INCORPORATION BY REFERENCE

[0001] The following documents are incorporated herein by reference as if fully set forth: U.S. Provisional Patent Application No. 62/842,805, filed May 3, 2019.

FIELD OF INVENTION

[0002] Embodiments of the present invention generally relate to submergible flexible piping, more particularly to a submergible fluid piping with a weighted jacket for use under water.

BACKGROUND

[0003] Submergible piping is laid on the sea floor to convey petroleum and gas products from one location to another. In such applications, the piping has to be maintained below the surface of the water on the sea floor. This is required to keep the piping on the right of way, and not interfere with fishing and other activities.

[0004] Some piping made of polymeric material is known; however, it is buoyant in seawater and requires additional weight to be added to ensure negative buoyancy to keep the piping submerged. Negative buoyancy for the currently known piping can be achieved by applying a cementitious mixture to lengths of pipe and curing the mixture to concrete, by attaching weights, including laying cement blankets over the piping or banding steel to the pipe, or using an outer steel pipe around a polymeric inner pipe.

[0005] However, in many applications it would be desirable to use flexible piping to allow for longer pipe runs without couplings, as well as to maintain flexibility after installation, for example on a sea bed. The concrete- coated pipes currently used do not offer flexibility, either because the pipe is rigid or because the cured concrete makes a flexible pipe rigid. Steel pipes and/or added weights corrode, and clamping on weights is slow and very expensive. Accordingly, adding separate weights is not optimal due to the time required and costs incurred, as well as the corrosion issue with steel and loss of flexibility.

[0006] In view of this, there is a need for a flexible piping for submarine applications that is inert to salt water, C02, H2S and a variety of petroleum product corrosion, that has a negative buoyancy.

SUMMARY

[0007] A submergible flexible pipe and a method for its production are provided. The submergible flexible pipe comprises a tube formed of polymeric materials and having one or more layers, and an extruded jacket encasing the tube. The jacket includes a weighted filler material to achieve a negative buoyancy that is held in position on the tube with a polymeric material so that the flexibility of the pipe is maintained.

[0008] The method the submergible flexible pipe includes forming a core tube; and extruding a jacket encasing the core tube, the jacket including encasing or including a weighted filler material so that the flexible pipe is negatively buoyant.

[0009] The core tube can be a thermoplastic tube having the desired properties, and can also include a reinforced thermoplastic tube. In this case, the method would further include forming a braided reinforcement layer around a circumference of the core tube to form the reinforced thermoplastic tube, and the extruding of the jacket would be around the reinforced thermoplastic tube.

[0010] Additional features of the submergible flexible pipe and its method of production are described in further detail below and in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing Summary as well as the following Detailed

Description will be better understood when reviewed in conjunction with the appended Figures which show exemplary embodiments of the invention. As the Figures are only intended to show exemplary embodiments, they should not be considered limiting with respect to the scope of the invention. In the drawings: [0012] Figure 1 is a cross-sectional view through a first embodiment of a submergible flexible pipe;

[0013] Figure 2 is a longitudinal cross-sectional view taken along line II-

II in Figure 1;

[0014] Figure 3 is a cross-sectional view of a second embodiment of a submergible flexible pipe;

[0015] Figure 4 is a longitudinal cross-sectional view taken along line

IV-IV in Figure 3; and

[0016] Figure 5 is a flow diagram for a method of making a submergible flexible pipe.

DETAILED DESCRIPTION

[0017] Certain terminology is used in the following description for convenience only and is not limiting. The words“inner,”“outer,”“inwardly,” and “outwardly” refer to directions towards and away from the parts referenced in the drawings. A reference to a list of items that are cited as“at least one of a, b, or c” (where a, b, and c represent the items being hsted) means any single one of the items a, b, c or combinations thereof. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import. Additionally, the figures are not drawn to scale and may be simplified for clarity.

[0018] While described in reference to a submergible flexible pipe for submarine conveyance of petroleum or natural gas materials, the present invention may be modified for a variety of other applications while remaining within the spirit and scope of the claimed invention, since the range of the potential applications is great, and because it is intended that the present invention be adaptable to many such variations.

[0019] As used in the present disclosure, “petroleum materials” and variations thereof as used herein includes both naturally occurring unprocessed crude oil, natural gas, and hydrocarbon containing products, including any impurities occurring naturally or introduced during extraction of the crude oil and natural gas, and refined crude oil and gas products. “Submarine” and variations thereof as used herein includes both below the surface of sea water and below the surface of fresh water. “Negative buoyancy” and variations thereof as used herein refers to an object that has a density greater than at least one of fresh water and/or sea water, generally understood to be about 1,000 kg per cubic meter and about 1,030 kg per cubic meter, respectively. A negatively buoyant object sinks in the fluid in which it is placed. As recited in the present disclosure,“flexible” as used to describe the inventive pipe means capable of assuming a radius of curvature less than or equal to about 10 feet without collapsing or kinking. The terms“pipe” and “hose” are both used to describe a tube used to convey water, gas, oil, or other fluid substances are intended to have their broadest meaning. Both terms are used in order to differentiate components of the invention.

[0020] Referring to Figures 1 and 2, a flexible pipe 100 according to a first embodiment is shown. The pipe 100 includes a hose 102 formed with one or more layers, including at least a core tube 104 formed from a material resistant to petroleum materials, preferably an extruded polymeric material. The core tube 104 may be extruded from a polymeric material or co-extruded from two or more polymeric materials and/or formed as multiple layers. An optional reinforcement braid can also be formed around and/or between the layer(s) of the core tube 104. The flexible pipe 100 also includes a jacket 108 formed from a polymeric material and a filler encasing the hose 102.

[0021] Preferably, the core tube 104 is made from polyethylene or polypropylene, and can also be made from or lined with other materials, such as Nylon, PVDF, PPS as well as PP and HDPE. Some of these materials have a density of less than 1000 kg per cubic meter and naturally float in fresh or sea water, or to the extent that the materials may have a specific gravity of greater than 1, (for example, nylon, PVDF, and PPS have specific gravities of 1.13, 1.25 and 1.78, respectively), the core tube 104 can still float because the oil and gas being transported within the pipe has a specific gravity of less than 1, making the filled tube buoyant. To counter this positive buoyancy, the jacket 108 is formed from a material or mixture of materials in sufficient quantity and volume to yield a flexible pipe 100 that, when filled with the liquid to be transported, particularly crude oil and natural gas products, has a density greater than about 1000 kg per cubic meter for fresh water applications and greater than about 1030 kg per cubic meter for sea water applications. The density can be further increased by adding additional weighted filler material to the mixture of materials to account for currents, tides, etc. In one preferred method of forming the jacket 108, the net weight or buoyancy of the pipe in salt water is determined, the weight or buoyancy of the fluid that will be flowing through the pipe 100 is calculated, and then a required weight or negative buoyancy of the heavy jacket is calculated to that it is sufficient to offset this total buoyancy. A factor for additional weight to account for currents, tides, etc. is than added.

[0022] The jacket 108 and the core tube 104 may be fixed together or displaceable with respect to each other axially, radially, and rotationally. For example, one of the jacket 108 and the core tube 104 may be able to move relative to the other in a direction parallel to the axis 110 (i.e., axially) or about the axis 110 (rotationally). When the flexible pipe 100 is curved about a point, one of the jacket 108 and the core tube 104 may move along a radius of curvature with respect to the other (radially displacement). The movement or slip between the jacket 108 and the core tube 102, while not required, can be useful in connection with bending of the pipe 100 by allowing the core tube 102 and the jacket 108 conform to different radii of curvature depending on the distance of each from the center of curvature.

[0023] In one embodiment, the jacket 108 comprises a polymeric material, which can be for example polyethylene or polypropylene, that is mixed with filler. The filler preferably has a specific gravity greater than 5 and can be, for example, a copper-based alloy, such as bronze, or barium sulfate, or another material that has a high enough density that is used in a great enough proportion to provide the pipe 100 with the fluid being transported therein a negative buoyancy. One embodiment uses a blend of polypropylene and powdered bronze which are fed into an extruder and formed around the core tube 104.

[0024] Referring to Figures 3 and 4, another embodiment of a flexible pipe 200 is shown. The flexible pipe 200 as illustrated includes a hose 202 comprised of a core tube 204, a braided reinforcement 206, and a jacket 208. The polymer and filler of the jacket 208 are chosen so that the flexible pipe is negatively buoyant in fresh water or sea water.

[0025] As discussed above regarding the embodiment of Figure 1, the flexible pipe 200 includes a core tube 204 formed from a polymeric material resistant to petroleum materials and may be formed in one or more layers. The core tube 204 may be formed from any of the suitable materials discussed above with regard to 104.

[0026] A braided reinforcement layer 206 is formed on at least part of the outer circumference 212 of the pipe 200. The reinforcement layer 206 is formed by intertwining a plurality of strands of flexible material such as natural or man-made fibers or wire around the core tube 204 which extend along the length L of the core tube 204. In one preferred embodiment, aramid and/or fiberglass fibers are used to form the reinforcement. However, other fibers could be used depending on the particular application. Other constructions for the reinforcement layer can also be used, such as winding one or more strands of material along the length of the core tube 204. Alternately, the reinforcement layer 206 may be encapsulated in the core tube 204 or between the core tube 204 and a subsequently formed layer of the hose 202. The reinforcement layer 206 provides added tensile strength, as well as resistance to radial deformation of the core tube 204, for example when carrying a pressurized fluid.

[0027] A jacket 208 of polymeric material, similar to jacket 108, is formed on and encases the core tube 204 and the reinforcing layer 206. In a preferred embodiment, the jacket 208 is an extruded layer of polymeric material and a filler of sufficient volume and density to produce a flexible pipe with a density greater than about 1000 kg per cubic meter, preferably greater than about 1030 kg per cubic meter.

[0028] As with the pipe 100 discussed above, the jacket 208 can be fixed or optionally can be displaceable with respect to the core tube 204 to enhance flexibility of the flexible pipe 200. A release material or layer may be applied to portions of the core tube 204 and the reinforcing layer 206 to enhance the slip between the layers. In the alternative or in addition, materials for the core tube 204 and the reinforcing layer 206 may be chosen to provide a degree of slip with the jacket 208.

[0029] The polymeric material for the jacket 208 is preferably chosen to remain flexible in the anticipated environment (e.g., fresh water or sea water) with the added filler. The filler is preferably a high density material (i.e. sufficiently dense to create a negative buoyancy for the pipe 200 in combination with the fluid to be transported therein) compatible with the polymeric material and with the anticipated environment. The filler and polymeric material may be the same as discussed above in connection with the jacket 108. In a preferred embodiment, the filler material is powdered and is dry mixed with pelleted polymeric material to form a filled polymer feedstock that is then heated to melt the polymer and extruded on the reinforcing layer 206 and the core tube 204 as a weighted jacket 208.

[0030] The jacket 208 provides continuous weighting built into the pipe

200 which is preferably co-extruded in a production facility, while providing flexibility of the pipe 208 so it can be rolled onto spools for transport from a manufacturing facility to a work site.

[0031] The submergible flexible pipe 100, 200 may be particularly useful in the submarine conveyance of petroleum materials.

[0032] A method 500 for making a submergible flexible pipe in accordance with embodiments of this invention is illustrated at Figure 5. At 502 the hose is formed comprising a core tube 104, 204, formed from one or more layers or polymeric material. In a preferred method, the core tube 104, 204 is formed in a continuous extrusion or co-extrusion process. The extrusion process may include a cooling step. In one embodiment, a woven or braided reinforcing layer 206 can optionally be located on, at least partially embedded in, or placed between layers of the core tube 104, 204.

[0033] At 504, the reinforcement layer 206 is formed at least partially around a circumference of the core tube 204 and extending along a length of the core tube 204. The reinforcement layer 206 may be a braided layer, or a woven layer, formed from intertwining strands of natural or man-made materials, such as aramid, fiberglass, or other fibers. The reinforcement layer 206 can also be formed from one or more strands of natural or man-made material extending longitudinally and/or at least partially wound around the circumference of the core tube 204.

[0034] The formation of the reinforcing layer 206 may be a continuous process as the core tube 204 is continuously formed at 502 or may be applied to a length of core tube 204. The reinforcing layer 206 may comprise one or more separately formed layers sequentially applied over a previous layer. Each layer may be braided, woven, or wound, or combinations thereof.

[0035] At 506, one or more optional polymeric layers are formed over the reinforced layer 206. In a preferred embodiment, the optional layer or layers are extruded in a continuous process over the reinforcing layer or layers.

[0036] At 508, a jacket 108, 208 is extruded onto the core tube 104, 204 and optionally the reinforcing layer 206 encasing the circumferential area of the hose 202, which may include the reinforcing layer 206. The jacket 108, 208 preferably includes a mixture of polymer and a filler so that the combination or the flexible pipe and the fluid to be carried therein is negatively buoyant in at least one of fresh water or sea water. The filler may advantageously be a powdered copper-based alloy, for example bronze, dry mixed with a polymeric material prior to extrusion of the jacket 108, 208.

[0037] After formation of the jacket 108, 208, the pipe 100, 200 may be stored as coiled lengths of several thousand feet in order to reduce seams, or can be stored as hnear lengths. At 510, the pipe 100, 200 is indicated as being rolled into a coil. The coil may be formed around a support, for example, a spool, having a radius of curvature of about 6 feet or greater.

[0038] Having thus described various embodiments of the present submergible flexible pipe in detail, it will be appreciated and apparent to those skilled in the art that many changes, only a few of which are exemphfied in the detailed description above, could be made in the submergible flexible pipe according to the invention without altering the inventive concepts and principles embodied therein. 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 to be embraced therein.

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