Operating principle at a glance:
Unbeatable: Direct Pipe® excavates the borehole and installs the pipeline in one single step.
Direct Pipe® in operation
Direct Pipe® is a one-step installation method for underground crossings in pipeline construction. A Pipe Thruster is used to push a prefabricated pipeline from a launch pit through the ground to the target point. The soil is excavated at the face by a tunnel boring machine.
In all projects so far, this new method has convinced our customers fully and beyond their expectations.
Efficient installation of pipelines for almost all geologies
The jacking system, consisting of a slurry-supported AVN microtunnelling machine and a Pipe Thruster, is assembled in the launch pit and welded to the prefabricated pipeline. Depending on the available space, the pipeline is laid out on roller blocks in sections that are as long as possible. While the AVN machine excavates the soil at the face, the Pipe Thruster generates the necessary jacking force to push the machine forward together with the pipeline.
Soil excavation and simultaneous installation of the pipeline in a single work step directly result in permanent support of the borehole. This enables safe tunnelling even in heterogeneous or permeable soils.
The excavation tools of the AVN Machine remove the soil
Hydraulic support using slurry suspension
Hydraulic slurry circuit through slurry pipes installed inside the pipeline
Pipe Thruster advances the AVN Machine through the pipeline
Pipeline
From the launch pit, the soil is excavated using a slurry-supported Herrenknecht Microtunnelling Machine (AVN).
Minimum foot print, maximum efficiency
The foot print of the equipment at the launch and reception points is very small with the Direct Pipe® method. Therefore, the technology can be implemented even in densely populated residential areas – simple, close-to-the-surface launch and reception pits are sufficient. It is no longer necessary to construct deep shafts. The microtunnelling machine is recovered in segments of approximately 3 meters in length after excavation is finished. In a final step, the supply and discharge lines are removed from the pipeline. The crossing is complete and the pipeline has been installed in one single step.
Functional principle
Sea outfall: environmentally friendly landfall in coastal areas
Direct Pipe® can be used for the landfall of offshore pipelines and wind farms. For this purpose, the tunnel boring machine with pipeline or protective pipe is driven out to sea from a launch pit on land. Once it has reached the destination, the tunnel boring machine is recovered from the seabed - the only maritime work step in a landfall. The machine is safely uncoupled using a specially developed recovery module. It can then be recovered using a floating crane or a lifting platform, or towed to the nearest port using buoyancy bodies.
Unique combination
By developing the Direct Pipe® method, Herrenknecht has achieved a breakthrough in pipeline installation. This combination of two already proven technologies has shown its value particularly in its high installation speeds. At the same time, the environment remains largely unaffected, mainly because the pipeline can be installed in one single step. Moreover, the method can be used practically in any ground condition.
Still got questions?
We are ready!
Steffen Dubé
President and General Manager Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser
Commercial Manager Herrenknecht Tunnelling Systems USA, Inc.