US3597779A

US3597779A - Multiconduit buoyed underwater line

Info

Publication number: US3597779A
Application number: US874163A
Authority: US
Inventors: George W Morgan
Original assignee: North American Rockwell Corp
Current assignee: Boeing North American Inc
Priority date: 1969-11-05
Filing date: 1969-11-05
Publication date: 1971-08-10
Anticipated expiration: 1988-08-10

Abstract

A flexible underwater line has a plurality of conduits layed in a helical configuration about a central core member. The central core member in turn has a group of spokes, extending radially therefrom and each group is disposed at spaced intervals along its length. The conduits are layed between the spokes so that the spokes protrude above the conduits and a ring-buoy is clamped about each group of spokes so that the spokes prevent the buoys from moving axially along the central core member.

Description

United States Patent [72] Inventor George W. Morgan Anaheim, Calif. [21 I Appl. No 874,163 [22] Filed Nov. 5, 1969 [45] Patented Aug. 10, I971 [73] Assignee North American Rockwell Corporation (54] MULTICONDUIT BUOYED UNDERWATER LINE 11 Claims, 4 Drawing Figs. [52] US. Cl 9/8 R, 174/ 101.5 [51] Int. Cl 02g 9/12 [50] Field of Search 9/8 R;

[56] References Cited UNITED STATES PATENTS 311,149 1/1885 Stevens 138/113 3/1920 Dray 138/103 3,332,093 7/1967 Skinner et al. 9/8 3,425,453 10/1965 Fuller 138/111 3,489,182 1/1970 Cameron... 9/8 3,517,110 6/1970 Morgan 9/8 Primary Examiner-Milton Buchler Assistant Examiner-Gregory W. OConnor Attorneys-L. Lee Humphries, Charles F. Dischler and Dominick Nardelli ABSTRACT: A flexible underwater line has a plurality of conduits layed in a helical configuration about a central core member. The central core member in turn has a group of spokes, extending radially therefrom and each group is disposed at spaced intervals along its length. The conduits are layed between the spokes so that the spokes protrude above the conduits and a ring-buoy is clamped about each group of spokes so that the spokes prevent the buoys from moving axially along the central core member.

Patented Aug. 10, 1971 3,597,779

2 Sheets-Sheet 1 INVENTOR. GEORGE W. MORGAN A T TORNE Y Patented Aug. 10, 1971 v 3,597,779

2 Sheets-Sheet 2 FIG 4 INVENTOR. GEORGE W. MORGAN A TTORNE' Y MULTICONDUIT BUOYEI) UNDERWATER LINE This invention relates to underwater lines and more particularly to flexible lines which may. for example, function as risers.

In my U.S. Pat. application, Ser. No. 72l,0l4 filed on Aug. l2, I968, now US. Pat. No. 3,526,086 and assigned to the same assignee as this patent application there is disclosed an underwater line wherein a plurality of conduits are layed in a helical configuration around a central core member which is capable of withstanding a relatively high tensile load. Therefore, when the underwater line is used as a riser, the top end of this core member is tied to a buoy to support all weight of the riser. This arrangement produces relatively large stresses in the core member near the buoy, especially in very long risers. Of course the stress decreases linerally with depth. Therefore, the core member is understressed at the lower end making inefficient use of the available material.

Therefore, an object of this invention is to produce a riser wherein efficient use of the material is made.

Another object of this invention is to provide means in a riser to periodically support the weight thereof to prevent the development of relatively large stresses.

These and other objects and features of advantages of the present invention will become more apparent from reading the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1 shows a portion of the complete riser incorporating the features of this invention;

FIG. 2 shows the central core member before wrapped with conduits and filler material;

FIG. 3 shows the riser with various items removed to show the novel features thereof; and

FIG. 4 is a section of the riser taken at one of the buoys, and at line 4-4.

Referring to the drawings and to FIGS. 2 and 3 in particular, there is shown the preferred embodiment of the novel riser which includes a core member preferably in the form of a metallic pipe or tube 11. Helically wound around the tube are a plurality of conduits or metallic tubes 12, for example, eight. Between the tubes 11 and 12 (FIG. 4) is disposed filler material, for example,

plastic threads

13 and 14 of various diameters so that substantially all the spacing between the tubes is filled and the tubes are prevented from rubbing against each other whenever the riser flexes due to sea currents. A suitable cover, for example a plastic sheet 17, is placed around the tubes 12 and plastic threads 13 and I4 and secured by suitable means. In addition buoys 21 are axially spaced along the riser to provide a slight amount of positive buoyancy to the riser. Since the buoys have positive buoyancy and tend to rise and since the tubes II and 12 have negative buoyancy and tend to sink, one feature of this invention is to provide means for transferring the shear forces therebetween.

As shown in FIG. 2, the shear force transferring means includes spoke groups spaced axially along the core member I1. Each group contains spokes 26 that are arranged evenly around a circle to extend radially. The spokes 26 can be, for example, spot welded to the core member 11 for structural strength. In addition the spokes in one group are preferably aligned with the respective spokes on each of the other groups. The conduits I2 lie in the sector formed by two spokes 26 as shown in FIG. 4. Since the conduits 12 are helically wound around the core member I], each conduit 12 advances preferably one sector in a clockwise direction as it winds around the core member as shown in FIG. 3. The

plastic threads

13 and 14 preferably twist in the same manner that the conduits twist. Since the groups 25 are axially spaced along the riser, the plastic sheet 17 preferably extends from one group 25 to the next one. The sheet 17 can be fastened in place by, for example, stitches 18. As seen in FIG. 3 the spokes 26 have a length so that they protrude beyond the plastic sheet 17. The buoys 21, which are toroidal in shape, are made into two similar sections with a semicircular channel-shaped metallic stitTner 31 disposed on the inner curved edge thereof. Suitable buoyant material 32 is molded onto the stiffners 31. Therefore when both buoy sections are bolted in place as shown in FIG. 4 the ends of the spokes are disposed within the channel-shaped stiffners 31 thereby preventing the buoys 21 from moving axially along the risers.

With the present disclosure in view, modifications thereof would appear to those skilled in the art. Accordingly, the invention is not limited to the illustrated embodiment but includes all such modifications and variations within the scope of the invention as defined in the appended claims.

What I claim is:

I. A riser comprising:

a core member adapted for extending substantially vertically in the ocean,

a plurality of conduits layed along side said core member,

means for bundling said conduits and core member together,

a plurality of spokes extending from said core member and through said bundling means, and

at least one buoy fixed to said riser and engaging at least one of said spokes so that said buoy is prevented from moving along said riser.

2. The riser of claim I wherein:

said spokes are disposed in at least one group and lying in a circle around said core member, and

said buoy is toroidal in shape and made of two similar sections,

both of said sections are clamped around said risers and engage all the spokes in one of said groups.

3. The riser ofclaim 2 wherein:

said groups are spaced along said riser and said conduits lie in the sectors formed by two spokes.

4. The riser of claim 1 wherein:

said conduits are helically wound around said core member,

and

filler material is placed between said conduits and core member to prevent rubbing therebetween when said riser flexes.

5. The riser ofclaim 1 wherein:

said buoy has a channel-shaped stiffener disposed at the inner curved periphery of each of said sections, and

the ends of said spokes are disposed within said channelshaped stiffener when said buoy is clamped to said riser.

6. The riser of claim 2 wherein:

said conduits are helically wound around said core member,

and

7. The riser of claim 3 wherein:

said conduits are helically wound around said core member,

and

8. The riser of claim 3 wherein:

9. The riser of claim 4 wherein said buoy has a channel-shaped stiffener disposed at the inner curved periphery of each of said sections, and

10. The riser ofclaim 6 wherein.

11. The riser of claim 7 wherein said buoy has a channelshaped stiffener disposed at the inner curved periphery of each of said sections, and 75 the ends Ffsaid spokes are disposed wifliihiaid cha hnel shaped stiffener when said buoy is clamped to said riser.

Claims

1. A riser comprising: a core member adapted for extending substantially vertically in the ocean, a plurality of conduits layed along side said core member, means for bundling said conduits and core member together, a plurality of spokes extending from said core member and through said bundling means, and at least one buoy fixed to said riser and engaging at least one of said spokes so that said buoy is prevented from moving along said riser.

2. The riser of claim 1 wherein: said spokes are disposed in at least one group and lying in a circle around said core member, and said buoy is toroidal in shape and made of two similar sections, both of said sections are clamped around said risers and engage all the spokes in one of said groups.

3. The riser of claim 2 wherein: said groups are spaced along said riser and said conduits lie in the sectors formed by two spokes.

4. The riser of claim 1 wherein: said conduits are helically wound around said core member, and filler material is placed between said conduits and core member to prevent rubbing therebetween when said riser flexes.

5. The riser of claim 2 wherein: said buoy has a channel-shaped stiffener disposed at the inner curved periphery of each of said sections, and the ends of said spokes are disposed within said channel-shaped stiffener when said buoy is clamped to said riser.

6. The riser of claim 2 wherein: said conduits are helically wound around said core member, and filler material is placed between said conduits and core member to prevent rubbing therebetween when said riser flexes.

7. The riser of claim 3 wherein: said conduits are helically wound around said core member, and filler material is placed between said conduits and core member to prevent rubbing therebetween when said riser flexes.

8. The riser of claim 3 wherein: said buoy has a channel-shaped stiffener disposed at the inner curved periphery of each of said sections, and the ends of said spokes are Disposed within said channel-shaped stiffener when said buoy is clamped to said riser.

9. The riser of claim 4 wherein: said buoy has a channel-shaped stiffener disposed at the inner curved periphery of each of said sections, and the ends of said spokes are disposed within said channel-shaped stiffener when said buoy is clamped to said riser.

10. The riser of claim 6 wherein: said buoy has a channel-shaped stiffener disposed at the inner curved periphery of each of said sections, and the ends of said spokes are disposed within said channel-shaped stiffener when said buoy is clamped to said riser.

11. The riser of claim 7 wherein: said buoy has a channel-shaped stiffener disposed at the inner curved periphery of each of said sections, and the ends of said spokes are disposed within said channel-shaped stiffener when said buoy is clamped to said riser.