U.S. patent number 3,739,591 [Application Number 05/147,834] was granted by the patent office on 1973-06-19 for method and apparatus for evaluating offshore pipeline laying operations.
Invention is credited to Raymond E. Jones.
United States Patent |
3,739,591 |
Jones |
June 19, 1973 |
METHOD AND APPARATUS FOR EVALUATING OFFSHORE PIPELINE LAYING
OPERATIONS
Abstract
Methods and apparatus for conducting evaluations of offshore
pipe-line laying operations and characterized by the performance of
inspection operations, in relation to submerged pipeline means,
prior to the termination of a pipeline laying operation. The
inspection operation is performed while a floating vessel means,
effecting the pipeline laying operation, remains operable to lay
and/or retrieve pipeline increment means containing a defect
detected during the inspection operation.
Inventors: |
Jones; Raymond E. (Houston,
TX) |
Family
ID: |
22523090 |
Appl.
No.: |
05/147,834 |
Filed: |
May 28, 1971 |
Current U.S.
Class: |
405/166;
405/168.4; 73/865.8; 405/168.1; 405/170 |
Current CPC
Class: |
F16L
1/235 (20130101); F16L 1/18 (20130101) |
Current International
Class: |
F16L
1/12 (20060101); F16L 1/235 (20060101); F16L
1/18 (20060101); F16l 001/00 () |
Field of
Search: |
;61/72.3,72.1,72.4
;73/151 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Shapiro; Jacob
Claims
What is claimed is:
1. A method of detecting a submerged pipeline condition, said
method comprising:
supporting a pipeline at an offshore location with
a first portion supported on a submerged surface,
a second portion supported on floating vessel means, and
a third portion extending through a body of water between said
first and second pipeline portions;
positioning pipeline condition detecting means within the interior
of a submerged portion of said pipeline;
increasing the length of said pipeline from said floating vessel
means so as to provide an additional submerged pipeline increment,
and
while the pipeline of increased length remains supported by said
floating vessel means and while said pipeline condition detecting
means remains within the interior of a submerged portion of the
pipeline of increased length, inducing relative movement between
the additional submerged pipeline increment and said pipeline
condition detecting means, and detecting a condition of said
additional submerged pipeline increment with said detecting
means;
said floating vessel means being operable to retrieve said
additional submerged pipeline increment by exerting a retrieving
force on said second pipeline portion.
2. A method of detecting a submerged pipeline condition, said
method comprising:
supporting a pipeline at an offshore location with
a first portion supported on a submerged surface,
a second portion supported on floating vessel means, and
a third portion extending through a body of water between said
first and second pipeline portions;
engaging said second pipeline portion by pipeline tensioning means
on said floating vessel means;
supporting said third pipeline portion, at least in part, by at
least partially submerged buoyant ramp means extending from and
connected with said floating vessel means;
positioning pipeline condition detecting means within the interior
of a submerged portion of said pipeline;
inducing relative movement between said first pipeline portion and
said pipeline detecting means by flexible draft means extending
from said pipeline detecting means through the interior of said
third pipeline portion, over said buoyant ramp means, and through
the interior of said second pipeline portion engaged by said
pipeline tensioning means on said floating vessel means; and
detecting a condition of said submerged pipeline portion with said
detecting means while the pipeline remains supported by said
floating vessel means;
said pipeline tensioning means on said floating vessel means being
continuously operable to retrieve said first pipeline portion on
board said floating vessel means by exerting a retrieving force on
said second pipeline portion so as to displace an increment of said
first pipeline portion into said second pipeline portion through
movement of said increment upwardly through said body of water,
over said buoyant ramp means, and onto said floating vessel
means.
3. A method as described in claim 1, wherein:
the step of inducing relative movement between said pipeline
condition detecting means and said additional submerged pipeline
increment responsively causes detection by said detecting means of
a buckle condition in said increment of said pipeline; and
wherein
a retrieving force is exerted on said second pipeline portion to
retrieve said increment of said pipeline containing said detected
buckle condition on board said floating vessel means.
4. A method of detecting a dimensional irregularity in an internal
cross section of a submerged pipeline portion, said method
comprising:
supporting a pipeline at an offshore location with
a first pipeline portion supported on a submerged surface,
a second pipeline portion supported on floating vessel means,
and
a third pipeline portion extending through a body of water between
said first and second pipeline portions;
propelling pipeline detecting means from said floating vessel means
sequentially through said second and third pipeline portions to
position said pipeline detecting means within the interior of said
first pipeline portion;
said pipeline detecting means, when disposed within the interior of
said first pipeline portion, being operable to detect an
irregularity in dimension in the cross section of said pipeline in
response to relative movement between said pipeline detecting means
and said first pipeline portion;
increasing the length of said pipeline from said floating vessel
means so as to provide an additional pipeline increment in said
first pipeline portion;
from said floating means, inducing relative movement between said
pipeline detecting means and said additional increment of said
first pipeline portion, with said relative movement being operable
to permit said pipeline detecting means to detect a dimensional
irregularity in the cross section of said additional increment of
said first pipeline portion; and
providing pipeline retrieving means on said floating means operable
to retrieve said additional increment of said first pipeline
portion in the event that said pipeline detecting means should
detect a dimensional irregularity in the cross section of said
additional increment of said first pipeline portion.
5. A method as described in claim 4:
wherein said second pipeline portion is engaged by pipeline
tensioning means on said floating vessel means;
wherein said third pipeline portion is supported, at least in part,
by at least partially submerged buoyant ramp means extending from
and connected with said floating vessel means; and
wherein said method additionally comprises inducing relative
movement between said first pipeline portion and said pipeline
detecting means by flexible draft means extending from said
pipeline detecting means through the interior of said third
pipeline portion, over said buoyant ramp means, and through the
interior of said second pipeline portion engaged by said pipeline
tensioning means on said floating vessel means;
said pipeline tensioning means being continuously operable to
retrieve said first pipeline portion on board said floating vessel
means by exerting a retrieving force on said second pipeline
portion so as to displace an increment of said first pipeline
portion into said second pipeline portion through movement of said
increment upwardly through said body of water, over said buoyant
ramp means, and onto said floating vessel means.
6. A method as described in claim 5, wherein:
the step of inducing relative movement between said pipeline
detecting means and said additional increment of said first
pipeline portion responsively causes detection by said detecting
means of a buckle condition in said additional increment; and
wherein
a retrieving force is exerted on said second pipeline portion by
said pipeline tensioning means to retrieve said additional
increment of first pipeline portion containing said detected buckle
condition on board said floating vessel means.
7. A method of detecting a dimensional irregularity in an internal
cross section of a submerged pipeline portion, said method
comprising:
supporting a pipeline at an offshore location with
a first pipeline portion supported on a submerged surface,
a second pipeline portion supported on floating vessel means,
and
a third pipeline portion extending through a body of water between
said first and second pipeline portions;
propelling pipeline detecting means from said floating vessel means
sequentially through said second and third pipeline portions to
position said pipeline detecting means within the interior of said
first pipeline portion;
said pipeline detecting means, when disposed within the interior of
said first pipeline portion, being operable to detect an
irregularity in dimension in the cross section of said pipeline in
response to relative movement between said pipeline detecting means
and said first pipeline portion;
connecting said pipeline detecting means with pipeline section
alignment means;
on said floating vessel means operating said pipeline section
alignment means to generally secure in longitudinal alignment a
first additional pipeline section with a terminus of said second
pipeline portion;
weldingly, and at least partially, interconnecting said first
additional pipeline section and said second pipeline portion
terminus, with said pipeline section alignment means
securing said first additional pipeline section and said second
pipeline portion terminus in longitudinal alignment, and
remaining connected with said pipeline detecting means; advancing
said first additional pipeline section on said floating vessel
means toward said body of water, with
said pipeline detecting means remaining connected with
said pipeline section alignment means, and
said pipeline section alignment means interconnecting and aligning
said first additional pipeline section and said second pipeline
portion terminus;
said advancing of said additional pipeline section on said floating
vessel means being operable to increase the length of said first
pipeline portion and provide an additional pipeline increment in
said first pipeline portion;
positioning a second, additional pipeline section in general
longitudinal alignment with said first additional pipeline
section;
moving said pipeline section alignment means toward said second
additional pipeline section, away from said first additional
pipeline section:
said movement of said pipeline section alignment means away from
said first additional pipeline section causing said pipeline
detecting means to move generally toward said additional increment
of said first pipeline portion, with this movement being operable
to permit said pipeline detecting means to detect a dimensional
irregularity in the cross section of said first pipeline
portion;
said movement of said pipeline section alignment means away from
said first additional pipeline section being operable to position
said pipeline section alignment means in position to secure, in
mutual longitudinal alignment, a terminus of said first additional
pipeline section and a terminus of said second additional pipeline
section; and
providing pipeline retrieving means on said floating means operable
to retrieve an increment of said first pipeline portion in the
event that said pipeline detecting means should detect a
dimensional irregularity in the cross section of said first
pipeline portion.
8. A method as described in claim 7:
wherein said second pipeline portion is engaged by pipeline
tensioning means on said floating vessel means;
wherein said third pipeline portion is supported, at least in part,
by at least partially submerged buoyant ramp means extending from
and connected with said floating vessel means; and
wherein said method additionally comprises inducing relative
movement between said first pipeline portion and said pipeline
detecting means by flexible draft means connected with said
pipeline section alignment means and extending from said pipeline
detecting means through the interior of said third pipeline
portion, over said buoyant ramp means, and through the interior of
said second pipeline portion engaged by said pipeline tensioning
means on said floating vessel means;
said pipeline tensioning means being continuously operable to
retrieve said first pipeline portion on board said floating vessel
means by exerting a retrieving force on said second pipeline
portion so as to displace an increment of said first pipeline
portion into said second pipeline portion through movement of said
increment upwardly through said body of water, over said buoyant
ramp means, and onto said floating vessel means.
9. A method as described in claim 8, wherein said pipeline
detecting means is propelled from said floating vessel means to
said first pipeline portion by:
pneumatically operating latch means to interconnect a source of
pressurized air with said pipeline detecting means;
in response to said interconnection of said source of pressurized
air with said pipeline detecting means,
extending drive means carried by said pipeline detecting means into
driving engagement with the interior of said pipeline, and
operating said drive means so as to exert a propelling force on the
interior of said pipeline tending to propel said pipeline detecting
means toward said first pipeline portion;
in response to operation of said drive means, propelling said
pipeline detecting means from said floating vessel means
sequentially through said second and third pipeline portion to said
first pipeline portion;
reducing the pressure of said pressurized air and in response to
said reduction of pressure
disconnecting said source of pressurized air from said pipeline
detecting means,
retracting said drive means out of driving engagement with the
interior of said pipeline means, and
discontinuing operation of said drive means; and
retrieving said source of pressurized air from said pipeline
detecting means sequentially through said second and third pipeline
portions to said floating vessel means.
10. A method as described in claim 9, wherein:
the step of inducing relative movement between said pipeline
detecting means and said additional increment of said first
pipeline portion responsively causes detection by said detecting
means of a buckle condition in said additional increment; and
wherein
a retrieving force is exerted on said second pipeline portion by
said pipeline tensioning means to retrieve said additional
increment of first pipeline portion containing said detected buckle
condition on board said floating vessel means.
11. Apparatus for detecting a submerged pipeline condition, said
apparatus comprising:
floating vessel means operable to support, at least in part, a
pipeline at an offshore location with
a first portion supported on a submerged surface,
a second portion supported on floating vessel means, and
a third portion extending through a body of water between said
first and second pipeline portions;
pipeline condition detecting means positioned within the interior
of a submerged portion of said pipeline;
said floating vessel means being operable to increase the length of
said pipeline so as to provide an additional submerged pipeline
increment;
means for inducing relative movement between the additional
submerged pipeline increment and said detecting means, while said
detecting means remains within the interior of a submerged portion
of pipeline and while said pipeline remains supported, at least in
part, by said floating vessel means;
said pipeline detecting means being operable to detect a condition
of said additional submerged pipeline increment while said pipeline
remains supported at least in part, by said floating vessel
means;
said floating vessel means being operable to retrieve said
additional submerged pipeline increment by exerting a retrieving
force on said second pipeline portion.
12. Apparatus for detecting a submerged pipeline condition, said
apparatus comprising:
floating vessel means operable to support, at least in part, a
pipeline at an offshore location with
a first portion supported on a submerged surface,
a second portion supported on floating vessel means, and
a third portion extending through a body of water between said
first and second pipeline portions;
pipeline condition detecting means positioned within the interior
of a submerged portion of said pipeline;
said pipeline detecting means being operable to detect a condition
of said submerged pipeline portion while said pipeline remains
supported at least in part, by said floating vessel means;
pipeline tensioning means on said floating vessel means operable to
engage said second pipeline portion;
at least partially submerged buoyant ramp means extending from and
connected with said floating vessel means and supporting, at least
in part, said third pipeline portion; and
flexible draft means extending from said pipeline detecting means
through the interior of said third pipeline portion, over said
buoyant ramp means, and through the interior of said second
pipeline portion engaged by said pipeline tensioning means on said
floating vessel means, said flexible draft means being operable to
induce relative movement between said first pipeline portion and
said pipeline detecting means; and
said pipeline tensioning means on said floating vessel means being
continuously operable to retrieve said first pipeline portion on
board said floating vessel means by exerting a retrieving force on
said second pipeline portion so as to displace an increment of said
first pipeline portion into said second pipeline portion through
movement of said increment upwardly through said body of water,
over said buoyant ramp means, and onto said floating vessel
means.
13. Apparatus as described in claim 11, wherein:
said pipeline condition detecting means comprises means operable,
in response to relative movement between said pipeline detecting
means and said pipeline, to detect a buckle condition in said
pipeline.
14. Apparatus for detecting a dimensional irregularity in an
internal cross section of a submerged pipeline portion, said
apparatus comprising:
floating vessel means operable to support, at least in part, a
pipeline at an offshore location with
a first pipeline portion supported on a submerged surface,
a second pipeline portion supported on floating vessel means,
and
a third pipeline portion extending through a body of water between
said first and second pipeline portions;
pipeline detecting means;
means for propelling said pipeline detecting means from said
floating vessel means sequentially through said second and third
pipeline portions to position said pipeline detecting means within
the interior of said first pipeline portion;
said pipeline detecting means, when disposed within the interior of
said first pipeline portion, being operable to detect an
irregularity in dimension in the cross section of said pipeline in
response to relative movement between said pipeline detecting means
and said first pipeline portion;
means for increasing the length of said pipeline from said floating
vessel means so as to provide an additional pipeline increment in
said first pipeline portion;
means operable from said floating means to induce relative movement
between said pipeline detecting means and said additional increment
of said first pipeline portion, with said relative movement being
operable to permit said pipeline detecting means to detect a
dimensional irregularity in the cross section of said additional
increment of said first pipeline portion; and
pipeline retrieving means on said floating means operable to
retrieve said additional increment of said first pipeline portion
in the event that said pipeline detecting means should detect a
dimensional irregularity in the cross section of said additional
increment of said first pipeline portion.
15. A method as described in claim 14 including:
pipeline tensioning means on said floating vessel means operable to
engage said second pipeline portion;
at least partially submerged buoyant ramp means extending from and
connected with said floating vessel means and supporting, at least
in part, said third pipeline portion;
flexible draft means extending from said pipeline detecting means
through the interior of said third pipeline portion, over said
buoyant ramp means, and through the interior of said second
pipeline portion engaged by said pipeline tensioning means on said
floating vessel means;
said flexible draft means being operable to induce relative
movement between said first pipeline portion and said pipeline
detecting means; and
said pipeline tensioning means being continuously operable to
retrieve said first pipeline portion on board said floating vessel
means by exerting a retrieving force on said second pipeline
portion so as to displace an increment of said first pipeline
portion into said second pipeline portion through movement of said
increment upwardly through said body of water, over said buoyant
ramp means, and onto said floating vessel means.
16. Apparatus as described in claim 15, wherein:
said pipeline detecting means comprises means operable, in response
to relative movement between said pipeline detecting means and said
additional increment of said first pipeline portion, to detect a
buckle condition in said additional increment.
17. Apparatus for detecting a dimensional irregularity in an
internal cross section of a submerged pipeline portion, said
apparatus comprising:
floating vessel means operable to support, at least in part,
a pipeline at an offshore location with
a first pipeline portion supported on a submerged portion,
a second pipeline portion supported on floating vessel means,
and
a third pipeline portion extending through a body of water between
said first and second pipeline portions;
pipeline detecting means;
propelling means for propelling said pipeline detecting means from
said floating vessel means sequentially through said second and
third pipeline portions to position said pipeline detecting means
within the interior of said first pipeline portion;
said pipeline detecting means, when disposed within the interior of
said first pipeline portion, being operable to detect an
irregularity in dimension in the cross section of said pipeline in
response to relative movement between said pipeline detecting means
and said first pipeline portion;
pipeline section alignment means;
means operable to connect said pipeline detecting means with
pipeline section alignment means;
said pipeline section alignment means being operable to generally
secure in longitudinal alignment a first additional pipeline
section with a terminus of said second pipeline portion;
welding means operable to at least partially interconnect said
first additional pipeline section and said second pipeline portion
terminus, with said pipeline section alignment means
securing said first additional pipeline section and said second
pipeline portion terminus in longitudinal alignment, and
remaining connected with said pipeline detecting means;
means for advancing said first additional pipeline section on said
floating vessel means toward said body of water, with
said pipeline detecting means remaining connected with said
pipeline section alignment means, and
said pipeline section alignment means interconnecting and aligning
said first additional pipeline section and said second pipeline
portion terminus;
said advancing of said additional pipeline section on said floating
vessel means being operable to increase the length of said first
pipeline portion and provide an additional pipeline increment in
said first pipeline portion;
means for positioning a second, additional pipeline section in
general longitudinal alignment with said first additional pipeline
section;
means for moving said pipeline section alignment means toward said
second additional pipeline section, away from said first additional
pipeline section;
said movement of said pipeline section alignment means away from
said first additional pipeline section causing said pipeline
detecting means to move generally toward said additional increment
of said first pipeline portion, with this movement being operable
to permit said pipeline detecting means to detect a dimensional
irregularity in the cross section of said first pipeline
portion;
said movement of said pipeline section alignment means away from
said first additional pipeline section being operable to position
said pipeline section alignment means in position to secure, in
mutual longitudinal alignment, a terminus of said first additional
pipeline section and a terminus of said second additional pipeline
section; and
pipeline retrieving means on said floating means operable to
retrieve an increment of said first pipeline portion in the event
that said pipeline detecting means should detect a dimensional
irregularity in the cross section of said first pipeline
portion.
18. Apparatus as described in claim 17:
pipeline tensioning means included in said floating vessel means
operable to engage said second pipeline portion;
at least partially submerged buoyant ramp means extending from and
connected with said floating vessel means and supporting, at least
in part, said third pipeline portion;
flexible draft means connected with said pipeline section alignment
means and extending from said pipeline detecting means through the
interior of said third pipeline portion, over said buoyant ramp
means, and through the interior of said second pipeline portion
engaged by said pipeline tensioning means on said floating vessel
means, said flexible draft means being operable to induce relative
movement between said first pipeline portion and said pipeline
detecting means; and
said pipeline tensioning means being continuously operable to
retrieve said first pipeline portion on board said floating vessel
means by exerting a retrieving force on said second pipeline
portion so as to displace an increment of said first pipeline
portion into said second pipeline portion through movement of said
increment upwardly through said body of water, over said buoyant
ramp means, and onto said floating vessel means.
19. Apparatus as described in claim 18, wherein said propelling
means comprises:
a source of pressurized air;
pneumatically operated latch means operable to interconnect a
source of pressurized air with said pipeline detecting means;
drive means carried by said pipeline detecting means;
positioning means operable to extend and retract said drive
means;
operating means operable in response to said interconnection of
said source of pressurized air with said pipeline detecting
means,
to actuate said positioning means and extend said drive means
carried by said pipeline detecting means into driving engagement
with the interior of said pipeline, and
actuate said drive means so as to exert a propelling force on the
interior of said pipeline tending to propel said pipeline detecting
means toward said first pipeline portion;
said drive means being operable to propel said pipeline detecting
means from said floating vessel means sequentially through said
second and third pipeline portion to said first pipeline
portion;
means for reducing the pressure of said pressurized air and
causing, in response to said reduction of pressure,
the disconnecting of said source of pressurized air from said
pipeline detecting means,
the actuation of said positioning means to retract said drive means
out of driving engagement with the interior of said pipeline means,
and
the discontinuing of actuation of said drive means; and
means for retrieving said source of pressurized air from said
pipeline detecting means sequentially through said second and third
pipeline portions to said floating vessel means.
20. Apparatus as described in claim 19, wherein:
said pipeline detecting means comprises means operable, in response
to relative movement between said pipeline detecting means and said
additional increment of said first pipeline portion, to detect a
buckle condition in said additional increment.
21. A method of eveluating an offshore pipeline laying operation,
said method comprising:
conducting an offshore pipeline laying operation;
during said offshore pipeline laying operation, supporting a
portion of said pipeline on floating vessel means, with the
floating vessel means being operable to effect retrieval of
previously laid pipeline increment means; and
prior to the termination of said offshore pipeline laying
operation, and while a portion of said pipeline is supported on
said floating vessel means and while said floating vessel means
remains operable to effect retrieval of previously laid pipeline
increment means, detecting a condition of a submerged portion of
said pipeline;
the step of detecting being performed by scanning a submerged
portion of the pipeline with pipeline condition detecting means
operable to detect a pipeline condition which is detectable prior
to the termination of the laying of said pipeline and is operable
to remain in said submerged portion of the pipeline after the
termination of the pipeline laying operation.
22. A method according to claim 21 wherein:
the steps of conducting the offshore pipeline laying operation and
supporting a portion of the pipeline on floating vessel means
comprise laying the pipeline from the floating vessel means and
onto a submerged surface with the pipeline profile including a
downwardly concave pipeline portion extending to a pipeline portion
on the submerged surface; and wherein
the step of detecting comprises detecting a pipeline condition at a
pipeline location beyond the downwardly concave pipeline portion.
Description
Offshore pipeline laying operations are complex and costly in
nature.
Contributing to the cost and complications entailed in offshore
pipelaying operations are the inspections which must necessarily be
performed to ensure that a pipeline, when laid, is in structurally
sound, safe, useable form.
Such inspection operations are concerned with detecting adverse
conditions which would impair the safety or operating efficiency of
the laid pipeline, or confirming a satisfactory condition.
One common fault sought to be detected involves a "buckle"
condition which might inadvertently result from stresses imposed
upon a pipeline during a laying operation. Such stresses would be
imposed on the pipeline as it was being manipulated from a
pipelaying barge, or other floating vessel means, downwardly
through a body of water into a position supported on a submerged
surface.
Traditionally, such inspection operations have been performed after
the pipeline laying operation has been completed. Where a buckle
condition has been detected utilizing this conventional inspection
technique, it has generally been necessary to resort to expensive
means for raising the buckled pipeline portion to the surface and
effect repairs.
At times, when it has not been feasible to raise a pipeline portion
containing a buckle, it has been necessary to go to the extreme
measure of either cutting out a buckled portion and effecting
underwater repairs or raising to the surface the entire portion of
the pipeline extending from the buckle area to a free end or
terminus of the pipeline.
Such repair operations can be extremely costly and entail several
hundred thousand dollars in costs. In addition, such repair
operations significantly delay the placing of a pipeline in
operating condition.
Bearing such contingencies in mind, it is a principal object of the
present invention to provide a pipeline inspection or condition
detecting operation which enables abnormalities to be detected
prior to the termination of a pipeline laying operation.
It is a particular object of the invention to provide such
techniques by means of which inspection or condition detecting
operations may be performed generally throughout the pipeline
laying operation so as to provide prompt indications of undesirable
or abnormal prior conditions, or confirm a satisfactory
condition.
It is a further object of the invention to provide such techniques
which enable abnormalities or defects to be detected before
underwater currents or tides have induced partial or complete
burying of pipelines, which burying might significantly impair
repair operations.
It is likewise an object of the invention to provide such
techniques which enable inspection or condition detection
operations to be performed while a pipeline laying barge, or other
floating vessel means effecting pipe-laying, remains operable to
retrieve previously laid pipeline increment means containing a
detected adverse condition.
In relation to a preferred embodiment of the invention, it is an
object to provide a pipeline condition detecting arrangement which
enables a detecting means to be propelled to a location within a
submerged pipeline section, and then be disconnected from an
extraneous power source which effected the propelling operation.
This disconnecting simplifies the subsequent detecting operation
and enables it to be performed without reliance upon power sources
carried by the detecting unit.
A still further object of the invention, in relation to the
preferred embodiment, is to enable scanning manipulation of the
pipeline condition detecting means to be effected by connecting the
pipeline condition detecting means to a conventional "line up
clamp" or pipeline alignment means. With this arrangement,
conventional manipulation of the line up clamp or pipeline
alignment means will serve to induce scanning movement of the
pipeline detecting means.
These objectives entail the consolidation of inspection and laying
operations, and thus might seem to be mutually conflicting because
of potential interaction or interference engendering operational
complications. However, it has been found that the objectives
heretofore set forth may be implemented, at least in part, by
practicing the following method aspects of the invention.
One such method aspect involves the performing of inspection or
pipeline condition detecting operations, in relation to a submerged
pipeline portion, while a portion of the pipeline remains supported
on floating vessel means such that the submerged pipeline portion
being inspected may be readily retrieved using laying apparatus and
techniques.
Another independent aspect of the invention relates to a method of
detecting a submerged pipeline condition where a pipeline is
supported at an offshore location with a first portion supported on
a submerged surface. In this technique, a second portion is
supported on floating vessel means and a third portion extends
through a body of water between the first and second pipeline
portions.
In this second method aspect, a pipeline condition detecting means
is positioned within the interior of a submerged portion of the
pipeline. Utilizing this detecting means, a condition of the
submerged pipeline portion is detected while the pipeline remains
supported by the floating vessel means. In addition, the floating
vessel means remains operable to retrieve the submerged pipeline
portion by exerting a retrieving force on the second pipeline
portion.
This technique is particularly advantageously employed in a third,
independently significant method aspect of the invention. In this
third method aspect of the invention the detecting means is caused
to undergo relative movement in relation to relatively newly laid
increment means of submerged pipeline means resting on a submerged
surface so as to indicate dimensional irregularities such as
buckles, etc.
In a fourth, independently significant, aspect of the invention the
pipeline indicating means is propelled from the floating vessel
means to its detecting location within the first pipeline portion.
In this fourth method aspect of the invention, scanning movement of
the pipeline condition detecting means is effected by connecting
the pipeline condition detecting means with conventional pipeline
section alignment means (i.e. a line up clamp) on the floating
vessel means. With this arrangement, normal repositioning of the
pipeline section alignment means as it is moved into alignment with
a new pipeline joint will induce relative movement of the pipeline
condition detecting means and relatively recently laid additional
increment means of the pipeline laying on a submerged surface. This
movement will cause the detecting means to scan the newly laid
increment means for irregularities.
A fifth facet of the invention, significant itself, relates to a
propulsion technique for operating the detecting means. This
propulsion technique entails the utilization of pressurized air to
concurrently (1) latch the detecting means in coupled engagement
with a source of pressurized air, (2) extend drive means into
engagement with the interior of a pipeline, and (3) actuate the
drive means for propulsion purposes. Reduction of the pressure of
the pressurized gas will serve to concurrently (1) uncouple the
source of pressurized air from the detecting means, (2) retract or
permit retraction of the drive means from effective driving
engagement with the pipeline interior, and (3) deactuate the drive
means itself.
A sixth independently significant aspect of the invention entails
the retrieval of a pipeline increment, containing an irregularity,
by operation of pipeline tensioning means used for normal laying
operations. This retrieval operation may serve to concurrently
retrieve the detecting means itself so as to enable it to be
rendered operational for subsequent detecting operations after the
impaired section has been replaced or reconditioned.
A seventh independently significant method aspect of the invention
entails the actual retrieval of a pipeline increment containing a
buckle condition or other irregularity, by merely reversing the
normal technique employed in the laying operation and retrieving
this increment on board the floating vessel used for pipeline
laying operations.
In conjunction with these independently significant method aspects
of the invention, which are mutually compatible so as to provide
cumulative benefits, the invention also contemplates various
combinations of apparatus elements which uniquely interact to
provide the advantageous functions heretofore described.
In describing the invention, reference will be made to preferred
embodiments by way of example. However, it will be recognized that
the preferred example is not limiting with respect to the scope of
the invention insofar as detecting apparatus is concerned,
pipelaying or retrieving apparatus is concerned, or the condition
being detected is concerned.
Bearing this in mind, the invention will now be described with
reference to certain illustrations.
DRAWINGS
Preferred embodiments of the invention are set forth in the
appended drawings.
In the drawings:
FIG. 1a schematically depicts an offshore pipeline laying operation
at the point in time where laying has been initiated and a pipeline
condition detecting means is positioned on the laying vessel. This
detecting means is disposed for subsequent propulsion to a location
disposed within a submerged pipeline portion resting on a submerged
surface;
FIG. 1b schematically illustrates the FIG. 1a assembly with the
pipeline condition detecting means disposed within the interior of
an increment of a submerged portion of a pipeline which is
generally resting on or located adjacent a submerged surface;
FIG. 1c schematically depicts the FIG. 1a assembly with the
pipeline condition detecting means disposed, as described in
connection with FIG. 1b, and operable to scan the interior of the
submerged pipeline increment in order to detect pipeline
irregularities. An upper portion of the pipeline supported on the
floating vessel means so as to permit retrieval of the submerged
pipeline increment being scanned. FIG. 1c also schematically
illustrates the interconnection of the pipeline detecting means
with a conventional line up clamp or pipeline alignment means which
is used to longitudinally align a new pipeline joint with the body
of the pipeline for welding or interconnecting purposes;
FIGS. 2a-2d provide enlarged, schematic views of operational
facilities located on the floating vessel means shown in FIGS.
1a-1c, it being understood that for purposes of ease and clarity of
illustration, not all of the components shown in FIGS. 2a-2d are
depicted in the schematic views of FIGS. 1a-1c;
FIG. 2a illustrates components as they would be arranged during an
initial welding operation, with the line up clamp or pipeline
alignment means securing a recently added pipeline section or joint
in longitudinal alignment with previously welded or assembled
joints for welding purposes. FIG. 2a further schematically depicts
the manner in which the previously welded pipeline body is engaged
by pipeline tensioning means which may be employed for pipeline
laying or retrieving purposes, as in the manner generally described
in Lawrence U.S. Pat. No. 3,390,532 and Lawrence U.S. Pat. No.
3,487,648. In FIG. 2a the pipeline section alignment means is
disposed in connected relation with a flexible draft device such as
a cable, rope, or chain, which extends from the pipeline section
alignment means through the pipeline interior to the pipeline
condition detecting means described in connection with FIGS.
1a-1c;
FIG. 2b schematically depicts the FIG. 2a components after the
welding of the new joint (which may comprise the welding of an
initial bead string or other partial or even complete welding),
with the new section having been advanced relative to the pipeline
vessel toward the submerged surface (normally effected by movement
of the pipeline vessel away from the previously laid pipeline
portion);
FIG. 2c depicts the FIG. 2b components with a second new pipeline
joint disposed in position to be longitudinally welded or otherwise
coupled to the remaining pipeline;
FIG. 2d illustrates the second additional pipeline increment or
joint disposed in longitudinal, contiguous alignment with the
previously welded pipeline body, with the line up clamp or pipeline
section alignment means being moved away from the previously laid
pipeline so as to bring it into alignment securing cooperation with
the junction between the second additional joint and the previously
welded joint. FIG. 2d further illustrates the movement of the
pipeline section alignment means which induces scanning or
condition detecting movement of the pipeline condition detecting
means described in connection with FIGS. 1a-1c;
FIG. 3 provides an enlarged, longitudinally extending, sectional
view of the submerged portion of the pipeline shown in FIG. 1c
containing the aforesaid pipeline condition detecting means, this
pipeline condition detecting means being shown in side elevation
within the interior of the longitudinally sectioned pipeline;
FIG. 4 provides a transverse sectional view of the FIG. 3 assembly,
and presents an end elevational view of a pressurized air operated
latching mechanism which serves to detachably secure a source of
pressurized air, i.e. a flexible air hose, to a power train
assembly of the pipeline condition detecting means, FIG. 4 being
viewed along section line 4--4 as shown in FIG. 3;
FIG. 5 provides a transverse sectional view of the FIG. 3 assembly,
as viewed along section line 5--5 of FIG. 3, and illustrates
resiliently biased centering wheels incorporated at the left end of
the pipeline condition detecting means, as shown in FIG. 3, and
further illustrates pneumatic connections extending to the latching
mechanism shown in FIG. 4;
FIG. 6 provides a transverse sectional view of the FIG. 3 assembly,
viewing the interior of the right end of the pipeline detecting
means as shown by reference to section line 6--6 of FIG. 3, and
depicts structural aspects of propelling components including
pneumatic motor actuated drive wheels and mechanisms for
selectively extending or retracting these drive wheels (i.e. for
exerting or releasing radially outwardly directed biasing force
exerted upon the biasing means);
FIG. 7 provides a transverse sectional view of the FIG. 3 assembly,
as viewed along section line 7--7 of FIG. 3, and illustrates in end
elevation, pneumatically biased centering wheels disposed at the
right end of the pipeline condition detecting means shown in FIG.
3;
FIG. 8 provides an enlarged, transverse sectional view of one of
three drive wheel components shown in FIG. 6, as viewed along
section line 8--8 of FIG. 6;
FIG. 9 provides an enlarged, transverse sectional view of a motor
support and reaction surface portion of one of the three drive
assemblies shown in FIG. 6, as viewed along section line 9--9 of
FIG. 6;
FIG. 10 provides a partially sectioned and enlarged view of the
previously noted latching mechanism, with components generally
disposed as shown in FIG. 3; and
FIG. 11 provides an enlarged, partially sectioned, side elevational
view of one representative centering wheel shown in elevation in
each of FIGS. 5 and 7.
DESCRIPTION OF PREFERRED EMBODIMENT
Overall Context of Invention
Pipe Laying Vessel
FIGS. 1a and 2a illustrate the overall context within which the
preferred embodiment of the invention is practiced.
As shown in these Figures, a pipeline laying installation 1
includes a floating vessel means 2. Floating vessel means 2 may
comprise a pipe-laying barge of the type now used in major offshore
pipeline laying operations, or for that matter any vessel operable
to effect pipelaying operations.
Laying barge 2 may be provided with a pipeline tensioning means 3
of the wheel or caterpillar type and generally corresponding in
mode of operation to the arrangement featured in Lawrence U.S. Pat.
No. 3,390,532.
Floating vessel means 2 may also include a buoyant ramp or
"stinger" 4 pivotally supported at connection joint 5 to one barge
end.
Connecting joint 5 may correspond to the hitch structure featured
in Lawrence U.S. Pat. No. 3,390,532. The buoyant ramp or stinger 4
may correspond generally to structures of the type featured in
Lawrence U.S. Pat. No. 3,390,532, Hauber U.S. Pat. No. 3,280,571,
and/or Rochelle et al. U.S. Pat. No. 3,507,126. A series of pipe
cradling, roller assemblies 6 may be provided on the barge 2 as
well as on the stinger 4, in the manner generally described in
Lawrence U.S. Pat. No. 3,390,532, so as to provide longitudinal
support underlying pipeline portions.
Such roller or cradle assemblies 6 serve to slidably support a
pipeline 7 being laid by the barge 2. While a series of such roller
assemblies 6 may be provided to provide a plurality of pipeline
supports spaced longitudinally along the pipeline, only one such
support 6 is schematically shown in FIG. 1a.
Welding
In many instances, it is contemplated that the invention may be
practiced in the context of a conventional welding-type, pipe
joining operation. In such an operation, one, or a series, of
welding stations, may be disposed longitudinally along the pipeline
portion supported on the barge 2. At each such welding station,
when the pipeline is substantially immobilized (except possibly for
wave action induced movement) relative to the barge 2, welding is
effected at a pipeline joint located at the station. Where multiple
stations are involved, each joint junction will be partially welded
at each of several welding stations, with the total welding
provided by the several weld stations producing a completed weld
joint.
One such representative weld station 8 is shown in FIG. 2a. Weld
station 8 may comprise an automatic welding unit or a conventional
station operated by manual welders.
Solely by way of example, the welding station 8 shown in FIG. 2a is
shown as the first welding station which would provide the initial
or "bead" weld between a new joint and the previously welded
pipeline body, in the event that a multiple welding station system
was being employed. It is also possible that station 8 could
comprise an automatic welding station where complete welding of the
joint would be completed.
Where multiple stations would be employed, several additional
stations 8 ordinarily would be interposed between the station 8,
shown in FIG. 2a, and the tensioning unit 3.
As shown in FIG. 2a, initial installation of a new pipeline joint
or increment 9 may be facilitated by a "line up clamp" or pipeline
alignment means 10. Such a pipeline alignment means 10 would serve
to secure the joint 9 in longitudinal and generally contiguous
alignment with the previously welded pipeline body 7.
Conventionally, pipeline alignment means 10, now well known in the
art, may comprise a body 11 supporting radially movable extendable
and contractible pipeline alignment clamps. Such alignment clamps
may be selectively motivated by pressurized air conveyed to them by
an air pipe (i.e. conduit or hose) 12. Air pipe 12, as shown in
FIG. 2a, will extend longitudinally of line up clamp 10. When
disposed in alignment position, alignment means 10 will be disposed
at the junction 13 between pipeline body 7 and new pipeline joint 9
and air pipe 12 will extend through the new joint 9. A flexible
branch air line 14 may be detachably connected with air pipe 12 and
serve to supply air to pipe 12 for transmittal to mechanism 10
under the manually controlled influence of valve 15 located in pipe
12.
In operation of this mechanism, with the clamp positioned generally
as shown in FIG. 2a, pressurized air would be supplied to pipe 12
so as to activate and radially extend the line up clamps of
mechanism 10. This extension of line up clamp elements would serve
to interlock or secure joint 9 in longitudinally aligned and
contiguous relation with pipeline body 7. The aligning and securing
operation of the clamps may be maintained by continuing to supply
air to mechanism 10 with valve 15 open or by closing the valve 15
so as to provide an entrapped body of clamp actuating pressurized
air in the pipe 12 and mechanism 10.
When the securing operation at station 8 has been completed, the
air pressure in pipe 12 may be reduced or vented so as to allow
radially inwardly directed retraction of the line up clamp elements
and thus permit relocation of the mechanism 10 for welding
operations relating to a second new joint.
During each securing operation, the tensioning means 3 will tend to
maintain the pipeline 7 generally stabilized in relation to the
pipeline laying vessel 2, while accommodating limited movement
induced by wave action as in the manner contemplated in Lawrence
U.S. Pat. No. 3,390,532 and Lawrence U.S. Pat. No. 3,487,648.
When welding has been completed, the pipeline vessel 2 will be
moved to the left, as shown in FIG. 1a so as, in essence, to cause
the new joint 9 to move relative to vessel 2 toward the previously
laid pipeline portion.
This "stop and go" operation will be continued until pipeline
laying is completed.
PIPELINE PROFILE
As shown in FIG. 1a, the pipeline laying operation there depicted
entails the laying of the pipeline 7 in a body of water 15.
Conventional techniques may be employed to both initiate and
terminate the pipeline laying operations depicted in FIGS. 1a
through 1c.
The pipeline 7 comprises a first portion 7a lying on a submerged
surface 16. Portion 7a, in general, will be substantially
completely supported by the submerged surface 16 such that it is no
longer subject to buckle inducing tendencies engendered during the
pipeline laying operation.
A second pipeline portion 7b will be supported by the tensioning
means 3 and roller assemblies 6 of the floating vessel means 2.
A third pipeline portion 7c extends through water body 15 between
the second pipeline portion 7b and the first pipeline portion
7a.
In general, pipeline portion 7c may be viewed as the portion
extending from the water surface 17 down to the general location of
a "tangency" point 18 where the pipeline moves into substantially
full supported engagement with the submerged surface 16.
As will be recognized, the references to pipeline portions 7a, 7b
and 7c do not refer to specific pipeline segments or joints, but
rather to general zones of a pipeline profile. During pipeline
laying operations a pipe segment or joint such as joint 9 will
sequentially pass from the vessel 2 to the surface 16 and move in
series through pipeline portions 7b, 7c and into portion 7a.
As will also be appreciated, during a pipeline laying operation, as
water depths vary and as the elevation or configuration of the
submerged surface 16 varies, the pipeline zone 7c may undergo
changes in shape, profile and/or dimension. In addition, as
pipeline laying progresses, the length of portion 7a will
continuously increase, with the configuration of portion 7a
depending upon the pipelaying route and the configuration of the
submerged surface 16 upon which it is resting.
By way of reference, this general mode of pipelaying is described
in Lawrence U.S. Pat. No. 3,390,532.
However, as will be appreciated, in view of the preceding and
subsequent discussions relating to the inventive contribution
herein presented, the invention may be practiced in the context of
a variety of pipeline laying techniques including those described
in Lawrence U.S. Pat. No. 3,487,648, Rochelle et al. U.S. Pat. No.
3,507,126, Lawrence U.S. Pat. No. 3,472,034, and other patents and
publications.
The general setting of the invention having been discussed, it now
becomes appropriate to consider structural details of a pipeline
condition detecting means which may be employed in the practice of
the invention.
Pipeline Condition Detecting Means
FIG. 1c schematically illustrates a pipeline condition detecting
means 19 disposed within the interior of pipeline portion 7a.
Pipeline condition detecting means 19 is connected with a flexible
draft device 20 such as a rope, cable, or chain which extends from
the detecting device 19 upwardly through the interior of the
pipeline body 7.
The manner in which draft device 20 is manipulated to induce
relative movement of detecting device 19 in relation to relatively
newly added or additional increments of pipeline portion 7a will be
subsequently described.
Suffice it to say, for the time being, that this relative movement
will permit scanning of such additional increments of pipeline
portion 7a very shortly after such increments have been laid on the
submerged surface 16. This will permit an operator to determine at
the earliest possible moment, or at least prior to the termination
of the pipeline laying operation, the condition of the pipeline as
it comes to rest on the submerged surface 16.
The condition being detected may be any of several conditions
normally considered during pipeline laying operations.
Desirably, of course, the condition detected will involve a status
devoid of unacceptable imperfections.
However, the detecting operation will be designed to locate
unacceptable conditions such as pipeline buckles. Such buckle
conditions would involve a distortion in pipeline cross section
dimensions, resulting from a conduit buckling which would occur as
pipeline joints move from the barge 2 through zone 7c to the
submerged surface 16.
Although the present discussion will be confined to the detection
of a buckle condition, it will be recognized that other adverse
conditions may be detected including cracks, faulty joints,
etc.
While a mechanical type of detecting unit will be subsequently
described, other detecting devices might be employed, including
those of an optical or television nature, and including those which
rely upon radiological, x-ray, sonic, or other radiated energy type
testing operations.
While it thus is apparent that the pipeline condition detecting
operation embraces a wide range of conditions and detection
apparatus, it will be appreciated that the invention is primarily
concerned with the location of a condition which is detectable
prior to the termination of the laying of the pipeline but which
will remain in the laid pipeline after the termination of the
laying operation unless detected and corrected.
Thus, the invention is to be distinguished from operations relating
to determinations of transient conditions which persist only during
the laying of the pipeline such as tension in the pipeline,
orientation of the profile of the pipeline portion 7c, etc.
Bearing the general scope of the detecting operation in mind,
structural details of a detecting mechanism operable to detect a
buckle condition will now be discussed.
Specific Structure of Buckle Detector
Structural details of buckle detector 19 are illustrated in FIGS.
3-11.
Referring now to FIG. 3, it will be seen that buckle detector 19
comprises a pair of mutually spaced, circular discs 21 and 22.
Discs 21 and 22 are interconnected by longitudinally extending and
circumferentially spaced framing members 23. Detector 19 is
connected with draft means 20 by way of a yoke 20a as shown in FIG.
3.
At least the foreward disc 21 will have a diameter such as to
enable it to move freely through an unbuckled pipeline interior but
be prevented from moving through the interior of a pipeline which
has been subjected to excessive buckling or cross-sectional
distortion. Thus, at least disc 21 will function as a buckle
detecting device.
Detector unit 19 includes, among its basic components, an air
conduit or manifold 24 and an air operated latching mechanism 25
which serves to detachably connect the air conduit 24 to a flexible
air hose 26.
Flexible air hose 26, when utilized, will extend from the mechanism
19 through the interior of pipeline 7. As shown in FIGS. 1a and 1c,
hose 26 may extend to a reel or hose assembly 27, which reel or
hose assembly is provided with means for connecting hose 26, in a
conventional manner, with a compressor or other source of
pressurized air. As will be recognized, the term "pressurized air"
is herein used in a generic sense to include any pressurized gas or
fluid.
Mechanism 19 is also provided with a plurality of centering wheels
28.
As shown in FIG. 5, three such centering wheels 28 are carried in a
symmetrical, radially oriented pattern by buckle detecting plate
21. Similarly, three other centering wheel assemblies 28 are
carried in a symmetrical and radially oriented arrangement by disc
22 in the manner generally depicted in FIG. 7.
In order to optimize the centering action of the wheel assemblies
28, the wheel patterns may be circumferentially displaced
180.degree. in the manner generally depicted in FIGS. 5 and 7.
A compressed air operated, propulsion system 29 included in buckle
detector 19 may comprise a series of three radially oriented and
symmetrically arranged drive wheel assemblies 30, each arranged for
radially outwardly directed biasing extension and radially inwardly
directed retraction or unbiasing movement. When retracted or biased
outwardly, each wheel assembly 30 will be positioned in driving or
propelling cooperation with the interior of the pipeline 7.
The propelling mechanism 29 serves to propel the detector 19 from
the vessel 2 to the pipeline portion 7a. After this propulsion is
effected, subsequent scanning movement of the detector 19 relative
to the pipeline is effected by the draft means 20.
Prior to considering the manner in which detector 19 is propelled
into operative position and utilized to detect a pipeline
condition, it will be appropriate to consider specific structural
and operational characteristics of the latching mechanism 25, the
drive wheel assemblies 30 and the centering wheels 28.
LATCHING MECHANISM
Structural details of the latching mechanism 25 are shown in FIGS.
3, 4, and 10.
As there shown, air conduit 24 of detector 19 is provided with a
flange face 31. Flange face 31 is operable to matingly and
generally sealingly and abuttingly engage a flange face 32 carried
by flexible air conduit 26.
The latch mechanism 25 which serves to secure the flange faces 31
and 32 in generally mutually abutting and sealed cooperation during
the propulsion of detector 19, comprises a plurality of pivoted
latch means 33.
As shown in FIGS. 3 and 4, two such latch means are provided each
comprising a body 34 connected to plate 21 by a pivot mount 35. A
pneumatically operated piston and cylinder-type actuator 36 is also
connected to plate 21 in association with each latch body 34. Air
for actuating the piston component 37 of each assembly 36 is
derived from a branch conduit 38 extending from the primary air
tube or conduit 24 of the detector 19. As shown in FIGS. 3 and 4,
the piston portion 37 includes a rod disposed in biasing
cooperation with an edge of the latching plate body 35.
Thus, when the flanges 31 and 32 are manually brought into abutting
cooperation, and pressurized air is supplied by conduit 26 to
conduit or manifold 24, this air will be transmitted through
conduit means 38 to piston and cylinder assemblies 36. This air
will actuate the assemblies 36 so as to cause the piston rod
components to bias plates 34 to the positions shown in FIGS. 3 and
10. In these positions, the plate bodies 34 serve to press the
flange 32 axially against the flange 31 and thus detachably
interlock the air source 26 with the detector 19.
When the pressure of air in conduit 26 is released, biasing
influence of assembly means 36 is obviated. With this biasing
influence thus obviated, the conduit means 26 may be pulled free of
the assembly 19.
If desired, the latch body elements 34 may be biased to a limited
extent into the latching position shown in FIG. 3 by torsion
springs or other spring means. However, while such spring means
would facilitate the initial connecting of the conduit means 26
with the detector 19, this biasing would not be sufficient in and
of itself to prevent the detachment of air hose 26 from the
detector 19 in response to the exertion of a pulling force on
conduit means 26.
Whatever arrangement is employed, it is contemplated that when the
air in conduit 26 is reduced in pressure, as by venting to the
atmosphere, or by otherwise effecting a substantial pressure
reduction, the conduit 26 will be retrievable to the deck of vessel
2 by the exertion of a pulling force on the conduit 26. However,
this pulling force will not induce any significant longitudinal
displacement of the detector 19 relative to the pipeline
interior.
As will also be recognized, the actuating assemblies 36 may also be
of the type which are spring biased to a retracted condition such
that when air pressure is reduced within these assemblies the
pistons will automatically retract so as to automatically cause the
plates or latches 34 to pivot outwardly and automatically free the
flange 32 for uncoupling purposes.
DRIVE WHEEL ASSEMBLIES
Structural details of the drive wheel means are generally depicted
in FIGS. 3, 6, 8 and 9.
As shown in these Figures, each such drive wheel assembly 30
comprises a base plate 39 mounted for radially outwardly or
inwardly directed movement by means of rail means 40 and 41 which
are secured to disc 22. A drive wheel 42 is journalled in bracket
means 43 and 44 by bearing assemblies 45 and 46 as generally
depicted in FIG. 8. Bracket means 43 and 44 are connected with base
plate 39, as shown in FIG. 8.
Each drive wheel 42 is connected with a drive shaft 47 which in
turn is connected, by a worm gear type transmission 48, with a
pneumatically actuated drive motor 49. Each drive motor 49, as
shown in FIG. 6, is supported by bracket means 50, which bracket
means is carried by base plate 39. As shown in FIG. 9, motor 49
provides a drive shaft 51 which serves to motivate or rotate the
worm gear element 52 in the transmission mechanism 48.
Each pneumatic drive motor 49, which is of a rotary character, is
motivated by and connected with a source of pressurized air. This
source of pressurized air as shown in FIGS. 3 and 6, may comprise a
flexible branch conduit 53 extending from main air conduit or
manifold 24.
With slide 39 biased radially outwardly, its associated drive wheel
42 will be disposed in frictional engagement with the interior of a
pipeline, in the manner generally shown in FIG. 3. This will permit
rotation of the drive wheel 42, as induced by operation of the
motor 49, to induce longitudinal movement or propulsion of the
detector assembly 19 relative to the pipeline 29 so as to cause the
detector 19 to be propelled sequentially through the pipeline
segments 7b and 7c to an operable location within the interior of
pipeline portion 7a, or other portion.
When the outwardly directing biasing force is removed from plate
39, sufficient inward movement of plate 39 will occur as to permit
the wheel 42 to be effectively disengaged from driving cooperation
with the interior of the pipeline. Such disengagement may entail
physical separation of the wheel from the pipeline interior or
merely sufficient movement to remove excessive frictional
interaction between the drive wheel 42 and the pipeline
interior.
Radially directed extension or contraction of the plate 39,
operable to manipulate the drive wheel 42 into and out of driving
cooperation with the pipeline interior, may be effected by a plate
movement controlling motor means such as a reciprocable piston and
cylinder assembly 54 associated with each unit 30.
Each such assembly 54 may comprise a pneumatically actuated piston
and cylinder assembly 54, the operation of which is effected by
pressurized air supplied by a branch conduit 55. As shown in FIG.
6, each such branch conduit 55 may be connected with and extend
from the manifold or main air conduit 24 of the detector 19.
A piston rod portion 56 of each assembly 54 is disposed for
radially directed reciprocation and is arranged in abutable or
engaged cooperation with the bracket 50.
Thus, when piston rod 56 is extended radially outwardly, the rod 56
will abuttingly engage the bracket 50 and cause the plate 39 to
move outwardly so as to bias the wheel 42 into driving cooperation
with the pipeline interior.
When the air pressure in mechanism 54 is reduced or vented to
atmosphere through the reduction of pressure in conduit 26, the
biasing influence of piston rod 56 will be removed.
With the outwardly directed biasing influence of piston rod 56
removed, the plate 39 will be free to retract radially inwardly so
as to obviate the formerly present radially outwardly directed
biasing force acting on its associated wheel 42 which served to
maintain wheel 42 in driving cooperation with the pipeline
interior.
As will be recognized, motor or positioning means 54 may be of the
automatic self-retracting type which would serve, when air pressure
was reduced in its interior, to automatically retract plate 39.
Where such automatic retraction was to be effected, the piston rod
56 would be connected with the bracket 50 or some other element
associated with plate 39 or possibly plate 39 itself.
As will be recognized, each of the drive wheel assemblies 30 will
function in the manner heretofore described, with the three
assemblies being simultaneously extendable in response to the
supplying of pressurized air to manifold 34.
As will also be appreciated, the drive wheels 42 in the three
assemblies 30 depicted in FIG. 6 will be generally concurrently
actuated or rotated for propelling purposes in response to the
supplying of pressurized air to manifold 24.
Thus, the supplying of pressurized air to manifold 24 by
pressurized air source 26 will serve to concurrently actuate the
previously noted operating components of the unit 19 and:
1. operate latch means 25 so as to secure source 26 with detector
19;
2. bias drive means, i.e. wheels 42, radially outwardly into
frictionally interacting and driving cooperation with the pipeline
interior; and
3. actuate or operate wheel means 42 so as to induce propelling of
the detector 19 through the pipeline interior.
As will also be appreciated, the reduction of pressure in conduit
26, for example, which may be effected by venting the conduit on
vessel 2 to the atmosphere, will concurrently serve to:
1. deactivate latch means 25 so as to permit or effect the
separation of conduit means 26 and detector 19;
2. remove the radially outwardly directing biasing force acting on
wheel means 42 (which may be considered as retraction of the wheel
means); and
3. deactivate the drive motors 54 associated with wheel means
42.
CENTERING WHEELS
With the mode of operation of the propulsion system having been
reviewed, it now becomes appropriate to consider structural aspects
of the centering wheel assemblies 28.
A representative wheel assembly 28 is shown in FIG. 11.
As there shown, each assembly 28 includes a body 57 which is
connected to its associated disc by a bracket means 58. A
telescoping inner component 59 is reciprocably mounted within the
body 52.
As shown in FIGS. 5 and 7, each body 57 is generally radially
oriented so as to permit generally radially oriented movement of
the component 59.
A coil spring 60 contained within body 52 may exert a radially
outwardly directed biasing force on each element 59, when the
element 59 has been moved radially inwardly of body 52 in response
to insertion of unit 19 into the interior of pipeline 7.
If desired, a retaining pin or rod 61 may be connected with
component 59. Such a rod would be telescopable through an inner end
wall of housing 57 and have a headed end 61a to limit outward
movement of component 59.
As shown in FIG. 11, each component 59 carries at its outer end a
centering wheel 62.
The yieldably biased nature of the wheel 62, as provided by the
action of spring means 60, will serve to ensure that the wheels 62
of the various assemblies 28 are concurrently brought into
centering cooperation with the pipeline interior.
The cooperative interaction of the various wheel means 62 will thus
serve to maintain an appropriate, limited clearance between
peripheries of discs 21 and 22 and the pipeline interior, at least
where an unbuckled pipeline interior is involved.
PIPELINE CONDITION DETECTING OPERATION
The structural and operating characteristics of detector 19 having
been reviewed, it now becomes possible to consider the overall
manner in which the invention is practiced so as to enable the
detector 19 to perform a pipeline scanning function during the
pipeline laying operation itself.
As will be appreciated from the foregoing discussion, this
operation will be conducted while tensioning means 3 remains
engaged with pipeline portion 7b. This engagement of the tensioning
means 3 with pipeline portion 7b will be such as to enable the
tensioning means 3 to operate to retrieve the pipeline in the event
that a buckle condition is detected.
This mode of retrieval is described, for example, in Lawrence U.S.
Pat. No. 3,390,532.
Such retrieval could be effected, for example, when the detector
19, in moving through an increment of the submerged pipeline
portion (ordinarily a newly added increment of portion 7a), would
detect a buckle condition in such an increment. When the buckle was
detected, the tensioning means would be operated so as to exert a
sufficient tensioning force on the pipeline portion 7b as to
retrieve enough of the previously laid pipeline so as to bring the
increment containing the buckle on board the vessel 2. This
retrieval of the pipeline increment containing the buckle would
also entail the concurrent retrieval of the detector 19 itself.
When the tensioned or buckled increment was on board vessel 2, it
would be repaired or replaced, and pipeline laying reinitiated. The
detector would be relocated and scanning resumed, employing the
operational techniques now to be described.
CONDITION DETECTING
This invention pertains to the detecting of an irregular or adverse
condition, or an acceptable condition, in a portion of a submerged
pipeline and may commence with an installation as shown in FIG.
1a.
With system elements disposed as shown in FIG. 1a, the initially
laid first portion 7a of a pipeline is supported on a submerged
surface 16 while a second portion 7b is supported by the tensioning
means 3 on the vessel 2. The tensioning means 3 is concurrently
operable to implement laying of the pipeline under tension or
effect retrieval of the previously laid pipeline for repair
purposes.
A third pipeline portion 7c extends through the body of water 15
between the first pipeline portion 7a and the second pipeline
portion 7b.
As shown in FIG. 1a, when detecting is to be initiated, the
detecting means 19 may be positioned within the interior of the
extremity of the pipeline portion 7b on lay barge 2, with the draft
means 20 connected with means 19 and extending possibly from a coil
or pneumatic winch mechanism, schematically depicted by the
reference numeral 63. Operators on board the vessel 2 would
position the flange 32 of the air hose 26 adjacent the flange 31 of
the detecting means 19. By supplying pressurized air through the
hose 26, the latch means 25 would be actuated so as to detachably
interconnect the source 26 of pressurized air with the detecting
means 19 and activate propulsion wheels 42. This actuation would
include (1) substantially concurrent actuation of the various drive
wheel extending motor means 54 so as to bias the wheels 42
outwardly into driving engagement with the pipeline interior and
(2) substantially concurrent actuation of the motor means 49 so as
to induce propelling rotation of the wheel means 42.
By appropriately "paying out" the air hose 26 and draft means 20,
the detecting means will propel itself through the interior of the
pipeline 7 until an operator determines, based on known profile
characteristics of the pipeline, that the detecting means 19 has
come to a rest either within the first pipeline portion 7a or
possibly within another submerged pipeline portion. For example,
the detecting means might be initially positioned in the vicinity
of the junction 18 between pipeline portions 7a and 7c, or even
within the pipeline portion 7c, depending upon the condition being
detected.
After the appropriate position of the detecting means 19 within the
pipeline interior has been effected, possibly as generally shown in
FIG. 1b, the pressure of air within air hose 26 would be reduced so
as to permit the decoupling of hose 26 and detecting means 19 in
the manner previously described. FIG. 1b depicts the flange
terminus 32 of the air hose 26 within pipeline portion 7c during
the retrieving or recoiling operation of this air hose, possibly as
implemented by winch means 63.
A portion of the flexible draft means 20 would then be disconnected
from coil means 63 and be connected with a pipeline alignment means
or line up clamp 10 as schematically shown in FIG. 1c.
The line up clamp would then be positioned within the interior of
the pipeline, possibly generally as shown in FIG. 2c.
A first additional pipeline segment or increment (i.e. joint) would
then be manipulated into position in axial alignment with the
pipeline terminus and the alignment clamp 10 might then be drawn
back into the position shown schematically in FIG. 2a where it
would be aligned with the junction 13 between pipeline body 7 and
new joint 9.
This manipulation could be facilitated by a cable or rope connected
with the air pipe 12, with the cable or hose being threaded through
the new joint 9 to permit alignment means 11 to be drawn into the
FIG. 2a position.
With the components disposed as shown in FIG. 2a, the detecting
means 19 is connected by flexible draft means 20 to the pipeline
alignment means 10. Concurrently, this pipeline alignment means is
interconnecting the pipeline portion 7b in longitudinal alignment
with the additional pipeline increment 9.
With the components disposed as shown in FIG. 2a, air would be
supplied through branch conduit 14 to air pipe 12, as permitted by
valve 15, so as to actuate the alignment means 10 and maintain its
clamps in aligning cooperation with the joint 9 and pipeline body
7.
During this operation, a flexible cable or rope 64 extending from
coil or winch means 63 may be detachably connected with the air
pipe 12.
After the welding operation at station 8 has been completed, the
laying barge 2 would move ahead, i.e. away from the previously laid
pipeline segments, so as, in essence, to displace the increment 9
into the first pipeline portion 7a as shown schematically in FIG.
2b.
During this movement, the line up clamp 10 may remain in its
expanded or actuated condition by virtue of a closed condition of
valve 15 serving to entrap pressurized air within pipe 12 and line
up clamp or alignment means 10. Alternatively, valve 15 may be open
and pipe 12 disconnected from air source 14. Under these
circumstances, the clamps of mechanism 10 would be retracted and
mechanism 10 would be frictionally immobilized within pipeline
portion 7b.
During this movement, which constitutes a part of the laying
operation, the tensioning means 3 would maintain appropriate
control tension on the pipeline.
During the movement operation depicted in FIG. 2b, not only may the
air conduit 14 be uncoupled from the pipe 12, but the rope or cable
64 may be disengaged from the air pipe.
With the components disposed as shown in FIG. 2b, conventional
techniques may be employed to bring a second additional pipeline
increment 65 into position in longitudinal alignment with the first
additional increment. This first increment, being at least
partially welded or secured to the pipeline body, now comprises a
terminus of the second pipeline portion 7b.
Throughout this operation, pipeline portion 7b, as well as second
increment 65, would be appropriately supported by roller or cradle
means 6, most of which are not shown.
With the components disposed as shown in FIG. 2c, a section of
cable or rope 66 may be threaded through the interior of joint 65
and connected with line 64 and the end of air pipe 12. The valve
15, if closed, may be opened so as to effect retraction of the
clamps in mechanism 10. Prior to retracting the clamp means 10, the
winch means 63 may be operated so as to take the slack out of the
interconnected draft means 64 and 66.
The winch means 63 may then be operated to move the alignment means
10 generally toward the new joint 65 and into position in aligning
cooperation with the juncture 67 between the joint 9 and the joint
65.
Thus, this movement of the alignment means 10, schematically
depicted in FIG. 2d, will thus serve to cause the detecting means
19 to move, or attempt to move, generally toward an additional
increment of the pipeline portion 7a which has moved into the
pipeline zone 7a as a result of the advancing movement of the barge
2 described in connection with FIG. 2b. The movement of the barge
described in connection with FIG. 2b, of course, served to cause an
additional increment of the pipeline to come to rest on the
submerged surface 16 so as to, in essence, extend the length of
pipeline portion 7a, i.e. cause an additional increment to move
into the zone designated 7a.
In other words, during the retracting movement of the line up clamp
or alignment means 10, the draft means 20 would have exerted a
retracting or pulling force on the detecting means 19. This pulling
force would have caused the detecting means 19 to move, or attempt
to move, within the interior of the submerged pipeline, generally
toward the vessel 2 and second pipeline portion 7b and through a
recently or newly added increment of portion 7a. This movement
would have permitted the detector to thus scan the interior of such
an increment of the pipeline portion 7a, with a view to detecting
irregularities such as a buckle condition.
In the event that a buckle condition is detected (due to an
inability to move unit 19 because of engagement of disc 21 with a
buckle), the tensioning means 3 may be operated to retrieve the
increment containing the buckle condition and the detector means 19
so that appropriate repairs may be initiated and pipelaying and
condition detecting resumed.
In the event that no irregularity is detected by the detecting
means 19, the alignment means 10 will be positioned at joint
juncture 67, as shown in FIG. 2d, so as to permit the additional
segment 65 to be disposed in generally abutting and longitudinally
aligned relation with the joint 9 so that interconnection or
welding of joints 9 and 65 may be effected. When the welding at
illustrated station 8, between aligned sections 9 and 65, is
terminated, the sequence of operations heretofore described may be
resumed.
As will be appreciated, prior to effecting the welding of joints 9
and 65, the air hose 14 would be reconnected with the air pipe 12
and the valve 15 opened to effect the actuation of the line up
clamp elements in the mechanism 10.
While in many operations the welding at station 8 would involve the
formation of an initial "bead" so as to weldingly and at least
partially interconnect the joints 9 and 65, under certain
circumstances, automated welding equipment may effect substantial
or complete welding of the joints 9 and 65 at the single welding
station shown in FIGS. 2a and 2d.
Optimum benefits of the invention are realized where the scanning
device or detecting means 19 is disposed in pipeline portion 7a
reasonably near the tangency point 18. This disposition of the
detecting means 19 will ensure that the scanning movement of the
detecting means 19 will take place through the most recently added
increment or increments of the pipeline which have come to rest on
the submerged surface 16. Following this technique, scanning of
pipeline increments which have passed through the zone 7b and 7c,
where buckling might occur, will be effected at the earliest moment
so that repairs may be made as expeditiously as possible.
Depending upon operating conditions, the detecting means 19 may
effect scanning of additional increments added to pipeline portion
7a somewhat after or before the point in time that such increments
have come to rest on the submerged surface 16.
ALTERNATIVE SCANNING TECHNIQUE
The scanning technique heretofore described is effected between
increments of lay barge movement which serve to cause pipeline
laying on surface 16.
In other words, as the lay barge 2 is moved ahead so as to displace
the joint 9 from the FIG. 2a to the FIG. 2b positions, an
additional increment of pipeline will be added to the pipeline
portion 7a, i.e. the submerged and suspended profile of the
pipeline will translate along the laying route so as to cause an
additional increment of the pipeline to come to rest on the
submerged surface 16 within the zone designated as first pipeline
portion 7a.
Those skilled in the pipelaying art and familiar with the
disclosure will recognize that the invention might also be
practiced by securing the detecting means 19, as for example by
connecting it with a stationary or immobilized drum of winch means
63, during the pipelaying or advancing movement of the lay
barge.
Under these circumstances, the advancing movement of the lay barge
would exert a pulling force on unit 19, through the draft means 20,
so as to cause scanning means 19 to move relative to the pipeline
during the actual advancing or laying movement of the lay barge
itself.
In any event, regardless of which scanning technique is employed,
the present invention contemplates that scanning or detecting
operations will be performed during the laying operation, that is
to say, between the termination and initiation of the laying of the
complete pipeline 7 and while the retrieving means 3 of the lay
barge 2 remains continuously operable to effect retrieval of a
defective pipeline section.
SUMMARY OF MAJOR ADVANTAGES AND OVERALL SCOPE OF INVENTION
A principal advantage of the invention resides in the provision of
a technique which enables defects in submerged pipelines to be
detected during the laying operation.
Defects may be determined almost as soon as a defective section has
come to rest on the submerged surface so as to enable repairs to be
made as expeditiously as possible.
Significantly, condition detecting is effected while the lay barge
or floating vessel means remains continuously operable to retrieve
a defective section for repair operations. Where the retrieval is
effected by the tensioning means, i.e. utilizing the pipelaying
equipment itself, proper and effective control over pipeline stress
may be maintained so as to minimize the chance of causing pipeline
tension during the repairing operation.
The necessity of resorting to underwater repairs or costly repairs
initiated after pipeline laying has been completed may be
avoided.
The technique described heretofore enables an operator to ensure a
customer at the completion of the laying operation, without further
delay, that the pipeline has been scanned for certain abnormalities
and is in an acceptable condition. In this manner, delays involving
subsequent inspection operations are avoided and the pipeline may
be placed in operating condition more quickly. Such savings in time
are particularly significant where weather conditions or other
factors limit the time available to complete pipeline laying
operations and place pipelines in operating condition.
In performing these detecting or scanning operations concurrently
with the pipelaying operation itself, a substantial savings in time
and money is effected.
The propulsion mechanism described in connection with the detecting
mechanism of the present invention is uniquely advantageous in that
it permits a propulsion power source to be effectively deactivated
and removed from the pipeline interior once the detecting means has
been appropriately located.
A variety of modified aspects of the invention have been heretofore
set forth. In summary, it will be recognized that the invention may
be practiced by:
1. employing substantial variations in pipeline laying techniques
and equipment;
2. detecting a wide variety of pipeline conditions;
3. performing detecting operations with a wide variety of detecting
apparatus; and
4. conducting the detecting operation itself either "in between"
increments of lay barge movement or concurrent with lay barge
movement, or possibly in both ways.
Such variations are indicative of the scope of the invention and it
will be apparent to those skilled in the pipelaying art and
familiar with this disclosure that such variations and other
additions, deletions, substitutions, and modifications may be made
within the scope of the invention as set forth in the appended
claims.
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