US3736760A

US3736760A - Laterally-stabilized stinger suspension system

Info

Publication number: US3736760A
Application number: US00187363A
Authority: US
Inventors: D Carstens; B Edwards
Original assignee: Fluor Corp
Current assignee: Fluor Corp
Priority date: 1971-10-07
Filing date: 1971-10-07
Publication date: 1973-06-05
Anticipated expiration: 1990-06-05

Abstract

A laterally-stabilized stinger suspension system is provided to reduce the bending moments exerted on conventional stinger hitches. The suspension system includes at least one diagonal strut articulately connected between the stinger and a point on the stern of the pipelaying vessel removed from the pipe ramp.

Description

United States Patent 1191 Carstens et al. 1 1 June 5, 1973 [54] LATERALLY-STABILIZED STINGER 3,620,027 11/1971 Nordell ..6l/48 SUSPENSION SYSTEM 3,283,515 11/1966 Pottorf ..61/46 [75] Inventors: Daniel K. Carstens; Beverly C. D.

Edwards, Jr., both of Houston, Tex. P im ry Examiner-Jacob Shapiro [73] Assignee: Fluor Corporation, Los Angeles, Att0mey Mlchael Breston Calif.

22 Filed: Oct. 7, 1971 [57] ABSTRACT PP -I 8 ,363 A laterally-stabilized stinger suspension system is pr0- vided to reduce the bending moments exerted on con- 52] US. Cl ..61/72.1 61/72.:3 vehhehel Stinger hitehes- The susPension system 51 1111.01. ..B63b 35 04 eludes at least one g n l strut iculately con- [58] Field of Search ..61/72.3 72.1 48 "eeted between the Stinger and a Point the 0f 1 d the pipelaying vessel removed from the pipe ramp.

[56] References Cited 5 Claims, 5 Drawing Figures UNITED STATES PATENTS 3,390,532 7/1968 Lawrence ..6l/72.3

PATENTEDJUN 5 I973 SHEET 1 BF 2 INVENTORS Beverly C. 0. Edwards Jr. Daniel Kai Corstens BY Michael P. Bruton ATTORNEY 3 mm GE m. \NN on S 31 1% E E d uF:

PATENTEDJUH 5 I975 3'. 736.760

sum 2 OF 2 FIG. 5

INVENTORS Beverly 0.0. Edward; Jr. Daniel Kai Comm:

BY Michael P. Bronon ATTORNEY LATERALLY-STABILIZED STINGER SUSPENSION SYSTEM BACKGROUND OF THE INVENTION In marine pipelaying operations, stingers are employed to support the pipeline during its descent from the pipelaying vessel into the body of water. Stingers are buoyant structures with a typical width of to feet and a length up to several hundred feet. A hitch normally connects the stinger to the pipe ramp on the pipelaying vessel. The hitch is sufficiently stiff to overcome the tendency of the stinger to move in a horizontal plane. Depending on the design of the stinger, a limited amount of rotation in the vertical plane may be allowable and desirable.

The cross-sectional areas of the buoyant chambers used to construct stingers are relatively large. Wind, wave action, and barge yawing can generate excessive and sometimes destructive bending moments at the stingers hitch connection. A hitch failure is time eonsuming and expensive to repair.

Various attempts have been made to stabilize the horizontal motions of a stinger. In one type stinger, articulated joints are provided between stinger sections to allow limited lateral movement therebetween. Other stingers employ suspension cables attached betweentheir trailing ends and an auxiliary vessel, buoy or float.

Such known lateral, stinger-stabilizing means are relatively complex and unreliable in operation. Others require complex, fluid-operated control systems, which frequently malfunction and are themselves subject to destructive wave action effects.

The problem of lateral stinger stabilization becomes even more acute for relatively long stingers, since the stinger, as far as its hitch is concerned, acts as a cantilever beam supported at the hitch.

SUMMARY OF THE INVENTION In its broadest aspects, the present invention contemplates the provision of lateral-stabilizing means for a stinger suspension which includes at least one diagonal strut articulately attached preferably near the free end of the stinger and the side of the barge stern opposite from the pipe ramp. The horizontal forces exerted on the stinger will then produce longitudinal tension or compression forces in the diagonal strut, thereby significantly reducing the intensity of the bending moments exerted on the stingers hitch. The stingers hitch and the diagonal strut form a triangular suspension which is allowed to rotate in a vertical plane about a horizontal axis forming the base of the triangle and extending through the horizontal pivots of the suspension. On the other hand, the triangular stinger's suspension system may be provided with universal joints, coupled to the stern of the pipelaying barge, to allow limited freedom of motion in the horizontal plane.

Accordingly, it is a main object of this invention to provide new and improved lateral-stabilizing suspension means which are simple to construct, which do not require complex fluid-operated mechanisms and controls, which eliminate the need for auxiliary floats, and which can be readily adapted for use with various types of conventional stingers.

As a direct advantage of the present invention, the construction of conventional stinger hitches can be greatly simplified without sacrifice in strength and dependability.

BRIEF DESCRIPTION OF THE DRAWINGS Presently preferred embodiments of the invention are illustrated in the drawings in which the same reference characters represent the same or similar parts and in which:

FIG. 1 is a diagrammatic plan view of a triangular stinger suspension system in accordance with the present invention;

FIG. 2 is a side elevation view of the system shown in FIG. 1;

FIG. 3 is a sectional-view taken on line 33 in FIG.

FIG. 4 is a plan view of a modified embodiment of the suspension system shown in FIG. 1; and

FIG. 5 is a sectional view on line 5--5 in FIG. 4.

Referring now to FIGS. 1-3 of the drawings, there is shown a laterally-stabilized stinger suspension system, generally designated as 10, for articulately coupling a conventional stinger 12 to the pipe ramp 14 at the stem 16 of a platform'lB floating in a body of water 20. Platform 18 is typically a pipelaying vessel or barge.

A simple stinger 12 can consist of (say) two paralleldisposed, longitudinal

buoyant chords

22 and 24 interconnected by a plurality of longitudinally-displaced cross-bracings 26. A plurality of rollers, such as sets of V-rollers 28, are longitudinally disposed along the stingers trajectory to rollably support the descending pipe portion 31 of a long pipeline 32.

Stinger 12 is pivotally coupled to ramp 14 by a conventionally-designed hitch 30 having

horizontal pivots

34 and 36 aligned along the same horizontal axis 35 to allow the stinger to freely rotate in a vertical plane.

Hitch 30 can become'subjected to high-bending moments created by horizontal forces acting against the vertical cross-sectional areas of the truss members of the stinger. In the past, such moments have frequently caused stinger hitch failures which were time consuming to repair and involved expensive down time.

In accordance with the present invention, the stinger suspension system 10 includes the conventional hitch 30 to which is added at least one diagonal strut 40 to form a triangular suspension having a base at the stern 16. The strut 40 is made slightly positively buoyant to allow it to float, if detached from stinger 12, and to minimize any vertical forces which might otherwise act on the horizontal pivot 37.

Suitable fastening means, generally designated as 42, connect the lower end of strut 40 to a support 44 on stinger 12. Support 44 is optimally positioned, as say near the free end of the stinger, for acceptable bending moments at the hitch 30. In one embodiment for a 110.

ft. stinger, the support 44 was located ft. from the stern of the barge. The fastening means 42 could simply be a vertical pivot means 46 to allow strut 40 to horizontally rotate relative to the stinger, especially when it is desired to store or transport the stinger on the deck of the barge.

The upper end of strut 40 is also articulately coupled to the stem 16, as by a horizontal pivot 37 whose longitudinal axis is in alignment with the longitudinal axis 35 of

pivots

34 and 36.

In this manner, the stinger suspension 10 will allow unhindered rotation of stinger 12 in the vertical plane.

Also, the

horizontal pivots

34, 36 and 37 form the base or leg of the triangular suspension 10. A triangle cannot change shape without changing the length of at least one of its sides. To absorb excessive horizontal forces there is provided in another embodiment an extensible means, as hereinafter described.

With Reference now to FIGS. 4 and 5, there is shown a modified stinger suspension system, generally designated as 100. Suspension 100, in addition to the elements previously described, now also includes a hitch 102 and a vertical pivot means 106. Hitch 102 allows stinger l2 limited rotation in a horizontal plane about a vertical pivot 104. Strut 40 can rotate about the vertical axis of pivot means 106. It will be noted that pivots 34, 36 and 37, in the modified embodiment of FIG. 4, serve the same function as in the embodiment shown in FIG. 1, that is the stinger can rotate about the horizontal axis 35.

To allow for the limited horizontal rotation, there is also provided in strut 40 an extensible means 110 which could be of any desired conventional construction. In the preferred embodiment, means lllil included a spring 112 having two plates 114 and 1 16 maintained, in longitudinal spaced-apart positions by long bolts 118, between stop means 120 and 122. The spring action is provided by flexible means, such as a rubber sleeve 124. Strut 40 is now made of two

arms

40A and 40B which are inter-connected by the extensible means 110. They can move longitudinally relative to each other within the limits defined by the

stop members

120, 122 and by the compressibility of the flexible sleeve 124.

In operation, since the

horizontal pins

34, 36 and 37- .moment which can be tolerated at the hitch 30. From the free end of the stinger up to the support 40, the stinger acts as a cantilever beam. The stinger portion between support 40 and the stem 16 of the barge acts as one leg of a triangular truss structure which, in response to bending moments and horizontal forces, causes strut 40 to become subjected to longitudinal forces either in compression or tension.

The vertical pivot 46 will allow very limited elongation or contraction of strut 40 in the embodiment shown in FIG. 1. The extensible means 110 will allow in the embodiment of FIG. 4, greater freedom of longitudinal extension or contraction, as well as limited rotation in a horizontal plane about the vertical pivots 46 and NM.

Accordingly, the apparatus of the present invention provides considerable advantages in carrying out underwater pipelaying operations. Although the invention has been described with reference to certain preferred embodiments, it will be apparent to those skilled in the art that additions, modifications, substitutions, and deletions not specifically described herein may be made which will fall within the scope of the appended claims.

What is claimed is:

1. A stinger suspension system for articulately suspending a stinger from a plateform floating in a body of water comprising:

first means articulately coupling a stinger to the stern of said platform to allow said stinger to rotate in a vertical plane,

at least one diagonal strut,

one end of said strut forming an angle with and being secured to said stinger,

second means articulately coupling the other end of said strut to said platform to allow said other end and said stinger to rotate in a vertical plane,

said first means, said second means and said one end of said strut forming a triangular suspension which significantly reduces the bending moments exerted on said first means as a result of horizontal forces acting on said stinger.

2. The stinger suspension system of claim l wherein,

said first means includes at least one horizontal pivot,

said second means is a horizontal pivot, and

said pivots being aligned along a longitudinal axis.

3. The stinger suspension system of claim 2 wherein said one end is pivotably attached to said stinger.

4. The stinger suspension system .of claim 1 wherein,

said first means allows said stinger to rotate in a horizontal plane,

said second means allows said other end to rotate in a horizontal plane, and

said strut includes extensible means to allow said strut to extend or contract along its longitudinal axis.

5. In combination: a stinger,

a suspension system for articulately coupling said stinger to a floatable platform, said system comprising:

first means including at least one horizontal pivot for articulately coupling said stinger to the stern of said platform to allow said stinger to rotate in a vertical plane,

at least one diagonal strut, one end of said strut forming an angle with and being attached to said stinger,

second means articulately coupling the other end of said strut to said stern of said platform, said second means including another horizontal pivot, and the axis of said one pivot and the axis of said another pivot being aligned to allow said stinger to rotate in a vertical plane about the aligned axes, and

said first means, said second means, and said one end of said strut forming a triangular suspension for reducing the bending moments exerted on said first means as a result of horizontal forces acting on said stinger.

l '2' it t i

Claims

1. A stinger suspension system for articulately suspending a stinger from a plateform floating in a body of water comprising: first means articulately coupling a stinger to the stern of said platform to allow said stinger to rotate in a vertical plane, at least one diagonal strut, one end of said strut forming an angle with and being secured to said stinger, second means articulately coupling the other end of said strut to said platform to allow said other end and said stinger to rotate in a vertical plane, said first means, said second means and said one end of said strut forming a triangular suspension which significantly reduces the bending moments exerted on said first means as a result of horizontal forces acting on said stinger.

2. The stinger suspension system of claim 1 wherein, said first means includes at least one horizontal pivot, said second means is a horizontal pivot, and said pivots being aligned along a longitudinal axis.

4. The stinger suspension system of claim 1 wherein, said first means allows said stinger to rotate in a horizontal plane, said second means allows said other end to rotate in a horizontal plane, and said strut includes extensible means to allow said strut to extend or contract along its longitudinal axis.

5. In combination: a stinger, a suspension system for articulately coupling said stinger to a floatable platform, said system comprising: first means including at least one hOrizontal pivot for articulately coupling said stinger to the stern of said platform to allow said stinger to rotate in a vertical plane, at least one diagonal strut, one end of said strut forming an angle with and being attached to said stinger, second means articulately coupling the other end of said strut to said stern of said platform, said second means including another horizontal pivot, and the axis of said one pivot and the axis of said another pivot being aligned to allow said stinger to rotate in a vertical plane about the aligned axes, and said first means, said second means, and said one end of said strut forming a triangular suspension for reducing the bending moments exerted on said first means as a result of horizontal forces acting on said stinger.