Direct Pipe®
Direct Pipe® is a combination of the microtunnelling and HDD methods and was used
for the first time anywhere in the world by SONNTAG.
A steel pipe is completely prefabricated before pipe-laying begins and is laid out
in its full length behind the pipe thrusters.
The steel pipe, welded onto a conventional microtunnelling machine and gripped by
the Pipe Thruster`s clamping until, advances through the ground towards the destination
pit. The supply and waste removal lines necessary for the operation of the microtunnelling
machine are pre-installed in the pre-fabricated steel pipes. The tried-and-tested
gyro compass system in combination with a spirit level ensures spot-on-accuracy
all the way to the destination pit.
Advantages over the microtunnelling method:
- Tunnel advance time is significantly reduced as time-consuming coupling operations
for lengths of pipe are no longer required.
- The tunnelling machine and the entire pipe length can be completely withdrawn if
insurpassable abstacles are encountered.
Advantages over horizontal direct drilling:
- The product pipe itself (e.g. gas pipe) can be advanced directly. There is no need
first to drive a protective pipe.
- Only the gas between the product pipe and the bore wall is filled with bentonite
(in horizontal direct drilling, the full bore must be filled with bentonite)
- The very minimum amount of space is needed around the destination pit.
- The planned route is followed to the centimetre thanks to precise advance measurement.
- The tunnel cross-section opened out is permanently supported by the tunnelling machine
or the product pipe and its “bentonite jacket”.