U.S. patent number RE28,922 [Application Number 05/499,431] was granted by the patent office on 1976-08-03 for column stabilized stinger.
This patent grant is currently assigned to Santa Fe International Corporation. Invention is credited to Samuel H. Lloyd, III.
United States Patent |
RE28,922 |
Lloyd, III |
August 3, 1976 |
Column stabilized stinger
Abstract
The stinger includes a base structure having a plurality of
upstanding stabilizing columns on opposite sides of its pitch and
roll axes and carrying pipeline supports which permit translational
movement of the pipeline relative to the stinger. The stinger is
pivotably secured behind the pipelaying barge and is ballasted from
a low draft condition with the base structure having freeboard to a
high draft condition. The pipeline supports progressively decrease
in height above the base structure from the end of the segment
nearest the barge whereat the pipeline is supported in the air
toward the opposite end whereat the aft pipeline support disposes
the pipeline below the mean waterline. The pipeline centerline
extending along the supports defines a radius of curvature at least
equal to and preferably much greater than the minimum allowable
radius of curvature for the pipeline. The stinger is preferably
configured such that the combined natural frequency of the stinger
and pipeline match as nearly as possible the natural frequency of
the pipelaying barge.
Inventors: |
Lloyd, III; Samuel H. (Los
Angeles, CA) |
Assignee: |
Santa Fe International
Corporation (Los Angeles, CA)
|
Family
ID: |
26744333 |
Appl.
No.: |
05/499,431 |
Filed: |
August 21, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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22634 |
Mar 25, 1970 |
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Reissue of: |
064267 |
Aug 17, 1970 |
03685305 |
Aug 22, 1972 |
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Current U.S.
Class: |
405/166; 405/171;
114/264; 405/168.1; 114/61.13 |
Current CPC
Class: |
B63B
35/03 (20130101); B63B 35/04 (20130101); F16L
1/225 (20130101) |
Current International
Class: |
B63B
35/03 (20060101); B63B 35/00 (20060101); B63B
35/04 (20060101); F16L 1/225 (20060101); F16L
1/12 (20060101); B63B 035/04 (); F16L 001/00 () |
Field of
Search: |
;61/72.3,72.1,46.5
;114/61,.5F |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Shapiro; Jacob
Attorney, Agent or Firm: LeBlanc & Shur
Parent Case Text
This application is a continuation-in-part of my copending
application Ser. No. 22,634 filed Mar. 25, 1970.
Claims
What is claimed and desired to be secured by United States Letters
Patent is:
1. A flotation member for laying pipeline on an underwater surface
from a floating vessel having a pipeline work deck elevated above
the mean waterline comprising:
an elongated base structure comprised of a pair of transversely
spaced hulls, at least a portion of said hulls converging toward
one another in one of the fore and aft directions;
a plurality of elements upstanding from said hulls with at least a
portion of said elements comprised of a plurality of stabilizing
columns located on opposite sides of the pitch and roll axes of the
member;
means for submerging said base structure and portions of said
upstanding elements below the waterline to obtain a high draft
floating condition, the displacement of the submerged base
structure and portions of said upstanding elements being sufficient
to maintain the member buoyant in a pipeline portion supporting
condition with the mean waterline located intermediate the height
of said columns;
coupling means carried by said base structure adjacent its forward
end for pivotally coupling the flotation member to the pipelaying
vessel;
and means carried by said flotation member for supporting a portion
of a pipeline for translational movement therealong, said pipeline
support means being located above said base structure at elevations
of decreasing height relative to said base structure in a forward
to aft direction along said flotation member, the pipeline support
means being adapted to receive pipeline payed out from the elevated
work deck of the pipelaying vessel.
2. Apparatus according to claim 1 including means for varying the
submergence of the flotation member in the high draft condition to
alter the natural period of the flotation member to preclude
amplification of flotation member motion due to interaction of wave
and flotation member motion.
3. Apparatus according to claim 1 wherein said stabilizing columns
have a substantially uniform cross-sectional area throughout their
height.
4. Apparatus according to claim 1 wherein said submerging means
includes means for ballasting and deballasting said base
structure.
5. Apparatus according to claim 4 wherein each of said hulls
include a plurality of compartments, valve means associated with
said compartments for introducing water ballast into and expelling
water ballast from said compartments.
6. Apparatus according to claim 1 wherein said support means
comprises a plurality of rollers disposed at longitudinally spaced
positions along said stinger and lying substantially coincident
with the longitudinal centerline of the stinger.
7. Apparatus according to claim 6 wherein at least a pair of said
columns are carried by each of said hulls, a plurality of support
struts extending between laterally adjacent columns, said rollers
being disposed on said support struts.
8. Apparatus according to claim 1 including said vessel, said
coupling means coupling said flotation member to the aft end of
said vessel to position the flotation member for receiving pipeline
payed out from said vessel.
9. Apparatus according to claim 8 wherein said vessel has a work
area adjacent one side of the vessel for assembling pipe sections,
said member being coupled to said vessel to lie in substantial
longitudinal alignment with said one vessel side.
10. Apparatus according to claim 8 wherein said vessel has a work
area substantially along the centerline of said vessel, said member
being coupled to said vessel such that the centerlines of said
vessel and said member lie in substantial longitudinal alignment
one with the other.
11. Apparatus according to claim 8 wherein said vessel includes a
base structure and a plurality of columns upstanding from said base
structure, and means for ballasting and deballasting said vessel
between high and low draft conditions, said vessel being column
stabilized in the high draft condition.
12. Apparatus according to claim 11 wherein said vessel has a work
area adjacent one side thereof for assembling pipe sections, said
vessel hull structure including a pair of elongated hulls spaced
one from the other on opposite sides of said vessel, and means
carried by the aft portion of the one hull on the same side of said
vessel as said work area and cooperable with said coupling means on
said stinger for releasably connecting said flotation member to
said vessel.
13. Apparatus according to claim 11 wherein said vessel has a work
area substantially along the centerline of said vessel for
assembling pipe sections, said vessel hull structure including a
pair of elongated hulls spaced one from the other on opposite sides
of said vessel, and means carried by the aft portions of said hulls
and cooperable with said coupling means on said flotation member
for releasably connecting said flotation member to said vessel.
14. Apparatus according to claim 8 wherein the natural period of
said flotation member and the pipeline portion carried thereby
substantially match the natural frequency of said vessel.
15. Apparatus according to claim 8 wherein said vessel and said
flotation member and pipeline portion carried thereby have
predetermined natural periods, and means for selectively ballasting
and deballasting the flotation member to substantially match the
natural period of the flotation member and pipeline portion carried
thereby with the natural period of the vessel.
16. Apparatus according to claim 1 wherein at least a pair of said
columns are carried by each of said hulls, said base structure
being configured to float the member in a low draft condition with
the base structure having freeboard, said submerging means
including means for ballasting said hull to change the draft of the
member from said low draft condition to said high draft
condition.
17. Apparatus according to claim 1 wherein said base structure
includes a keel spaced below said hulls, and means connecting said
hulls and said keel one to the other.
18. Apparatus for laying pipeline on an underwater surface
comprising;
a floating vessel having a pipeline work deck elevated above the
mean waterline;
a flotation member having an elongated base structure;
a plurality of elements upstanding from said base structure with at
least a portion of said elements comprised of a plurality of
stabilizing columns located on opposite sides of the pitch and roll
axes of said flotation member;
means for submerging said base structure and portions of said
upstanding elements below the waterline to obtain a high draft
floating condition, the displacement of the submerged base
structure and portions of said upstanding elements being sufficient
to maintain the flotation member buoyant in a pipeline portion
supporting condition with the mean waterline located intermediate
the height of said columns;
means carried by said base structure adjacent its forward end
pivotally coupling said pipelaying vessel and said flotation member
one to the other;
and means carried by said flotation member for supporting a portion
of a pipeline for translational movement therealong, said pipeline
support means being located above said base structure at elevations
of decreasing height relative to said base structure in a forward
to aft direction along said flotation member, the pipeline support
means being adapted to receive pipeline payed out from the elevated
work deck of said vessel;
said flotation member comprising the sole means for supporting the
pipeline as it is payed out from said vessel. .Iadd.19. Apparatus
for laying pipe on an underwater surface comprising:
a floating vessel including a pair of elongated hulls disposed in
spaced side-by-side relation;
a working platform including a generally horizontally disposed
pipeline work deck on which pipe sections are joined end to end one
with the other and from which work deck the pipeline is payed out
from the aft end of said vessel;
means for supporting said platform in fixed spaced relation a
predetermined height above said hulls including columns connected
to said hulls and said platform, at least three of such columns
being connected with each of the hulls on opposite sides of the
roll axis of the vessel, at least one column on each hull being
disposed adjacent the aft end of said hull;
said elevated pipeline work deck on said platform and said columns
being relatively disposed such that pipeline is payed out from said
pipeline work deck and from the aft end of said vessel at an
elevation no lower than the juncture of the upper ends of the
aftmost columns on said hulls and the underside of said
platform;
the distance between the extremities of said vessel along its
longitudinal centerline being substantially greater than the
distance between the extremities of said vessel along its
transverse centerline;
said hulls having ballast compartments for ballasting said vessel
to alter its draft between a low draft hull supported floating
condition with the hulls having freeboard and a high draft
semisubmerged column stabilized floating and pipelaying condition
with said pipeline work deck elevated above the mean waterline
whereby pipeline payed out from said elevated pipeline work deck
and from the aft end of said vessel, when the vessel lies in said
high draft pipelaying condition, curves downwardly toward the water
as it extends through the air between the aft end of the vessel and
a location spaced from said vessel at which the pipeline enters the
water;
said columns having predetermined cross-sectional areas and being
located on the hulls to provide righting moments about the pitch
and roll axes of said vessel when in high draft condition; and
means connected to the aft end of said vessel and extending
generally longitudinally therefrom for supporting at least the
downwardly curved portion of the pipeline payed out from said
elevated pipeline work deck and the aft end of said vessel which
extends through the air between the aft end of the vessel and the
location spaced from said vessel at which the pipeline enters the
water, said support means including means for maintaining the
radius of curvature of the downwardly curved pipeline portion
greater than the radius of curvature which would permit bending
stresses on the pipeline in excess of its allowable bending stress,
said maintaining means including a plurality of discrete supports
longitudinally spaced one from the other along said support means
and arranged such that a curved line through successive ones of
said supports has a radius of curvature greater than the radius of
curvature which would permit bending stresses on the pipeline in
excess of its allowable bending
stress. .Iaddend. .Iadd.20. Apparatus according to claim 19
including means for adjusting the elevation of said supports
relative to said work deck. .Iaddend..Iadd.21. Apparatus according
to claim 19 including means for adjusting the elevation of said
supports relative to the mean waterline, and means carried by said
vessel and coupled to said adjusting means for controlling the
elevation of said supports relative to the mean waterline from said
vessel. .Iaddend..Iadd.22. Apparatus according to claim 19
including means for pivotally connecting said support means and
said vessel adjacent the aft end of said vessel. .Iaddend..Iadd.23.
Apparatus according to claim 19 wherein said work deck is located
at an elevation at least 15 feet above the mean waterline when said
vessel lies in said high draft condition. .Iaddend. .Iadd.24.
Apparatus according to claim 19 including means for pivotally
connecting said support means and said vessel adjacent the aft end
of said vessel, said work deck being located at an elevation at
least 15 feet above the mean waterline when said vessel lies in
said high draft condition. .Iaddend..Iadd.25. Apparatus according
to claim 19 wherein said supports include at least a forwardmost
pair of longitudinally spaced supports for supporting the pipeline
portion which extends through the air and which pair of supports
lie at an elevation above the mean waterline, at least one
additional support located aft of the forwardmost pair of supports
on said support means for supporting a portion of the pipeline
below the mean waterline and which latter support lies at an
elevation below the waterline. .Iaddend. .Iadd.26. Apparatus
according to claim 19 wherein said elevated pipeline work deck
extends substantially along the centerline of said vessel and said
pipeline support means extends substantially longitudinally along
the centerline of the vessel extended from the aft end of the
vessel. .Iaddend..Iadd.27. Apparatus according to claim 19 wherein
said elevated pipeline work deck extends longitudinally
substantially along one side of the centerline of said vessel, said
pipeline support means extending longitudinally from the aft end of
the vessel and from said one side of the vessel. .Iaddend..Iadd.28.
Apparatus according to claim 19 including a crane located adjacent
said one end of the vessel, said vessel including structure below
said crane defining an opening through which the pipeline passes as
the pipeline is transferred from the vessel to the support means.
.Iaddend. .Iadd.29. Apparatus according to claim 24 wherein each of
said hulls has top and bottom substantially planar horizontally
disposed surfaces extending substantially perpendicular to a
vertical plane through the longitudinal centerline of said vessel
with the transverse horizontal dimension of each hull being greater
than its vertical dimension for a major portion of the length of
said hulls so as to provide increased mass resistance to movement
of said hulls through water in a vertical direction when said
vessel lies in said high draft column stabilized semisubmerged
pipelaying condition, said columns being substantially constant in
cross section for substantially their entire height between said
platform and said hulls, at least one of said columns on each said
hull having a dimension in the longitudinal direction greater than
its dimension in the transverse direction, said maintaining means
including a plurality of discrete supports longitudinally spaced
one from the other along said pipeline support and arranged such
that a curved line through successive ones of said supports has a
radius of curvature which would permit bending stresses on the
pipeline in excess of its allowable bending stress. .Iaddend.
.Iadd.30. Apparatus for laying pipe on an underwater surface
comprising:
a floating vessel including a pair of elongated hulls disposed in
spaced side-by-side relation;
a working platform including a generally horizontally disposed
pipeline work deck on which pipe sections are joined end to end one
with the other and from which work deck the pipeline is payed out
from the aft end of said vessel;
means for supporting said platform in fixed spaced relation a
predetermined height above said hulls including columns connected
to said hulls and said platform, at least three of such columns
being connected with each of the hulls on opposite sides of the
roll axis of the vessel, at least one column on each hull being
disposed adjacent the aft end of said hull;
said elevated pipeline work deck on said platform and said columns
being relatively disposed such that pipeline is payed out from said
pipeline work deck and from the aft end of said vessel at an
elevation no lower than the juncture of the upper ends of the
aftmost columns on said hulls and the underside of said
platform;
the distance between the extremities of said vessel along its
longitudinal centerline being substantially greater than the
distance between the extremities of said vessel along its
transverse centerline;
said hulls having ballast compartments for ballasting said vessel
to alter its draft between a low draft hull supported floating
condition with the hulls having freeboard and a high draft
semisubmerged column stabilized floating and pipelaying condition
with said pipeline work deck elevated above the mean waterline
whereby pipeline payed out from said elevated pipeline work deck at
the aft end of said vessel, when the vessel lies in said high draft
condition, curves downwardly toward the water as it extends through
the air between the aft end of the vessel and a location spaced
from said vessel at which the pipeline enters the water;
said columns having predetermined cross-sectional areas and being
located on the hulls to provide righting moments about the pitch
and roll axes of said vessel when in high draft condition;
means connected adjacent the aft end of said vessel and extending
generally longitudinally therefrom for supporting at least the
downwardly curved portion of the pipeline payed out from said
elevated pipeline work deck which extends through the air between
the aft end of the vessel and a location spaced from said vessel at
which the pipeline enters the water, said support means including a
flotation member having an elongated base structure, a plurality of
elements upstanding from said base structure comprised of a
plurality of stabilizing columns located on opposite sides of the
pitch and roll axes of the member;
means for submerging said base structure and portions of said
upstanding elements below the waterline to a high draft floating
condition, the displacement of the submerged base structure and
portions of said upstanding elements being sufficient to maintain
the member buoyant in a pipeline portion supporting condition with
the mean waterline located intermediate the height of at least a
plurality of said columns;
coupling means carried by said base structure adjacent its forward
end for pivotally coupling the flotation member to said vessel;
and
means carried by said flotation member for supporting the pipeline
for translational movement therealong and at elevations of
decreasing height relative to said base structure in a fore to aft
direction along said
flotation member. .Iaddend. .Iadd.31. Apparatus according to claim
30 wherein said elevated pipeline work deck extends substantially
along the centerline of said vessel and said flotation member
extends substantially longitudinally along the centerline of the
vessel extended from the aft end of the vessel. .Iaddend..Iadd.32.
Apparatus according to claim 30 wherein said elevated pipeline work
deck extends longitudinally substantially along one side of the
centerline of said vessel, said flotation member extending
longitudinally from the aft end of the vessel and from said one
side of the vessel. .Iaddend..Iadd.33. Apparatus according to claim
30 including a crane located adjacent said one end of the vessel,
said vessel including structure below said crane defining an
opening through which the pipeline passes as the pipeline is
transferred from the vessel to said flotation member. .Iaddend.
.Iadd.34. Apparatus for laying pipe on an underwater surface
comprising:
a floating vessel including a pair of elongated hulls disposed in
spaced side-by-side relation;
a working platform including a generally horizontally disposed
pipeline work deck on which pipe sections are joined end to end one
with the other and from which work deck the pipeline is payed out
from one end of said vessel;
means for supporting said platform in fixed spaced relation a
predetermined height above said hulls including columns connected
to said hulls and said platform with at least one column on each
hull disposed adjacent the aft end of said hull;
said elevated pipeline work deck on said platform and said columns
being relatively disposed such that pipeline is payed out from said
pipeline work deck and from the aft end of said vessel at an
elevation no lower than the juncture of the upper ends of the
aftmost columns on said hulls and the underside of said
platform;
the distance between the extremities of said vessel along its
longitudinal centerline being greater than the distance between the
extremities of said vessel along its transverse centerline;
said hulls having ballast compartments for ballasting said vessel
to alter its draft between a low draft hull supported floating
condition with the hulls having freeboard and a high draft
semisubmerged column stabilized floating and pipelaying condition
with said pipeline work deck elevated above the mean waterline
whereby pipeline payed out from said elevated pipeline work deck at
the aft end of said vessel, when said vessel lies in said high
draft pipelaying condition, curves downwardly toward the water as
it extends through the air between the aft end of the vessel and a
location spaced from said vessel at which the pipeline enters the
water;
said columns having predetermined cross-sectional areas and being
located on the hulls to provide righting moments about the pitch
and roll axes of said vessel when in high draft condition;
means connected to the aft end of said vessel and extending
generally longitudinally therefrom for supporting at least the
downwardly curved portion of the pipeline payed out from said
elevated pipeline work deck which extends through the air between
the aft end of the vessel and a location spaced from said vessel at
which the pipeline enters the water, said support means including
means for maintaining the radius of curvature of the downwardly
curved pipeline portion greater than the radius of curvature which
would permit bending stresses on the pipeline in excess of its
allowable bending stress, said maintaining means including a
plurality of discrete supports longitudinally spaced one from the
other along said support means and arranged such that a curved line
through successive ones of said supports has a radius of curvature
greater than the radius of curvature which permit bending stresses
on the pipeline in excess of its allowable bending stress; and
means for pivotally connecting said support means and said vessel
adjacent the aft end of said vessel, said work deck being located
at an elevation at least 15 feet above the mean waterline when said
vessel lies in said
high draft condition. .Iaddend. .Iadd.35. Apparatus according to
claim 34 including means for adjusting the elevation of said
supports relative to said support deck. .Iaddend..Iadd.36.
Apparatus according to claim 34 including means for adjusting the
elevation of said supports relative to the mean waterline, and
means carried by said vessel and coupled to said adjusting means
for controlling the elevation of said supports relative to the mean
waterline of said vessel. .Iaddend. .Iadd.37. Apparatus according
to claim 34 wherein each of said hulls has top and bottom
substantially planar horizontally disposed surfaces extending
substantially perpendicular to a vertical plane through the
longitudinal centerline of said vessel with the transverse
horizontal dimension of each hull being greater than its vertical
dimension for a major portion of the length of said hulls so as to
provide increased mass resistance to movement of said hulls through
water in a vertical direction when said vessel lies in said high
draft column stabilized semi-submerged pipelaying condition, said
columns being substantially constant in cross section for
substantially their entire height between said platform and said
hulls, at least one of said columns on each said hull having a
dimension in the longitudinal direction greater than its dimension
in the transverse direction, said maintaining means including a
plurality of discrete supports longitudinally spaced one from the
other along said pipeline support and arranged such that a curved
line through successive ones of said supports has a radius of
curvature greater than the radius of curvature which would permit
bending stresses on the pipeline in excess of its allowable bending
stress. .Iaddend. .Iadd.38. Apparatus according to claim 34 wherein
said elevated pipeline work deck extends substantially along the
centerline of said vessel and said pipeline support means extends
substantially longitudinally along the centerline of the vessel
extended from the aft end of the vessel. .Iaddend..Iadd.39.
Apparatus according to claim 34 wherein said elevated pipeline work
deck extends longitudinally substantially along one side of the
centerline of said vessel, said pipeline support means extending
longitudinally from said one end of the vessel and from the aft
side of the vessel. .Iaddend..Iadd.40. Apparatus according to claim
34 including a crane located adjacent the aft end of the vessel,
said vessel including structure below said crane defining an
opening through which the pipeline passes as the pipeline is
transferred from the vessel to the support means. .Iaddend.
.Iadd.41. Apparatus for laying pipe on an underwater surface
comprising:
a floating vessel including a pair of elongated hulls disposed in
spaced side-by-side relation;
a floating vessel including a pair of elongated hulls disposed in
spaced side-by-side relation;
a working platform including a pipeline work deck on which pipe
sections are joined end to end one with the other and from which
work deck the pipeline is payed out from one end of said
vessel;
means for supporting said platform in fixed spaced relation a
predetermined height above said hulls including columns connected
to said hulls and said platform, at least three of such columns
being connected with each of the hulls on opposite sides of the
roll axis of the vessel with a pair of such columns being located
near respective opposite ends of each of said hulls on opposite
sides of the pitch axis of the vessel and another of said columns
being located at an intermediate position on each hull;
the distance between the extremities of said vessel along its
longitudinal centerline being substantially greater than the
distance between the extremities of said vessel along its
transverse centerline;
said hulls having ballast compartments for ballasting said vessel
to alter its draft between a low draft hull supported floating
condition and a high draft semisubmerged column stabilized floating
and pipelaying condition with said pipeline work deck elevated
above the mean waterline whereby pipeline payed out from said
elevated work deck at one end of said vessel when said vessel lies
in said high draft condition curves downwardly toward the water as
it extends through the air between said one vessel end and a
location spaced from said vessel at which the pipeline enters the
water;
said columns having predetermined cross-sectional areas and being
located on the hulls to provide righting moments about the pitch
and roll axes of said vessel when in high draft condition;
means for providing a significantly greater righting moment about
the transverse pitch axis of the vessel than the righting moment
about the longitudinal roll axis of the vessel when said vessel is
in high draft semisubmerged operating condition, the latter means
including at least three of the aforementioned columns connected
with each of the hulls on opposite sides of the roll axis of the
vessel with pairs of such columns being located near opposite ends
of each of said hulls on opposite sides of the pitch axis of the
vessel and another of said columns being located at an intermediate
portion on each hull and with the configurations and areas of said
columns and the distances of said columns from the longitudinal
roll axis and transverse pitch axis of said vessel being such that
in the vessel's semisubmerged operating condition the latter means
provides a significantly greater righting moment about said
transverse pitch axis than about said longitudinal roll axis;
and
means connected to one end of said vessel and extending generally
longitudinally therefrom for supporting at least the portion of the
pipeline payed out from said elevated pipeline work deck which
extends through the air between said one vessel end and a location
spaced from said vessel at which the pipeline enters the water,
said support means including a flotation member having an elongated
base structure, a plurality of elements upstanding from said base
structure comprised of a plurality of stabilizing columns located
on opposite sides of the pitch and roll axes of the member;
means for submerging said base structure and portions of said
upstanding elements below the waterline to a high draft floating
condition, the displacement of the submerged base structure and
portions of said upstanding elements being sufficient to maintain
the member buoyant in a pipeline portion supporting condition with
the mean waterline located intermediate the height of at least a
plurality of said columns;
coupling means carried by said base structure adjacent its forward
end for pivotally coupling the flotation member to said vessel;
and
means carried by said flotation member for supporting the pipeline
for translational movement therealong and at elevations of
decreasing height relative to said base structure in a fore to aft
direction along said flotation member. .Iaddend. .Iadd.42.
Apparatus according to claim 41 wherein said elevated pipeline work
deck extends substantially along the centerline of said vessel and
said flotation member extends substantially longitudinally along
the centerline of the vessel extended from said one end of the
vessel. .Iaddend..Iadd.43. Apparatus according to claim 41 wherein
said elevated pipeline work deck extends longitudinally
substantially along one side of the centerline of said vessel, said
flotation member extending longitudinally from said one end of the
vessel and from said one side of the vessel. .Iaddend..Iadd.44.
Apparatus according to claim 41 including a crane located adjacent
said one end of the vessel, said vessel including structure below
said crane defining an opening through which the pipeline passes as
the pipeline is transferred from the vessel to said flotation
member. .Iaddend. .Iadd.45. Apparatus according to claim 18 wherein
said vessel comprises
a pair of elongated hulls disposed in spaced side-by-side
relation;
a working platform spaced above said hulls a predetermined height
and carrying said work deck;
means for supporting said platform in fixed spaced relation above
said hulls including columns connected to said hulls and said
platform;
the distance between the extremities of said vessel along the
longitudinal centerline of said vessel being substantially greater
than the distance between the extremities of said vessel along the
transverse centerline of said barge;
said hulls having ballast compartments for ballasting said vessel
to alter its draft between a low draft hull supported floating
condition and a high draft semisubmerged column stabilized floating
condition;
said columns having predetermined cross-sectional areas and being
located on the hulls to provide righting moments about the pitch
and roll axes of said vessel when in high draft condition;
the area of said columns, the number thereof and the distance of
said columns from the longitudinal and transverse centerlines of
said vessel being such as to provide a greater righting moment
about the transverse pitch axis than the righting moment about the
longitudinal roll axis when said vessel is in high draft
semisubmerged condition. .Iaddend..Iadd.46. Apparatus according to
claim 18 wherein said pipeline support means are located to support
the pipeline such that the radius of curvature of the pipeline lies
within its allowable radius of curvature whereby rupture of the
pipeline is avoided. .Iaddend..Iadd.47. Apparatus according to
claim 18 wherein said pipeline work deck supports the pipeline at
an elevation on the order of about 15 feet above the mean waterline
at the location where the pipeline is transferred between said
vessel and said flotation member. .Iaddend. .Iadd.48. A column
stabilized semisubmersible pipelaying barge and pipeline support
apparatus comprising:
a pair of elongated hulls disposed in spaced side-by-side
relation;
a working platform spaced above said hulls a predetermined height
including a pipeline work deck, and means on said work deck for
securing pipe sections in end-to-end relation one to the other to
form a pipeline extending generally parallel to the longitudinal
centerline of said barge;
means for supporting said platform in spaced relation above said
hulls including columns connected to said hulls and said platform
on opposite sides of the pitch and roll axes of said barge;
the distance between the extremities of said barge along the
longitudinal centerline thereof being substantially greater than
the distance between the extremities of said barge along its
transverse centerline;
said hulls having ballast compartments for ballasting said barge to
alter its draft between a low draft hull supported floating
condition with the hulls having freeboard and a high draft
semisubmerged column stabilized floating and pipelaying condition
with the pipeline work deck elevated above the mean waterline
whereby pipeline payed out from said elevated pipeline work deck,
when said barge lies in said high draft condition, curves
downwardly toward the water as it extends through the air between
said elevated pipeline work deck and a location at which the
pipeline enters the water,
said columns having predetermined cross-sectional areas and being
located on the hulls to provide righting moments about the pitch
and roll axes of said barge when in said high draft condition;
an elongated pipeline support pivotally connected to said barge and
extending generally longitudinally in a predetermined attitude
relative to said barge for supporting at least the downwardly
curved portion of the pipeline payed out from said elevated
pipeline work deck which extends through the air between said barge
and the location at which the pipeline enters the water, and
means for maintaining said elongated pipeline support in said
predetermined attitude relative to said barge thereby to maintain
the radius of curvature of the downwardly curved pipeline portion
greater than the radius of curvature which would permit bending
stresses on the pipeline in excess of its allowable bending stress.
.Iaddend. .Iadd.49. Apparatus according to claim 48 wherein the
pivotal connection between said pipeline support and said barge
lies at an elevation below said work deck and below the pipeline at
like longitudinal location along said barge as the longitudinal
location of said pivotal connection along said barge.
.Iaddend..Iadd.50. Apparatus according to claim 49 wherein each of
said hulls has top and bottom substantially planar horizontally
disposed surfaces extending substantially perpendicular to a
vertical plane through the longitudinal centerline of said vessel
with the transverse horizontal dimension of each hull being greater
than its vertical dimension for a major portion of the length of
said hulls so as to provide increased mass resistance to movement
of said hulls through water in a vertical direction when said
vessel lies in said high draft column stabilized semisubmerged
pipelaying condition. .Iaddend..Iadd.51. Apparatus according to
claim 50 wherein said columns are substantially constant in cross
section for substantially their entire height between said platform
and said hulls. .Iaddend..Iadd.52. Apparatus according to claim 51
wherein said pivotal connection lies at an elevation below the
elevation of said top hull surfaces. .Iaddend. .Iadd.53. Apparatus
according to claim 48 wherein said pipeline work deck is generally
horizontally disposed, at least three columns disposed on each said
hull, said work deck and said columns being relatively disposed
such that pipeline is payed out from said pipeline work deck at an
elevation no lower than the juncture of the upper ends of the
columns and the underside of said platform. .Iaddend..Iadd.54.
Apparatus according to claim 48 wherein one of said three columns
is disposed adjacent the aft end of said vessel, said work deck and
said columns being relatively disposed such that pipeline is payed
out from said pipeline work deck and from the aft end of said
vessel at an elevation no lower than the juncture of the upper ends
of the aftmost columns on said hulls and the underside of said
platform, said pipeline support being pivotally connected to said
barge adjacent its aft end and extending generally longitudinally
therefrom for supporting at least the downwardly curved portion of
the pipeline payed out from said elevated pipeline work deck and
the aft end of said vessel which extends through the air between
said barge and the location at which the pipeline enters the water.
.Iaddend. .Iadd.55. Apparatus according to claim 54 wherein each of
said hulls has top and bottom substantially planar horizontally
disposed surfaces extending substantially perpendicular to a
vertical plane through the longitudinal centerline of said vessel
with the transverse horizontal dimension of each hull being greater
than its vertical dimension for a major portion of the length of
said hulls so as to provide increased mass resistance to movement
of said hulls through water in a vertical direction when said
vessel lies in said high draft column stabilized semisubmerged
pipelaying condition, said columns being substantially constant in
cross section for substantially their entire height between said
platform and said hulls, at least one of said columns on each said
hull having a dimension in the longitudinal direction greater than
its dimension in the transverse direction, said maintaining means
including a plurality of discrete supports longitudinally spaced
one from the other along said pipeline support and arranged such
that a curved line through successive ones of said supports has a
radius of curvature greater than the radius of curvature which
would permit bending stresses on the pipeline in excess of its
allowable bending stress, said work deck being located at an
elevation at least 15 feet above the mean waterline when said barge
lies in said high draft column stabilized pipelaying condition.
.Iaddend. .Iadd.56. Apparatus according to claim 55 including means
for adjusting the elevation of said supports relative to said work
deck. .Iaddend..Iadd.57. Apparatus according to claim 55 including
means for adjusting the elevation of said supports relative to the
mean waterline, and means carried by said vessel and coupled to
said adjusting means for controlling the elevation of said supports
relative to the mean waterline from said vessel. .Iaddend.
Description
The present invention relates to a subaqueous pipe and cable laying
apparatus and particularly relates to a column stabilized stinger
for pipe or cable laying barges having elevated working
platforms.
Increased activity in offshore gas and oil exploration and
development has created an insistent demand for cables and
pipelines connecting the offshore sites with onshore terminals. For
example, it is often desirable to directly connect an offshore oil
producing well with an onshore terminal by means of a pipeline laid
along the sea floor whereby oil issuing from the well may be
directly communicated to the onshore terminal. Apparatus for laying
pipelines along the sea floor has been provided in the past and
oftentimes includes pipelaying barges whereon the pipes are
connected one to the other and then payed out from the barge for
disposition on the seabottom as the barge advances. Pipelines, of
the type commonly employed for this purpose, are capable of
resisting bending stresses within predetermined limits. Such
stresses would not normally be exceeded in shallow water pipelaying
operations. However, as the water depth increases, the length and
hence weight of pipe which must be supported from the pipelaying
barge increases with the pipeline obtaining a generally S-shaped
configuration between the barge and the seabottom, the radiuses of
curvature of the pipe tending to decrease as the distance between
the barge and seabottom or water depth increases. Hence, there is a
limit to the radius of curvature which a specified pipeline can
obtain without incurring bending stresses exceeding the maximum
allowable bending stresses for that particular pipeline and which
stresses would result in rupture of the pipeline.
Stingers have been employed in the past in efforts to overcome the
foregoing and other problems associated with laying subaqueous
pipelines, particularly in deep water. Stingers, either fixed or
articulated, comprise devices used to support the pipeline after it
has been payed out from the barge and prior to its disposition on
the seabottom. Conventionally, the stinger connection to the
pipelaying apparatus, which is normally a surface floating barge,
is located at or near the operating waterline of the lay barge. An
inclined ramp is conventionally constructed on the lay barge to
assist in obtaining the proper curvature of the pipeline as it
enters the stinger, the ramp usually terminating at the operating
waterline. The inclined ramp, however, reduces the available work
space on the lay barge due to its disposition near the waterline.
More importantly, the surface floating pipelaying barge is subject
to wind and wave action which causes excessive barge and stinger
motion. As is usually the case, pipelaying operations must be
terminated in medium to high seas (waves in excess of 4 or 5 feet)
due to large heave motions of the stinger and pipelaying vessel and
mismatched vertical motion between the pipelaying barge and the
stinger due to wave action. When large heave motions are obtained,
there is increased likelihood that the pipeline will exceed its
allowable bending stress and rupture.
Accordingly, it is desirable to employ a pipelaying vessel which
has minimum motion response to wave excitation forces whereby the
vessel can be substantially motionless even in high seas. Such a
vessel having a minimum motion characteristic is disclosed in my
U.S. Pat. application Ser. No. 705,175, filed Feb. 13, 1968 and is
characterized by the provision of a plurality of stabilizing
columns having a base flotation stucture at their lower ends and a
work platform adjacent their upper ends. This vessel is supported
in a low draft condition by the base flotation structure and in a
high draft condition, by preferably ballasting the base structure,
by the residual displacement of the base structure and the
submerged portion of the columns. In the high draft condition with
the mean waterline located intermediate the height of the columns
and with the base structure fully submerged, the vessel obtains
minimum motion response to wave action. As a necessary condition to
its effective employment, the work deck of this vessel must be
elevated a considerable distance above the mean waterline (even in
the high draft condition the work deck is about 15 to 20 feet above
the mean waterline). Apart from the foregoing, it has also been
found desirable to maintain the work area or platform on which the
pipeline sections are connected one to the other and from which the
sections are paved out onto the stinger well above the mean
waterline such that work can be efficiently conducted and continued
even during heavy seas. Thus, when employing a column stabilized
vessel for pipelaying operations on which the work platform is both
necessarily and desirably elevated above the mean waterline in the
high draft column stabilized condition of the vessel or when a
conventional ramp-less barge is employed wherein the work area for
connecting and paying out the pipe sections is elevated a
significant distance above the mean waterline, there is a large
length of pipeline which must be supported in the air from the
elevated after deck portion of the column stabilized or ramp-less
pipelaying barge to the point at which the pipeline enters the
water (in addition to the portion of the pipeline extending from
the surface of the water to the seabottom). A conventionally
constructed stinger cannot be employed by itself for this purpose
as it is simply not designed to provide support for and transition
of the pipeline from an elevated work deck through the air to its
point of entry into the water. Also, the frequency response of the
conventional stinger (having a relatively large water-plane area)
to wave action would not normally be the same as or bear any
relation to the frequency response of the pipelaying barge to wave
action and this would result in mismatched heave motions
deleterious to effective pipelaying operations particularly in
heavy seas.
Accordingly, it is a primary object of the present invention to
provide a novel stinger for subaqueous pipeline laying operations
from a lay vessel having an elevated work deck.
It is another object of the present invention to provide a column
stabilized stinger for supporting a pipeline as it is payed out
from a pipelaying vessel in a manner to minimize and substantially
eliminate heave motions of the pipeline due to excitation forces
caused by wave action on the pipelaying barge and stinger.
It is still another object of the present invention to provide a
column stabilized stinger for supporting the air length of a
pipeline between the elevated work area of a pipelaying barge and
the point of entry of the pipeline transition into the water as
well as for supporting an immersed portion of the pipeline in a
manner to substantially preclude rupture of the pipeline due to
relative motion of the pipelaying barge and the ground supported
pipeline.
It is a further object of the present invention to provide a column
stabilized stinger having a natural frequency matched as nearly as
possible to the natural frequency of the accompanying pipelaying
barge when in a pipeline supporting condition to preclude relative
motion between the pipelaying barge and the stinger due to wave
action on both the barge and stinger.
It is a still further object of the present invention to provide a
column stabilized pipelaying barge and a column stabilized stinger
configured to minimize barge and stinger motion due to excitation
forces thereon caused by wave action (hereinafter called "motion
minimizing characteristics").
These and further objects and advantages of the present invention
will become more apparent upon reference to the following
specification, claims and appended drawings, wherein:
FIG. 1 is a perspective view illustrating one form of a pipelaying
apparatus constructed in accordance with the present invention;
FIG. 2 is a fragmentary side elevational view thereof;
FIG. 3 is a side elevational view of one form of a column
stabilized stinger constructed in accordance with the present
invention;
FIG. 4 is a cross-sectional view thereof taken generally about on
line 4--4 of FIG. 3;
FIG. 5 is a top plan view of the stinger hereof;
FIG. 6 is an end elevational view of the stinger hereof;
FIGS. 7, 8, 9 and 10 are cross-sectional views thereof taken
generally about on lines 7--7, 8--8, 9--9, and 10--10 respectively
in FIG. 3;
FIG. 11 is a perspective view of another form of pipelaying
apparatus hereof;
FIG. 12 is a fragmentary side elevational view thereof; and
FIG. 13 is a fragmentary cross-sectional view thereof taken about
on line 13--13 in FIG. 12.
Referring now to FIG. 1, there is illustrated a form of the present
invention in which a pipelaying barge, generally indicated 10, is
illustrated towing a column stabilized stinger, generally indicated
12 for laying pipeline indicated 14. In the form of the invention
illustrated in FIG. 1, the pipelaying barge is, per se, a column
stabilized barge and may be of the type disclosed in copending
application Ser. No. 705,175 filed Feb. 13, 1968 of common assignee
herewith, the disclosure of which application is incorporated
herein by reference as though herein fully set forth.Iadd., said
application Ser. No. 705,175 being parent application to
application Ser. No. 161,865 filed July 9, 1971 as a continuation
of application Ser. No. 705,175 incorporated herein by reference
and which application Ser. No. 161,865 issues as U.S. Pat. No.
3,835,800 dated Sept. 17, 1974.Iaddend.. Briefly, pipelaying barge
10 comprises a pair of transversely spaced elongated hulls 16 each
carrying a plurality of upstanding stabilizing columns 18. Columns
18 support a work platform 20 adjacent their upper ends, platform
20 lying in spaced relation above hulls 16 a predetermined height
at least equal to the maximum anticipated wave height and
preferably comprising upper and lower decks 22 and 24 respectively.
The hulls 16 include ballast compartments, not shown, and barge 10
is configured such that it floats in an unballasted low draft
condition with the hulls having freeboard when in transit between
work sites, with the mean waterline M.W.L. lying below the top side
of the hulls 16. At a work site, for example, astride a track along
the seabottom on which pipeline is to be laid, the hull
compartments are ballasted to submerge the hulls and portions of
columns 18 such that the mean waterline is located at approximately
one-half the effective height of columns 18 as illustrated whereby
a high draft condition and substantial transparency to wave action
is obtained. Furthermore, the cross-sectional area and
configuration of columns 18, the weight distribution of barge 10
and the geometry of submerged hulls 16 are such as provide vessel
motion minimizing characteristics in roll, pitch, and heave in the
high draft condition illustrated in FIG. 1. That is to say, barge
10 is configured to provide minimum motion response to wave
excitation forces in the high draft condition. Additionally, the
vessel is configured to have long natural periods in heave, pitch
and roll in the high draft condition and which periods are beyond
the range of anticipated wave periods as to avoid motion
amplification due to interaction of vessel and wave motion. It will
be appreciated that auxiliary equipment including cranes C for
storing, manipulating, racking, connecting, etc. the various pipe
sections to be laid are carried by pipelaying barge 10 on work
platform 20 and that in the ballasted high draft pipelaying
condition the work platform 20 remains elevated a substantial
distance above the mean waterline, for example, on the order of 15
to 20 feet. Particularly, the pipe sections P.S. stored on upper
deck 22 are lowered by cranes C through an opening 26 in upper deck
22 for disposition in a work area generally indicated 28 along one
side of the vessel on lower deck 24, the assembled pipeline being
payed out from the between deck work area aft onto the stinger 12
for disposition on the seabottom. Thus, by locating the assembly
area for the pipe sections between decks 22 and 24, the workmen can
work in an enclosed protected area. Further, by such disposition,
the height of the pipe above the mean waterline is reduced as
compared with dispensing the work area in the open on deck 22 and
this reduces the design requirements for the stinger as discussed
hereinafter. Also, it is desirable in pipelaying operations
conducted in deep water to apply a predetermined axial tension to
the pipeline in order to reduce the curvature of the generally
S-shaped pipeline portion which extends between the pipelaying
apparatus and the seabottom. To this end, a plurality of rollers,
not shown, can be disposed in the work area 28 on lower deck 24 in
a position engaging about the pipe. The rollers can be controlled
by a suitable drive mechanism, not shown, to provide a constant
tension on the pipe thereby to increase the radius of curvature of
the depending pipeline in comparison with the radius of curvature
of an un-tensioned pipeline. As will be appreciated, the pipeline
is thus laid in tension with the barge being periodically stopped
such that additional pipe sections can be added and secured to the
pipeline and advanced such that the additional sections can be
payed out from the barge. For purposes of this application, the
term pipeline as employed herein is intended also to include one or
more cables within its scope.
Referring now to FIGS. 2, 3 and 4, stinger 12 is preferably an all
steel tubular welded construction including a generally
triangularly shaped base or hull structure 30 having a pair of
transversely spaced elongated tubular or pontoon-like members 32
connected one to the other by a plurality of diagonally disposed
cross tubular members 34 and a pair of transversely extending
tubular members 36 located centrally of stinger 12. The elongated
members 32 converge inwardly toward one another at opposite ends of
stinger 12 with a central portion of members 32 between cross
members 36 lying generally parallel one with the other. Tubular
members 32 are generally symmetrical with respect to one another
about a longitudinal axis. A lower centrally disposed tubular keel
38 depends from tubes 32 by a framework including a plurality of
diagonally extending inwardly inclined tubular braces 40 connecting
between central tube 38 and respective tubular members 32. Keel 38
extend short of the opposite ends of stinger 12 and its forward end
is connected to a pair of outwardly diverging tubular members 42.
The forward ends of members 42 are, in turn, connected with a pair
of transversely spaced forwardly and inwardly converging tubular
members 44, members 42 and 44 lying in a common substantially
horizontal plane. Suitable diagonally and transversely extending
cross braces 45 and 46 respectively are provided between members 44
and their forward ends are connected with upwardly inclined tubular
members 48 (FIG. 3). The forward ends of tubular members 32 and
members 48 are connected to a transversely extending cross member
50 carrying a pair of laterally spaced hinge mountings 52.
Specifically, each hinge mounting 52 includes a pair of vertically
extending spaced plates 54 having registering openings 56 for
receiving hinge pins 58 for connecting the stinger to the barge 10.
Particularly, as seen in FIGS. 1 and 2, the barge 10 includes a
pair of transversely spaced, vertically extending plates 60 carried
on the hull 16 below work area 28, the plates 60 having openings
and being receivable between the plates 54 of hinge mountings 52
with hinge pins 58 providing the stinger to barge coupling. A
cylindrical flotation tank 64 is disposed between and below members
32 above members 44 to provide additional buoyancy to stinger
12.
Turning now to the aft end of stingers 12, keel 38 has a reduced
diameter extension 66 connected to a tubular subassembly 68 having
a rectangular plan form as seen in FIG. 4. A plurality of upwardly
and inwardly inclined tubular members 67 are connected at their
lower ends to the corners of rectangular subassembly 68 and are
connected at their upper ends to the aft end portions of tubular
members 32. As seen particularly in FIG. 9, this arrangement
provides an upwardly opening channel shaped slot 69 at the aft end
of stinger 12 whereby pipeline can issue from stinger 12 from a
point directly above the lowermost portion of stinger 12.
As specifically illustrated in FIGS. 3, 7 and 8, there is provided
a pipeline supporting and stinger stabilizing structure upstanding
from the base or hull structure 30. This upstanding structure
includes a plurality of stabilizing columns 70 suitably secured at
their lower ends to the tubes or pontoon-like members 32. Columns
70 extend upwardly from the upper surface of base structure 30 an
effective height which may be equal to and is preferably greater
than the maximum anticipated wave height, i.e., the vertical
distance between wave crest and trough. In the preferred
embodiment, five pairs of columns 70 are equally longitudinally
spaced one from the other along base structure 30 with the column
arrangement on each tube or pontoon-like member 32 being
symmetrical with respect to the column arrangement on the other
tubular or pontoon-like member 32. As illustrated in FIGS. 3 and 5,
columns 70 are preferably circular in cross section and constant in
cross-sectional area throughout their effective height. Columns 70
provide for motion minimizing characteristics when the stinger
segment lies in a semisubmerged high draft operating condition as
described hereinafter and provides stability to the stinger when
disconnected from the barge. The upstanding structure also includes
a forward pair of columns 72 and 74 having like characteristics as
columns 70. Column 72 is however disposed on the centerline of
stinger 12 on a cross tubular member 76 connecting between members
32 whereas column 74 upstands from one of the longitudinal members
32. Longitudinally extending support struts 77 extend between the
upper ends of columns 70 on opposite sides of stinger 12. Also, a
pair of diagonal tubular supports 79 connect between members 32 and
the central longitudinal support member 77 to reinforce the
pipeline support structure.
A plurality of pipeline supporting carriages, generally indicated
at 78 are preferably mounted along the longitudinal centerline of
stinger 12 on support members 80 which preferably extend
transversely between corresponding stabilizing columns 70
upstanding from the tube-like members 32. A similar carriage is
carried by columns 72 and 74 at the forward end of stinger 12 and
on the rectangular subassembly 68 at the aft end of stinger 12. At
best illustrated in FIGS. 7-8, each pipeline support carriage 78
includes a base 82 secured to its associated support member 80.
Base 82 mounts a pair of laterally upwardly inclined supports 84,
which, in turn, mount laterally inclined rollers 86. By inclining
rollers 86 as illustrated, there is formed a trough for receiving
the pipeline whereby the latter is maintained against lateral
movement relative to stinger 12 on pipeline support carriages 78.
Pipeline support rollers 86, of course, permit translational
movement of the pipeline relative to stinger 12 for disposition on
the seabottom.
As illustrated in FIG. 3, the pipeline support carriages 78 are
carried by the stabilizing columns 70 in a progressively decreasing
height above the base structure 30 from the end of the stinger
nearest the pipelaying vessel toward the opposite end of the
stinger whereat the aft pipeline support carriage is disposed below
members 32 such that a curved line extending along carriages 78 has
a radius of curvature at least equal to and preferably greater than
the minimum allowable radius of curvature for the particular
pipeline portion carried by the stinger. That is to say, the
pipeline supporting carriages 78 support the pipeline in a manner
such that the radius of curvature of the pipeline portion is always
greater than that radius of curvature which would permit bending
stresses on the pipeline in excess of the maximum allowable bending
stress. The carriage support member 80 are preferably adjustable in
height along the columns relative to base structure 30, by means
not shown, whereby the radius of curvature of the portion of the
pipeline extending over the carriages 78 can be preselected, if
desired, in accordance with the characteristics of the pipeline
being laid to avoid pipeline rupture.
Referring now to FIG. 5, it will be seen that each of the
pontoon-like members 32 is compartmented to form a plurality of
ballast chambers 90 for varying the draft of stinger 12. Any number
of chambers 90 can be provided as desired to perform the intended
ballasting and deballasting function and each chamber is provided
with a remotely controlled valve 92 for selectively opening and
closing the associated chamber to the surrounding sea. The
ballasting and deballasting of the stinger is preferably controlled
from the pipelaying barge. To this end, and in addition to suitable
conventional controls, not shown, for operating valves 90 remotely,
there is provided a suitable air pump, schematically illustrated at
93 in FIG. 2 in communication with each chamber 90 by a conduit 94
which, through a tee connection 95, lies in communication with a
pair of conduits 96, each serving the compartments 90 in the
respective tubular members 32. Conduits 95 and 96 serve as both
exhaust lines for permitting air to vent from compartments 90 when
ballasting stinger 12 and supply lines for introducing air into
compartments 90 when deballasting stinger 12 in a manner and for
reasons to be described. Suitable remotely controlled valves 97 are
provided in air lines 95 to selectively vent compartments 90 and to
provide communication between pump 93 and compartments 90.
In use, stinger 12 is coupled to the pipelaying barge 10 by hinge
connections 54, 56 and 60. In the normal transit condition to a
work site, for example, in transit to an area where pipeline is to
be laid, the barge 10 is maintained in an unballasted low draft
condition whereby the hulls 16 support the barge in the water and
float with freeboard. Similarly, the stinger 12 is also maintained
in an unballasted condition whereby the base or hull structure 30
supports stinger 12 in the water in a low draft condition with the
tubular hull members 32 floating with freeboard. At the work site,
both the ballast compartments in the barge 10 and in the stinger 12
are ballasted to submerge the respective hulls 16 and base
structure 30 such that the columns 18 on barge 10 and columns 70
and 72 on stinger 12 are submerged for approximately one-half their
effective height, thereby locating the mean waterline above the
upper surface of the hulls 16 and base structure 30. The ballasting
of stinger 12 is accomplished by remote actuation of valves 92 to
permit ingress of sea water into compartments 90 while the air
valves 97 are also remotely actuated to vent air from ballast
compartments 90 through lines 94 and 96 to atmosphere at pump 93 (a
suitable valve, not shown, being provided at pump 93) and thereby
permit the ingress of ballast water.
When the barge and stinger are ballasted to their working draft
conditions, the pipeline carried by the barge can then be assembled
on the work area 28 and payed out onto the carriage supports 78 and
through the slot 72 at the aft end of stinger 12 for disposition on
the seabottom. As the pipeline is initially payed out from barge 10
onto carriage supports 78, the remotely actuated valves 92 are
opened to provide free communication between the surrounding
seawater and compartments 90 and valves 97 are actuated to connect
the air pump to air lines 94 and 96. The compartments 90 are
progressively deballasted as additional pipeline is payed out from
the barge onto stinger 12. By progressively deballasting
compartments 90 as additional pipeline is disposed onto stinger 12,
the latter is maintained in a predetermined column stabilized high
draft position relative to the pipelaying barge 10 and the draft of
stinger 12 is not substantially altered as the weight of the
additional pipeline is added thereto.
It will be appreciated that the displacement of the submerged
portions of columns 70, 72 and 74 and the residual displacement of
the base structure 30 are adequate to maintain stinger 12 in a
floating semisubmerged or high draft condition supporting the
pipeline on carriages 78. In this manner, wave action is prevented
from acting against base structure 30 and acts only on columns 70,
72 and 74 and the pipeline support structure in the open frame area
between columns 70, 72 and 74 and above base structure 30. This
reduces the adverse effect of wave action on the stinger 12 which,
by proper configuration of the columns and the weight and
displacement of stinger 12, has excellent motion minimizing
characteristics in the floating high draft condition.
It will be appreciated that a primary purpose of utilizing both a
column stabilized stinger and a column stabilized pipelaying barge
is to minimize the vertical heave motions of these floating
structures due to wave action. Ideally, this is accomplished by
submerging stinger 12 and barge 10 to approximately one-half the
effective height of the respective columns to preclude wave action
against their respective base structures. The present pipelaying
apparatus can accordingly operate efficiently in high sea
conditions, for example, sea conditions having waves 11 to 12 feet
in height or higher with minimum motion response to wave action.
However, even when operating in the high draft condition with the
motion minimizing characteristics afforded by the particular
configuration of the pipelaying barge and column stabilized
stinger, there is some response to wave action, i.e., the wave
action against columns 18 and 70, 72 and 74. Because of this, when
the natural period of the combined pipelaying barge and stinger is
the same as or close to the period of the waves according to
existent sea conditions, there is amplification of the motion of
the entire pipelaying apparatus which may become so excessive as to
interfere with pipelaying operations even though both the barge and
stinger are semisubmerged to the usual operating condition with the
mean waterline located at approximately one-half the effective
height h of stabilizing columns 18 and 70, 72 and 74. It is
therefore desirous to alter the motion of the apparatus when such
motion amplification occurs and this can be accomplished by either
ballasting or deballasting concurrently both the barge and stinger
within certain predetermined limits to submerge or emerge the barge
and stinger to a greater or lesser extent from the ideal
submergence which locates the mean water surface at one-half the
effective height h. The maximum variation of submergence of the
stinger from the ideal submergence by ballasting or deballasting
the stinger is, however, limited to distances within a range which
do not reorient the barge and stinger to positions wherein wave
action there against causes excessive impact. Thus, to preclude
excessive barge and stinger heave motion and impact caused by
interaction of the barge and stinger with wave motion, a maximum
variation, i.e., submergence or emergence of barge 10 and stinger
12 as by ballasting or deballasting, respectively from the ideal
submergence of one-half h, is such that the distance between the
mean water surface and either the upper end of the columns 18 and
70, 72 and 74 or the topside of the hulls 16 and base structure 30
is not less than 0.75 of the mean wave height. It is thus
significant that the foregoing barge and stinger have optimum
stability characteristics in the floating semisubmerged or high
draft condition.
It will thus be appreciatd that stinger 12 provides adequate
support for the pipeline as the latter is payed out from the
pipelaying barge 10. Particularly, stinger 12 supports that length
of pipeline which extends through the air from the elevated work
area 28 on deck 24 adjacent the aft end of the pipelaying barge to
the point of entry of the pipeline into the water in a manner which
substantially precludes relative heave motion of stinger 12 and
pipelaying barge 10. These features permit the work area 28 on
which the pipe sections are connected one to the other and payed
out from the barge to lie at an elevated position above the mean
waterline for example, on the order of about 15 feet. Note that the
air length of the pipeline between the work deck and its point of
entry into the water is fully supported and that the pipeline
obtains a radius of curvature in its transition from the work deck
to the water well within the allowable radius of curvature whereby
rupture of the pipeline is avoided.
It will be appreciated that stinger 12 also provides support for an
immersed portion of the pipeline from its point of entry into the
water at the mean waterline (about medially of the length of
stinger 12) to the aft end of the stinger whereby the use of
articulated linkages, etc. employed in conventional stingers is
entirely eliminated. Thus, stinger 12 serves to fully support the
pipeline as it transitions through the air from an elevated
position well above the mean waterline on the barge to a submerged
position well below the mean waterline at the aft end of the
stinger without the requirement of any additional supporting
structure. Moreover, this is provided in a manner such that the
pipeline, when supported by the stinger, obtains a radius of
curvature well within the allowable radius of curvature whereby
rupture of the pipeline is avoided.
It is a further particular feature hereof that the column
stabilized stinger can be employed with barges of conventional
construction and having elevated work areas or column stabilized
barges of the type herein illustrated, that is, a column stabilized
type barge as disclosed in application Ser. No. 705,175 of common
assignee herewith. To this end, stinger 12 is constructed to obtain
a specified natural period. When the pipeline portion is laid over
the stinger and the stinger attached, this combination provides a
known predetermined natural period. Note that this natural period
can be altered by changing the submergence level to vary the draft
and displacement of the stinger thereby obtaining a natural period
of the stinger and pipeline combination which is adjustable to a
limited extent within a predetermined range. The natural period of
a pipelaying barge is known from its physical characteristics. By
matching the natural period of the stinger including the pipeline
carried thereby, with the pipelaying barge, that is, by
particularly configuring the stinger and considering the weight of
the pipeline to provide a natural period approximating the natural
period of the barge with which the stinger will be utilized, it is
possible to match their natural periods whereby substantially
identical stinger and pipelaying barge response to wave action can
be achieved. Where the combination of stinger and pipeline has a
natural period which cannot be altered by variation in the
submergence level by ballasting or deballasting to approximate the
natural period of the pipelaying barge with which the vessel will
be utilized, the stinger 12 can be constructed to obtain a natural
period more nearly approximate to the natural period of the
pipelaying barge by proper design of the cross section area of the
columns, by altering its weight and displacement, its length and
width configuration and other factors.
In the preferred embodiment hereof illustrated in FIGS. 1-10,
particularly configured for employment with the column stabilized
barge described and illustrated in my copending application Ser.
No. 705,175 filed Feb. 13, 1968, stinger 12 has an overall length
of about 178 feet and a beam from centerline to centerline of
members 32 of about 20 feet. The centerlines of the members 32 at
the aft end of a stinger 12 are about 9 feet apart whereas the
corresponding portions at the forward end of stinger 12 are about
10 feet apart. The centerline of keel 38 depends a vertical
distance of about 10 feet from a horizontal plane containing the
centerlines of members 32. Members 32 preferably have outside
diameters of 42 inches and stabilizing columns 70, 72 and 74
preferably have an outside diameter of about 20 inches. Columns 70
upstand from the centerlines of members 32 a distance of about 31
feet. Diagonal bracing 40 preferably has outside diameters of 2
feet while transversely extending members 36 have outside diameters
of 30 inches. The centerlines of columns 70 are longitudinally
spaced about 26 feet one from the other and are disposed
symmetrically about the pitch axis. Anodes, not shown, are
preferably disposed on the stinger to preclude corrosion.
Referring now to the embodiment hereof illustrated in FIGS. 11-13,
there is disclosed a stinger 12a for use with a pipelaying barge
10a of a type similar to that disclosed in my copending application
Ser. No. 705,175 filed Feb. 13, 1968, wherein the work area for
assembling and paying out pipe sections from the barge is disposed
along the longitudinal centerline of the pipelaying barge rather
than along one side thereof as disclosed in the embodiment hereof
illustrated in FIGS. 1-10 hereof. The stinger in this form is
similar to the stinger described and illustrated with respect to
FIGS. 1-10 hereof and like reference numerals are applied with the
parts in this form being designated by a letter a following the
reference numeral.
The base structure 30a of stinger 12a is substantially identical
with the base structure 30 previously described except that the
members 32a constituting the forward portion of stinger 12a lie in
spaced parallel relation one to the other rather than converged
inwardly toward one another as in the previous embodiment. The keel
38a extends forwardly to the forwardmost portion of stinger 12a and
suitable diagonal bracing 40a and vertically extending bracing
interconnect keel 38a with the longitudinal members 32a.
At the forward end of stinger 12a there is provided a pair of
members 100 connected to the forward ends of members 32a, members
100 lying in a common plane with members 32a and diverging
outwardly in a forward direction for connection with a transverse
member 102. Also, a member 104 connects with the forward end of
keel 38a and extends upwardly for connection with member 102. Hinge
mounts 106 are provided on the opposite ends of member 102 for
hingedly connecting stinger 12a to the hulls 16a barge 10a.
Specifically, barge 10a includes a pair of vertically extending
plates 108 disposed on the inboard sides at the aft ends of each of
hulls 16a. Plates 108 have a series of vertically spaced openings
and hinge pins couple hinge mountings 106 to plates 108 at selected
elevations therealong whereby stinger 12a is pivotally connected to
barge 10a.
In this form, there is provided a central tunnel between decks 22a
and 24a for assembling and paying out pipeline onto the centrally
disposed stinger 12a. An opening is provided through the upper deck
22a adjacent the forward end of barge 10a whereby pipe sections
carried on deck 22a can be lowered into the pipe assembly area on
lower deck 24a by the cranes. By disposing stinger 12a along the
extended centerline of barge 10a, the stinger and hence the
pipeline carried thereby is less susceptible to roll motions than
in the form previously described. Balanced forces also act on the
stinger in this stinger-barge configuration. As in the previous
form, stinger 12a supports the pipeline issuing from barge 10a as
the pipeline makes the transition through the air from the aft end
of barge 10a to its point of entry into the water and also supports
an immersed portion of the pipeline from the point of entry in the
water to the aft end of stinger 12a. Thus, additional stinger
segments or articulated linkages as are commonly employed in the
prior art are eliminated.
The invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. The
present embodiments are therefore to be considered in all respects
as illustrative and not restrictive, the scope of the invention
being indicated by the appended claims rather than by the foregoing
description, and all changes which come within the meaning and
range of equivalency of the claims are therefore intended to be
embraced therein.
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