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Easy Pipe used for long distance, large diameter pipes in difficult ground.

While the advantages and effectiveness of microtunneling and horizontal directional drilling (HDD) in suitable ground conditions have been widely used for more than 30 years, both systems have their limitations in some ground conditions and the relative cost terms. Herrenknecht AG has developed a new method for the trenchless installation that combines elements of both the microtunneling and HDD processes to overcome these limitations on longer distance, larger diameter bores in some of the more arduous ground types, particularly in more environmentally sensitive areas. The new process is known as Easy Pipe.

Herrenknecht's new Easy Pipe method has been developed to create a technology that will provide an economic no-dig solution for the installation of a pre-prepared and tested non-tensile pipeline with relatively large diameters of between 800 and 1,400 mm (32 and 56 inches) over comparably long installation lengths of between 500 and 1,000 m (1,650 and 3,300 feet) in difficult soil types such as gravel, rubble, rock, etc.


Easy Pipe installation requires a microtunneling unit to be prepared and assembled in the launch pit. The cutter head is launched and guided in the conventional microtunneling way along a planned alignment.

The difference between the jacking pipes used by Easy Pipe and conventional ones is that the special design allows them to be used as jacking pipes in the forward direction while allowing them to be retracted from the completed bore to pull in the product pipe. This is because the joints between the jacking pipe sections bolt together with a design that will withstand thrust and pullback forces of up to 6,300 kN (630 tons).The close proximity of the jacking pipes' outer wall to the bore wall also avoids the potential for collapse of the bore in unstable ground formations.

After the cutter head has reached the target pit, it is separated from the jacking pipe string and replaced by a specially designed connection pipe that also connects to the product pipe. The jacking pipes are then pulled back using the bi-directional jacking frame, simultaneously pulling the product pipe into position. In the launch pit the individual jacking pipes are successively removed along with all other equipment until the product pipe arrives at the launch shaft.

The connection pipe and jacking frame are removed from the pit leaving the product pipe in place to be finally connected to the remainder of the pipeline on either side of the obstacle(s) crossed. (253) 833-7366,

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Publication:Underground Construction
Date:Nov 1, 2006
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