Note: Descriptions are shown in the official language in which they were submitted.
~0 ~ ~ ~ 9 6
B-29431-CIP-2
HYDROCLEANING OF THE EXTERIOR SURFACE OF
A PIPELINE TO REMOVE COATINGS
CROSS REFERENCE TO RELATED APPLICATION
Reference may be had to our European Patent Application No. 0343878
published November 29th, 1989 which describes an apparatus and method for
0 the hydrocleaning ofthe exterior surface of a pipeline to remove various types
of coatings.
20 ~ ~ ~ 9 ô
BACKGROUND & SUMMARY OF THE INVENTION
The present invention relates generally to
improvements ln 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 publishedpatent
application , oil and gas transmission pipelines of
large diameter (e.g. 12 inches - 60 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
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
sub;ect 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 pro;ects.
The preferred form of apparatus described in the
above-noted earlier 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
20 ~ ~ ~ 9 ~
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 convolutlons
during movement of the frame relatlve 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 urglng 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
ln 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 re~pective
pivotal frame sections. Drive wheels were mounted to
the upper frame section for engaging the pipeline
surface and advancing the frame relative to the
,~,
20 11~196
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 tractlve 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.
Although the above-described arrangement was found
to work quite well, problems were noticed in respect of
certain ma;or pipeline variations and deviations from
the normal. These deviations involved "out of
roundness" of the pipe (usually caused by bending of
the pipe); excessively thick coal tar coatings
(possibly up to three inches in some sections) along
the line and, in some areas, varying thicknesses of
coatings around the pipe's circumference especially
toward the bottom and, finally, wrinkles in the
pipeline surface particularly in the region of bends.
When the above-described hydrocleaning apparatus
was used to treat pipeline portions having any or all
of the above conditions, certain problems became
evident. Many of the problems arose because the above-
referred to pivotally mounted lower frame sections
would move inwardly and outwardly relative to the
center of the pipeline as the wheels thereon followed
the pipeline surface. The drive wheels on the upper
frame section would of course be in firm contact with
upper surface portions of the pipeline at all times as
well. Hence, when irregularities of the type noted
above were encountered, the lower frame sections would
pivot slightly relative to the upper frame section thus
3s varying the relative orientations between the
9 6 Z
suspension linkages for the liquid jetting modules
mounted on the upper frame section and the suspension
linkages for those mounted on the lower frame sections.
This was found to give rise to losses in cleaning
efficiencies for several reasons. Firstly, it will be
realized, particularly after a review of the
disclosures of the above-noted publishedapplication,
that for maximum efficiency the rotation axis for each
of the rotary swing arm nozzle assemblies should pass
directly through the pipeline axis. However, once the
relative positions of the module suspension linkages
had been altered by virtue of the pipeline
irregularities noted above, the rotation axes for
certain of the swing arms could no longer pass through
the pipeline axis. The distances the water ~ets had to
travel from the respective nozzles of the swing arm
assemblies to the pipeline surface ~referred to as the
side standoff distances in the above-noted patent
applications) were no longer equal to each other thus
causing a loss in cleaning efficiency. Furthermore,
although the diameters of the rotary swing arm nozzle
assemblies were originally chosen such that the
cleaning paths swept out by same would overlap at least
slightly on the pipeline surface under normal
conditions, the irregular conditions noted above and
the resulting changes in the relative orientations
around the pipeline surface could in certain cases
cause this overlap to be lost with the result being
that longitudinally extending streaks of unremoved
coating were left on the pipe. While an increase in
swing arm length might have been of assistance in some
cases, it had to be kept in mind that in many cases,
for example a machine having five swing arm assemblies,
that the amount of permissible increase in swing arm
6 ao~
length was very limited due to the possibility of one
swing arm contacting an ad;acent one during operation.
In order to alleviate the problem noted above, the
present invention in one aspect provides a modified
frame arrangement wherein the above-noted lower frame
sections each include a pair of independently pivotable
frame portions. A first one of each of these frame
portions is pivotable from the open position into a
predetermined or set closed position ~as by virtue of
suitable stops being provided on the cooperating frame
portions) relatlve to the upper frame section. The
second one of each of the frame portions has wheels
(idler and/or drive wheels) mounted thereon for
engaging the pipeline surface at locations generally
opposed to the locations where the drive wheels on the
upper frame section engage the pipeline surface
thereby, as before, to provide the desired degree of
tractive force.
Suitable actuators, as before, are provided for
moving the pairs of pivotable frame portions between
the open and closed positions. These actuators are
arranged to resiliently bias at least the above-noted
second ones of the frame portions toward the closed
position such that the wheels thereon engage the
pipeline surface in pressurized relation thereby to
follow irregularities in the pipeline surface and to
assist the drive wheels in providing the required
tractive force.
The liquid jetting modules are mounted to the frame
via their suspension linkages with certain of these
modules being mounted to the upper frame section as
before. However, the remaining liquid jetting modules
are mounted via their respective suspension linkages
only to the above-noted first ones of the pivotable
frame portions so that when the latter are in their
2 ~ fi z1
predetermined closed positions (as defined by their
respective stops) the positions which the suspension
linkages for the liquid jetting modules occupy relative
to one another around the pipeline surface are
essentially independent of the variable positions of
the above-noted second ones of the frame portions as
the wheels thereon follow irregularities and/or out of
round conditions in the pipeline surface.
By virtue of the above arrangement, the previously
noted problems of longitudinal streaking and loss in
cleaning efficiencies due to "side stand off"
variations are greatly d;min1~hed.
Another problem associated with the earlier form of
hydrocleaning apparatus described in the above-noted
published application concerns the mounting arrangement
for the several liquid ~etting modules. It was
previously noted that suspension linkages were used to
connect each module to the frame and to permit
independent movement of the modules relative to the
frame and to one another radially inwardly and
outwardly relative to the pipeline when in use. Guide
wheels were located on both the forward and rearward
portions of each module for contacting the pipeline
surface during relative movement therealong. The
linkage arrangements as described in the above patent
applications are parallel arm linkages and as the
modules were moved inwardly and outwardly they were
retained in parallel positions relative to the pipeline
axis. This arrangement was found to work very well in
most situations but in cases where relatively thick
pipeline coatings were encountered, it was found that
with the forward guide wheel riding up on the
relatively thick coating, the miniml1m standoff distance
between the pipeline surface and the rotary swing arm
nozzle was excessive at the rear portion of the nozzle
pass. While the standoff distance at the forward
portion of the pass was acceptable as this was being
governed by the front guide wheel, a system had to be
found to move the nozzles' rearward pass lnwardly
towards the pipeline surface so as to permit the normal
m~ n ~ m~lm standoff distance of, for example, one-half
inch, to be obtained for the rear pass of each swing
arm revolution.
In order to alleviate the above problem the
invention in a further aspect provides for a transverse
pivot arrangement which secures each module to its
associated suspension linkage so as to permit pltching
motions of the modules to take place as the guides
thereon follow irregularities in the pipeline surface.
As a result of this pitching motion, a desired ~ln~mllm
standoff distance between the rotary swing arm nozzles
and the pipeline surface can be maintained at both the
rearward and forward extremities of the path of motion
of the rotary swing arms thus helping to ensure good
cleaning efficiencies even in the case of relatively
thick coatings.
The transverse pivot described above typically
defines an axis passing through the rotation axis of
the associated swing arm nozzle assembly. A further
desirable feature includes the provision of an
adjustment mechanism associated with the pivot to
provide for adjustment of the orientation of the nozzle
rotation axis in a plane passing through the pivot axis
and transverse to the pipeline axis thereby to enable
the previously noted side standoff distances to be
adjusted and equalized.
Notwithstanding what has been stated above
regarding the desirability of providing the transverse
pivot for securing each module to its associated
linkages, there are situations which may be encountered
,~
20 111 196
wherein no pitching or rocking of the modules is
desired. Accordingly, as a further feature, means are
provided for locking each module relative to a portion
of its suspension linkage such that, in use, only the
S forward guide contacts the pipeline surface with the
module moving radially inwardly and outwardly in
generally parallel relation to the pipeline surface as
the forward guide encounters pipeline surface
irregularities, including various coating thicknesses
and the like.
In the hydrocleaning apparatus as described in the
aforementioned publishedapplication,~eliquid
jetting modules are positioned on the frame between
fore and aft sets of drive wheels. In the course of a
hydrocleaning operation it will be appreciated that the
high velocity liquid jets are cutting through the
coatings with the result being that particles of
coatings such as particles of coal tar, large and small
pieces of plastic tape and adhesive released from the
pipeline surface all tend to become caught under the
loaded rear drive wheels with the result being that
some of these materials may be pressed back onto the
pipeline surface. This phenomenon is called "tabbing"
and this material must be scraped off the surface by
hand. Also it was noted that strips of the plastic
tape tend to get caught in the drive chains and this
eventually builds up sufficiently to break the chain.
In order to alleviate the above-noted problem, the
present invention in a further aspect provides for all
of the drive wheels to be located on the frame such as
to be disposed forwardly of the modules and hence
forwardly of the region of contact of the liquid jets
with the pipeline surface. In this way, the pipeline
surface materials (e.g. old coating materials)
dislodged by these jets do not interfere with the
lo ~ 19 6
action of the drive wheels thus avoiding tabbing and
fouling of the pipeline surface. Hence, in a preferred
embodiment of the invention, the liquid ~etting modules
and their associated suspension linkages pro~ect or
extend rearwardly of the hydrocleaning frame assembly
in what might be termed a cantilever fashion.
For all forms of hydrocleaning machines some form
of protective shrouding is needed, firstly, to prevent
injury to personnel due to the ultra high water
pressures and rotating equipment involved, and
secondly, in order to satisfy environmental concerns.
In the operation of the hydrocleaning equipment a mist
is created containing liquid and small particles of
debris and this must be contained well enough so as not
to allow more than perhaps 5% of it or so to escape to
the surroundings. The shrouding must be capable of
accomplishing the above objectives and, moreover, it
must enable the water ~etting modules to move radially
inwardly and outwardly during operation without
possibility of interference between ad~acent shrouds.
Accordingly, in a further aspect of the invention,
each of the water jetting modules includes a shroud,
with the shrouds of ad;acent modules being in
overlapping relation to one another such that the
shrouds together define an annular array surrounding
and confining the rotary swing arm nozzles all around
the pipeline when in use so as to substantially prevent
random escape of liquid and removed debris. The
overlapping relationship between the ad~acent shrouds
allows for substantial radial motions of the liquid
jetting modules and their shrouds relative to one
another while avoiding both interference between as
well as the formation of gaps between the shrouds
through which liquid and debris might escape.
2 ~ 9 6
11
In a preferred form of the invention resilient
sealing flaps extend between ad;acent shrouds in the
overlap regions to further inhibit escape of materials
from between the shrouds. Certain of the lowermost
shrouds are provided with recess means for receiving
liquid and debris with an opening being provided for
draining liquid and debris from the recess. The
shrouds typically include side wall portions which
extend toward the pipeline surface into closely spaced
proximity thereto to avoid escape of liquid and debris.
It was previously noted that suspenslon linkages
are provided for connecting the modules to the frame
with suitable actuators being provided for positively
moving these modules toward or away from the pipeline
surface. A further improvement concerns the provision
of time delays associated with certain of the actuators
and arranged to permit the radial movements of the
modules to take place in a predetermined sequence which
is so selected as to avoid interference between
ad;acent shrouds during this radial motion either
toward or away from the pipeline surface.
In the period when the older pipelines were being
constructed, the most common type of pipe coating
utilized was coal tar with an outer wrap. The most
common outer wrap at the time was asbestos felt. Since
1972, asbestos has been recognized as a hazardous
material. Any time this material is present in a
working environment, extreme care must be taken to
prevent the asbestos from becoming airborne and inhaled
by working personnel. Both EPA and OSHA have
promulgated regulations concerning such environments.
It is generally accepted that there is no danger to
the personnel or environment during application of such
an outer wrap because the asbestos is non-friable and
encapsulated in tar. However, during the removal
12 ~ ~ fi~
process, the condition of the coating is much
different. with age, the coal tar and outer wrap
become brittle, forming a hard, easily broken coating.
In this condition, the asbestos is friable and any
mech~n; cal action to the asbestos results in its
becoming airborne. Prior methods of removing such
coatings included wire brushes, knives, hammers and
scrapers. These mechanical techniques each created
dust upon removal of the coating, thus rendering these
techniques unacceptable under today's safety
considerations when there is an asbestos content in the
coal tar coating.
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 ls
therefore greatly needed.
Further features and advantages of the invention
will become readily apparent from the following
description of a preferred embodiment of same.
13
BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS:
FIGURE 1 is a cross-section view of a hydrocleaning
apparatus according to the lnvention; certaln detalls,
such as the drive assemblies, having been omitted;
FIGURE 2 is a front end elevation view of the frame
assembly and drive, the liquid jetting modules and
their suspension linkages having been omltted;
FIGURE 3 is a side elevation view of the
hydrocleaning apparatus, several of the liquid ~etting
modules and their suspension linkages and shrouds
having been omitted;
FIGURE 4 is a side elevation view of a liquid
~etting 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 slde elevation
vlews 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 1 3B 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 hydraullc system.
~ fi ~ ~ 9 ~
14
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
The basic principles relating to hydrocleaning of a
pipeline surface are set out in detail in our above-
noted published applications and need not be repeate.d here.
The above published 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 12
along the pipeline P. The cleaning paths thus defined
by the several swing arm nozzles 24 ideally overlap
somewhat at their marginal edges, as indicated by the
letters OL in EIGURE 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
2 ~ ff ~ ~
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)~
s 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 publishedapplication)
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 (FIGURE3)
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
~ ~ q ~
16
in FIGURE 1, such closed position being provided by
ad;ustable 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 ~etting module 22 vla a respective
parallel arm suspension linkage 26 to be described ln
detail later on. When frame portions 50 are in the
predetermined closed posltions 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
2 ~ 6
17
necessary radial adjustability to accommodate a wide
variety of pipeline diameters.
The frame portions S0, 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 commo~
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.
18
The above-noted front and rear drive assemblies 14,
16 need not be described in detail. They are mounted
to the upper frame section 40 by way of multi-hole
brackets 74 permitting substantial radial adjustment to
accommodate a wide variety of pipe sizes as noted in
our published 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 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
at the tips of the arms, all as described in our
earlier published 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
9 ~
19
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
multi-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
2~ 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
20 2~-9 ~ ~ ~ 6
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
s stand-off distances (see our published 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
21
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 swlng arm nozzles to
be inspected and repalred 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 ad~ustable
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
8-12, the shroud assembly is shown in further detail.
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 ad~acent
shrouds allows for substantial radial motions of the
22
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 ad~acent shrouds to further lnhibit 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 module (FIGURE 4 ) . The fore and
aft end walls 144, 146 extend normal to top wall 143
and in use pro~ect inwardly into close proximity to the
pipeline surface, the free edges of these walls being
curved to match the pipellne 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 a~commodate 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 ad~acent 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
23 2 0 ~ ~ 1 9 6
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 fltted together
which receives the downwardly draining liqulds and
debris. A suitable opening 154 allows thls materlal to
escape into a suitable collector.
As noted previously, the several modules 22 and
their suspenslon 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 ad~acent 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 ls 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 positlons 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
3~ disbursal of small fibers into the surrounding air
2 0 ~ 6
-24-
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
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 4~~, 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 more enhanced ability to deflect debris off the
nozzle.
The manner of operation of the hydrocleaner
described above will be readily apparent to those
skilled in this art on review of this disclosure and
the disclosures contained in our published 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.
