Pilot Tube Microtunneling

Published: May 13, 2017 | Last updated: July 5, 2023

What Does Pilot Tube Microtunneling Mean?

Pilot Tube Microtunneling is defined as an alternate microtunneling system for sizes 8” through 18” and larger nominal internal diameter pipe. Pilot tube microtunneling is a multistage method which includes pilot tube boring. This method allows for accurately installing a product pipe to line and grade by use of a guided pilot tube, followed by upsizing to install the product pipe.


Trenchlesspedia Explains Pilot Tube Microtunneling

Pilot Tube Microtunneling is a multistage version of multiple trenchless methods. The main aspects of this installation process is putting a pilot tube on line and grade and then pipe-jacking steel casing into place followed by removal the spoils by auger excavation. This method is appropriate for softer soils and lengths up to 400 linear feet. The pilot tube method uses an auger boring unit and pilot tube guidance system, sized for microtunnelinng. The pilot auger is guided along the design pathway at the appropriate depth to ream the initial bore accurately.

The pilot tube method itself was originally a microtunneling method used to install small service lateralss. The process, initiated in a manhole, uses a theodolite — similar to a surveyor’s level — a camera mounted on the auger, an LED target and a computer and screen to provide the operator with information for a precision bore. As the auger/pilot rods emerge at the exit side of the bore, the rods are removed from the auger and the pipe is pulled through the bore.

The microtunneling process’ success has led to its application in larger bores to ensure that piping follows design pathways direction and grade with extreme accuracy.


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