Drilling Tools / Systems
There are several categories of horizontal directional drilling, which are based on the physical scale of the operation, including the size of pipes to be installed as well as the overall bore path distance and depths to be achieved. For example, mini-HDD, also know as "guided boring", is typically used for the relatively shorter distances, shallower depths, and smaller diameter pipes associated with local distribution lines, in comparison to maxi-horizontal directional drilling (maxi-HDD), typically used for longer distances, greater depths, and larger diameter pipes, such as major river crossings. Although the industry demarcations between the categories vary somewhat, mini-HDD is typically employed for placing pipes up to 12 inches diameter, and boring segments less than 600 feet in length, at depths up to 15 feet. Maxi-HDD is capable of accurately boring holes on the order of a mile in length, and placing pipes of 48 inches or greater, at depths up to 200 ft. Midi-HDD refers to equipment and technology of intermediate capabilities.