Page 478 - Trenchless Technology Piping Installation and Inspection

428 App endix D

Pilot bore: The action of creating the first (usually steerable) pass of any
boring process, which later requires back-reaming or similar enlarging
process to install the product pipe. Most commonly applied to horizontal
directional drilling but also used in pilot tube microtunneling and guided
auger boring systems.
Pilot tube method: See pilot tube microtunneling.
Pinch rollers: Used to control the thickness of the resin impregnated tube
during wet-out.
Pipe bursting: A pipe replacement method for breaking the existing pipe
by brittle fracture, using force from within, applied mechanically, the
remains being forced into the surrounding ground. At the same time a
new pipe, of the same or larger diameter, is drawn in behind the bursting
tool. The pipe-bursting device may be based on an impact moling tool to
exert diverted forward thrust to the radial bursting effect required, or by
a hydraulic device inserted into the pipe and expanded to exert direct
radial force or a static hammer. For new pipe, generally a HDPE pipe is
used, but currently PVC, ductile iron, clay and GRP is also used. Also
known as pipe cracking and pipe splitting.
Pipe displacement: See pipe bursting.

Pipe eating: A pipe replacement technique, usually conducted by use of
a horizontal directional drilling rig, in which a defective pipe is pulverized
during the backreaming operation. Also microtunneling machines
can be used where the existing pipe is excavated together with the
surrounding soil as for a new installation. The microtunneling shield
machine will usually need some crushing capability to perform effectively.
The defective pipe may be filled with grout to improve steering
performance.
Pipe jacking: A system of directly installing pipes behind a shield
machine by hydraulic jacking from a drive shaft, such that the pipes form
a continuous string in the ground.
Pipe ramming: A nonsteerable system of forming a bore by driving an
open-ended steel casing using a percussive hammer from a drive pit.
The soil may be removed from the casing by augering, jetting, or
compressed air.
Pipe reaming: A variation of directional boring, pipe reaming can be
used to replace existing clay, asbestos cement, non-reinforced concrete
and PVC pipe. A reamer is pulled through the existing pipe, which cuts
the pipe into small pieces. The pipe pieces are flushed out the borehole
with the drilling fluid.
Pipe segment: A specific portion of the sewer or pipeline system; which
usually runs between two structures (e.g., manhole, trap tanks, sumps);
identified with unique sewer or pipe structure ID number.