Note: Descriptions are shown in the official language in which they were submitted.
1060488
This invention relates to apparatus for aligning a
new section of pipe with an existing pipe section to facilitate
welding the new section to an end of the existing pipe section.
Large sections of pipe are usually welded to one
another to create continuous lengths of pipe ~nown sometimes
as pipeline. In order that the weld between sections of pipe
should be continuous and strong it is essential to ensure that
ends of the pipe are brought against one another and aligned
with one another so that both sections are concentric about
the same axis. Various pieces of apparatus have been used for
this purpose and although some are quite useful they are ex-
pensive and they require considerable maintenance.
It is an object of the present invention to provide
a relatively simple apparatus which both aligns and clamps a
new section of pipe in a position relati~e to an existing
section of pipe to facilitate welding and which can be dis-
~ engaged readily and moved along the new pipe section into
j psition for welding the next new section of pipe.
Accordingly, apparatus is provided for use in
aligning a new pipe section with an existing pipe section
` to facilitate welding the new pipe section to the existing
pipe section. The apparatus is adapted to fit within the pipe
sections and to be moved longitudinally along the pipe sections
and includes an actuator means disposed longitudinally and
including a longitudinal rod; a plurality of spaced-apart radial
elements; means fixedly coupled to the actuator means and
defining radial guides for the radial elements to guide the
elements between a withdrawn position and an engagement posi-
j tion in which the elements are positioned to engage both the
existing and the new pipe sections to thereby align the new
pipe section with the existing pipe section; and a plurality
of links attached one to each of the radial elements and to
~k
--2--
1060488
the longitudinal rod. The links are inclined outwardly and away
from the actuator means whereby a longitudinal force from the
actuator means in a direction towards the links creates a com-
pressive force in the links to cause the links to move the
elernents in the respective radial guides from the withdrawn to
the engagement positions.
The invention will be better understood with reference
to the drawings, in which: ,~
Fig. 1 is a cut-away perspective view of a preferred
embodiment of pipe aligning apparatus according to the invention
and showing end portions of a pair of pipe sections in ghost
outline;
Fig. 2 is a compound sectional view on line 2-2 of
Fig, 1 showing parts of the apparatus used to contact adjacent
end portions of the pipe sections, an upper half of the figure
showing the parts in a withdrawn position and a lower half
showing the parts in an engagement position, the background
elements behind the section having been omitted for clarity
of drawing;
Fig. 3 is a sectional view on line 3-3 of Fig. 1 and
illustrates a latch for locating the apparatus relative to the
-, end of an installed pipe section; and
Fig. 4 is a perspective view of another part of the
apparatus and illustrating a clamping mechanism for locking
the apparatus in position in the installed pipe section.
;i
Reference is first made to Fig. 1 which illustrates
apparatus according to a preferred embodiment of the invention
and designated generally by the numeral 20. An installed pipe
section 22 is shown in ghost outline together with a further
pipe section 24 which is about to be welded to the installed
section pipe 22. The apparatus consists essentially of a
pneumatic actuator 26 having a hollow piston rod 28 and coupled
1060488
at its outer extremity to a pneumatic supply line 30 and radial
engagement elements 32 coupled to the piston rod 28 so that
operation of the pneumatic actuator 26 results in moving the
elements 32 radially outwards into engagement with the inner
surfaces of the pipe sections 22, 24. This movement aligns the
pipe section 24 with the pipe section 22 and permits welding to
take place to join these sections. After such joining, the
actuator is de-energized and the apparatus can then be drawn
through the pipe section 24 which then effectively becomes an
installed pipe section and the apparatus is moved to the end
of this section (not shown in the drawings) for attachment of
another pipe section.
There are three main structural parts in the appara-
tus, namely a pair of heavy circular discs 34, 36 and a cylinder
assembly 37 forming a mutual part of the actuator 26. The
assembly 37 includes a series of stepped rods 40 which are
welded tothe outer surface of a pneumatic cylinder 42 and
located in an end ring 44 welded to one end of the cylinder
42. The cylinder has an end wall 43 and beyond the end ring
44, the rods 40 have reduced diameters which are threaded to
receive nuts 46 to clamp the end cover 38 in sealing contact
with the end ring 44. Preferably a gasket would be used in
; this joint, although for clarity of drawing, no gasket is
shown. The rods 40 are also of reduced diameter where they
pass through the discs 34, 36 and cylindrical sleeves 48 are
positioned between the disc to act as spacers. Outer ends of
the rods 40 are threaded to receive nuts 50 which hold the discs
in position on the rods 40.
A first paix of wheel assemblies 52 (one of which can
be seen) are attached to the cylinder 42 adjacent end cover 38
and a further pair of wheel assemblies 54 are attached to disc
34 on a surface facing the end cover 38. The wheel assemblies
1060488
52, 54 project slightly beyond disc 34 and end cover 38 so that
the apparatus can be moved within pipe 22 with these wheels in
contact with the inner surface of the pipe.
The basic structure also includes four guide shoes 56
which project axially and which are welded to the disc 36 for
guiding pipe section 24 into position on the apparatus.
The pneumatic actuator 26 also includes a piston 58
consisting of a flexible lip seal element 60 in engagement with
a smooth inner surface of the cylinder 42 and rigidified by re- ,
spective inner and outer circular elements 62, 64. All of the
elements 62, 64 and 60 are located on the piston rod 28 at a
portion 66 of reduced diameter so that the elements 62, 64 and
60 can be drawn into tight engagement with a shoulder at the
end of this portion using a nut 68. This nut is threaded onto
a threaded portion 70 having a smaller diameter than that of
the portion 66. Although it cannot be seen in this view, it
should be remembered that the piston rod 28 is hollow through-
out its length so that pressurized air can be transmitted from
the supply line 30 to a chamber 72 created between the piston 58
and the end cover 38. It should also be noted that end wall 43
defines a hole 71 to vent the space between the piston 58 and
end wall 43.
Piston 58 is biased toward a rest position by a coiled
compression spring 74 located about the piston rod 28 and be-
tween elements 64 and end wall 43. As will be described, when
, the piston is energized it moves longitudinally from the rest
position shown in Fig. 1 to a displaced position in which the
engagement elements 32 are in frictional engagement with the
inner surfaces of the pipe sections 22, 24. This movement of
the piston is guided by the piston rod which slides in suitably
formed central opening in end plate 43 and disc 36. Suitable
bearings can be provided if preferred.
~060488
Reference is now made to Figs. 1 and 2, with partic-
ular reference to Fig. 2 to describe the connection between the
piston rod 28 and the engagement elements 32. The upper half of
Fig. 2 illustrates the parts when the piston is in the rest posi-
tion and the lower half illustrates the parts after the piston
has moved into a displaced position under the influence of com-
pressed air supplied by way of air supply 30 and longitudinal
opening 75.
Piston rod 28 has pairs of brackets 76 attached to the
10 rod in generally radial fashion and such that each pair is paral-
- lel to one another. Each pair of brackets supports one of a
series of short links 78 on respective pivot pins 80 and the
links are also pivoted to respective pins 82, each of which is
supported between similar outer parts of engagement elements 32.
These o~ter part~ are separated from one another by spacers which
are welded to the outer parts. For clarity of drawing, the
spacers have been omitted. Each of the elements 32 sits in a
corresponding one of pairs of radial guides 84, 86 formed in the
- discs 34, 36 to guide the elements between withdrawn and engage-
20 ment position. The outer surfaces of the elements 32 define
lands 87, 89 separated by a recess 91 which ensures that the
elements are not damaged during welding of the pipe sections.
As will be seen from a comparison of the upper and
lower parts of Fig. 2, when the piston rod 28 is moved to the
right of Fig. 2 (i.e., away from end cover 38), the links 78
are forced to rotate about pins 80 thereby increasing the radial
distances between the center of piston rod 28 and pivot pins 82.
As a result, the elements 32 move radially in the guides 84, 86
and come into engagement with the inner surfaces of the in-
30 stalled pipe section 22 and the pipe section 24 which is aboutto be welded to the pipe section 22. The elements 32 can be
disengaged after the pipes are welded to one another by simply
1060488 :
venting the air supply so that the spring 74 (Fig. 1) will re-
turn the piston to the rest position thereby drawing the elements
32 radially inwards.
The basic structure necessary to locate two pipe sec-
tions has been described. However, it will be appreciated that
further detail can be added to provide a more advantageous struc-
ture. For instance, positive location of the wheels of wheel
assemblies 52, 54 will better track the apparatus as it moves
through the pipe. Also, when the apparatus is drawn through
the pipe it would be preferable to have means for locating the
apparatus on the end of the pipe section before a subsequent
section is engaged. Further, if the apparatus could be locked
in position once it is located at the end of the pipe section
this would ensure that the apparatus is not dislodged when
,~' another pipe section is brought into position. Yet a further
,~ improvement to the basic invention could be made by providing
means for permit welding in atmospheres of inert gas which are
sometimes used in special welding techniques.
~ Positive location of the wheel assemblies is provided
20 by a biased wheel 88. This wheel is suspended by a pivot pin
90 located in a pair of pivoted arms 92, 94 which in turn are
suspended from a pin 96 attached by a suitable bracket to the
end cover 38. A coiledtension spring 98 is coupled both to the
arms 92, 94 and to the plate 38 to bias the wheel 88 outwardly
into contact with the inner surface of pipe section 22. Conse-
quently, there is a reactive force at the wheel assemblies 52
which tends to maintain these wheels in contact with the inner
surface of the pipe section 22 thereby tending to cause the
apparatus to move longitudinally inside the pipe with a minimum
of helical tracking.
It will be appreciated that once the pipe section 24
has been welded to the installed section 22, the apparatus must
--7--
-
1060488
be drawn down the pipe section 24 to the end of this section.
Although the apparatus can be located by eye, as ~entioned, it
is preferable to include some structure which will automatically
position the apparatus on the end of the pipe section. Suitable
str~cture is shown in perspective in Fig. 1 and in side view in
Fig. 3 which also illustrates the operation of the structure.
Referring initially to Fig. 1, a latch 100 is provided on a
lowermost one of the elements 32. The latch consists of a pair
of pawls 102 ganged together on a pin 104 which is rotatably
mounted in this element 32.
The pawls 102 are shown in ghost outline in Fig. 3
in a withdrawn position. This is the position the pawls occupy
as the apparatus is drawn along the pipe section. It will be
evident that when the latch reaches the end of the pipe section
the pawls will fall downwardly until a step formed in the ends
of the pawls locates on the end of the pipe section. The pawls
are then adjacent a safety stop 106. Once the pawls have fallen
into this position, the apparatus can be pushed toward the pipe
for positive engagement of the pawls and proper location.
As previously mentioned, it is preferable if the
apparatus can then be locked in this position so that when a
further pipe section is brought into engagement with the orig-
i inal pipe section the further section will dislodge the pawls
; - inwardly into a position shown in Fig. 3 in broken outline.
The latch is then no longer effective and will not have any
effect on the welding procedure to be performed on the pipes.
A suitable form of lock or clamp is illustrated partly
in Fig. l but more descriptively in Fig. 4 where it can be seen
that the disc 34 has a locking mechanism 108 attached to it.
This mechanism is controlled either manually or by a pneumatic
actuator operating through ganged control rods 110. These rods
project through disc 36 (see Fig. 1) and continue on to project
--8--
1060488
through disc 34. The ends of the rods contain ends of a pin 112
which, as also seen in Fig. 3, rides in a slot 114 formed in a
cam element 116. This element is pivoted on a pin 118 suspended
bet~leen a pair of support arms 120 welded to the disc 34 and,
consequently, when the control rods 110 are pushed through the
disc 34, there is a resulting turning moment applied to the cam
element 116 to cause the cam element to rotate about the pin 118
such that an upper cam surface 122 moves generally towards the
disc 34.
A cam follower 124 is in the form of a roller mounted
; for rotation on a pin 126. Ends of the pin are engaged in a
pair of parallel legs 128, 130 which are attached at their
upper ends to a cross bar 132. The legs 128, 130 provide clear-
ance about the piston rod 28 and an e~tension piece 134 projects
upwardly from the cross bar 132 and rides in a bearing lock 136
attached to the disc 34. A collar 138 is provided on the pro-
' jection 134 to prevent excessive downward movement through the
~, bearing block 136 and a cup-shaped friction element 140 is pro-
vided at the e~tremity of the projection 134.
When it is desired to lock the apparatus in position
in a pipe, the locking mechanism 108 is actuated by creating a
longitudinal force in the control rods 110 to push the cam ele-
ment 116 and thereby rotate this element about the pin 118. As
a result, the surface 122 of the cam element passes under the
cam follower l24 and the shape of the surface 122 is such that
~, an upward motion is imparted to the follower 124. Consequently,
the structure which includes the iegs 128, 130 and cross bar
132 moves upwardly carrying the projection 134 through the bear-
ing block 136. The friction element 140 is then forced into
engagement with the inner surface of the pipe and the parts are
proportioned such that this engagement with the pipe results in
some distortion of the element 140 sufficient to permit the cam
^ - ~
~060488
follower 124 to locate in a shallow cylindrical recess 142 in
the cam surface 122. The force which was applied to the con-
trol rods 110 can then be removed and the mechanism will remain
in a locked position with sufficient compressive force in the
friction element 140 to ensure that there is adequate resist-
ance to longitudinal movement of the apparatus along the pipe.
When it is desired to unlock the mechanism 108 a ten-
sile force is applied to the rods 110 resulting in dislodging
the cam follower 124 from the recess 142 and thereby allowing
the cam to return to the position shown in Fig. 4. Again,
although this structure is to be found in a preferred embodi-
ment of the invention, it is not essential if an operator pre-
fers to use a simpler structure and to rely on his skill to
ensure that the apparatus is not moved inside the existing
pipe section when a further pipe section is brought into con-
tact with an existing section.
~ A further feature of the preferred embodiment which
; is not necessary in some applications is the provision of seals
which will permit the chamber formed between discs 34, 36 to be
filled with inert gas to enhance welding conditions where inert
gas welding is desirable. As seen in Fig. 4, the disc 34
carries a flexible sealing ring 144 supported by a metal ring
, 146 attached by screws 148 to the disc 34. Also, a seal 150 is
provided at the center of the disc 34 and proportioned to fit
snugly about the piston rod 28. This seal is attached to disc
34 by a ring 152 and screws 154. The disc 36 (Fig. 1) also
carries a seal similar to that shown in Fig. 4 on disc 34.
However, it will be appreciated that the seal on disc 36 will
have to be in sections to accommodate the guides 56. This seal
is indicated by the numeral 156 in Fig. 3.
Although the sealing system will not be perfect, the
seals will limit the loss of inert gases which are pressurized
~ 1060488
- above the welding location and which pass between the ends of
the pipe before welding takes place. This compares favorably
with previous welding techniques where usage of inert gas was
considerable and in fact it was very difficult to ensure that
.,. I .
the welding location was immersed in inert gas.
It will now be appreciated that the apparatus accord-
ing to the invention simplifies the attachment and welding of a
section pipe to an existing pipe section. Firstly, the appara-
tus aids in guiding the new section of pipe into position and
because the apparatus has been located using latch 100 and
~- locking mechanism 108 there is little likelihood that the new
section of pipe will dislodge the apparatus from its required
position in the existing pipe. Consequently, once the new pipe
section has been placed quite closely against the existing pipe,
the pneumatic actuator can be energized to bring the elements
32 (Fig. 1) into engagement with the pipe sections. This en-
gagement can at first be quite light so that the new section
can be brought into position by pushing it longitudinally
' against the existing pipe and then further energizing of the
- 20 actuator will result in a strong locking action which will both
' retain the new pipe section in position and align it with the
existing pipe.
After welding has taken place, the locking mechanism
, 108 is disengaged and the apparatus can then be drawn longitud-
inally through the new pipe section and into position for re-
ceiving yet another section of pipe. This process is continued
along the pipe until the necessary length of pipeline has been
, created.
Although the preferred embodiment has been found to
be most suitable, it will be appreciated that some variations
can be made within the scope of the invention. For instance,
the links 78 and associated parts could be replaced by a suitable
1060488
cam or wedge action provided that the elements 32 are restrained
and biased inwardly so that they would return to an inner or
disengaged position such as that shown at the top of Fig. 2.
Similarly, although a pneumatic actuator is to be preferred, it
is possible to use a hydraulic actuator and similarly the stop
mechanism could be actuated directly by a pneumatic actuator or
by a hydraulic actuator in place of the cam and follower arrange-
ment. Modifications such as these are within the scope of the
invention.
'
-12-
