Underwater pipeline sealing apparatus

Apparatus for preventing flow of water from a first underwater pipeline portion forward of the apparatus to a second underwater pipeline portion rearward of the apparatus. At least one wedge-shaped member is mounted on a carriage of the apparatus for grippingly engaging the internal wall of a pipeline for preventing movement of the apparatus in a rearwardly direction upon application of force to the carriage urging the carriage in a rearwardly direction in the pipeline. In order to provide frictional contact with the pipeline wall so that gripping engagement thereof may be effected, the member is continually urged into sliding engagement with the pipeline wall during movement of the apparatus through the pipeline in a forwardly direction. The apparatus is further provided with an annular elastomeric member responsive to water pressure from forwardly of the apparatus for sealingly engaging the pipeline wall to prevent flow of water from the first underwater pipeline portion to the second underwater pipeline portion.

This invention relates to the laying of underwater pipeline. More 
particularly, this invention relates to apparatus for preventing flow of 
water from a first underwater pipeline portion forward of the apparatus to 
a second underwater pipeline portion rearward of the apparatus. 
The laying of an underwater pipeline ordinarily involves connecting a 
plurality of pipe sections together in end-to-end relationship on a work 
barge and subsequently lowering the connected sections into the water in 
sequence as the work barge moves in the direction in which the pipeline is 
being laid. A catenary is thus formed between the sea bottom and the work 
barge. The pipeline is susceptible to buckling and breakage in the area of 
the catenary, particularly during rough seas. Unless the pipeline is 
otherwise sealed against the influx of water from a point of breakage 
thereof, such breakage will cause the previously laid section of pipeline 
on the sea bottom to become flooded with water. Once this occurs, the 
pipeline must be dewatered before the end thereof is raised to the surface 
for repairs so that pipeline laying operations can continue. 
A dewatering operation is time consuming and expensive because it requires 
that a pipeline pigging device be run through the entire line from the 
shore station or platform to the point at which the damage exists. This 
may necessitate pigging of the line over a distance of several miles and 
may require the use of high pressure compressors for extended periods of 
time. In addition, it may be difficult to provide compressors with the 
required capacity and pressure ratings at the necessary location, 
particularly if the pipeline is one which extends from an offshore 
platform or similar installation. 
Efforts have been made to provide apparatus for use in pipe laying 
operations which prevents the flow of water into and thus obviates the 
need for dewatering the previously laid section of pipeline on the sea 
bottom if breakage in a pipeline should occur. Such an apparatus will 
typically be disposed in a pipeline at the sea bottom to be towed through 
the pipeline as the pipeline is laid so that it is continually adjacent to 
and rearwardly of the catenary portion to seal the pipeline against the 
influx of water into the remainder of the pipeline if breakage in the 
catenary region were to occur. 
Since such an apparatus is carried within a pipeline as a form of insurance 
against the eventuality that a rupture of the pipeline will occur and 
should therefore be continuously in condition to actuate to seal the 
pipeline, it is highly desirable that such an apparatus be reliable. 
However, various such devices of the prior art use elaborate and expensive 
means such as sensor valves, compressed air equipment, electrical 
circuitry, and piston-cylinder arrangements for actuation thereof. Since 
such means, due to their complexity, may occasionally fail for various 
reasons which are readily apparent, it is not unlikely that a device using 
such actuation means will fail at the very moment it is needed to seal a 
pipeline. Other such devices with retractible arms for gripping a pipeline 
wall may become ineffective by the arms pivoting in a direction lengthwise 
of a pipeline past the point where they would otherwise grip a pipeline 
wall thus extending in a rearwardly direction of the device. Such pivoting 
may occur, for instance, if this type of device is not properly centered 
in a pipeline. 
It is an object of the present invention to provide such an apparatus which 
is more reliable. 
It is a further object of the present invention to provide such an 
apparatus which is inexpensive and substantially maintenance-free yet is 
more reliable such that there is little or no cause for concern as to 
whether or not it will function when there is a pipeline rupture. 
It is a still further object of the present invention to provide such an 
apparatus which more effectively seals a pipeline.

FIG. 1 illustrates a pipeline 10 being laid on a sea bottom 12 from a work 
barge 14 as the work barge moves in the direction illustrated at 16 in 
which the pipeline in being laid. As illustrated, the pipeline 10 forms a 
catenary portion illustrated at 18 between the work barge 14 and sea 
bottom 12 which portion is susceptible to buckling and breakage, 
particularly during rough seas. If breakage were to occur without the 
pipeline 10 being otherwise adequately protected as provided herein, the 
previously laid section 20 of pipeline on the sea bottom 12 will become 
flooded with water as previously indicated. 
Referring to FIG. 1 along with FIG. 2, there is provided for the purposes 
of preventing such an influx of water into the pipeline section 20 an 
apparatus generally indicated at 22 for preventing flow of water from a 
first underwater pipeline portion 24 forward of the apparatus to a second 
underwater pipeline portion 26 rearward of the apparatus. Thus, a purpose 
of the apparatus 22 is to seal a pipeline 10 against the flow of water 
into a dry pipeline portion (second underwater pipeline portion 26) if 
there is a breakage in the area of the catenary portion 18 (first 
underwater pipeline portion 24) while the pipeline 10 is being laid on the 
sea bottom 12. 
A tow line 32 may be provided for attachment to a forward portion of the 
apparatus 22 for towing of the apparatus in a forwardly direction 28 
through the pipeline 10 as it is being laid so that it may be continually 
disposed in a section of the pipeline which is rearward of and adjacent 
the catenary portion 18 as the pipeline is laid. For the purposes of this 
specification and the claims, a "forwardly direction" of an apparatus, 
illustrated at 28, is defined as a direction along the apparatus opposite 
to the direction of water flow against which the apparatus is constructed 
to seal when the apparatus is disposed in a pipeline, and a "rearwardly 
direction" of an apparatus, illustrated at 30, is defined as a direction 
along the apparatus which is the same direction as the direction of water 
flow against which the apparatus is constructed to seal when the apparatus 
is disposed in a pipeline. 
The apparatus 22 is provided with a carriage 36 upon which is mounted a 
means, generally indicated at 38, for grippingly engaging a pipeline 
internal wall 40 to prevent movement of the apparatus 22 in the rearwardly 
direction 30. Means, generally indicated at 42, are also provided for 
sealing the pipeline 10 against the flow of water from a first underwater 
pipeline portion 24 to a second underwater pipeline portion 26. 
In order to provide centering of the apparatus 22 in a pipeline 10 as well 
as decreased resistance to forward movement of an apparatus 22 through a 
pipeline 10, a set of wheels 44 mounted on forward portion of the 
apparatus 22 and another set of wheels 45 mounted on a rearward portion of 
the apparatus 22 are preferably provided. A set of wheels preferably 
comprises a plurality of wheels spaced to contact a pipeline internal wall 
at various points which are spaced apart circumferentially thereof. Means 
such as leaf springs 47 may be provided on one or more wheels of each set 
of wheels 44 and 45 to bias or urge the upper wheels against a pipeline 
wall. Caster wheels with rubber treads have been found to work 
satisfactorily although various other types of suitable wheels may be 
employed. 
The pipeline gripping means 38 is preferably provided with at least one but 
preferably three or more carriage members 48 which are proportionately 
spaced circumferentially about a centrally disposed carriage portion 46 
and each of which extends radially outwardly therefrom to a surface 50 
which engages a wedge-shaped member 52 and which surface is spaced from 
but inclined to a pipeline wall 40 when the apparatus 22 is disposed 
within a pipeline 10. A wedge-shaped member 52 has a first surface 56 
preferably annularly shaped to cnform to the shape of the pipeline 
internal wall 40 for engagement therewith, and a second surface 54 which 
slidably engages complementary surface 50 on carriage member 48. 
Referring to FIG. 5, means such as, for example, recess 58 formed in 
wedge-shaped member 52 at surface 54 to define a portion for interlocking 
with complementarily shaped portion 60 of member 48 is preferably provided 
to prevent disengagement of the wedge-shaped member 52 from carriage 
member 48 but to allow sliding of wedge-shaped member 52 in the forward 
and rearward directions 28 and 30 respectively of the apparatus 22 along 
the surface 50 of carriage portion 46. The recess 58 has a width 62 at 
points furtherest from surface 56 which is less than a width 64 at 
corresponding points closer to surface 56 to provide portions 66 of 
wedge-shaped member 52 which overlap a portion 68 of carriage member 48 to 
provide such interlocking means. 
Referring to FIGS. 2 and 6, the wedge-shaped member 52 is tapered in the 
forwardly direction 28 such as to have a lesser spacing between first and 
second surfaces 56 and 54 respectively at a forward porion thereof as 
illustrated at 70. The spacing increases with increasing distance along 
the wedge-shaped member 52 in the rearwardly direction 30 to a greater 
spacing, illustrated at 71, at a rearward portion thereof. For purposes of 
this specification and the claims, the spacing between first and second 
surfaces 56 and 54 respectively is measured in a direction normal to the 
first surface 56. Member 52 is slidably mounted on the carriage member 
surface 50 as aforesaid for movement in forward and rearward directions 28 
and 30 respectively and into gripping engagement with a pipeline wall 40 
for preventing movement of apparatus 22 in the rearwardly direction 30 
upon application of force urging carriage 36 in the rearwardly direction 
30 in the pipeline 10. 
However, if wedge-shaped member 52 is not already in contact with a 
pipeline wall 40 at the time force is applied to the carriage 36 urging 
the carriage in the rearwardly direction 30, then the wedge-shaped member 
52 may just ride the carriage 36 resulting in movement of the carriage in 
the rearwardly direction 30 without the wedge-shaped member 52 ever 
contacting the pipeline wall 40 for gripping engagement thereof. In other 
words, in such a case there would not be any frictional force or other 
resistance to movement of the wedge-shaped member rearwardly which 
resistance would tend to cause movement of carriage member 48 in the 
rearwardly direction 30 relative to wedge-shaped member 52 so that 
wedge-shaped member 52 could be urged outwardly into gripping engagement 
with a pipeline wall 40. In accordance with an aspect of this invention, 
there is provided means such as, for example, spring 72 for urging the 
wedge-shaped member 52 into sliding engagement with the pipeline internal 
wall 40 to provide such frictional force for use in urging wedge-shaped 
member 52 into gripping engagement with a pipeline internal wall 40 if the 
carriage 36 is urged in the rearwardly direction 30. Such a means is best 
shown in FIG. 4 wherein a support plate 74 is shown rigidly attached at a 
suitable location on the carriage such as at carriage member 48. Spring 
guide means such as tubular guide 76 and rod 82 extends between the 
support plate 74 and member 52 for positioning of the spring 72. Tubular 
guide 76 extends through an aperture 78 in the support plate 74 and in a 
forwardly direction 28 of the apparatus 22 toward the wedge-shaped member 
52. A nut 80 is brazed or otherwise fastened to the tubular guide 76 at 
the rearward end thereof. Rod 82 is threadedly or otherwise attached at 
one end to the wedge-shaped member 52 at aperture 84 and extends through 
the tubular guide 76. Guide nut 80 is threadedly engaged to the rod 82 for 
jacking the wedge-shaped member 52 in a rearwardly direction 30 for 
positioning of the wedge-shaped member 52 away from the pipeline wall 40 
when it is desirable to do so such as during insertion of the apparatus 22 
into a pipeline. Another nut 86 is brazed or otherwise fastened to the rod 
82 rearwardly of guide nut 80 to prevent backing off and subsequent 
disengagement of guide nut 80 from the rod 82. Spring 72 is mounted under 
compression about tubular guide 76 and rod 82 over the distance, 
illustrated at 88 in FIG. 4, between the wedge-shaped member 52 and the 
support plate 74 to urge the wedge-shaped member 52 into sliding 
engagement but not gripping engagement with the pipeline wall 40 
continuously and reliably as the apparatus 22 is pulled in a forwardly 
direction 28 through a pipeline. The strength of the spring 72 may be 
selected in accordance with engineering principles of common knowledge to 
those of ordinary skill in the art to which this invention pertains. 
The support plate aperture 78 is preferably provided with an oversize 
diameter relative to the tubular guide diameter as illustrated in FIG. 4 
so that wedge-shaped member 52 may self-adjust for alignment variations 
whereby its first surface 56 may more effectively align against a pipeline 
wall 40. For example, for a tubular guide diameter of 5/8 in. (1.6 cm.), 
the support plate aperture diameter may be 11/4 in. (3.2 cm.). 
Referring to FIGS 5 and 6, recesses 90 are preferably formed in the second 
surface 54 at innermost points thereof. These recesses 90 extend in the 
forward and rearward directions 28 and 30 respectively at both the forward 
and rearward ends of the second surface 54 to provide a ledge 92 centrally 
located between the forward and rearward ends of the wedge-shaped member 
52 to effect slight tilting of the wedge-shaped member 52 as it is pulled 
through a pipeline for more effective alignment of the first surface 56 of 
the wedge-shaped member 52 with a pipeline wall 40. 
The wedge-shaped member 52 is preferably comprised of steel which is case 
hardened by liquid carburizing to a Rockwell hardness of about 55 to 58 on 
the "C" scale so that it has a hardness greater than a typical pipeline 
wall hardness. The first surface 56 of the wedge-shaped member 52 is 
preferably provided with coarse teeth 94 to provide improved ride of the 
wedge-shaped member 52 over weld beads. For example, a tooth length to 
tooth height ratio of 5 to 1 is considered to be satisfactory. In order to 
lessen the possibility of the teeth 94 scoring a pipeline wall, the teeth 
points 96, which contact the pipeline wall 94, are preferably flattened to 
a width, as illustrated at 98 in FIG. 6, of perhaps 0.2 in. (0.5 cm.). 
Although a preferred means for urging the member 52 into sliding 
engagement with a pipeline internal wall 40 has been illustrated, the 
scope of this invention is not limited to such means but is meant to 
include other types of suitable structures for urging the wedge-shaped 
member 52 into sliding engagement with a pipeline internal wall such as, 
for example, a spring under tension attached to a forward portion of the 
wedge-shaped member 52. 
Referring to FIGS. 2 and 7, the sealing means 42, according to a preferred 
embodiment of this invention, is provided with an annular, generally 
cup-shaped, water impervious elastomeric member 102 sealingly attached to 
a water imprervious partition means such as plates 100 and 110 at least 
one of which is in turn sealingly attached such as by the weld illustrated 
at 104 to a portion of the carriage 36 to provide a water impervious area 
bounded by the tip 112 of the elastomeric member 102. The elastomeric 
member 102 extends from its points of attachment to partition plates 100 
and 110 in a forwardly direction 28 of the apparatus 22 as well as in a 
direction, illustrated at 106, toward a pipeline wall 40 and terminates a 
tip 112 when the apparatus 22 is disposed within a pipeline 10. This 
elastomeric member 102 may be composed of any suitable material such as, 
for example, rubber or urethane. It has a maximum diameter, illustrated at 
108, in its relaxed shape which is less than the inside diameter of the 
pipeline. By "relaxed shape" is meant, for the purposes of this 
specification and the claims, the equilibrium shape which an elastomeric 
member attains following the removal of stress therefrom such as the 
removal of water pressure acting thereagainst. For a pipeline having an 
inside diameter of 22.8 in. (57.9 cm.), the elastomeric member 102 may 
have, for example, a maximum diameter in its relaxed shape of 21.75 in. 
(55.25 cm.). The elastomeric member 102 is responsive to water pressure 
from forwardly of the apparatus 22 for flexing movement to a shape having 
a diameter equal to at least the inside diameter of a pipeline 10 to 
thereby sealingly engage a pipeline wall 40. 
Partition plate 100 preferably has a diameter equal to approximately the 
diameter 108 of the elastomeric member 102 in its relaxed shape and is 
disposed adjacent to and rearwardly of the elastomeric member 102 to 
restrict flexing movement of the elastomeric member 102 in the rearwardly 
direction 30 beyond its points of attachment to partition plate 100 and 
110. Otherwise, water pressure may force the elastomeric member 102 to 
flex rearwardly so that its tip 112 engages a pipeline wall 40 and then 
flex further rearwardly so that its tip 112 disengages the pipeline wall 
40 whereby the pipeline wall is no longer sealed against the flow of 
water. 
To provide attachment of the elastomeric member 102 to the partition means, 
an inner terminal portion of elastomeric member 102 may be disposed 
between partition plate 100 and a radially outwardly projecting portion 
114 of partition plate 110 which projecting portion is also on a forward 
portion of the plate 110. The terminal portion of elastomeric member 102 
may be sealingly clamped therebetween by suitable clamping means such as 
bolts 122 and one or more shims 124. However, this invention is not meant 
to be limited to such means for sealingly clamping the elastomeric member 
to partition members. The scope of this invention is meant to encompass 
any suitable means for providing a water impervious area within the 
confines of the elastomeric member tip 112. 
It is desirable that the elastomeric member 102 have sufficient rigidity to 
adequately withstand the pressure of water which will normally be applied 
against it yet have sufficient flexibility to readily and reliably flex so 
that its tip 112 engages a pipeline wall for sealing thereof. A suitable 
elastomeric member thickness can be determined by applying engineering 
principles of common knowledge to those of ordinary skill in the art to 
which this invention pertains. For a polyester urethane material and a 
pipeline inside diameter of 22.8 in (57.9 cm.), a thickness, illustrated 
at 118 in FIG. 7, of the elastomeric member 102 in the range of about 3/4 
to 1 in. (2 to 2.5 cm.) has been found to be satisfactory. However, in 
order to more adequately conform the elastomeric member 102 to 
longitudinal weld seams for improved pipeline sealing in accordance with a 
preferred embodiment of this invention, a reduced thickness tip 112 may be 
provided. For the elastomeric member 102 described above, a tip 112 having 
a thickness, illustrated at 120 in FIG. 7, of about 1/4 in. (0.6 cm.) over 
a distance of about 11/4 in. (3 cm.) is believed to be satisfactory 
although a gradual change in effectiveness is expected as the tip 
thickness is changed within the range of about one-fourth to one-half of 
elastomeric member thickness 118. For the purposes of the specification 
and the claims, a "reduced thickness tip" of an elastomeric member is 
defined as a tip having a thickness which is not more than about one-half 
of a thickness of the remainder of the elastomeric member. 
Although the sealing means 42 is preferably disposed rearwardly of the 
gripping means 38 as shown in FIG. 2, this invention is not meant to be 
limited thereto. For example, the sealing means 42 may be located 
forwardly of the gripping means 38. 
In order to prevent torque from being tranmitted to the apparatus by towing 
line or cable 32 which torque may tend to cause rotation of the apparatus 
22 in the pipeline 10, a suitable swivel means, illustrated at 126, is 
preferably provided for attaching the cable 32 or other towing line to the 
apparatus 22. In order to maintain the apparatus 22 in an upright position 
such as shown in FIG. 2 and stable against rotation during its movement 
through a pipeline, the apparatus 22 is preferably provided with ballast 
means such as one or more ballast plates 116 to counteract most forces 
which may tend to cause rotation of the apparatus 22 to a different 
position than its upright position during use. By "ballast plates" is 
meant, for the purposes of this specification and the claims, plates 
applied to an underside of an apparatus and having a weight equal to at 
least five percent of the overall weight of the apparatus (exclusive of 
the weight of the ballast plates). For example, ballast plates 116 having 
a total weight of 100 lbs. (45 kg.) are considered to be satisfactory for 
an apparatus having an overall weight exclusive of the weight of the 
ballast plates 116 of 1200 lbs. (545 kg.). 
During normal pipe laying operations, the apparatus 22 is positioned in the 
section of pipeline rearwardly of and adjacent the catenary 18, and may be 
pulled my means of a small diameter cable 32. As the apparatus 22 is 
pulled through the pipeline 10, the swivel means 126 acts to prevent 
torque from being transmitted by the towing cable 32 to the apparatus 22 
and to prevent the cable 32 from becoming twisted-up, and the weight of 
the ballast plates 116 maintain the apparatus 22 in an upright position 
and stable against rotation during its movement through the pipeline 10. 
Meanwhile, the wedge-shaped members 52 are continually and reliably urged 
by springs 72 into sliding engagement with the pipeline wall 40 to provide 
frictional contact for use in urging of the wedge-shaped members 52 into 
gripping engagement with the pipeline wall 40. In the event of a pipe 
buckle followed by a rupture in the catenary region 18 of the pipeline, 
the pressure of water entering the pipeline 10 through the rupture would 
act on the carriage 36 and partition means in a rearwardly direction 30 of 
the apparatus 22. As a result, the carriage 36 will be urged in the 
rearwardly direction 30 and, since the wedge-shaped members 52 are already 
in sliding engagement with the pipeline wall 40 and providing frictional 
contact therewith, the wedge-shaped members 52 will be forced into 
gripping engagement with the pipeline wall 40 thereby preventing further 
rearward movement of the apparatus 22. Meanwhile, water pressure acting in 
the rearwardly direction 30 on the elastomeric member 102 becomes 
sufficient to overcome the stiffness of the elastomeric member which then 
flexes or deflects until it sealingly engages the internal wall 40 of the 
pipeline. When this occurs, the flow of water is stopped and the full 
pressure head of the water is exerted on the elastomeric member 102 
maintaining it tightly sealed against the internal wall 40 of the 
pipeline. The pipeline 10 may then be recovered in a conventional manner 
and repaired without the necessity of time consuming and expensive 
dewatering operations. 
Thus, since the apparatus 22 of the present invention does not require any 
internal power source, sensing devices, electrical apparatus, compressed 
air means, or any other complex devices which are likely to fail from time 
to time, it is easily seen that the present invention provides an 
inexpensive yet more reliable apparatus for preventing flow of water from 
a first underwater pipeline portion forward of the apparatus to a second 
underwater pipeline portion rearward of the apparatus. 
Certain features of this invention may sometimes be used to advantage 
without a corresponding use of the other feature. It is also to be 
understood that the invention is by no means limited to those specific 
embodiments which have been illustrated and described herein, and various 
modifications thereof may indeed be made which come within the scope of 
the present invention as defined by the appended claims.