Boart Longyear

Double Head Drilling Flushing Heads

Double head drilling systems have a flushing system to introduce flushing media into the inner drill string at the upper rotary head or drifter. Flushing media exits the drilling system at the ejection bell mounted below the lower rotary head. These flushing heads are uniquely designed for the specific double-head drilling system, the head mounting, and the sizes of the tools being used for the job.

Components used in and with the Drive Drilling Flushing head include the following.

Flushing body
The flushing body of the flushing head on a dual head drilling system mounts either on the top rotary head (on a rotary-rotary system) or below the drifter (on a rotary-percussive system). In both cases the flushing body is matched to the specific rotary head or drifter of the drilling system.

Flushing ring and seals
The flushing ring is held stationary by the mounting bracket fixed to the drifter while the flushing body rotates. The flushing ring is the connection point for the flushing hose and has upper and lower lip seals to contain the flushing media. The TwinDrive™ thread is used for both the balance rod and flushing bell. The TwinDrive thread makes it easier to unscrew the balance rod or flushing bell and is better at withstanding the percussive forces from the hydraulic drifter.

Balance rod
The balance rod in a double-head drilling system is used to connect the inner drill string of the system to the upper rotary head or drifter. The length and thread on the rod is specific to the drilling system being used. Length of the balance rod must be specified at the time of order.
The mounting bracket, which is matched to the hydraulic drifter, keeps the flushing ring stationary on the flushing body.

Ejection bell
The ejection bell in dual head drill systems is mounted directly under the lower rotary head. The ejection bell design is unique to the rotary head it is used on. Flushing media and cuttings exit the drilling system through the large opening in the ejection bell.

Casing flange
The casing flange is the connection point for the outer casing used in the drilling system. It is mounted directly to the ejection bell and has a thread to match the casing being used.