Note: Descriptions are shown in the official language in which they were submitted.
CA 02206768 2000-02-09
2
BACKGROUND & SUMMARY OF THE INVENTION
The present,invention relates generally to
improvements in apparatus for effecting hydrocleaning
of the exterior surfaces of pipelines and the like,
including pipeline sections, so as to remove coatings
and miscellaneous contaminants from the pipeline
exterior surface.
As described in the above-noted published European patent
application , oil and gas transmission pipelines of
large diameter (e. g. 12 inches - fi0 inches) are usually
coated and then buried before being used for
transportation of fluid. The coatings serve to reduce
corrosion caused by the various soils and weathering
I5 conditions encountered. Various forms of coating
materials have been used over the~years. Coal tar
products were and are well known as coating materials
and, more recently, polyethylene tape layered coatings
have been used. However, over the years, these
coatings have deteriorated in many instances and
several pipeline operators have experienced failures in
old coatings. These failures usually involve debonding
between parts of the coating and the pipe. Despite the
use of cathodic protection, the debonded areas are
subject to pitting corrosion and to stress corrosion
cracking and in very severe cases pipe failures have
occurred under pressure. As a result, many operators
have initiated coating rehabilitation projects.
The preferred form of apparatus described in the
above-noted European patent application incorporated a
main frame adapted to at least partially surround a
portion of a pipeline and suitable means for advancing
the frame relative to the pipeline in the lengthwise
direction when in use. A multiplicity of liquid
jetting modules were mounted to the frame in
J
CA 02206768 1997-06-11
3
circumferentially spaced relation to each other so as
to substantially surround the pipeline when in use.
Each such module included a rotary swing arm nozzle
thereon having a rotation axis, in use, disposed
substantially normal to the pipeline surface for
directing liquid jets onto the pipeline surface in a
series of closely spaced-overlapping convolutions
during movement of the frame relative to and lengthwise
of the pipeline. Suitable guides, e.g. guide wheels
located on each module, made contact with the pipeline
surface during movement relative thereto. Suitable
suspension linkages connected each module to the frame
and a biasing arrangement was provided for urging the
respective modules toward the pipeline surface while
permitting independent movement of the modules relative
to the frame and to one another radially inwardly and
outwardly relative to the pipeline as the respective
guides contacted and followed the pipeline surface when
in use.
The frame configuration for the above-noted
hydrocleaner typically included an upper section shaped
to surround an upper portion of the pipeline when in
use and a pair of lower frame sections pivotally
mounted to lower opposed extremities of the upper
section for movement between open and closed positions.
When the lower sections were in the open position the
frame could be lowered downwardly onto the pipeline and
the lower sections thereafter closed around the lower
portion of the pipeline so that the frame at least
partially surrounded the pipeline. Certain of the
liquid jetting modules were mounted to the upper frame
section while others were mounted to the respective
pivotal frame sections. Drive wheels were mounted to'
the upper frame section for engaging the pipeline
surface and advancing the frame relative to the
z j
CA 02206768 1997-06-11
4
pipeline while the lower frame sections were provided
with idler wheels and/or further drive wheels which
acted generally in opposition to the drive wheels on
the upper frame section thereby to help provide the
required tractive forces. An actuator system for
pivoting the lower frame sections was provided with
suitable biasing means thereby to ensure that the lower
idler and/or drive wheels were kept in close
pressurized engagement with the.pipeline surface so as
to provide the required tractive.force.
The present divisional provides, in one aspect
an apparatus for cleaning an exterior surface of a
pipe. positioned within a longitudinal passage of said
..apparatus, said apparatus comprising:
~. :' ~ ' a frame having a forward end and a rearward end, said
frame defining said longitudinal passage therethrough of a
size sufficient to accommodate said pipe such that, by
relative movement between said pipe and said frame, said
pipe is able to effectively pass longitudinally through said
frame from said forward end to said rearward end;
at least one cantilever arm having a proximal end
. portion and a distal end portion, the proximal end portion
of'each cantilever arm being mounted on said frame with the
distal end portion of the respective cantilever arm
extending rearwardly beyond said rearward end of said frame;,
and
each said distal end portion having at least one jet
module mounted on the respective distal end portion with
said at least one jet module being positioned rearwardly of
said rearward end of said frame, each said jet module
comprising at least one liquid jet nozzle directed toward
. . the ..exterior _surface of said gipe.~
r i
CA 02206768 1997-06-11
One embodiment provides a plurality of
said cantilever arms, with the distal end
portion of each said cantilever arm having at least one of
said jet modules mounted thereon at a location rearwardly of
5~ said rearward end of said frame:
Preferably said plurality~of cantilever arms
are at least substantially equally spaced about the
circumference of said longitudinal passage.
Typically, each of said jet nozzles produces a
1~ liquid jet that traces a path on the exterior surface of
said pipe, whereby the liquid jet paths overlap to provide
complete circumferential cleaning of the exterior surface
of said pipe.
A preferred embodiment includes a front set of
at least one wheel mounted on said frame forward of the jet
modules to contact the exterior surface of the pipe, and
a rear set of at least one wheel mounted on said frame
forward of the jet modules and rearward of said front
set to contact the exterior surface of the pipe, at least
one of the wheels being a drive wheel to provide relative
longitudinal movement between said apparatus and said pipe.
At least one drive motor may be connected to
the at least one drive wheel to rotate the at least one
drive wheel in contact with the exterior surface of said pipe.
~5 Typically, each said jet module has a guide mounted
thereon to ride along the exterior surface of said pipe to
effect radial movement of the respective jet module relative
to the exterior surface of the pipe upon the respective guide
CA 02206768 1997-06-11
6
encountering surface irregularities along the exterior surface
of the pipe.
Preferably each said jet module has an adjustable
stop mounted thereon to retain the guide associated with the
respective jet module in a predetermined position such that
the associated guide does not contact the exterior surface
of the pipe when the apparatus is in use.
In a preferred embodiment there are a plurality
of said jet modules positioned rearwardly of said rearward
end of said frame, said plurality of said jet modules being
at least substantially equally spaced about the circumference
of said longitudinal passage, wherein each of the jet nozzles
rotates to produce a liquid jet that traces a path on the
exterior surface of said pipe, whereby the liquid jet paths
of adjacent jet modules overlap to provide complete
circumferential cleaning of the exterior surface of said pipe.
Another aspect of the invention provides an apparatus
for cleaning an exterior surface of a pipe positioned within
a longitudinal passage of said apparatus, said apparatus
comprising:
a frame having a forward end and a rearward end, said
frame defining said longitudinal passage therethrough of a
size sufficient to accommodate said pipe such that, by
relative longitudinal movement between said pipe and said
~5 frame, said pipe is able to effectively pass longitudinally
through said frame from said forward end to said rearward
end;
at least.one drive assembly mounted on said frame, said
at least one drive assembly having at least one rotatable
3U drive member for effecting said relative longitudinal
movement between said pipe and said frame;
T
CA 02206768 1997-06-11
7
a plurality of cantilever arms, each of said cantilever
arms having a proximal end portion and a distal end portion,
the proximal end portion of each cantilever arm being
connected at least to a respective connection point on said
frame with the distal end portion of the respective
cantilever arm extending rearwardly of said at least one
drive assembly;
the distal end portion of each cantilever arm having at
least one jet module mounted on the respective distal end
portion with said at least one jet module being positioned
rearwardly of said at Least one drive assembly, each said
jet module comprising at least one liquid jet nozzle
. directed toward the exterior surface of said pipe, whereby
each said liquid jet nozzle produces a liquid jet that
traces a liquid jet path on the exterior surface.of said
pipe to effect cleaning along a region extending lengthwise
of said pipe as said pipe effectively moves longitudinally
through said frame from said forward end to said rearward
end, with said plurality of cantilever arms being spaced
about the circumference of said longitudinal passage such
that said jet modules at least substantially surround said
pipe when in use whereby each liquid jet path overlaps other
liquid jet paths during said relative longitudinal movement
between said frame and said pipe to thereby effect cleaning
of the pipe all around the complete circumference of the
exterior. surface of the portion of the pipe which
effectively passes longitudinally through said frame from
said forward end past said rearward end while avoiding
contact between the at least one rotatable drive member of
said at least one drive assembly and the resulting cleaned
surface of said pipe.
CA 02206768 1997-06-11
8
Pipeline owning companies are currently confronted
with many thousands of miles of pipe coated with
asbestos materials without an adequate removal method
in existence. Without a safe removal technique, the
companies must either lower line pressures, shut down
the line or replace it. Development of an approved~and
safe cleaning and removal technology which complies
with environmental and personnel safety standards is
therefore greatly needed.
lu Further features and advantages of the invention
will become readily apparent from the following
description of a preferred embodiment of same.
i
CA 02206768 1997-06-11
- 9 -
BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS:
FIGURE 1 is a cross-section view of a hydrocleaning
apparatus according to the invention; certain details,
such as the drive assemblies, having been omitted;
FIGURE 2 is a front end. elevation view of the frame
assembly and drive, the liquid betting modules and
their suspension linkages having been omitted;
FIGURE 3 is a side elevation view of the
hydrocleaning apparatus, several of the liquid betting
modules and their suspension linkages and shrouds
having been omitted;
FIGURE 4 is a side elevation view of a liquid
betting module and its suspension linkage;
FIGURES 5, 6 and 7 are top, side and top views
respectively of various components of the module
suspension linkage;
FIGURES 8 and 9 are section and side elevation
views respectively of the overall shroud assembly with
shrouds in their overlapping relationship, the swing
arms being shown in phantom and the rest of the machine
having been omitted;
FIGURES 10, 11 and 12 are plan, end elevation and
side elevation views of a shroud;
FIGURES 13A and 13B are side elevation views of a
module and its suspension linkage showing the module at
various pitch angles relative to the pipeline surface; and
FIGURE 14 is a schematic of the hydraulic system .
CA 02206768 2000-02-09
- lU -
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
The basic principles relating to hydrocleaning of a
pipeline surface are set out in detail ir~ our above-
noted published European application and need not be repeated here.
The above published European application also describes
all the various pieces of support equipment required
including the side boom tractor, pipe cradle and bridle
assembly, water and hydraulic pumps, prime mover and
water supply tanks etc.
Referring now to the drawings, the hydrocleaning
apparatus 10 includes a frame 12 adapted to at least
partially surround a portion of a pipeline P when in
use. The frame 12 is supported and driven along the
pipeline P by way of spaced apart fore and aft drive
assemblies 14, 16 (FIGURE 2 and 3) including pairs of
drive wheels 18, 20 which engage the pipeline surface
to propel the entire apparatus forwardly.
A plurality of liquid jetting modules 22 are
mounted to the frame 12 in circumferentially spaced
relation so as to substantially surround the pipeline
when in use. Each module 22 has a rotary swing arm
nozzle 24 thereon, each being rotated about an axis
(which in use is substantially normal to the pipeline
surface) for directing liquid jets on to the pipeline
surface in a series of closely spaced overlapping
convolutions during forward advance of the frame L2
along the pipeline P. The cleaning paths thus defined
by the several swing arm nozzles 2~ ideally overlap
somewhat at their marginal edges, as indicated by the
letters OL in FIGURE 1, thus helping to ensure that no
uncleaned longitudinal streaks are left on the
pipeline. The jetting modules 22 are mounted to the
frame 12 by respective suspension linkages 26 which
CA 02206768 2000-02-09
_ 1~ _
allow radial motion of the modules inwardly and
outwardly relative to the pipeline axis.
Each of the modules is provided with a shroud 28
(shown in section in FIGURE 1 for purposes of clarity),
these shrouds being disposed in an overlapping
configuration all around the pipeline and the swing arm
nozzles 24 to reduce escape of contaminants into the
environment and for safety reasons, all as will be
described in further detail hereafter.
Returning now to the frame 12, it will be seen that
it is made up from sturdy tubular members welded and
connected together to provide the necessary strength
and rigidity. Frame 12 includes an upper frame section
40 of a generally inverted U-shape, as seen end-on, so
as to surround the upper portion of the pipeline P when
in use, section 40 comprising three sub-sections 42
rigidly connected together by welds and including
longitudinal frame elements 44 rigidly securing fore
and aft frame portions together. Frame 12 also
includes a pair of lower opposed frame sections 46
pivotally mounted via hinges 48 to lower opposed
extremities of the upper section 40 for movement
between open and closed positions. When these lower
sections 46 are in the open position, the entire
hydrocleaner can be lowered downwardly onto a pipeline
(as described in the above-noted European application)
and the lower frame section 46 then closed around a
lower portion of the pipeline as shown in FIGURE 1.
The lower frame sections 46 each comprise a pair of
independently pivotable frame portions 50, 52 (FIGURES)
each of rigid triangular outline configuration. The
first frame portions 50 are pivotable from the open
position into a predetermined or~fixed closed position
relative to the upper frame section 40 about their
hinges 48. The predetermined closed position is shown
CA 02206768 1997-06-11
- 12 -
in FIGURE 1, such closed position being provided by
adjustable hinge stops 54 co-acting between a rigid
extension arm 56 fixed to each frame portion 50 and a
bracket 58 fixed to the lower portions of the upper
frame section 40. The adjustable stop 54 may comprise
- a threaded stud and lock nut configuration well known
as such. '
The first frame portions 50 serve to each mount a
respective water jetting module 22 via a respective
10~ parallel arm suspension linkage 26 to be described in
detail later on. When frame portions 50 are in the
predetermined closed positions against stops 54, the
rotation axes of the respective swing arm nozzles 24
(including those mounted to the upper frame section)
all pass substantially through the axis~of the pipeline
and this condition is maintained regardless of out of
round pipeline and other irregularities as noted
previously. Hence, a shorter swing arm length can be
used while still providing the desired amount of
overlap OL of the cleaning paths provided. For example
it was found that five swing arms could be used around
pipe as small as 16 inches OD without the risk of the
swing arms touching each other when set at normal
stand-off distances. Streaking problems and side
stand-off distance variations were greatly reduced.
The second frame portions 52 serve to mount
respective idler wheels 58 (FIGURE2) which engage the
pipeline surface at locations generally opposed to the
locations where the drive wheels 18, 20 (which are
mounted to the upper frame section) engage the
pipeline. The idler wheels may, if desired, be
replaced with further_sets of drive wheels and
associated drive assemblies to provide extra tractive
force. Multi-hole mounting plates 60 provide the
' r
CA 02206768 1997-06-11
- 13 -
necessary radial adjustability to accommodate a wide
variety of pipeline diameters.
The frame portions 50, 52 are each provided with
their own hydraulic actuators 60, 62 respectively, each
of which acts between a respective lug fixed to the
upper frame section 40 and an associated extension arm
fixed to the frame portion 50, 52. Actuators 60 for
the first frame portions 50 (to which the lower modules
22 are mounted) are. secured to the above-noted
extension arms 56 while actuators 62 for the second
frame portions 52 (to which the idler wheels 58 are
mounted) are secured to similar extension arms 66
(FIGURE 2).
All of the actuators are supplied via a common
hydraulic supply and control circuit 68 (FIGURE 14) of
a conventional nature having a pre-charged pressure
accumulator 70 therein. Hence, when the lower frame
sections are closed, the first frame portions 50 are
brought into the pre-set positions against the stops 54
while the second frame portions 52 are resiliently
biased inwardly as a result of the action of the
accumulator to bring the idler wheels into tight
engagement with the pipeline surface thereby to enhance
the tractive force the drive wheels 18, 20 are capable'
of supplying. As the idler wheels 58 encounter
pipeline irregularities of the type noted previously,
the second frame portions 52 are free to pivot inwardly
or outwardly. However, since the first frame portions
50 remain in their fixed positions against~the steps
54, the relative orientations of the suspension
linkages 26 for the water jetting modules are in no way
affected by these motions of the frame portions 52 as
the idler wheels follow irregularities in the pipeline
surface.
CA 02206768 2000-02-09
_ 1 4 _
The above-noted front and rear drive assemblies 14,
I6 need not be described in detail. They are mounted
to the upper frame section 40 by way of multi-hale
brackets 74 permitting substantial radial adjustment to
accommodate a wide variety of pipe sizes as noted in
our published European patent application. Each drive assembly
includes a hydraulic motor 76 which is connected to a
reduction gear box 78, the output of the latter being
conveyed to the associated drive wheel 18, 20 via a
chain and sprocket drive 80. The hydraulic supply and
control system for the wheel drive motors 76 is shown
in FIGURE 14 and includes main control valve 82 with
on-off, reverse and forward functions and the usual
over-pressure relief and safety valves, none of which
need be described in detail.
Referring to FIGURES 4-7 one of the modules 22 is
shown, partly in cross-section. Reference may be had
to our published European patent application for details of
the structure. The rotary swing arm assembly 24 is
mounted to the output shaft 84 of a commercially
available rotary swivel assembly 90 which is mounted to
the module frame 91 and connected to the high pressure
source (e. g. 20,000 to 35,000 psi) by supply lines (not
shown). The swivel is driven in rotation at a suitable
speed (e.g. 1000 RPM depending on rate of advance and
other factors as outlined in our prior patent
applications) by way of hydraulic motor 92 and
intermediate gear drive box 94. The high pressure
water passes axially through the shaft 84 and thence
along the swing arms 96 and through the jet nozzles 98
of the tips of the arms, all as described in our
earlier published European patent application.
The previously noted suspension linkage 26 for
mounting each module 22 to the frame 12 of the machine
will be described in further detail. Essentially, the
CA 02206768 1997-06-11
- 15 -
linkage ensures that the module can move in and out in
a radial direction while the swing arm axis is
maintained in substantial alignment with the pipeline
axis. Thus each linkage 26 comprises a parallel arm
linkage including upper and lower rigid control arms
100, 102. The forward ends of arms 100, 102 are
pivotally mounted at spaced pivot points 104, 106 to a
mufti-hole adjustment bracket 108 which in turn is
secured to the machine frame (the multiple holes
accommodate adjustments in respect of a wide variety of
pipe sizes). The trailing ends of arms 100, 102 are
pivotally attached at spaced pivot points 108, 110 to
an end link 112, the latter having a somewhat .
triangular configuration as seen side-on. A hydraulic
cylinder 114 extends from a lug on adjustment bracket
108 to a lug 116 near the trailing end of the lower
control arm 102. As cylinder 114 is advanced and
retracted the parallel arm linkage is moved radially
inwardly and outwardly relative to the pipeline surface
along with the module 22 fixed thereto.
The control valves and hydraulic circuit for all
the hydraulic cylinders 114 are shown in FIGURE 14.
The hydraulic circuit includes a pressurized
accumulator 116 which acts to cause each cylinder to -
bias its associated linkage and attached module toward
the pipeline surface when the equipment is in use.
The above-noted end link 112 of the suspension
linkage 26 is connected to the module 22 by a pivot
assembly 120 defining a transverse pivot axis passing
through the rotation axis of the swing arm assembly 24.
Pivot assembly.120 includes a laterally spaced pair of
eye bolts 122; each mounted in a respective flange 124
fixed to the end link 112. Transverse studs 126 pass
through the "eyes" of these eye bolts 122 and into the
frame 91. of the module 22. By adjusting the adjustment
CA 02206768 2000-02-09
-ZW
nuts 128 on the eye bolts, the swing arm rotation axis
orientation can be adjusted in a plane transverse to
the pipeline axis and passing through the pivot axis
defined by the eye bolts. This enables the nozzle side
stand-off distances (See our published European application for
details) to be adjusted and equalized.
With the pivot arrangement just described, the
module 22 is free to pitch about the above-noted pivot
axis during operation. It will of course be noted that
each module includes fore and aft guide and support
wheels 130, 132 for supporting the module on the
pipeline surface. When the module 22 is entirely free
to pitch about the above-described pivot axis, both of
these guide wheels 130, 132 will be in contact with the
pipeline surface at all times. In cases where thick
coatings are being removed, the forward guide wheel 130
can ride up on the coating while the other guide wheel
132 rides on the cleaned pipeline surface. The whole
module pitches to and fro to the extent needed to
accommodate the changes in coating thickness
encountered as well as any other surface
irregularities. This helps to ensure that the minimum
standoff distances (e. g. about 1/2 inch) at the fore
and aft nozzle passes remain substantially equal
regardless of coating thickness. However, there are
other situations, as where one is dealing with fairly
thin coatings, where one wishes to keep the module
parallel to the pipeline axis at all times and the rear
guide wheel 132 clear of the pipeline surface as to
prevent "tabbing" down of removed coating materials
onto the pipeline surface by the action of this guide
wheel. Therefore, in order to enable the module 22 to
be effectively locked to prevent the pitching motion
referred to, the end link 112 is provided with
adjustable stops 134 in the form of studs which are
w
CA 02206768 1997-06-11
- 17 -
rotated outwardly until they touch the top of the
module frame as best seen in FIGURE 4. When this has
been done, only the forward guide wheel 130 contacts
the pipeline surface.
Another advantage associated with the module pivot
axis arrangement noted is that any module 22 can be
tilted forwardly or rearwardly (see FIGUREs 13A and 13B
for example) thereby to permit the swing arm nozzles to
be inspected and repaired fairly readily.
It will be noted that the modules 22 are allocated
rearwardly of the frame 12 of the machine in what might
be termed a cantilever fashion and rearwardly of the
fore and aft sets of drive wheels 18, 20. As noted
previously, this is advantageous since the drive wheels
cannot.contact the cleaned pipeline surface and act to
tamp down pieces of removed tape, adhesive and other
debris onto the cleaned surface, reference being had to
the earlier discussion regarding "tabbing" of the
pipeline surface. When the rear module guide wheel 132
is held clear of the pipe surface by the adjustable.
stops 134 described previously, the tabbing problem
should be substantially overcome.
The need for protective shrouding was discussed
previously and the shrouds 28 were noted briefly in
connection with FIGURE 1. With reference now to FIGURE
R_~ 2 +hr~ chrrn~rl accPmhl v i ~ chown i n f~iri-har riAf-ai 1 _
, ........ .....~.~...... .....................1 _.... ....~.... _... -
.............. ...........
Each module 22 includes its own shroud rigidly fixed
thereto and the shrouds of the adjacent modules are
shown in FIGURES 1, 8 and 9 as defining an overlapping.
annular array fully enclosing the swing arm nozzle
assemblies 24 all around the outside of the pipeline.
A substantial degree of overlap between adjacent
shrouds is provided by the angled shroud overlap wings
140. The overlapping relationship between adjacent
shrouds allows for substantial radial motions of the
CA 02206768 1997-06-11
' i
- lti -
modules and their shrouds relative to one another while
at the same time the formation of substantial gaps
between the shrouds is substantially avoided. Also,
resilient sealing flaps 142 extend between the overlap
portions of adjacent shrouds to further inhibit the
escape of liquid and debris.
One shroud is shown in detail in FIGURE 10-12. The
shroud includes a flat top wall 143 which is bolted on
to the frame 91 of the mqdule (FIGURE 4). The fore and
aft end walls 144, 146 extend normal to top wall 143
and in use project inwardly into close proximity to the
pipeline surface, the free edges of these walls being
curved to match the pipeline surface contour. These
end walls also include mounting brackets 148 for
mounting the above-noted fore and aft module guide
wheels 130 , 132. The overlap wing 140 is angled
relative to the intermediate section of the shroud and
is of somewhat greater dimension in the lengthwise
(travel) direction than the intermediate shroud section
thereby to accommodate the next adjacent shroud without
interference. The opposing side of the shroud is also
angled inwardly and provided with a flared marginal
portion to which is connected a resilient flap 142, the
flap extending all along the free edge of that side of
the shroud. When the shrouds are in their overlapping
configuration, the flap 142 contacts the interior of
the overlap wing 140 of the next adjacent shroud.
As will be seen from FIGURE 8, the shrouds are
somewhat different from one another depending on their
locations. The uppermost~shroud 28A, being overlapped
on both sides by the overlap wings of shrouds 28B and
28C, does not have an overlap wing at all but is
provided with a sealing flap 142 on both of its sides
to effect sealing engagement with shrouds 28B and 28C.
The lowermost shrouds 28D and 28E differ from shrouds
CA 02206768 1997-06-11
- 19 -
28B and C by the inclusion, at their lower ends, of an
enlarged collector portion 150, 152 shaped to form a
recess or sump when the shrouds are fitted together
which receives the downwardly draining liquids and
debris. A suitable opening.154 allows this material to
escape into a suitable collector.
As noted previously, the several modules 22 and
their suspension linkages 26 are each provided with a
hydraulic actuator 114 to move the modules 22 including ,
their shrouds 28 toward and away from the pipeline
surface as when moving over certain obstacles that
might be encountered on the pipeline surface. In order
to.prevent interference between adjacent shrouds 28
during such radial movement, time delays are
incorporated into certain of the hydraulic lines to the
actuators 114 to achieve the desired result. The
preferred way of avoiding interference is to move the
modules and attached shrouds inwardly in the time
sequence in which they naturally move under gravity.
For example, starting with all modules "out", the top
(12 o'clock) module 28A will fall first, then the 10
and 2 o'clock modules 28B and C will fall
simultaneously and finally the modules 28D and E at the
8 and 4 o'clock positions will rise simultaneously. An-
orifice is fitted into the flow circuit of the actuator
for the 4 o'clock position, module 28E, so that it
rises into position after the 8 o'clock module 28D is
in place thereby avoiding interference. When "opening"
up the modules, the above sequence is reversed.
As noted previously, many of the coatings that are
to be removed from pipe contain hazardous materials,
such as asbestos. Because of the degradation of the
coating on the pipe being repaired, the asbestos is
frequently in a friable condition, prone to ready
35, disbursal of small fibers into the surrounding air
CA 02206768 2000-02-09
- 20 -
space. Clearly, such contamination must be kept to a
minimum.
During tests of the efficacy of an apparatus
designed in accordance with teachings of the present
invention on certain pipe coatings, specifically
polyethylene tape, it was found that the particular
cleaning action of the rotating swing arm nozzles 24
would tend to shred the tape and force the tape into
the inner bend of the nozzles where it turns again
along the axis of rotation of the nozzles to end in the
nozzles themselves. The tape debris could be caught
and wrapped about the arm in this inner bend to the
point where it would affect the efficiency of the
nozzles, and possibly even prevent them from rotating
IS as designed. A solution to this problem was found by
installing paddles 220 across the inner bend on the
nozzles 22 as seen in FIGURE 4. The paddles shown cut
across the inner bend at an angle of 4S°, although it
is clear that other angles may be utilized. Further,
the inner edge of the paddle may be curved, rather than
straight as shown, which would be expected to have even
a mare enhanced ability to deflect debris off the
nozzle.
The manner of operation of the hydrocleaner
~5 described above will be readily apparent to those
skilled in this art on review of this disclosure and
the disclosures contained in our published European patent
application.
Numerous~variations and modifications will readily
occur to those skilled in this- art upon reading the
above description, and without departing from the
spirit or scope of the invention. For definitions of
the invention reference is to be had to the appended
claims.
