DK176006B1 - Ship anchoring device and method for its use - Google Patents

Description

DK 176006 B1

Ship anchoring device and method for its use

The present invention relates to marine embedding anchors and their associated anchoring elements and in particular to anchors of the type disclosed in International Patent Application PCT / NL92 / 001144 (published as WO93 / 03958) and in the present application International Patent Application PCT / GB96 / 01755 (published as W096 / 39324).

Marine embedding anchors embedded by tensile anchor members 10 or by direct anchor elements are generally attached to an anchor line to provide connection to an object to be anchored or retained in water over an anchor bottom.

A tensile anchor anchor is embedded in that the anchor is pulled (dragged) horizontally across the anchor bottom using anchor elements comprising an anchor line, to provide horizontal as well as vertical penetration along a curved anchorage path into the ground at the anchor bottom. The tensile anchor anchor comprises a planar or curved plate or wing-shaped anchor flap and a leg attached to the anchor flap and adapted to provide an attachment point for attaching an anchor line, such a leg being arranged such that the anchor provides a rope line from the geometric center of gravity of the anchor tab, whereby the line alignment - relative to a forward edge of the anchor tab measured in an anterior / posterior symmetry plane of the anchor - forms a forward open angle with respect to the forward direction of the anchor tab, where a drag force applied the anchor at the point of attachment by the aid of the anchor line when the anchor is placed on the surface of the seabed - causes the embedding of the anchor by intrusive movement into the soil in the seabed i -: substantially the forward of the anchor tab. An anchor of this type and associated anchor member will hereinafter be referred to as anchor anchor and associated anchor anchor as described above.

In contrast, an anchor with direct anchorage will be embedded in that the anchor is pushed vertically into an anchorage base or inclined vertically using anchorage elements comprising a pushing wave or comprising a driving force, e.g. is developed gravitationally, hydraulically or explosively. The directly embedded anchor comprises a flat or curved plate or wing anchor tab adapted to house the anchor member and is designed to provide an attachment point for attaching an anchor line, the anchor having a minimum projected area where resistance to the penetration of the anchor into an anchorage floor is minimal, which provides an attachment point for the anchor line locatable in such a way that a traction exerted in the anchor line will cause the anchor to move substantially perpendicular to the direction of the anchor line. minimally projected area. Such an anchor and its anchor element will then be referred to as anchor anchor and associated anchor element as described above.

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Marine anchors are usually made of steel and are often coated with paint to protect against corrosion. Such a coating, which is softer than steel, is vulnerable to abrasion of hard particles in a seabed soil, which plows a series of grooves into it, which cumulatively results in the coating being removed. This abrasive effect increases the area of the coefficient of friction of the coated anchor with respect to the material consisting of seabed soil particles that slip underwater to exceed the usual range of 0.3 to 0.6, which applies to a non-coated anchor. The accompanying increase in the frictional force of the coated anchor increases its resistance to drag when buried in the seabed, thereby increasing its holding capacity, but this increased holding capacity again drops to the level of an uncoated anchor as the coating peels off upon grinding. So far, the focus of product developers has taken a different direction when it comes to increasing the anchoring capability.

15

Increases in the holding capacity of tensile anchors have been achieved as a result of maximizing the area of the anchor tab, the development of stabilizing elements, optimized selection of forward open angles for adaptation to specific soil types, minimizing the diameter of the anchor line, and streamlining to avoid overcurrent flow. the anchor is stopped while simultaneously ensuring that the drag exerted by the anchor line at the surface of the seabed is as close to the horizontal as possible.

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Increases in the holding capacity of anchors with direct anchoring have been achieved as a result of maximizing the area of the anchor tab, streamlining, minimizing the diameter of the anchor line and reducing the minimum projected area.

5

It is well known that the forward open angle of a tensile anchor must have a certain size to fit a particular type of seabed soil. Thus, a tensile anchor will be able to provide maximum holding capacity in sand if the forward open angle is approx. 45 ° and maximum holding-10 ability in soft clay if approx. 65 °. In addition to these values for the forward angle, the holding capacity will decrease progressively until the anchor tab of the towbar anchor eventually backs out of the seabed after first penetrating there.

However, when the forward open angle is set to 65 ° for soft clay, an insignificant holding ability in sand will be achieved. When the angle is set to 45 ° for sand, very low holding capacity in soft clay will be achieved. No intermediate angle has been found to provide optimum performance in both sand and soft clay. Although compromise angles of between 50 ° and 56 ° have been used before, performance within acceptable deviations from the normal for sand and soft clay has not been achieved. Selecting a forward open angle to achieve an acceptable performance in the case of a specific soil will thus reduce the possibility of using tensile anchor in a wide range of soil types.

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The objects of the present invention include, inter alia, increased usability of tensile anchors and decreased penetration resistance for both tensile anchors and direct anchors as well as associated anchoring elements as described above.

5

According to one aspect of the present invention, an anchor and associated anchoring element as described above are characterized in that at least one of the anchor and its anchoring element comprises a low friction outer surface with a lower coefficient of friction relative to soil particles from the seabed sliding there. above the water than it occurs in the same way on the outside surfaces, usually of steel or painted steel, now known for marine anchors.

in

Preferably, the outer surface is made of a low friction material.

15

Preferably, the outer surface is made of a coating with a low friction lubricant which adheres to the anchor.

Preferably, the coating comprises a layer made of at least one of the following substances polytetrafluoroethylene, ethylene chlorotrifluoroethylene copolymer, graphite and diamond, most preferably diamond.

6 DK 176006 B1

Preferably, the coating comprises a layer made of at least one of a liquid lubricant as well as a semi-solid, fat-like lubricant.

Preferably, the liquid lubricant is at least one among water and vegetable oil.

Preferably, the vegetable oil is at least one among olive oil, rapeseed oil, sunflower oil, coconut oil, and palm oil.

Preferably at least one of the coating materials comprises low friction materials as well as the lubricant a water repellent substance which prevents adhesion of seabed soil to an outside surface of the anchor.

Preferably, the water repellent substance comprises a silicone material.

15

Preferably, the lubricant can be pumped and lubricated to form the coating.

Preferably, the lubricant is either biodegradable or degradable after a short time.

7 DK 176006 B1

Preferably, the lubricant comprises a retarding substance of delayed action, wherein the lubricity of the lubricant is significantly reduced after a period which can be determined.

Preferably, the low friction outer surface comprises a lubricated surface.

Preferably, the coefficient of friction of the outer surface with respect to soil particles from the seabed (e.g. sand) sliding over the water over 10 will not exceed 0.27 and further preferably will not exceed 0.2.

Preferably, the low friction outer surface will be on at least one of the anchor tab and the anchor cap and anchor anchor member.

Preferably, at least one of the anchor and anchor embedment element will comprise refilling elements for replenishing lost lubricant from the outside surface due to entrainment, with soil from the seabed sliding over it.

Preferably, the lubricant will be delivered via a closed channel to the outer surface, upon which a layer of lubricant is maintained upon application, with soil from the sea floor sliding over it.

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Preferably, a number of lubricant outlets will be adjacent and spaced along a forward edge of the outer surface.

Preferably, the lubricant backfill element will include a lubricant container serving as a supply container.

Preferably, the container will be emptied by a pump which can be operated by soil on the sea floor moving relative to the outside surface, whereby the lubricant contained in the container is measured relative to the movable displacement of the anchor in the soil. on the seabed for supply to the leading edge of the outer surface as the anchor and the anchoring element penetrate into the seabed.

According to a further aspect of the present invention, there is provided an apparatus for attaching to at least one anchor and associated anchoring elements as described above, characterized in that the apparatus comprises supply means for supplying lubricant to an outer surface of at least one of the anchor and associated anchoring means, whereby a layer of the lubricant can be established on the surface by carrying with soil from the seabed which slides over it.

DK 176006 B1 g

Preferably, the apparatus comprises elements of the container containing the lubricant, as well as pump means for pumping lubricant from the container elements to the outside surface.

Preferably, the apparatus comprises measuring means by which the lubricant is measured to provide the external surface with respect to the movement of the surface in the soil on the seabed.

Preferably, the pumping means and measuring means comprise a 10-blade ground turbine which can be rotated by the ground striking them and connected via a drive shaft to a pump, whereby the pumping of the lubricant from the container to the outside surface is proportional to the earth's movement relative to the apparatus. .

Preferably, the lubricant supply means will comprise a closed tubing attached to a leading edge of the outer surface and perforated with holes spaced apart along the edge from which the lubricant may escape and be lubricated. the outside surface when carried with soil from the seabed that slides over it.

20

Preferably, the container elements comprise a flexible cushion tank.

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Preferably, the tensioning anchor apparatus comprises differential supply elements for differential supply of lubricant to a guide and backboard pair of exterior surfaces of the anchor.

Preferably, the differentiating supply elements will comprise a shuttle-controlled valve that reduces lubricant flow to a minimum on the back and starboard pairings of exterior surfaces as the anchor tips in transverse direction due to the accompanying gear roll, thereby releasing frictional forces, tipping is discouraged.

10

Preferably, a tensile anchor comprises at least one of the low friction surfaces and lubricants, and has a forward open angle β greater than 66 ° for use in soft clay and greater than 46 ° for use in sand.

15

Preferably, the angle β is in the range of 68 ° to 80 ° for soft clay, and between 50 ° and 68 ° for sand, more preferably 70 ° to 77 ° for soft clay, and between 56 ° and 64 ° for sand. .

Preferably, a tensile anchor for use in soil types with both sand and soft clay contains at least one of the low friction surface and lubricating element, and has a forward open angle β of between 54 ° and 64 °, more preferably of between 58 ° and 62 °.

11 DK 176006 B1

Preferably, a direct anchor anchor and associated anchor means as described above will comprise at least one of the low friction surface and the lubricating element.

5

Embodiments of the present invention will now be described with reference to the accompanying exemplary drawings, in which

FIG. 1 is a side elevational view of a tension anchor and associated anchor 10 of the present invention;

FIG. 2 is a front elevation of the embodiment of FIG. 1,

FIG. 3 is a plan view of the embodiment of FIG. 1, 15

FIG. 4 shows that in FIG. 1 in the direction D and equipped with the device according to the invention,

FIG. 5 is a front elevation of the one shown in FIG. 4, turbine and pump shown, 20

FIG. 6 is a partial sectional view AA of the anchor tab of FIG. 4 shown on larger scale, 12 DK 176006 B1

FIG. 7 is a partial sectional view BB of the insert of FIG. 4 on an enlarged scale,

FIG. Figure 8 shows a side elevation of a direct anchor anchor and associated anchor member according to the present invention, and

FIG. 9 shows that in FIG. 8 after the cable is pulled on and its anchoring elements removed.

According to a first embodiment of the present invention, a tensile anchor 1 (Figs. 1-3) for tensile anchorage in anchor bottom soil comprises a leg 2 pivotally connected at one end to a plate or wing-shaped anchor tab 3 by means of a pin 4, and at its other end to anchor line 5 by means of a shackle 6 pivotally attached to the hole 7 in the shank 2. An-15 notch 3 has a negative V-shape and the anchor 1 is symmetrical about a plane XX (Fig. 2). The upper surfaces 8 of the anchor tab 3 are planar with an angle α of the negative V of 20 ° at each side of the plane of symmetry X-X. A line in plane XX joining the center of a shackle hole 7 and the geometric center of gravity C on the upper surfaces of the anchor tab 3 forms a forward open angle β with a forward direction F (Fig. 1) for the anchor tab 3. The angle β exceeds 65 ° when used in soft clay, and exceeds 45 ° when used in sand. The angle β is generally set to between 66 ° and 80 ° for soft clay and 46 ° and 68 ° for sand.

The forward direction F is parallel to the intersection of the surface planes 8 13 DEG 176006 B1 in the plane of symmetry X-X and essentially defines the general direction for the angular movement of the anchor tab 3 in the seabed soil as the anchor 1 is pulled through. The locking mechanism housing 9 contains a mechanism for locking the insert 2 relative to the anchor tab 3 at a specific adjustable open angle β. The mechanism inside the housing 9 is actuated to allow the calf to move from the position shown in point S1 of FIG.

1, providing a forward open angle β within the above specified area for burying the anchor for tensile anchoring in a position S2 (shown in dotted line), wherein the shank 2 is substantially perpendicular to the anchor tab 3 and defines the anchorage setting of the anchor, where the anchoring force is applied via cable 5 substantially normal to the anchor tab 3. When the anchor 1 has a fixed setting for the leg 2 as at S1, the forward open angle β is preferably within the range 54 ° to 64 °, the area 58 ° to 62 ° is particularly preferred and it will be possible to use the anchor in seabed soil types with both sand and soft clay.

Stabilizers 10 are attached to the rear ends 11 of the anchor tab 3, spaced from each side in the plane of symmetry X-X. Anchor tab 3 has upper and lower exterior surfaces 8 and 12, respectively, while the liner 2 has exterior side surfaces 20 13. The housing 9 with the locking mechanism has exterior side faces 14. These exterior faces 8, 12, 13 and 14 are together with the outer surfaces of the stabilizers 10. coated with a low friction material comprising at least one of the following: polytetrafluoroethylene, ethylene chlorotrifluoroethylene copolymer, graphite, diamond or the like. In case the low friction coating is rendered ineffective in that it is water-sucking and thereby allows soil from the seabed to develop adhesion thereto, in addition to the shear forces of the soil, a water repellent substance (e.g., a silicone material) will be included in the coating. to prevent such attachment. The low friction coating ensures that the coefficient of friction relative to the soil particles from the seabed that glides over it is less than the coefficient of friction which would be similarly formed on bare or painted steel surfaces. The resulting reduced coefficient of friction will, in turn, ensure that the 10 frictional forces against an anchor 1 that withstand intrusion into the seabed are reduced.

As indicated earlier, soil types in the seabed contain abrasive particles that progressively remove the abovementioned low friction materials, as the anchor 1 penetrates below the seabed surface. In certain types of seabed soil, substantial removal may occur by grinding the softer coatings before a desired depth of penetration of the anchor 1 below the seabed surface has been achieved. This may result in non-damped frictional forces reappearing, which may prevent the anchor 1 from reaching the desired penetration depth.

According to another embodiment of the present invention (Figures 4-7), a solution to the problem of abrasive removal of low friction coating is provided: the anchor 1 is provided with the apparatus 15 (Fig. 4) which refills the low friction coating as it is removed by sliding abrasive soil from the seabed over the outside surfaces of the anchor.

The apparatus 15 comprises a container 16 attached to the back of the bottom surface 12 of the anchor tab 3 and containing a liquid lubricant 17, connected to a pipe 18 to the inlet of a rotary fluid pump 19 driven by a ground turbine 20 via the shaft 21. The liquid pump 19 (Figs. 4 and 5) is mounted on a strut 22 secured to the front of the lower surface 12 of the anchor tab 3. When ground from the sea floor strikes the turbine 20, it is caused to rotate the shaft. 21 to operate the pump 19 as the anchor 1 moves. in the seabed. The outlet for the liquid pump 19 is connected to a first conduit 23 for a pendulum controlled valve 19A with two outlet ports fixed to the underside of the anchor tab 3, 15 which directs the same amount of lubricant to each outlet port as long as the anchor 1 is in a vertical direction with lay 2 lying in a vertical plane. The outlet ports of the valves 19A are connected by pipes 23P, 23S, to thick-walled pipes 24P, 24S, which are axially aligned parallel to and attached to the front edges (P) and starboard (S) front edges 25P and 25S of anchor tab 3, respectively.

The outlet of the liquid pump 19 is further connected by a second (partially flexible) pipe 26 to the thick-walled pipe 27, which is axially aligned parallel to and attached to the leading edge 28 of the leg 2. The thick-walled pipes 24P, 24S and 27 has sealed ends 29 and are perforated with small holes 30 which, in diametrically opposite pairs, are spaced longitudinally apart along each thick-walled pipe, thereby letting the lubricant 17 pumped around there by the pump 19 on each side of each thick-walled tube along the lengths of the leading edges 25P.25S and 28 of 5 anchor tab 3 and insert 2, respectively (Figs. 6 and 7).

When the tensile anchor 1 is in motion in the soil of the seabed with the shank 2 lying in a vertical plane, lubricant 17 escaping from the small holes 30 will be carried off the ground and spread over the surfaces 8, 12, 13 10 and 14, then frictional forces exerted are reduced as long as the supply of lubricant 17 from the container 16 takes place. The container 16 has sufficient capacity to allow complete lubrication of the surfaces 18, 12, 13 and 14 until the desired penetration of the anchor 1 below the seabed surface has occurred. Some of the exterior surfaces of the anchor line 15 5 may also be provided with lubricant 17 in a similar manner. Due to the very small size of the holes 30 and the high fluid pressure produced by the pump 19, blocking of the holes 30 with soil material will be substantially excluded.

If the anchor 1 rolls with accompanying gear so that the shaft 2 is brought out of its vertical plane, the pendulum controlled valve 19A will ensure that the supply of lubricant is reduced to the bottom of the thick-walled pipes 24P and 24S, thereby increasing the frictional forces on the lower side of anchor tab on I - - - ^^^ - DK 176006 B1 17 due to lack of lubricant. Hereby, the anchor 1 is caused to seek to rotate in the opposite direction with respect to the yaw movement effected by the rolling motion. This effect can be enhanced by lubricating the outer surfaces of the stabilizers 10 in a similar manner. Thus, differentiated supply of lubricant to suitable surfaces can provide automatic control of the roller and gearing in the anchor 1.

Conveniently, the container 16 is constituted by a cushion tank made of a flexible sheet material secured with clamps to the rear end of the bottom 10 surface 12 of the anchor tab 3. The lubricant 17 is thereby subjected to the same pressure externally on the container 16, so there is no pressure differential across the flexible sheet material. The container 16 can therefore have a light construction. Since the liquid pump 19 is driven by the earth turbine 20 via the shaft 21, the supply speed of lubricating oil 17 to 15 the outer surfaces of the anchor 1 will be proportional to the displacement of the anchor in the seabed soil.

The amount of lubricant per length unit of anchor movement is selected such that a constant film thickness of lubricant 17 is maintained on the 20 exterior surfaces. Thus, a liquid capacity of the 13 liter container will maintain a 0.1 mm thick layer of lubricant on the outside surfaces of a 10m2 area of the anchor tab of the anchor 1 (total lubricated area: 26m2) over a penetration path length of 50m despite loss of lubricant 18 DK 176006 B1 the rack for the passed ground. An appropriately specified lubricant can reduce the coefficient of friction by the order of 0.3 to 0.6 to as little as 0.05, thereby reducing the friction forces by a factor of up to 12 depending on soil type.

5

The maximum depth of penetration into the soil of the seabed for a draft anchor anchor is a function of the forward open angle, the diameter of the embedded portion of the anchor line, the angle of elevation of the anchor line to the horizontal at the surface of the seabed, and the shear strength of the soil. The penetration 10 web is curved and eventually horizontal when the web reaches its maximum penetration depth. If the frictional force generated by the ground on the seabed sliding across the outer surfaces of the anchor is reduced by the use of a water-repellent low friction lubricant, a reduction in line tension is achieved during installation, thereby obtaining a given penetration depth on the track. However, the shape of the web itself is not affected by the value of the frictional force.

A tensile anchor of the type described in the above-mentioned international patent applications is associated with this advantage of reducing line tension during installation. Such an anchor is loaded at 90 ° to the tab after the tensile anchorage is completed by increasing the forward open angle β to 90 °. The pull-out capacity of the anchor, when loaded at 90 ° relative to the tab, is not significantly affected by occurrence. stones of lubricant. However, the ratio of extraction capacity to (lubricant-reduced) installation voltage in the anchor line 5 will be increased.

In particular, the ratio of the pull-out capacity to the horizontal tension component of the anchor line 5 will be increased by 50 percent or more in soft clay types using the water-repellent low-friction coating on the anchor 1. The drag on the mooring pole thus required by an anchor installation vessel may be reduced. significantly, thereby greatly reducing installation costs.

10 Since lubrication of an anchor with tensile anchor reduces the line tension at all points of the penetration path, the holding capacity of the anchor will be reduced. Lubrication of a tensile anchor could therefore be considered to be a step in the wrong direction. However, it has been found that increased holding capacities can be achieved in sand and soft clay types when the outer surfaces 15 of an anchor are coated with a lubricant to allow a higher value of the forward open angle to be consumed relative to the angle known so far as being the limiting value, which - if exceeded - causes the penetration and holding capacity to fall dramatically in a specific soil type.

20

This limiting value is inversely proportional to the extent of the frictional force developed by seabed particles sliding across the surfaces of the anchor. Any reduction in frictional force due to lubrication allows an increase in the limiting value of the forward open angle. Thus, a greater maximum penetration depth and thus greater holding capacity can be obtained by assuming a larger forward open angle than has hitherto been possible with a non-lubricated anchor with tensile anchorage, regardless of the reduction in the line tension of the anchor arising from a given penetration depth caused by the use of a lubricant.

The amount of lubricant 17 in the container 16 can be determined such that the container is emptied at a certain point in the trajectory of the anchor 10 anchor 1. After this point, the frictional forces on the anchor will thus be fully recovered and a large increase in holding capacity will be achieved at a penetration depth. , which would be impossible without lubrication.

Furthermore, the lubricant 17 is selected to be environmentally acceptable or biodegradable, or rapidly degradable. Thus, water can be used in clay types, although vegetable oils such as olive oil, rapeseed oil, sunflower oil, coconut oil or palm oil would be preferable in both sandy and clay types. In addition, a substance with inhibitory, delayed effect which serves to abolish the lubricant's lubricating action after a predetermined time can be incorporated into the lubricant and added thereto at the pump 19 from a separate container. Such a choice or modification of the lubricant prevents the anchor from depositing permanently lubricated sliding planes in the seabed and in addition increases the holding capacity of the tensile anchor shortly after the installation has been completed to a given depth below the seabed surface by restoring frictional forces. In clay types, the excess pore pressure in the soil in the lubricated sliding planes caused by the injection of water from the apparatus, if water is used as lubricant, will eventually disappear after anchor 1 has passed as equilibrium is restored in the pore pressure.

Furthermore, coating with lubricant allows a tensile anchor to penetrate sand at a high value of a forward open anchor which has heretofore been only applicable in soft clay. A lubricated anchor with a simple forward open angle within the range of 56 ° to 64 ° and in particular the range 58 ° to 62 ° will provide a performance which is within acceptable deviations from the optimum with respect to sand and soft clay when used in one or the other of these soil types, thereby providing a valuable increase in the usefulness of the anchor.

15

In addition, the tensile anchor coated with lubricant has the ability to penetrate alternating layers of sand and soft clay without the tab being trapped in a contact surface between sand and underlying soft clay. This capability has not existed in the previously known towing anchor, 20 although it has been proposed in applicant's co-pending international patent application No. PCT / GB98 / 00109 filed January 22, 1998 and entitled "Anchor for Marine Use" (Submitted under the number WO ).

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In accordance with a third embodiment of the present invention, an anchor 1A for direct anchorage (Fig. 8) for edge anchoring in an anchorage floor in a vertical direction will comprise that of Figs. 1-7, modified so that the stabilizers 10 are omitted and the length of the leg 2A is considerably reduced. In all other respects, FIG. 4 is identical to that of FIG. 1 to 7 show anchor 1 and have the same reference numerals.

A heavy, oblong cylindrical wave 33 serves as a rigid pushing member to drive the anchor 1A vertically into the seabed with its weight. The wave 33 (Fig. 8) has a tapered drawbar at the lower end of which is a rear end 35 of the anchor 1A tab 3. At an upper end of the wave 33 there is an eye which forms the connecting link to the lowering and raising line 37 by means of the shackle 38. A slidable release pin 39 of the drawbar 34 passes through the hole 32 in the eye 31 of the tab 3 (Figs. 5 and 9) and serves to hold the tab 3 of the towbar 15 34 while submerging the anchor and the wave to the seabed. but which breaks down due to the earth's resistance to releasing the anchor 1A from the wave 33 to allow re-entry of the wave 33 after complete anchoring of the anchor 1A. The anchoring operation is performed by immersing the anchor 1A and the wave 33 on the seabed by means of the line 37, which is rolled out of a game on a 20 single anchor handling vessel (AHV), where the anchor line 5 is unrolled in tandem with another play on the AHV. Unrolling of the ropes is continued and the tension of the rope 37 decreases progressively as the resistance to the ground penetration supports an increasing portion of the underwater weight of the anchor 1A and the underwater weight of the anchor and relieves the tension of the rope 37. underwater weight, line 37 becomes slack and anchorage of anchor 1A is completed. The wave 33 is pulled out of tab 3 of the anchor 1A and away from the seabed by 5 raising via line 37. Rotation of the anchor 1A so that the anchor tab 3 is perpendicular to the load exerted by the anchor line 5 is then simply performed by pulling in line 5 (Fig. 9), whereby the anchor 1A achieves maximum pull-out capacity. The wave 33 includes outer low friction surfaces 40, and the anchor 1A includes low friction surfaces as described above with reference to the anchor 1. The presence of low friction surfaces in general, and the lubricant delivered specifically, on the anchor 1A and the wave 33 greatly reduces the penetration resistance encountered. , when the anchor 1A is submerged to a given depth below the seabed surface 41 (Fig. 8).

Consequently, the weight required by the wave 33 will be sufficiently reduced 15 for embedding by weight alone, without the need to use a hammer hammer on the wave, as it would otherwise have been commonly practiced for the last hundred years. Eg. shows comparison of non-lubricated and lubricated arms with a diameter of 0.86m needed to install a direct anchor anchor with a pull-out capacity of 700 tonnes and with 20 12m2 anchor tab area and weighing 8 tonnes (Fig. 8), with a load safety factor of 1.25 in normally consolidated clay with a shear strength gradient of 1.6 Kpa / m and a sensitivity of 2 that 24 DK 176006 B1

Non-lubricated Lubricated Weight of wave 356 tons 141 tons Length of wave 78 m 31 m

Power needed to bring wave 409 tonnes to 147 tonnes

It is clear that the surfaces of an anchor with direct anchorage and associated wave make a very large difference in terms of the weight and the 5 forces involved in the installation operation. In the case where no lubrication has taken place, the excess length and weight of the wave will make direct anchoring of the anchor impossible in practice and the force required to retract it is beyond what is possible for the games at almost all of the anchor handling vessels available today worldwide.

10

Of course, it is an option to modify the structural details of the present invention. In particular, it is possible that the lubricant container may comprise a metal cylinder containing a piston which is actuated by a spring or gas to pressurize the lubricant and may be attached to the anchor line 5 above the surface of the seabed or even disposed on the anchor installation vessel and the apparatus on the anchor provided by a pipe attached along the length of the anchor line from container to anchor. Furthermore, the anchor of the invention may have a leg formed of a plurality of wires and an anchor cap having a different shape than that of FIG. 1-4. The surfaces 13 will then be found on each of the wires comprising the calf.

Claims (41)

A ship anchoring device comprising any of an anchor (1) and anchor element (33) for the anchor (1), which anchoring device is adapted to penetrate into the seabed, as well as fasteners (6, 7) for attaching an anchor line (5) to the anchoring device, characterized in that the anchoring device comprises an external surface (8) having a coefficient of friction with respect to seabed particles lying below the sea surface sliding thereon which is less than the corresponding coefficient of friction for a nude or painted steel surface. Anchoring device according to claim 1, characterized in that the outer surface (8) is made of a low friction material. Anchoring device according to claim 2, characterized in that the outer surface (8) is formed of a coating with a low friction lubricant which adheres to the device. Anchoring device according to claim 3, characterized in that the coating comprises a layer consisting of at least one of the substances polytetrafluoroethylene, ethylene chlorotrifluoroethylene copolymer, graphite and diamond. 27 DK 176006 B1 Anchoring device according to claim 2, characterized in that the outer surface is at least one of a liquid lubricant and a semi-solid, grease-like lubricant. Anchoring device according to claim 5, characterized in that the liquid lubricant is at least one water and vegetable based oil. ! Anchoring device according to claim 6, characterized in that the vegetable-based oil comprises any one of olive oil, rapeseed oil, sunflower oil, coconut oil and palm oil. Anchoring device according to any one of claims 3-7, characterized in that at least one of the coating, said low friction material and the lubricant, comprises a water-repellent substance which prevents adhesion of the seabed to the external surface of the device. Anchoring device according to claim 8, characterized in that the water-repellent substance comprises a silicone material. 28 DK 176006 B1 Anchoring device according to any one of claims 5 to 9, characterized in that the lubricant can be pumped and lubricated to form the coating. Anchoring device according to any one of the preceding claims, characterized in that the outer surfaces (8) lose substantially their low friction properties at the end of a period during the application of the device. Anchoring device according to any one of claims 5 to 11, characterized in that the lubricant is at least either biodegradable or degradable after a short time. Anchoring device according to claim 12, characterized in that the lubricant contains a retarding substance of delayed action, whereby the lubricity of the lubricant is abolished after a predetermined time. i i Anchoring device according to claim 1, characterized in that said outer surface comprises a lubricated surface. 29 DK 176006 B1 Anchoring device according to any one of the preceding claims, characterized in that the coefficient of friction of the outer surface with respect to e.g. sand slipping over does not exceed 0.27 and, more preferably, does not exceed 0.2. 5 Anchoring device according to any one of the preceding claims, characterized in that said outer surface (8) is on at least one of the anchor tab (3) and the anchor plate (2) of an anchor and the anchor embedding element (33). 10 Anchoring device according to claim 3 or claim 5, characterized by at least one of the anchor (1) and the embedding element (33) comprising refilling elements (16) for refilling of lubricant lost from the outer surface (8) as a result of carrying of the lubricant as soil from the seabed slides across the surface (8). Anchoring device according to claim 1, characterized by the lubricant being supplied via a closed channel (18) to the outer surface (8), on which a layer of lubricant is thus maintained at application as soil from the seabed slides across the surface (8). thereof. Anchoring device according to claim 17, characterized in that the lubricant is delivered via a closed channel (26) to a leading edge (28) of the outer surface (8) of at least one of the anchor tab (3) and the anchor assembly ( 2), whereby a layer of the lubricant is thereby maintained by transport as soil from the seabed slides over it. Anchoring device according to claim 19, characterized in that a plurality of lubricant outlets (30) are disposed and spaced apart along the leading edge (25, 28) of the outer surface. Anchoring device according to claim 19 or 20, characterized by the lubricant refill element comprising a lubricant material container (16) and serving as a supply container. Anchoring device according to claim 21, characterized in that the container is emptied by means of a pumping device (19) which is operated by movement of the seabed soil relative to the anchor, whereby the lubricant present in the container (16) is measured proportionally to that of the anchor. movable displacement in the seabed so as to supply the leading edge (25, 28) of the outer surface as the anchor penetrates the seabed. 31 DK 176006 B1 Anchoring device according to any one of the preceding claims and comprising an anchor (1), characterized in that the anchor (1) comprises means (9) for adjusting the adjustment of the anchor tab (3) relative to the anchor insert (2), whereby the leg (2), in the operative position of the anchor (1) in the seabed, is adjusted in relation to the tab (3) such that the tension in the anchor (1) via an anchor cable (5) is substantially normal to the upper one. surface of tab (3). ! Anchoring device according to claim 1 and in the form of a tensile embedding anchor, characterized in that the anchor has a forward open angle β exceeding 66 ° for use in soft clay and exceeding 46 ° for use in sand. A tensile embedding anchor according to claim 24, characterized in that the angle β is in the range of 68 ° and 80 ° for soft clay and 50 ° and 68 ° for sand, the range 70 ° and 77 ° being preferred for soft clay and 56 ° and 64 ° for sand. Anchoring device according to claim 1 and in the form of a solid bed tensile embedding anchor and for use in both sand and soft clay, characterized by the anchor having a forward open angle β which is in the range 54 ° to 64 °, the area 58 ° to 62 ° is preferred. 32 DK 176006 B1 26 DK 176006 B1 P a t e n t k r a v: Anchoring device according to claim 24 or claim 25, characterized by the apparatus comprising measuring means (19, 20), by which the lubricant is measured for supplying the outer surface (25, 28) proportionally to the movable displacement of the armature. seabed soil. Anchoring device according to claim 1 and in the form of a direct embedding anchor and associated embedding means. Anchoring device according to claim 28, comprising a lubricating means supply device attached to at least one of said direct embedding anchors and associated embedding means, wherein the lubricant supplying apparatus comprises supply means for supplying a lubricant to an outer surface of at least one of the anchor and anchor embedding means 15. of lubricant can be established on the surface by entrainment as soil from the sea floor slides over it. Apparatus for supplying lubricant and attaching to at least one of an anchor (1A) and an anchor embedding element (33), characterized in that the apparatus comprises supply means (18, 19, 26) for supplying a lubricant (17 ) to an outer surface of at least one of the anchor (1A) and the anchor embedment means (33), whereby a layer of lubricant in the ___ ---- - ... - 1 DK 176006 B1 33 can be established on the surface (8) upon application , when soil from the seabed slides over it. Apparatus according to claim 30, characterized in that the apparatus comprises container elements (16) containing the lubricant and pump means (19) for pumping lubricant from the container means (16) to the outer surface (8). Apparatus according to claim 31, characterized in that the container means (16) comprises a flexible cushion tank. Apparatus according to claim 30, characterized in that the apparatus comprises a ground turbine (20) with blades which can be rotated as the ground strikes them and is connected via a drive shaft to the pump means (19), whereby the lubricant is pumped out proportionately to the earth's movement. in relation to the anchor to which the device is attached. Apparatus according to claim 30, characterized in that the means for supplying the lubricant comprises a closed conduit (27) to which 20 is attached and aligned to an anterior edge of the outer surface and perforated with holes (30) located at a distance along the edge from which the lubricant can escape and be lubricated over the outside surface by application as seabed soil slides over it. 34 DK 176006 B1 Apparatus according to claim 30, characterized in that differentiated supply means (19A) are provided for differential supply to a backboard and starboard pair of outer surfaces of the anchor. 5 Apparatus according to claim 35, characterized in that the differential supply means (19A) comprises a pendulum controlled valve which reduces the flow of lubricant to the bottom of the outboard or starboard pair of exterior surfaces as the anchor (1) tips in the transverse direction 10 due to the roll of accompanying yawning, thereby restoring frictional forces so that yawning and thus the rocker are counteracted. Tensile embedding anchor comprising an apparatus for supplying lubricant according to claim 30, characterized in that the anchor 15 has a forward open angle β exceeding 66 ° for use in soft clay and exceeding 46 ° for use in sand. 38. Solid bed tensile embedding anchors for use in both sand and soft clay and comprising the lubricant supply apparatus of claim 30, 20, characterized in that the anchor has a forward open angle β which is in the range of 54 ° to 64 °, the range 58 ° to 62 ° is preferred. in 35 DK 176006 B1 A method of placing an anchor (1A) by means of anchor embedding means (33), the anchor (1A) comprising an anchor tab (3) and a leg (2A) attached to the anchor tab (3), characterized in at the following steps: 5 a) applying a low friction surface (8.40) to any of the anchor (1A) and the embedding means (33), b) causing the anchor (1A) to be supported by the embedding means (33) carrier (39) on the embedding means (33) to form a combination comprising the anchor (1A) and the embedding means (33); c) mounting a support cable (37) on the embedding means (33) for immersing the combination (1A) , 33) on the seabed where the anchor (1A) is to be placed and mount an anchor cable (5) on the shaft (2A) of the anchor (1A), 15 d) guided to submerge the combination (1A, 33) to a contact position on the surface of the seabed (e) cause the embedding member (33), by virtue of its weight, to directly embed an appeal right (1A) in the seabed from the contact position; (f) releasing the embedded anchor (1A) from the embedding means (33); at the sea surface by means of the anchor cable (5), and (h) resume the embedment means (33) from the seabed by means of the support cable (37). Method according to claim 39, characterized in that the placement of the anchor is carried out by a single anchor handling vessel at the sea surface, the support cable (37) and the anchor cable (5) being unwound from this vessel during the controlled immersion step of the combination (1A, 33). Method according to claim 39 or claim 40, characterized in that in the operating position of the anchor (1A), the pull on the anchor cable (5) will be substantially normal for the tab (3) of the anchor (1A).