Internal alignment clamp

An internal alignment clamp for use in welding together the confronting ends of a pair of end-to-end pipe lengths comprises a body having an arcuate segment at the opposite ends of which are pivoted a pair of force applying arms movable into and out of engagement with the inner surfaces of such pipes. Mounted on the clamp body is a radially adjustable carriage equipped with a pair of driveable wheels that support the clamp for movement longitudinally of the pipes. An extensible and retractable ram is connected to the force applying arms and to the carriage and is operable to extend the arms and retract the driveable wheels, thereby enabling the arcuate segment of the clamp and the arms to bear against the inner surfaces of the pipes and conform their configurations. An insert is provided to span any gap which exists between the confronting ends of the arms in their expanded positions.

This invention relates to an expansible and contractable hydraulic 
alignment clamp adapted to be located within and at the juncture of two 
confronting pipe lengths and which is operable to reform and align the 
confronting ends of the pipe lengths to conform to each other in 
preparation for welding the two lengths together. 
BACKGROUND OF THE INVENTION 
Large diameter lengths of pipe intended for use as vessels, tanks, or 
sections of a pipeline normally are cylindrical at the time they are 
manufactured. However, as such pipe lengths are stored, transported, or 
conditioned for welding to another length, it is more common than not that 
the pipe lengths will assume an oval configuration. If the lengths are to 
be welded together with as little mismatch between their confronting ends 
as is possible, therefore, the confronting ends of the pipe lengths must 
be reformed so that their configurations conform to one another. This has 
been done in the past by welding dogs or clips to the pipe sections 
adjacent their confronting ends so that wedges and the like can be used to 
effect relative adjustment of the ends. After two pipe lengths have been 
secured together, the dogs and clips are burned or ground off, but these 
practices are time consuming. They also are objectionable since heat 
stressing of the pipes is possible resulting in permanent damage thereto. 
There also have been proposed various kinds of internal alignment clamps 
which may be fitted within one length of pipe in a position to span the 
joint between such pipe and another similar pipe. Such clamps are 
necessarily heavy, cumbersome units and require the expenditure of 
considerable effort and ingenuity in locating them in proper position 
relative to the joint between the two pipes. Further, such clamps usually 
have a gap in expanded condition which prevents full engagement between 
the clamp and the internal surfaces of the pipes, thereby providing for 
the possibility of misalignment at the zone of such gap or the discharge 
of weldment into the pipes through the gap. 
SUMMARY OF THE INVENTION 
A clamp constructed in accordance with the invention comprises a body 
having an arcuate segment the surface of which is adapted to bridge the 
joint between a pair of end-to-end pipe lengths. In circumferential 
prolongation of the segment are two arcuate force applying arms or limbs 
pivoted at corresponding ends on the body. The opposite ends of the arms 
confront one another. A hydraulic operating ram is mounted at one end on 
the body and extends radially of the latter and is connected to the 
confronting ends of the arms by a force multiplying toggle linkage so that 
reciprocation of the ram effects radial expansion and contraction of the 
arms. 
Expansion of the arms results in the provision or enlargement of a gap 
between those ends of the arms which are coupled to the ram. A spanner may 
be inserted in such gap to fill the latter and the spanner is radially 
adjustable so as to cause the radially outer surface of the spanner to be 
located at a level corresponding to that of the outer surfaces of the 
arms. The gap between the arms is tapered in a direction transversely of 
the length of the arms and the spanner is correspondingly tapered so as to 
enable it to be fitted into the gap even though the length of the latter 
may vary. 
The clamp body is mounted on a frame extending in a direction away from the 
clamp body and parallel to the axis of a pipe in which the clamp is 
accommodated. At that end of the frame remote from the clamp is mounted a 
plurality of radially extending wheels which are adapted to engage the 
inner surface of a pipe within which the clamp is positioned so as to 
enable the clamp to be self supporting. 
The clamp body is provided with a radially reciprocable carriage on which 
are mounted powered driving wheels that are movable into and out of 
engagement with the inner surface of the pipe. The carriage is coupled to 
the ram which drives the force applying arms in such manner that, when the 
arms are in radially contracted condition, the driving wheels bear against 
the inner surface of the pipe and support the clamp for movement 
longitudinally of the pipe. When the clamp arms are radially extended by 
the drive ram, however, the carriage automatically is moved to a position 
in which the driving wheels are withdrawn from engagement with the inner 
surface of the pipe. The clamp then has only an arcuate segment of its 
body and the clamp arms in engagement with the pipe.

DETAILED DESCRIPTION 
Apparatus constructed in accordance with the invention is especially 
adapted for use in welding two pipe lengths 1 and 2 of large diameter to 
one another. For example, the apparatus has been used successfully in 
welding together pipes of up to eight feet in diameter. There is no known 
reason, however, that the apparatus could not be used for welding together 
pipes of even greater diameter. When preparing pipe lengths such as those 
indicated at 1 and 2 for welding, it is common to chamfer or bevel the end 
of each pipe and position the chamfered ends in confrontation with one 
another. Normally, such pipes are supported on spaced apart, powered 
rollers R as is indicated in FIG. 3 by means of which the pipes may be 
rotated about their own longitudinal axes. 
When the confronting ends of large diameter pipes are placed adjacent one 
another, it is not uncommon for a mismatch to be present, even though the 
two pipes originally were of identical diameter. The mismatch usually is 
due to one or both of the pipes assuming an elliptical, rather than 
cylindrical, configuration during storage, transport, or other handling. 
If a proper weld is to be made between the two pipes lengths 1 and 2, 
therefore, the mismatch must be corrected by reforming one or both of the 
pipes so that their configurations match as much as possible. Apparatus 
constructed in accordance with the invention attains such objective. 
A clamp constructed in accordance with the invention comprises a body 3 
composed of spaced apart, parallel steel plates 4 and 5 each having an 
arcuate segment formed on a radius R-1 (FIG. 3). The radius R-1 preferably 
corresponds substantially to the radius of the pipes lengths 1 and 2 when 
the latter are cylindrical. The plates 4 and 5 forming the body 3 also are 
provided with arcuate segments formed on a radius R-2 which is shorter 
than the radius R-1. Each radius R-2 is of uniform length, but the center 
of each radius is offset to one side of a center line passing through the 
center of the body 3. The plates 4 and 5 forming the body 3 are cut 
diametrally to form a channel 8 flanked by a pair of sections 9. The free 
ends 10 of the sections 9 are flat as is best shown in FIG. 3. 
Between the arcuate surfaces 6 and 7 of the body 3 is a pair of radially 
extending steps 11 each of which is of such radial dimension as to 
correspond to the width of one end of an arcuate force applying arm or 
link 12. Each of the arms 12 is composed of two, spaced apart, parallel 
steel members 13 and 14 and each has an inner arcuate surface formed 
substantially on the radius R-2 and an outer arcuate surface formed on a 
radius R-3 which corresponds in length to the radius R-1, but has its 
center offset from the vertical center line of the body 3, as is shown in 
FIG. 3. Each arm 12 has welded thereto one end of a mounting link 15 the 
opposite end of which is journaled on a pivot pin 16 carried by the body 
3. Each arm 12, therefore, extends in prolongation of the arcuate segment 
of the body 3 and is movable relative to the body between radially 
expanded and contracted positions. 
When the arms 12 are contracted radially, as shown in FIG. 3, the 
offsetting from the center line of the centers of the radii R-2 and R-3 
makes it possible for the outer surface 6 of the body 3 and the outer 
surfaces of the arms 12 to form a member having an ovate, rather than 
cylindrical, configuration. Upon radial expansion of the arms, in a manner 
yet to be explained, the outer surfaces of the body and the arms will form 
a generally circular member having a diameter corresponding substantially 
to the inside diameter of the pipes 1 and 2. 
Operating means for radially expanding and retracting the arms 12 is 
designated generally by the reference character 18 and comprises a double 
acting hydraulic ram 19 having a cylinder 20 accommodated in the space 8. 
Fixed to the base of the cylinder is a mounting ear 21 that is positioned 
between the plates 4 and 5 and pivoted thereto by a pin 22. Extending from 
the upper end of the cylinder 20 is a piston rod 23 that extends into a 
hollow, rectangular housing 24 and is secured thereto by means of a 
clevice 25 and pin 26. The housing 24 is in telescoping relation with the 
cylinder 20 and thus is capable of axial movements relative thereto in 
response to extension and retraction of the piston rod 23. 
The arms 12 and the ram 19 are interconnected by force magnifying toggle 
links 27, corresponding ends of which are pivoted by pins 28 to the 
respective arms 12 and the opposite ends of which are pivoted by pins 29 
to projections 30 carried by the housing 24. The arrangement is such that 
the extension of the ram 19 causes the links 27 to move the arms 12 
radially outwardly about their respective pivots 16 from the positions 
shown in FIG. 3 to the positions shown in FIG. 4. When the ram 19 is in 
its fully extended position, the pivot pins 28 and 29 will lie on a 
straight line and the arms 12 will be in their position of maximum 
extension. In such positions of the arms 12 the outer surfaces of the body 
and the arms will form a true circle except for a gap 31 which lies 
between the confronting ends 32 of the arms 12. Theoretically, the 
diameter of the circle formed by the surfaces of the arms 12 when the 
latter are in their positions of maximum extension should correspond to 
the inside diameter of the pipes 1 and 2, but in practice the diameter of 
such circle is a little greater than the inside diameter of the pipes. 
This difference enables the clamp to compensate for differences in wall 
thickness between two supposedly identical pipes. 
It has been pointed out heretofore that the body 3 is composed of parallel, 
spaced apart plates and that the arms also are composed of parallel, 
spaced steel plates. Obviously such members could be formed of single 
thickness components, but the weight of the clamp would be increased 
greatly. Further, it is preferred to provide arcuate strips or inserts 33 
of copper, or other metal to which weldment does not adhere, between the 
plates of the body and arms, and at their outer peripheral edges, to fill 
the space between the plates. The strips removably may be retained in 
place in any suitable manner. 
As is apparent from FIG. 4, the gap 31 between the confronting ends 32 of 
the arms 12 could be substantial when the arms are in their fully extended 
positions. Should the pipe 1 or 2 be deformed radially inwardly in the 
region of the gap, therefore, expansion of the arms 12 would not 
necessarily result in reformation of such pipe at the gap. Accordingly, 
apparatus constructed in accordance with the invention preferably includes 
a spanner 34 having a head 35 formed on an arc corresponding to the arc on 
which the outer surface of each arm is formed. The head has a width at 
least as great as the thickness of the arms 12 and is secured to a 
reciprocable support stem 36 of a conventional jack body 37 having a base 
38 which removably may be supported on the housing 24. 
As is best shown in FIG. 5, the arm-forming plates 13 and 14 are not 
coextensive in length, but are circumferentially offset so that the gap 31 
between the confronting ends 32 of the arms is wedged-shaped in plan view. 
Accordingly, the ends 39 of the spanner head 35 are inclined so as to form 
a truncated wedge. The spanner head, therefore, may be wholly or partially 
accommodated in the gap 31 and form a continuation of the arcuate outer 
surfaces of the arms 12 and the inserts 33. 
A clamp constructed in accordance with the preferred embodiment of the 
invention includes a frame and supporting wheels by means of which the 
clamp may be self supporting either in or out of a pipe. Preferably, the 
wheels are capable of being driven so that the clamp may traverse a pipe 
of any length. 
The frame is designated generally by the reference character 42 and 
comprises a pair of upper arms 43 welded at corresponding ends to the 
plate 4 of the body 3. The arms 43 converge rearwardly from the clamp body 
and are joined to a block 44. The frame also includes a pair of lower, 
parallel members 45 which are welded at corresponding ends to the member 4 
of the body 3 and extend rearwardly therefrom and are joined to plates 46. 
A crossbar 47 is secured to and spans the lower frame members 45. Upwardly 
converging braces 48 extend between and are secured to the members 44 and 
46. 
Fixed to the members 46 is a pair of rectangular housings 49 in each of 
which is mounted a correspondingly shaped support 50 equipped at its lower 
end with a clevice 51 in which is journaled a wheel 52. As is best shown 
in FIG. 2 the members 49 and 50 diverge downwardly so that the wheels 52 
may engage the inner surface of a pipe at points spaced on opposite sides 
of a vertical plane passing through the center of the pipe. Preferably, 
the wheel supports 50 are extensible and retractable axially of the 
respective housing 49 in any conventional manner. 
The frame 42 carries a pair of stablizers 53 at its upper end and each 
stablizer comprises a preferably square sleeve 54 within which is a 
reciprocable stem 55 provided at its free end with a clevice 56 in which 
is journaled a wheel 57. Braces 58 reinforce the sleeves 54. Within each 
of the sleeves 54 is a spring 59 which biases the associated wheel 
upwardly. A suitable stop (not shown) reacts between each stem 55 and its 
associated sleeve 54 to limit the extent to which the wheels 57 may 
project upwardly. 
Adjacent the clamp body 3 is a driving wheel mounting plate 60 having 
upwardly inclined projections 61 to which are welded rectangular housings 
62 like the housings 49 and in which similar wheel supports 63 are 
mounted. Each support has a clevice at its lower end in which is 
accommodated a driving wheel 65 that is fixed on an axle 66 journaled in 
the clevice 64. Each axle 66 is coupled to a drive transmitting shaft 67 
by means of universal joints 68, 69 and to a second drive shaft 70 of a 
transmission 71 that is coupled to and driven by a hydraulic motor 72 
supported on the mounting plate 60. 
The driving wheel mounting plate 60 is carried by a vertically reciprocable 
carriage 75 comprising a pair of parallel, diametrally extending frame 
bars 76 adjacent the body member 4 and straddling the ram 19. At their 
upper ends the frame bars 76 are secured to the ram housing 24 by 
connecting bars 77. The carriage 75 also comprises a pair of diametrally 
extending, spaced apart frame bars 78 which confront the body member 5 and 
straddle the ram 19. The frame bars 78 also are connected to the ram 
housing 24 at their upper ends by connecting bars 79. The pairs of frame 
bars 77 and 78 thus are located on opposite sides of the body 3 and are 
joined at their upper ends to the housing 24 so as to move with the 
latter. 
For purposes of stabilizing the carriage, the body members 4 and 5 
preferably are slotted, as indicated at 80, for the reception of 
transversely extending bars 81 which are secured at corresponding ends to 
the frame bars 76 by pins 82 and at their opposite ends to the frame bars 
78 by similar pins 83. The driving wheel mounting plate 60 is bolted, 
welded, or otherwise suitably fixed directly to the frame bars 76 of the 
carriage 75. 
The construction and arrangement of the driving wheel mounting plate 60 and 
the carriage 75 are such that, when the ram 19 is in its retracted 
position, as shown in FIGS. 1-3, the carriage 75 is in a downwardly or 
radially outwardly extended position and the drive wheels 65 project 
beyond the arcuate surface 6 of the body 3 so as to be able to bear 
against the inner surface of a pipe and support the clamp in an upright 
position in conjunction with the wheels 52. When the ram 19 is extended, 
however, the housing 24 moves upwardly, to the position shown in FIG. 4, 
thereby causing corresponding movement of the carriage 75 and, 
consequently, upward or radially inward movement of the drive wheels 65 to 
a position in which they are radially inward from the peripheral surface 6 
of the body 3. The surface 6 of the body, therefore, may rest directly 
upon the inner surface of the pipe. Thus, expansion of the arms 12 does 
not subject the wheels 65 to any stresses. 
When the drive wheels 65 are in their projected, clamp supporting position 
and when the arms 12 are contracted, driving of the reversible hydraulic 
motor 72 in one direction or the other will enable the clamp to be driven 
longitudinally of a pipe within which the clamp is located. The wheels 57 
will be projected by their springs 59 into engagement with the upper inner 
surface of the pipe and will stablize the movement of the apparatus 
through the pipe. 
Means for operating the ram 19 and the driving wheels 65 may comprise any 
one of a number of conventional mechanisms. Preferably, however, the frame 
42 supports a hydraulic fluid reservoir 85 connected by suitable and 
conventional conduits (not shown) to the ram 19 and the hydraulic motor 72 
and to a pump 86 that is driven by an electric motor 87. A reel 88 also is 
mounted on the frame 42 and around which is wound a flexible electrical 
cable 89 provided with a manually operable control box 90 which enables 
the motor 87, the pump 86, the motor 72, and the ram 19 to be controlled 
via suitable, conventional valving (not shown). The cable 89 will be 
connected in a conventional manner to a suitable source of electrical 
power. 
FIG. 1 illustrates the clamp located within the pipe 1 and with the body 3 
bridging the joint between the confronting ends of the pipes 1 and 2. As 
shown, the pipes have a substantial mismatch at their upper ends. In the 
positions of the parts shown in FIG. 1, the frame 42 is supported by the 
wheels 52 and 65 and the arms 12 are contracted. Thus, the clamp may be 
adjusted by operation of the drive wheels 65 to any desired position 
longitudinally of the pipe 1. 
When the clamp is properly positioned relative to the joint between the 
pipes, extension of the ram 19 will cause the driving wheels 65 to be 
retracted, as stated above, thereby enabling the surface 6 of the body 3 
to lower and bear against the adjacent ends of the pipes 1 and 2. As the 
ram 19 continues to expand, the arms 12 will move outwardly into 
engagement with the inner surfaces of the pipes 1 and 2 and gradually 
reshape or reform the configurations of the latter so that they conform to 
one another. The mismatch indicated in FIG. 1, therefore, will be 
eliminated. 
If it is necessary or desirable to use the spanner 34, it may be inserted 
into the gap 31 in a direction transversely of the body 3 and supported 
atop the housing 24. The stem 36 is adjusted so that the head 35 bears 
forcibly against the inner surfaces of the pipes 1 and 2. The welding of 
the pipes 1 and 2 to each other then may be commenced. 
If the rollers R are powered, as is preferred, the pipes 1 and 2 may be 
rotated as they are welded, thereby avoiding the necessity of a welder's 
having to move around the circumference of the pipes. 
Following completion of the weld, the ram 19 may be retracted, whereupon 
the arms will contract radially and the drive wheels 65 again will be 
moved into clamp-supporting position against the inner surface of the pipe 
1. The drive wheels then may be operated so as to enable the apparatus to 
traverse the length of the pipe 2 and locate the clamp in a position to 
make another weld to another pipe. 
Clamps according to the invention may be constructed in a variety of sizes 
for use with different diameter pipes and vessels. It also is possible, 
however, to enlarge the size of any such clamp. This characteristic is 
illustrated in FIG. 6 wherein an arcuate extension 92 is provided for 
attachment to the body 3 and two extensions 93 are provided for attachment 
to the arms 12. 
The extension 92 is composed of parallel, arcuate plates spaced apart 
according to the spacing between the plates 4 and 5 of the body 3. At the 
outer periphery of the two plates forming the extension 92 is a strip 94 
of copper or the like which forms a smooth outer surface. The inner and 
outer radii of the extension 92 are on the center of the radius R-1. 
Each of the extensions 93 has parallel, arcuate plates spaced apart like 
the plates 4 and 5 and between which is a strip 95 of copper or the like 
at the outer periphery. The inner radius of each plate of the extension 93 
corresponds to the radius R-3 and the outer radius has a length 
corresponding to the outer radius of the extension 92. The centers of the 
radii of the extensions 93 corresponds to the centers of the radii R-2. 
The extensions 92 and 93 are removably maintained on the body 3 and the 
arms 12 by plate-like members 96 which bridge the body and the arms and 
are removably secured thereto by bolts or the like. When the extensions 
are secured to the body and arms, the operation of the clamp is the same 
as has been described, but the diameter of the clamp is enlarged. 
The confronting ends of the extensions 93 adjacent the gap 31 are shaped 
like the corresponding ends of the arms 12 so as to provide a tapered gap 
between the extensions. This gap may be filled by the insert 34 in the 
same manner that it fills the gap 31. 
The disclosed embodiment is representative of a presently preferred form of 
the invention, but is intended to be illustrative rather than definitive 
thereof. The invention is defined in the claims.