Page 271 - Trenchless Technology Piping Installation and Inspection

Pr oject Considerations for Pipe Replacement Methods 235

FIGURE 6.5 The impactor process combines HDD with pipe bursting.
(Source: HammerHead ® .)

6.3.2 Impactor Method
The patented impactor method is a system that combines the HDD
method with pipe bursting, as shown in Fig. 6.5. The bursting head
(impactor) receives air through the HDD drill rod. The drill rod is
connected to an air supply and bores to an entry manhole. Then the
drill rod is pushed through existing pipe to the next manhole or exit
pit. Then, the impactor device, after it is attached to the drill stem and
to the new pipe, is activated and pulled into the existing pipe. While
pulling back, the impactor system bursts the existing pipe by com-
bined action—of pulling using the HDD rig and hammering with the
impactor device—breaking the existing pipe and replacing it with the
new pipe. The impactor system overcomes blocked existing pipes.
Contact Hammerhead Company for more details.

6.3.3 Pipe Ejection, Extraction, or Insertion
This method pushes or jacks a new pipe into the existing deteriorated
pipe. This system utilizes the columnar strength of segmented
“bell-less” jacking pipe to advance the “lead train” through the exist-
ing pipe. The lead train consists of five sections: the lead a heavy steel
guide pipe which maintains the alignment within the center of the
existing pipe; the cracker which fractures the existing pipe; the cone
expander which radially expands the fractured line into the sur-
rounding soil; the front jack, a hydraulic cylinder, which provides
axial thrust to the penetration/compaction pieces; and the pipe
adapter, which provides mating surfaces, linking the new pipe to the
front jack.
The last section, the pipe adapter, is fitted with a lubricant injec-
tion port where lubricant (polymer or bentonite) can be injected
into the annular space surrounding the new replacement pipe; the