | Hammer OD | Top Sub Thread | Effective Length | Pilot Bit Diameter | Air Consumption |
|---|---|---|---|---|---|
| 185 mm | API 3 1/2 REG pin | 1025 mm | ≥140 mm | 35 m³/min @ 24 bar |
Selection should start with the required final bore diameter and the existing pilot-hole size. The drill-string connection, available compressor output, rock hardness and abrasiveness should then be checked so that the reamer, pilot system and drilling rig operate as a matched setup.