Note: Descriptions are shown in the official language in which they were submitted.
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PIPE BURSTER WITH SPHERICAL BURSTING MEMBER
FIELD OF THE INVENTION
[0001] This invention relates generally to preparation for trenchless
replacement of
old pipe, and in particular to the bursting or cutting ofsubterranean pipe to
allow the insertion
of new pipe therein,
SUMMARY OF THE INVENTION
[00021 The present invention is directed to a pipe-burstitng apparatus for use
with a
drill string. The pipe-bursting apparatus comprises a frame connectable with
the drill string
and at least one substantially spherical pipe-bursting member. The spherical
pipe-bursting
rnember is supported by the frame and operable in response to movement of the
drill string.
[0003] The present,invention further includes a horizontal directional
drilling system.
The horizontal directional drilling system comprises a drivo machine, a drill
string having a
first end and a senond end, and a pipe-bursting apparatus. 'I'he first end, of
the drill string is
operatively connected to the drive machine and the pipe-bursting apparatus is
operatively
connected to the second end of the drill string. The pipe-bursting apparatus
comprises a
frame operatively connected to the drill string and at least one
substantially, spherical pipe-
bursting member. The spherical pipe-bursting member is supported by the frame
and
operable in response to movement of the drill string.
[0004] Finally, the present invention includes a method for bursting pipe
using a
horizontal directional drilling system. 'fhe horizontal directional drilling
system includes a
rotary drive machifie, a drill string having a first end and a second end, and
a pipe-bursting
apparatus operatively connected to the second end of the drill string. The
first end of the drill
string is operatively connected to the rotary drive machine. The pipe-bursting
apparotus
comprises a frame and a spherical pipe-bursting member supported by the frame.
The
method comprises operating the spherical pipe-bursting member by rotating the
dril l string.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a dingrammatic representation of a near surface horizontal
directional
drilEing machine acting on an uphole end of a drill string that,. in turn,
supports a
pipe-bursting apparatus constructed in accordance with the presertt invention
connected to a
replacement pipe.
[0006] FIG. 2 is a fragmented, side elevational, partly sectional view of a
pipe section
used with a dual-member drill string.
[00101 FIG. 3 is a fragmented, side elevational, partly sectional view of a
preferred
rotary drive machine used with the prasent invention.
[0011] FIG. 4 is a side elevational, partly sectional view of a first
embodiment of the
pipe-bursting apparatus usable with a single-member drill string. A plurality
of spherical
pipe-bursting members are shown disposed about the circumference of the
apparatus.
[0012] FIG. 5 is a side elevational, partly sectional view of another
embodiment of
the pipe-bursting apparatus of the present invention that is also usable with
a single-member
dr3ll string. The apparatus of FIG. 5 shows the plurality of spherical pipe-
bursting members
disposed longitudinally along the axis of rotation of the pipe-bursting
apparatus.
[00131 FIG. 6 is a side elevational, sectional view of yet another embodiment
of the
present invention usable with a dual-member drill string. The pipe-bursting
apparatus of
FIG 6 is shown having a plurality of recirculating spherical pipe-bursting
rnernbers. The
recirculating action of the spherical pipe-bursting members is driven by
rotation of the inner
member of the dual-member drill string.
[0014] FIG. 7 is a side elevational, sectional view of an alternative
embodiment of the
present invention. The embodiment of FIG. 7 uses the inner member of a dual-
member drill
string to drive movement of longitudinally aligiied spherical pipe-bursting
menibers. The
pipe-bursting apparatus also has a pair of oppusing Cutting members used to
cut the in situ
pipe.
[0013] FIG. 8 is a fragmented, side elevational, partly sectional view of an
alternative
pipe-bursting apparatus. The apparatus of FIG. t has a plurality of spherical
pipe-bursting
members and a percussive tool operatively connected to the pipe-bursting
apparatus.
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[0016] FIG. 9 is a side e.levational view of a pipe-bursting apparatus of the
present
invention. The apparatus of FIG. 9 has a plurality of spherical pipe-bursting
members and a
cutting member connected to the frame of the apparatus. Operation of the
cutting member is
driven by a rod supported by the frame.
[00171 FIG. 10 is a side elevational view of a pipe-bursting apparatus of the
present
invention. The pipe-bursting apparatus of FIG.. 10 has a plurality of
spherical pipe-bursting
members disposed about the outer circumferenee of the frame of the apparatus.
Operation of
the pipe-bursting members of FIG. 10 is driven by a race connected to a
rotatable rod
supported by the frame.
[00181 FIG. 11 shows yet another embodiment of the present invention having a
plurality of spherical pipe-bursting members. The a.pparatus of FIG. 11 has an
eccentric cam
supported by the rotatable rod. The cam is shown in a position to cause
advancement of a
portion of the spherical pipe-bursting members from the frame.
[0019) FIG 12 is a side elevational, sectional view of an alternative
embodiment of
the apparatus shown in FIG 11. The apparatus of FIG. 12 has a flywheel that
causes
vibration of the spherical p.ipe-bursting members.
[0020] FIG. 13 is a side elevational view of an embodiment of the pipe-
bursting
appatatus of the present invention. The apparatus of FIG. 13 is shown
operatively connected
to the downhole end of a dual-member drill string. The apparatus comprises a
biasing
member adapted to offset the pipe-bursting apparatus from the centerline of
the in situ pipe.
[0021] FIG. 14 illustrates an alternative embodiment of the pipe-bursting
apparatus of
FIG. 13. The apparatus of FIG. 14 is connectable with the downhole end of a
dual-member
drill string such that the longitudinal axis of the frame is offset from the
longitudinal axis of
the dual-member drill string. FIG, 14 further illustrates the use of a gearing
arrangement to
translate rotation of the inner member of the drill string to rotation of the
rotatable rod.
DETAILED DESCRIPTION OF THE PREFERRBD EMBODIMENTS
[0022] Trenchless replacement of in situ or existing subterranean pipelines
provides
an efficient and cost effective way of replacing aged pipe and/or expanding
the capacity of
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existing pipe. Several devices have been developed to accomplish these
objectives.
However, there remains an ongoing need for improved pipe replacement tools.
[00231 Turning now to the drawings in general and FIG. I in particular, there
is
shown therein a horizontal directional drilling machine 10. FIG. I illustrates
the usefulness
of horizontal directional drilling by demonstrating that a replacement pipe 12
can be installed
without the need for digging an open trench along the desired path. To install
the
replacement pipe 12, a drill string 14 is inserted through the old pipe 16 and
emerges from an
exit pit 18. The downhole end 20 of the drill string 14 is then coupled to a
pipe-bursting
apparatus 24 and the replacement pipe 12. The replacement pipe 12 is towed
through the
existing borehole 22 behind the pipe-bursting apparatus 24 as the old pipe 16
is burst 26.
[0024) Considerable force is necessary to burst the old pipe 16 and pull the
new
pipe 12 through the burst pipe 26. As used herein, "burst" or "pipe-bursting"
means bursting,
cuttin.g, fragmenting, expanding or any other action which ruptures the old
pipe 16 to permit
replacement thereof. The present invention is directed to devices and methods
for improving
pipe-bursting and old pipe replacement operations.
[00251 The horizontal directional drilling machine 10 generally comprises a
frame 28
for supporting a drive machine 30. The drive machine 30 is movably supported
on the
frame 28 between a first position and a second position. Movement of the drive
machine 30,
by way of an axial movement means (not shown), between a first position and a
second
position axially retracts or advances the drill string 14 and a pipo-bursting
apparatus 24
through the borehole 22.
[00261 The drill string 14 is operatively connected to the drive machine 30 at
an
uphole end 32. The pipe-bursting apparatus 24 is coupled to the downhole end
20 of the drill
string 14. In the present invention the drill string 14 transmits torque and
axial force to the
pipe-bursting apparatus 24 to break-up the old pipe 16.
100271 In accordance with several aspects of the present invention, the term
drill
string may either mean a single-member drill string or a dual-member drill
string. Any drill
string capable of transmitting torque and/or axial force to the pipe-bursting
apparatus may be
used.
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10028] 'Itirning now to FIG. 2, there is shown one of a plurality of dual-
member pipe
sections 34 comprising a dual-member drill string 14. The dual-member pipe
section 34
comprises a hollow outer member 36 and an inner member 38 positioned
longitudinally
therein. The inner member 38 and outer member 36 are connectable with the
inner members
and outer members of adjacent dual-member pipe sections to form the dual-
member drill
string. 14 (FIG. 1). The interconnected inner members may be independently
rotatable of the
interconnected outer members to drive operation of the pipe-bursting apparatus
24.
[0029] The outer member 36 is preferably tubular having a pin end 40 and a box
end 42. The pin end 40 and the box end 42 are correspondingly threaded. The
pin end 40 is
provided with tapered external threads 44, and the box eiid 42 is provided
with tapered
internal threads 46. Thus, the box end 42 of the outer msmber is connectable
to. the pin
end 40 of a like dual-member pipe seotion 34. Similarly, the pin end 40 of the
outer
member 36 is connectable to the box end 42 of a like dual-member pipe. section
34.
[0030] The external d'cameter of the pin end 40 and the box enc142 of the
outer
member 36 may be larger than the external diameter of the central body portion
48 of the
outer member. The box end 42 of the outer member 36 forms an enlarged internal
space 50
for a purpose yet to be described.
[00311 The inner member 38 is preferably elongate. In the preferred dual-
member
pipe section 34, the inner member 38 ]s integrallyformed and comprises a solid
rod.
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However, in some instances a tubular inner member 38 may be preferred for the
transportation of drilling fluid along the inner member of the drill string.
[0032] Preferably, the inner member 38 of the dual-member pipe section is
provided
with a geometrically-shaped pin end 52 and with a box end 54 forming a
geometrically-
shaped recess corresponding to the shape of the pin end 52 of the inner member
38. As used
herein, "geometrically-shaped" denotes any configuration that permits the pin
end 52 to be
slidably received in the box end 54 and yet transmit torque between adjacent
pipe sections 34.
The geometrically-shaped pin end 52 and box end 54 prevent rotation of the pin
end 52
relative to the box end 64 when thus connected. A preferred geometric shape
for the pin
end 52 and box end 54 of the inner member 38 is a hexagon. The box end 54 of
the inner
member 38 may be pinned, forged, welded or attached to the inner member by any
suitable
means.
[0033] The pin end 52 of the inner member 38 is disposed within the box end 42
of
the outer member 36. It will now be appreciated that the box end 42 of the
outer member 36
forms an enlarged internal space 50 for housing the pin end 52 of the inner
member 38. This
arrangement facilitates easy connection of the dual-member pipe section 34
with adjacent
pipe sections, the drill string 14, and the drive machine 30.
[0034] Turning now to FIG. 3, the drive machine 30 for driving operation of
the
pipe-bursting apparatus 24 is shown in~more detail. Because the outer member
36 and inner
member 38 rotate independently of each other, the drive machine 30 may have
two
independent drive groups for driving the outer members independently of the
inner members.
It will be appreciated that while the drive machine of FIG. 3 will be
described for use with a
dual-member drill string, a similar drive machine 30 having only one drive
group may be
used to drive rotation of a single-member drill string.
[0035] The drive machine 30 thus preferably comprises a carriage 56 supported
on
the frame 28. Supported by the carriage 56 is an outer member drive group 58
and an inner
member drive group 60. The outer member drive group 58 drives the outer member
36. The
inner member drive group 60 drives the inner member 38. The drive machine 30
also
comprises a biasing assembly 62 for urging engagement of the pipe sections. A
suitable drive
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machine 30 having an outer member drive group 58 for driving the outer member
36, and an
inner member drive group 60 for driving the inner member 38 is disclosed in
more detail in
U.S. Pat. No. RE 38,418, the contents of which are incorporated herein by
reference.
[0036] Turning now to FIG. 4, there is illustrated therein a first embodiment
of the
pipe-bursting apparatus 24A for use with the previously described horizontal
directional
drilling system 10. The pipe-bursting apparatus 24A includes a frame 64 having
a first
end 66 and a second end 68 and a longitudinal axis 69. As seen in FIG. 4, the
frame 64 of the
present embodiment may generally be characterized as a conical housing which
supports at
least one substantially spherical pipe-bursting member 70. Preferably, a
plurality of pipe-
bursting members 70 are supported by the frame and disposed about the outer
circumference
of the housing. The pipe-bursting members 70 are disposed about the outer
circumference of
the frame 64 in a plane substantially perpendicular to the longitudinal axis
69 of the frame.
[0037] As illustrated in FIG. 4, the frame 64 is substantially conical such
that the
diameter of the housing increases from the first end 66 to the second end 68.
Preferably, the
greatest diameter of the frame is greater than the largest internal diameter
of the old pipe 16.
The large diameter of the housing forces fragments 26 of the old pipe 16 into
the surrounding
soil and allows for the replacement pipe 12 to be drawn into the borehole 22.
The frame 64
may be constructed to include a connection member 72 to allow towing of the
replacement
pipe 12 (FIG. 1) into the borehole 22. An expander known in the industry may
be used
between the apparatus and the replacement pipe to facilitate installation of a
larger
replacement pipe.
[0038] In FIG. 4, the apparatus 24A is shown with a rod 74 supported by the
frame
64. The rod 74 has internal threads 76 to provide a connection to the drill
string 14 that is
capable of transmitting torque from the drill string to the pipe-bursting
apparatus 24A for
rotating and positioning the apparatus within the borehole 22. Thus, the rod
74 is fixed to the
frame 64 so that rotation of the drill string 14 is transmitted to the frame.
Rotation of the drill
string 14 and the pipe-bursting apparatus 24A will drive operation of the
spherical pipe-
bursting members 70 in a manner yet to be described. The rod 74 may have an
internal
passage 78 for transporting drilling fluid from the drill string 14. Outlet 80
is provided so
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that drilling fluid transported through the drill string 14 and into the rod
74 may exit the
apparatus into the borehole 22. Fluid outlets may also be directed to the
spherical pipe-
bursting members 70 for lubrication and cooling.
[0039] The frame 64 may have a plurality of host pipe cleaning elements 82
supported at the first end of the frame. The pipe cleaning elements may be
carbide cutting
elements adapted to remove obstructions and/or debris from the interior of the
old pipe 16
before the old pipe is burst by the pipe-bursting members 70. . Spoils
produced by the
cleaning elements 82 are washed away by drilling fluid exiting outlet 80. '
[0040] The spherical pipe-bursting members 70 are supported in a track 84 that
extends generally around the frame 64 so that the spherical pipe-bursting
members are
disposed about the circumference of the frame in a plane substantially
perpendicular to the
longitudinal axis 69 of the frame. The apparatus 24A of FIG. 4 may have
multiple tracks
disposed around the circumference of the frame 64. Two tracks 84 are shown in
FIG. 4 to
support the plurality of spherical pipe-bursting members 70 in two separate
planes that are
perpendicular to the longitudinal axis 69. The tracks 84 are formed to retain
the spherical
pipe-bursting members 70 within the tracks during operation of the apparatus
24A. However,
the spherical pipe-bursting members 70 may be sized so that they are capable
of movement
within the tracks 84 as the apparatus 24A is rotated by the drill string 14
and within the old
pipe 16.
[0041] In operation the drill string 14 is rotated by the drive machine 30.
Rotation of
the drill string is transmitted to the pipe-bursting apparatus 24A by the
threaded
connection 76. As the pipe-bursting apparatus 24A is rotated, the drive
machine 30 also
applies axial force to the pipe-bursting apparatus by either pulling or
pushing the apparatus
through the old pipe 16. The axial movement and rotation of the pipe-bursting
apparatus 24A
causes the pipe-bursting members 70 to roll within the tracks 84. The rolling
action of the
pipe-bursting members 70 as they engage the old pipe 16 converts much of the
rigid pull or
push load exerted on the pipe-bursting apparatus into concentrated radial
loads. The
concentrated radial loads produce high tensile hoop stress in the old pipe 16.
Thus, as the old
pipe 16 is engaged by the rolling spherical pipe-bursting member 70 the radial
force exerted
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on the old pipe exceeds that of a fixed angle cone bursting apparatus. It will
be appreciated;
however, that both rotating and axially moving the pipe-bursting apparatus are
not required to
cause bursting of the old pipe 16. For example, axial movement of the pipe-
bursting
apparatus 24A will cause rolling of the spherical pipe-bursting members 70
within the
tracks 84 and provide the bursting action.
[0042] Turning now to FIG. 5 there is shown therein an alternative embodiment
of the
pipe-bursting apparatus of FIG. 4. The pipe-bursting apparatus 24B of FIG. 5
is shown
having a frame 64 connectable with the drill string 14 (FIG. 1) and a
plurality of pipe-
bursting members 70. The frame 64 is connectable with the drill string 14
using a threaded
connection 76 supported on a rod 74. The rod 74 is supported by the frame 64
to transmit
rotation and axial movement of the drill string to the pipe-bursting apparatus
24B.
[0043] A connection member 72 is shown supported by the frame 64 and connected
to the replacement pipe 12. The connection member 72 pivotally connects the
replacement
pipe 12 to the frame 64 so that the replacement pipe may be towed into the
borehole 22 as the
pipe-bursting apparatus 24B is axially advanced. The connection member 72 may
have a
bearing assembly 88 that allows the pipe-bursting apparatus 24B to rotate,
relative to the
replacement pipe 12, in response to rotation of the drill string. Further, the
pivotal connection
point 90 allows the relationship between the longitudinal axis 69 of the pipe-
bursting
apparatus 24B to change relative to the longitudinal axis 92 of the
replacement pipe 12
without placing unnecessary stress upon the connection member 72 or the
replacement pipe.
[0044] The spherical pipe-bursting members 70 are longitudinally aligned on
the
frame 64 in tracks 86 that are generally axial with the longitudinal axis 69
of the frame. A
preferred configuration may have four separate tracks 86 spaced equidistant
about the
circumference of the frame and sized to hold three pipe-bursting members 70
each.
However, it will be appreciated that the number of tracks 86 and spherical
pipe-bursting
members 70 may be varied to suit the size and type of old pipe 16 and
replacement pipe 12.
[0045] Referring now to FIG. 6 there is illustrated therein a pipe-bursting
apparatus 100 that is connectable with a dual-member drill string 14. The pipe-
bursting
apparatus 100 generally comprises a frame 102, a rod 103 supported within the
frame, and at
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least one spherical pipe-bursting member 70 supported by the frame. The
spherical pipe-
bursting member 70 is operable in response to movement of the drill string 14.
[0046] The frame 102 may be generally elongate having a first end 104 and a
second
end 106. The first end 104 of the frame 102 has internal threads 108 for
connecting the
apparatus 100 to the pin end 40 of a correspondingly threaded outer member 36
of a dual-
member drill string 14 (FIG. 2). The frame 102 may comprise a substantially
conical housing
having a smaller diameter at its first end 104 and a larger diameter at the
second end 106.
[0047] The frame 100 is generally constructed to have two tracks 110 for
supporting a
plurality of pipe-bursting members 70 on the frame. The tracks 110 are
comprised of a pipe
engaging segment 112, a return segment 114, and an internal channel
characterized as a drive
segment 116. The pipe engaging segment 112 is generally axial with the
longitudinal axis 69
of the apparatus 100 and extends lengthwise along an outer surface 118 of the
frame 102 and
supports the spherical pipe-bursting members 70 for engagement with the old
pipe 16. The
spherical pipe-bursting members 70 are driven along the pipe engaging segment
112 in the
direction indicated by arrow 120 by in a manner yet to be described.
[0048] The rod 103 is rotatably supported by the frame 102 and connectable
with the
inner member 38 of the drill string 14. Bearings 122 support the rod 103
within the housing
for co-axial rotation therein. Preferably, the rod 103 may comprise a
geometrically-shaped
pin end 124 at one end and a connection member 125 at the other. The
geometrically-shaped
pin end 124 provides for easy connection with a correspondingly-shaped inner
member 38
(FIG. 2). The use of a geometrically-shaped pin end 124 to connect the rod 103
to the inner
member 38 is preferred; however, connection may be accomplished in any way
that allows
for torque transmission from the inner member of the drill string to the rod
103. The rod also
may have an internal passage 126 for delivering drilling fluid to the tracks
110 of the
apparatus 100. Drilling fluid is used to lubricate the spherical pipe-bursting
members 70 and
the rod 103, and to wash away debris.
[0049] In the present embodiment, the rod 103 may comprise a drive member
adapted
to move the spherical pipe-bursting members 70 linearly along the longitudinal
axis 69 of the
frame 102. The drive member of rod 103 has a threaded segment 127 forming a
series of
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ridges 128 used to move the spherical pipe-bursting members 70 linearly and
parallel to the
axis of rotation 69 of the frame 102.
[0050] When the inner member 38 of the dual-member drill string 14 is rotated
in a
first direction, the threaded segment 127 of the rod 103 communicates with the
spherical
pipe-bursting members 70 present in the drive segment 116. This interaction
causes the
spherical pipe-bursting members 70 to travel in direction X as the rod 103
rotates. Moving
the spherical pipe-bursting members 70 in direction X through the drive
segment 116 causes
movement of the spherical pipe-bursting members present in the pipe-engaging
segment 112
and the return segment 114. Thus, rotation of the rod 103 causes the spherical
pipe-bursting
members to travel along the track 110 so that as the members travel the pipe-
engaging
segment 112 of the track within which they function to burst the old pipe 16.
[0051] In operation, the spherical pipe-bursting members 70 travel along the
pipe
engaging segment 112 until they reach the return segment 114. At the
intersection of the pipe
engaging segment 112 and the return segment 114 the spherical pipe-bursting
members 70
turn towards the longitudinal axis 69 of the apparatus 100 and make their way
to the drive
segment 116. When the members 70 arrive at the drive segment 116 they
encounter the
rotating rod 103 and the ridges 128. As previously described, the ridges 128
push the
spherical pipe-bursting members 70 in direction X which causes the members 70
within the
pipe engaging segment 112 to roll in the direction indicated by arrow 120.
[0052] Turning now to FIG. 7, there is shown another embodiment of the pipe-
bursting apparatus. The pipe-bursting apparatus 200 is connectable to a dual-
member drill
string and comprises a frame 202, a rod 204 rotatably supported on the frame,
and a plurality
of spherical pipe-bursting members 70 operable in response to rotation of the
rod. The pipe-
bursting members 70 are supported within tracks 206 and moveable around the
tracks in
response to rotation of the rod 204.
[0053] The frame 202 comprises an uphole end 208 having internal threads 210
for
connecting the apparatus 200 to the pin end of a correspondingly threaded
outer member of a
dual-member drill string (FIG. 2). The uphole end 208 of the frame comprises a
pipe cutting
assembly 214 supported by the frame 202 and operable in response to axial
movement of the
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drill string. The pipe cutting assembly comprises bearings 218 and pipe
cutting
members 220. The pipe cutting members 220 are fixed to the frame 202 so that
they are
capable of rotating when the pipe-bursting apparatus is axially advanced along
the old pipe.
The pipe-cutting members 220 extend radially beyond the frame 202 a sufficient
distance to
allow the pipe-cutting members to score or cut the old pipe before the
spherical pipe-bursting
members 70 burst the old pipe. The pipe-cutting assembly further comprises an
internal
passage adapted to support the rod 204 for rotation therein.
[0054] The rod 204, having a first end 222 and a second end 224, is supported
by
bearings 218 within the internal passage for co-axial rotation therein. The
first end 222 of the
rod 204 may comprise the previously described geometrically-shaped pin end 226
for
connection with a correspondingly shaped pin end of the inner member of a dual-
member
pipe section 34 (FIG. 2). The first end of the rod has an inlet 229 that
directs drilling fluid
into a generally elongate cavity 230. The cavity 230 transports drilling fluid
to the
tracks 206, the spherical pipe-bursting members 70 and the cutting members
220.
[0055] The second end 224 of the rod 204 may be integrally formed with the
frame 202 and forms a generally conical housing 228 for supporting the
spherical pipe-
bursting members 70. The rod 204 and housing 228 are integrally formed so that
rotation of
the rod 204 by the inner member and axial movement of the apparatus 200 will
drive
movement of the spherical pipe-bursting members 70 about the track 206 and
cause bursting
of the old pipe.
100561 In operation, the outer member 36 of the drill string is axially
advanced
through the old pipe so that the cutting members 220 are rolled along to score
or cut the old
pipe. The inner member 38 of the drill string is rotated to drive rotation of
the rod 204.
Rotation of the rod 204 causes the conical housing 228 to rotate about the
longitudinal
axis 69 of the apparatus 200. Rotation of the housing 228 will cause the pipe-
bursting
members 70 to roll along the tracks 206 while axial movement of the housing
will increase
the radial load and burst the old pipe.
[0057] Turning now to FIG. 8 there is shown therein another embodiment of the
pipe-
bursting apparatus of the present invention. In this embodiment, the pipe-
bursting
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apparatus 300 has a percussive assembly 302 connected to the frame 304.
Percussive
assembly 302 assists the bursting operation by supplementing the axial force
applied to the
pipe-bursting apparatus 300 by the drive machine 30 with a series of short,
high intensity
impacts. The percussive tool may comprise a pneumatically or hydraulically
powered
hammer assembly. The percussive tool may also be adapted for operation in
response to
rotation of a rod 306 supported by the frame 304. A suitable hammer assembly
is described
in U.S. Patent Application No. 10/139,304 entitled Rotary Driven Drilling
Hammer, the
contents of which are incorporated herein by reference. Fluid or air may be
supplied to the
percussive tool either through the rod 306 or through the replacement pipe 12
from the exit
pit.
[0058] The pipe-bursting apparatus 300 may be constructed so that it is
connectable
to any dual-member pipe section 34 (FIG. 2). The pipe-bursting apparatus 300
comprises the
frame 304 and the rod 306 rotatably supported within the frame. The frame 304
comprises
internal threads 308 for connecting the apparatus to the pin end 40 of the
outer member 36
(FIG. 2). The frame 304 is also adapted for connection to the replacement pipe
12 for towing
the replacement pipe into the borehole as the pipe-bursting apparatus 300 is
axially advanced.
The rod 306 may comprise a geometrically-shaped pin end (not shown), as
described with
reference to FIG. 7. Bearings 310 support the rod 306 for rotation within the
frame 304.
[0059] The general shape of the frame 304 is preferably conical, increasing in
diameter from an uphole end 312 to a downhole end 314. The preferred conical
shape of the
frame 304 allows for the uphole end 312 to pass through the existing inner
diameter of the
old pipe with little resistance. However, the increase in diameter of the
housing allows the
spherical pipe-bursting members 70 to engage the old pipe with increasing
tensile hoop stress
as the apparatus 300 is axially advanced and the diameter of the housing
increases.
[0060] The spherical pipe-bursting members 70 are supported by the frame 304
in
tracks 316 for movement therein. The tracks 316 of apparatus 300 support the
spherical pipe-
bursting members so that the members are disposed about the circumference of
the housing in
a plane perpendicular to the longitudinal axis of the frame 304. A series of
channels 318
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transport drilling fluid to the spherical pipe-bursting members 70 from the
rod 306 to
lubricate the spherical pipe-bursting members and wash away debris.
[0061] As the pipe-bursting apparatus 300 is pulled back by the horizontal
directional
drilling machine 10, the replacement pipe 12 is pulled into the newly expanded
borehole.
The outer member of the drill string is rotated by the drive machine 30 to
cause the spherical
pipe-bursting members 70 to roll through the tracks 316. The inner member 38
transmits
torque to the rod 306 by way of the connection between the rod and the inner
member.
Rotation of the rod is translated by the percussive assembly 302 into axial
impacts upon the
pipe-bursting apparatus 300. The axial impact forces generated by the
percussive assembly
assist the spherical pipe-bursting members 70 to burst the old pipe 16 as the
replacement
pipe 12 is pulled into position.
[0062] Referring now to FIG. 9, there is shown therein yet another embodiment
of the
present invention. The pipe-bursting apparatus 400 is connectable to a dual-
member drill
string and comprises a frame 402, a rod 404 rotatably supported on the frame,
and a spherical
pipe-bursting member 70. The spherical pipe-bursting member 70 is supported on
the
frame 402 and operable in response to movement of the drill string. The
embodiment of
FIG. 9 illustrates the use of a cutting member 406 comprising a plurality of
cutting teeth 408
and positioned in advance the plurality of spherical pipe-bursting members 70
to cut the old
pipe and remove debris from the borehole.
[0063] The frame 402 comprises a generally conical housing having a first end
408
and a second end 410. The first end 408 of the frame 402 may have threads for
connecting
the frame to the outer member of a dual-member drill string. The frame 402 has
an internal
passage 412 that extends along the entire length of the frame. The passage 412
has several
branch channels 414 that carry drilling fluid to the spherical pipe-bursting
members 70.
[0064] Spherical pipe-bursting members 70 are supported by the frame 402 in a
plurality of tracks 416 that are disposed about the circumference of the
conical housing. The
tracks 416 are sized to allow the spherical pipe-bursting members 70 to roll
around the
circumference of the frame 402. The tracks 416 support the spherical pipe-
bursting
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members 70 so that they are disposed about the frame 402 in a plane
perpendicular of the
longitudinal axis of the apparatus 400.
[0065] The rod 404, having a first end 418 and a second end 420, is supported
by
bearings 422 and 424 for co-axial rotation within the frame 402. The first end
418 of the
rod 404 may be connectable with the inner member of a dual-member drill string
in a manner
previously described herein.
[00661 The second end of the rod 404 comprises the cutter 406 to cut the old
pipe 16
(FIG. 1) and remove debris and/or obstructions from the borehole. The cutter
406 is shown
positioned outside of the frame 402 so that as the apparatus 400 is advanced
through the old
pipe, the cutter is positioned in front of the spherical pipe-bursting members
70. The
cutter 406 is integral with the rod 402 and rotatable in response to rotation
of the inner
member of the drill string. The cutter 406 may comprise a plurality of carbide
tipped cutting
members 426 used to cut the old pipe in advance of engagement with the
spherical pipe-
bursting members 70.
[0067] Turning now to FIG. 10, there is shown another embodiment of the pipe-
bursting apparatus. In this embodiment, the pipe-bursting apparatus 500
comprises a
race 502 supported by a rod 504 for rotation therewith. The race 502 is
adapted to roll a
plurality of spherical pipe-bursting members 70, disposed about the
circumference of the
frame 506, in response to rotation of the inner member of the drill string.
[0068] The pipe-bursting apparatus 500 comprises the frame 506 and a rod 504
rotatably supported within the frame. The frame comprises an uphole end 508
and a
downhole end 510. The uphole end 508 comprises internal threads 512 for
connecting to the
pin end of a correspondingly threaded pipe section. The downhole end 510 of
the frame 506
is adapted for connection to a swivel connector assembly 514. A pipe puller
(not shown)
may be attached to the connector assembly 514 for towing the new pipe into the
borehole as
the pipe-bursting apparatus 500 is axially advanced.
[0069] Referring still to FIG. 10, the rod may comprise the previously
described
geometrically-shaped pin end (not shown) for connecting the rod to the inner
member of the
drill string. Bearings 516 and 518 support the rod 504 for rotation within the
frame 506.
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[0070] The pipe-bursting apparatus 500 uses spherical pipe-bursting members 70
to
burst the old pipe. The spherical pipe-bursting members 70 are supported on
the frame 506
using tracks 520 and at least one race 502. The spherical pipe-bursting
members 70 are
adapted to be engaged by the rotating race 502, described hereinafter. The
spherical pipe-
bursting members 70 may be constructed from a durable resilient material such
as case
hardened steel which is capable of resisting the high tensile hoop stresses
placed on the old
pipe.
[0071] The race 502 is supported on the rod 504. The race 502 comprises a
plurality
of bearing surfaces having tracks 522 and channels 524 for transporting
drilling fluid to the
spherical pipe-bursting members 70 from the rod cavity 526. The race 503 is
shown
integrally formed with the rod 504 for fixed rotation therewith. However, it
will be
appreciated, that a removable race may be used for attachment to and removal
from the
rod 504.
[0072] The inner member drive group 60 of the drive machine 30 rotates the rod
504.
Rotating the rod 504 causes rotation of the race 502 within the frame 506.
Rotation of the
race 502 causes rolling of the spherical pipe-bursting members 70 within the
tracks 520.
Rolling of the spherical pipe-bursting members 70 in conjunction with axial
advancement of
the apparatus to burst the old pipe.
[0073] Referring now to FIG. 11, there is shown a pipe-bursting apparatus
constructed in accordance with the present invention. In pipe-bursting
apparatus 600 of
FIG. 11 the spherical pipe-bursting members 70 oscillate in and out of the
frame 602 in
response to rotation of the rod 604. The apparatus 600 comprises an eccentric
cam 606
supported on the rod 604 for rotation therewith and adapted to advance the
spherical pipe-
bursting member from within the frame.
[0074] The pipe-bursting apparatus 600 may be constructed so that it is
connectable
with the downhole end of any dual-member drill string. The pipe-bursting
apparatus 600
comprises the frame 602 and the rod 604 rotatably supported within the frame.
The
frame 602 connected to the outer member is generally conical and comprises a
swivel
connector 608 for towing the replacement pipe 12 (FIG. 1) into the borehole as
the pipe-
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bursting apparatus 600 is axially advanced. The frame 602 may further define
an
opening 610 through which the spherical pipe-bursting member 70 is advancable
and
retractable through the opening 610.
[0075] The pipe-bursting members 70 are supported by the frame 602 in a cavity
616
that holds the members within the frame but allows them to advance and retract
in response
to rotation of the rod 604 by the inner member. When the spherical pipe-
bursting
members 70 are retracted into the frame 602, the members extend into an
internal
chamber 618 defined by the frame.
[0076] The pipe-bursting apparatus 600 comprises the eccentric cam 606
supported
on the rod 604. The eccentric cam 606 comprises a plurality of channels for
transporting
drilling fluid to the spherical pipe-bursting members 70. The cam 606 is
supported on the
rod 604 for fixed rotation therewith. Rotation of the eccentric cam 606 causes
oscillating
advancement of the spherical pipe-bursting members 70 through the opening 610
when the
cam engages the members. When the spherical pipe-bursting members 70 are not
engaged by
the cam 606 the members are retracted into the frame's internal chamber 618 by
the external
force exerted against the members by the old pipe or borehole.
[0077] Turning to FIG. 12, there is illustrated an alternative embodiment of
the pipe-
bursting apparatus shown in FIG. 11. The pipe-bursting apparatus 700 is
connectable to a
dual-member drill string and comprises a frame 702, a rod 704 rotatably
supported on the
frame, and a spherical pipe-bursting member 70 operable in response to
rotation of the rod.
The embodiment of FIG. 12 shows the use of an eccentric flywheel 706 fixed to
the rod 704
for rotation therewith. Rotation of the eccentric flywheel 706 causes
vibration of the
spherical pipe-bursting members 70 which is used to assist the members in the
bursting
operation. Vibration of the spherical pipe-bursting members 70 during the
bursting operation
helps to reduce frictional resistance exerted on the apparatus 700, enhances
bursting
operations, helps to stabilize the soil in the new borehole, and reduces
frictional drag against
the replacement pipe 12 being towed into the borehole.
[0078] Referring now to FIGS. 10 and 13, the pipe-bursting apparatus 500 of
FIG. 10
is shown with a biasing tool assembly 528 connectable with the uphole end 508
of the
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apparatus 500. The biasing tool assembly 528 allows corrections to the grade
of the
replacement pipe 12 to be made as it is towed into the borehole behind the
apparatus 500.
The biasing tool 528 comprises a plurality of opposing radially extending
biasing
members 530 and 532 adapted to offset the pipe-bursting apparatus from the
centerline of the
borehole (not shown). Biasing members 530 are longer than biasing members 532.
Thus, as
shown in FIG. 13, when biasing menlbers 530 are at the twelve o'clock position
shown in
FIG. 13, the apparatus 500 is steered towards the six o'clock position.
[0079] In operation the outer member of the dual-member drill string is used
to rotate
the biasing members 530 and 532 supported on the outer member 534 pf the
biasing
assembly 528 for steering. A beacon (not shown) comprising an orientation
sensor may be
used with the apparatus or the biasing assembly to sense and communicate the
orientation of
the biasing tool and the apparatus to the operator. Once the biasing assembly
528 is properly
oriented, the inner members of the drill string are rotated by the drive
machine 30 to rotate a
drill string drive 536 of the biasing assembly. The drill string drive 536 is
operatively
connected to a rod drive 537 supported on the rod 504 to transmit rotation of
the inner
member of the drill string to the race 502 supported on the rod. When a grade
correction is
desired, the outer member of the drill string is selectively rotated to move
the biasing
members 530 into a new orientation and the apparatus is axially advanced.
[0080] Turning now to FIG. 14, there is shown therein an alternative
embodiment of
the biasing tool assembly 528 of FIG. 13. In the enibodiment of FIG. 14 a
plurality of
opposing radially extending biasing members 540, of equal length, are
supported by a
housing 538. The biasing tool assembly 528A of FIG. 14 comprises the housing
538, and a
drill string drive 536 connectable with a rod drive 537. The inner member
drive 536
comprises a rod gear drive 542 adapted to matingly engage a gear 544 supported
on the
rod 504 of the pipe-bursting apparatus 500.
[0081] The gear relationship between the rod 504 and the inner member drive
536
translates rotation of the inner member of the drill string into rotation of
the rod and thus
rotation of the race 502 fixedly supported by the rod. This relationship
between the inner
member drive 536 and the rod 504 allows the longitudinal axis 69 of the frame
506 and the
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longitudinal axis of the drill string 544 may be offset relative to each
other. Thus, when the
longitudinal axis of the drill string 544 is offset below the longitudinal
axis 69 of the
apparatus 500, as shown in FIG. 14, the apparatus may be axially advance while
holding the
biasing tool assembly 528A in fixed rotational orientation to make desired
grade corrections.
If no grade correction is necessary, the outer member of the drill string may
be continuously
rotated so that the apparatus 500 is not biased to one side of the borehole.
[0082] The present invention also comprises a method for bursting pipe using a
horizontal directional drilling system 10. The method employs a horizontal
directional
drilling machine and a drill string. A pipe-bursting apparatus of the present
invention is
operatively connected to the second end of the drill string. Preferably one of
the
pipe-bursting apparatus 24A, 24B, 100, 200, 300, 400, 500, 600 or 700 as
described herein,
may be used in carrying out this method.
[0083] Having determined the need for replacing the old pipe 16 without
digging a
trench, the drill string 14 may be inserted through the section of old pipe to
be replaced 16.
The pipe-bursting apparatus is connected to the downhole end of the drill
string 14 as it
protrudes from the far end of the old pipe. After connecting the pipe-bursting
apparatus 24 to
the drill string 14, the apparatus is positioned within the old pipe by
advancing, withdrawing
or rotating the drill string. Once the pipe-bursting apparatus has been
positioned, the drill
string is rotated to and the apparatus is axially advanced to operate the
spherical pipe-bursting
members supported on the frame of the pipe-bursting apparatus.
[0084] If the method of the present invention is performed using a dual-member
drill
string, operation of the spherical pipe-bursting members may be driven by
rotation of the
inner member of the drill string. The pipe-bursting apparatus may be properly
positioned by
axially advancing and rotating the outer member of the drill string. Once
positioned, the
inner member of the drill string is rotated to drive operation of the
spherical pipe-bursting
members.
[0085] Various modifications can be made in the design and operation of the
present
invention without departing from the spirit thereof. Thus, while the principal
preferred
construction and modes of operation of the invention have been explained in
what is now
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considered to represent its best embodiments, which have been illustrated and
described, it
should be understood that within the scope of the appended claims, the
invention may be
practiced otherwise than as specifically illustrated and described.
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