Dual wall drill pipe is a drill tool that uses directly driven internal drill rod based on the horizontal directional drilling machine, in which, the torque was transmitted to the drill bit directly by the drill rod and the push-full force was conveyed to the drill bit directly through the external drill rod, and the internal and external drill rods work simultaneously to achieve straight drilling and when directional drill is required, the internal and external drill rods will stop working and after optimum angle is available, the external drill rod will achieve directional drill and later, the internal and external drill rod will work together to achieve straight drilling and finally directional drilling of rock will be accessible.

• Single rotary head, with simple mechanical structure.
• The single rotary head adopts hydraulic servo, simpler than dual rotary head and easy for installation and dismantling of the external drill rod.
• The internal drill rod uses square plug connection, which can be plugged in and drawn out directly and the workers could only operate the hydraulic vice to install and dismantle the internal drill rod, which is energy and time saving.
• Dual wall drill pipe has a simple mechanical and hydraulic system, which is more cost effective in both the production and renovation of the machine as compared with the internal threaded connection.
• The dual wall drill pipe features quick drilling speed, high production efficiency, with the drill depth available in 9-10m per hour in 60MPA rocks and the drilling efficiency more than doubled, while the traditional drilling only achieves around 4m.
• No external pump is required for drilling work and it also occupies less construction area and features low mud consumption, while the traditional drilling process will have mud consumption up to 1.5 cubic meters/min, and dual rod for 0.3-0.4 cubic meters/min.
• It has precise directional effect, which can equal to directional precision of the soil layer.

Case 1
Drilling tube: 100m, 200-PE pipe.
Limestones, rock hardness: 60Mpa.
Directional drilling: 13 hours.

Case 2
Drilling tube: 180m, 200 PE pipe.
Limestones, rock hardness: 60Mpa.
Directional drilling: 15 hours.

Case 3
Drilling tube: 150m, 110-4 holes pipes.
Mud stone, rock hardness: 10Mpa.
Directional drilling: 8hours.