Helical endless splice

Abstract

The invention is directed to an end-for-end splice that joins two ropes. The splice comprises a helical section and a tapered section and, in these sections, strands of one rope are tucked into the other rope in a helical pattern. Moreover, in the tapered section, the tucked in strands have a decreasing volume in the direction of away from the center of the splice. This splice configuration was found to lead to a relatively small diameter and excellent CBOS performance.

Description

[0001] Title: Helical endless splice

[0002] The invention is in the field of splices for synthetic ropes. In particular, the invention is directed to end for end splices of synthetic ropes used in dynamic Cyclic Bending Over Sheaves (CBOS) type applications.

[0003] Synthetic ropes (i.e. ropes based on synthetic, polymer-based fibers) are used in the field for hoisting and lifting under various conditions. Thanks to their relatively low weight but comparable mechanical and strength characteristics compared to their preceding steel wire ropes, SWRs, synthetic ropes can advantageously be used for lifting load over long distances, of a few hundred meters to several kilometers. Synthetic ropes may for example be employed in marine and offshore for deep water mooring, deep-water lifting and the like. In these applications, the ropes are exposed to wear and otherwise damaging. Replacing partially worn or damaged ropes entirely is however not always economically most attractive, and there is according a need to remove the worn or damages parts of the rope and join the remaining good parts of the rope back together by splicing. However, as the rope typically run over sheaves and are collected in drums, the splicing has to meet special requirements. For example, the diameter of the splice should not be too large with respect to the diameter of the original rope, as the splice will otherwise not run smoothly over sheaves and in the drum where the rope is collected. Also, the splice should have a good lifetime when run over sheaves and not work loose or be damaged otherwise. In addition, as the splicing typically has to be carried out on-site, for example on board of a seaborn vessel or platform, the splice should not be too long or the splicing will become very complicated or impossible. Ideally, the splicing process is as simple as possible.

[0004] In the art, various end-for-end splices (also referred to as endless splices) for synthetic ropes are known. WO 2013 / 134033 describes a splice having a spiral and tucked strand sections to connect a first and second rope, which splice is having a spiral section and in the tuck sections, strands of either ropes extend longitudinally to pass under and over the strands of the other rope.

[0005] Another known end-for-end splice is referred to in the art as the Hakama splice. In this splice, pairs of two unbraided strands of the ropes are tucked in the longitudinal direction under and over a crossing of two neighboring strands of a different lay direction (an “X” in the rope). A drawback of the Hakama splice is its relatively large diameter (about 1.6 to 2.0 times its nominal diameter) and its physically tough way to produce.

[0006] The ropes in both the splice procedure of WO 2013 / 134033 as well as in the Hakama splice must be of the same diameter to be spliceable.

[0007] It is an object of the present invention to provide an improved splice that addresses one or more of the above-mentioned drawbacks.

[0008] The present inventor found that this object can be met by providing a splice that comprises a helical section and a tapered section. In both sections, strands of one rope are tucked into the other rope in a helical pattern. Moreover, in the tapered section, the tucked in strands have a decreasing volume in the direction away from the center of the splice. This splice configuration was found to lead to a relatively small diameter and excellent CBOS performance. Also, the splice can be made relatively short without this being detrimental to the mechanical performance of the splice. Finally, the splice according to the present invention allows for the joining of ropes of different diameter ropes with outstanding efficiency.

[0009] The present invention is accordingly directed to a spliced synthetic rope comprising:

[0010] - a first rope comprising a first plurality of strands;

[0011] - a second rope comprising a second plurality of strands; and

[0012] - a splice connecting the first and second rope, which splice comprises a splice center; wherein the splice comprises at least a helical section that comprises a first and a second helical section, and two tapered sections positioned at either side of the helical section and at either ends of the splice; wherein the first helical section comprises one or more strands of the first rope that are tucked in a hehcal pattern into the second rope and wherein the second helical section comprises one or more strands of the second rope that are tucked in a helical pattern into the first rope; and wherein the tapered sections comprise a first and second tapered section that respectively comprises one or more of strands of the first and second rope that are tucked in a hehcal pattern into the second and first rope, which strands (i.e. the strands that are tucked in the tapered sections) have a decreasing volume in the direction of away from the splice center.

[0013] The splice center is the spot at the middle of the splice. In a typical embodiment, the splice center is located in the center of the helical section and in between the first and second helical sections. The first helical section may then be located directly adjacent the first tapered section while the second helical section may then be located directly adjacent the second tapered section. It may be appreciated that the splice may comprise additional sections as well. These additional sections may be in between the helical section and one or both of the tapered sections. However, preferably the splice comprises only the helical and tapered sections.

[0014] In a preferred embodiment, the strands that are tucked in a helical pattern are bundled in sets of two or more, typically two, neighboring strands. In a typical embodiment, two or more neighboring strands are bundled, preferably twisted, in a new set of strands and tucked as such into the other rope. This applies preferably to all strands in the hehcal and tapered sections. Typically, strands in synthetic ropes are based on a plurality of yarns that are twisted in a certain orientation (also referred to as handedness), for example in a left-hand or a right-hand twist. In a further preferred embodiment, the set of strands that are bundled are twisted together in a same lay direction as the individual strand orientation. Thus, for example, a set of two neighboring left-hand oriented strands of the first rope may be bundled and twisted in a left-hand orientation before they are tucked in a helical pattern in the second rope. This has some similarity to a traditional Lang lay construction. It is further preferred that the strands are divided in equal amounts of left- and right-hand oriented sets.

[0015] The helical and tapered sections comprise strands that are tucked in a helical pattern. Preferably essentially all strands in the helical and tapered sections are tucked in a helical pattern and even more preferably, essentially all strands in the entire splice are tucked in a helical pattern. Tucking in a helical pattern means that the strands are tucked under and over strands of the other rope in a helical or spiral manner, if the other tope has a braided construction. If the other rope has a laid construction, tucking in a helical pattern means that the strands are laid in a helical or spiral manner next to the strands of the other rope.

[0016] In the next paragraphs, the tucking pattern of the splice will be elucidated by taking tucking of the strands of the first rope into the second rope as an example. It may be appreciated however that the same principles apply to the tucking of the strands of the second rope into the first rope. In fact, in a preferred embodiment, the construction of the splice is essentially symmetrical, i.e. there preferably exists an essential mirror symmetry in the splice at the splice center which allows for a more efficient load transfer and a lower stress concentration in the splice.

[0017] In a typical embodiment wherein the second rope is a braided rope, the one or more strands of the first rope are tucked in the first helical section in a helical pattern comprising at least 10, preferably at least 15 helical tucks over and under the strands of the second rope. In the first tapered section, the one or more strands of the first rope are typically tucked in a helical pattern comprising at least 5, preferably at least 7 helical tucks over and under strands of the second rope. The number of strands of the second rope under which and over which the strands of the first rope are tucked may appropriately be selected. Preferably, this number is the same for all tucks of a particular strand of the first rope that is being tucked in the helical section. In fact, more preferably it is the same for all strands of the first rope in the helical section. In a most preferred embodiment, the strands of the first rope are tucked into the second rope in an as natural possible way, meaning that the original construction is followed as much as possible. Thus, if the original construction of the second rope is an ‘over two and under two construction’, said number of strands of the second ropes under which and over which the strands of the first ropes are tucked is most preferably the same: two over and two under. In other words, in a particular embodiment, the first and second rope have a same original construction pattern (e.g. braiding or laying pattern), and the one or more strands of the first and second ropes that are tucked in the helical and / or tapered sections in the second and first ropes respectively, each lay against a respective neighboring strand of the second and first ropes respectively thereby following the original construction pattern of the second and first ropes respectively. The strands that are tucked into the helical and / or tapered section are preferably placed essentially next to (i.e. not on top of) their neighboring strands of the second rope. The strands are thus preferably tucked within the valley (or gap) between the construction strands of the second rope. Placing strands essentially next to their neighboring strands thus means that these strands are placed within and not on top of the original construction of the second rope as much as possible. Placing the strands on top of their neighboring strands would result in a larger diameter of the particular splice section.

[0018] The orientation of the helical pattern in which the strands of the first rope are tucked in the second rope in the helical section can depend on the orientation of the twist of the yarn and thus optionally of the twist of the set of strands, if these are bundled and twisted. Preferably, the orientation of said helical pattern is the opposite of the orientation of the twist of the yarn and of the optional twist of the bundle of strands. Thus, for example, a set of two neighboring left-hand oriented strands of the first rope that are optionally bundled and twisted in a left-hand orientation, this set is preferably tucked in a right-hand helical pattern in the second rope.

[0019] Advantageously, when the total number of strands of the rope is divided in an equal number of left- and right-hand oriented bundle sets and these bundles are tucked into the other rope in a different lay direction (i.e. left-handed oriented bundles are tucked in a right-handed lay direction, and vice versa), several new crossings between these tucked-in strands are created, resulting in an improved coefficient of friction between these strands within the splice. This allows an overall shorter splice length needed as compared to conventional splices. Further, bundling and twisting the strands together will also improve the overall coefficient of friction between these strands within the splice, further allowing a shorter splice length as compared to conventional splices. In addition, bundling and twisting the strands together reduces the volume of the two separate strands, leading to an overall thinner splice.

[0020] The tapered section is preferably constructed in the same manner as the helical section. Preferably, the only difference is that the tapered section has a decreasing diameter in the direction away from the splice center, whereas the helical section has an essentially constant diameter. The tucking as elucidated herein-above for the first helical section therefore also applies to the first tapered section, and in extension also to the second tapered section, mutatis mutandis.

[0021] The first and second tapered sections are typically provided by a reducing strand volume in steps of at least 1 / 25 of the original strand volume. Strand volume reduction can be provided by cutting out part of each of the strands that are tucked into the rope. In a typical embodiment, the strand volume is reduced in at least two steps of at least 1 / 10 of the original strand volume, more preferably in two steps of 1 / 3 of the original volume.

[0022] The first and the second ropes may be the same or different in terms of construction pattern, rope diameter and material. Advantageously, the present invention allows for the splicing of ropes with outstanding efficiency and performance, even if the ropes are different.

[0023] In a particular embodiment, the first rope having diameter dl is spliced with the second rope having diameter d2, while dl and d2 are the different. The diameter of a rope as used herein refers to the nominal diameter of said rope, meaning the diameter of a circumscribed circle that encloses all strands of the rope. In principle, there is no limitation to the allowable difference in dl and d2 for the ropes to be spliceable in accordance with the present invention. If the diameters of the ropes differ more than about 20% (based on the thickest rope, i.e. if dl>d2, (dl-d2) / dl x 100% > about 20%), it may be preferred to adjust the volume of one of the ropes. On the other hand, if the diameters of both ropes differ less than about 20%, based on the thickest rope, the ropes can generally be spliced without adjusting the volume of any of the ropes.

[0024] Adjusting the volume of a rope can be achieved by cutting, preferably tapering, the rope. In embodiments wherein the thickest rope (i.e. the rope having the highest diameter) is also the strongest rope (in terms of breaking strength), the volume of the thickest rope is adjusted. Typically, the volume of the rope is adjusted to match the strength of the thinnest rope (i.e. the rope having the lowest diameter). If both ropes are based on the same material and a similar construction (e.g. both braided or both laid), matching the strengths of the ropes will result in ropes have about the same diameters. Matching the strengths of the ropes herein means that the strengths of the ropes approximate each other, and that the difference in breaking strength of the ropes after adjustment is small than before the adjustment. Preferably, matching means that the ropes have a difference in breaking strength of less than about 80%, preferably less than 50%, more preferably less than 20%, most preferably than about 10%, based on the strongest rope.

[0025] In embodiments wherein the thickest rope is the weakest rope, it may be preferred to limit or omit volume adjustment. In embodiments wherein the rope diameters differ substantially (e.g. more than 20% based on the thickest rope) but sufficient volume adjustment is not preferred due to a resulting mismatch in rope strengths, it may be preferred to use one or more bridging ropes that can overcome the difference in diameter between both ropes. For instance, if ropes having a difference in diameter of 40% (based on the thickest rope) are to be spliced, but volume adjustment of the thickest rope is not preferred, a bridging rope having a difference of 20% (based on the thickest rope) between both ropes can be used to bridge the ropes. The bridging rope can be spliced with the ropes at either ends using the splicing method of the present invention (i.e. including helical and tapered sections as described herein).

[0026] The first and the second rope may independently be braided or laid ropes. Preferably, both ropes are braided. Moreover, the first and second rope may have the same or a different number of strands. Preferably, both ropes have the same number of strands.

[0027] In embodiments wherein the original construction of the first and second ropes are laid ropes, the stands of the first rope preferably follow the laid construction of the second rope in the first helical and first tapered sections, and vice versa. In embodiments wherein the original construction of the first rope is a braid while the second rope is a laid rope, the stands of the first rope preferably follow the laid construction of the second rope in the first helical and first tapered sections, while the stands of the second rope preferably follow the braid construction of the first rope in the second helical and second tapered sections. In embodiments wherein the first and second ropes have different number of strands, the number of stands of both ropes in the splices is preferably adjusted to a common factor. With common factor is herein meant a common mathematical factor, i.e. a number that divides the numbers of both strands, leaving no remainder for either rope. For instance, if the first rope has 12 strands and the second rope has 8 strands, both ropes have common factors of 2 and 4. In that embodiment, the strand of the first rope can be bundled into 4 sets of 3 bundled strands, while the strands of the second rope can be bundled into 4 sets of 2 bundled strands. As such, the sets of bundled strands of both ropes can be tucked while following the natural construction patterns of the ropes. Similarly, if the first rope is a laid rope having 6 strands laid around a core, and the second rope is a braided rope having 12 strands, the ropes have 2 and 6 as common factors. The six strands of the first rope can remain unbundled, while the 12 strands of the second rope can be bundled into 6 sets of 2 bundled strands. The core can be separately included in the spliced as described herein below. And as described herein as well, the bundled strands are preferably neighboring strands and preferably bundled and twisted.

[0028] Preferably, the common factor is a suitable factor, meaning that it is sufficiently high enabling a high number of tucks and high number of crossings between the tucked-in strands. If the ropes have more than one common factor, preferably the highest factor is selected for the splice. Moreover, a factor of 2 is generally not suitable. If the first and second ropes have no suitable common factor, the strands of one or both ropes in the splice may be unraveled to the yarn or sub-stand level and reconstructed in new strands that allow a common factor. For instance, if the first rope is a laid rope having 6 strands laid around a core, and the second rope is a braided rope having 8 strands, the ropes only have a common factor of 2. In such embodiment, the 6 strands of the first rope can be unraveled to the yarn level and reconstructed into e.g. 8 or 4 new strands, followed by directly tucking (i.e. without bundling) the new strands into the second rope. Similarly, the 8 strands of the second rope can be unraveled to the yarn level and reconstructed into e.g. 6 or 3 strands, allowing directly tucking these strands into the first rope.

[0029] The first and second rope may each independently comprise a core around which the respective strands are constructed. In typical rope constructions, the core is not or very limited load bearing. Therefore, the tucking of the core is less important compared to the tucking of the strands. The core can be included in the splice by dividing the yarns of the core over the strands of the rope, by tucking the core in its entirety into the construction of the other rope (helical and / or longitudinal), or in case both ropes contain a core, the cores can be spliced separately.

[0030] Advantageously, the splice according to the present invention is relatively easy to construct because of its relatively short length. The splice may for example have an overall splice length of less than 240 times the diameter of the first and / or second rope. However, it may also be less than 180 times less than this diameter. For reasons of ease of construction, the splice is preferably as short as possible, for example less than 150 times, such as about 120 times or less than that with respect to the diameter of the first and / or second rope. However, for reasons of strength, the splice preferably has a minimal length of 100 times with respect to the diameter of the first and / or second rope, more preferably the splice has a length of more than 120 times the diameter of the first and / or second rope. Thus, in preferred embodiments, the splice has an overall splice length in the range of 100 to 240, more preferably 120 to 180, such as about 150 times the diameter of the first and / or second rope.

[0031] The helical section is preferably longer than the tapered sections taken together. Typically, the ratio between the length of the helical section and tapered sections is more than 1:1, preferably more than 3:2, more preferably 2:1 or more. In a typical embodiment, the first and / or second helical sections each independently have an overall splice length of less than 80 times the diameter of the first and / or second rope. Preferably, the first and / or second helical sections each independently have an overall splice length of less than 60 times, more preferably less than 50 times, most preferably about 40 times the diameter of the first and / or second rope.

[0032] Advantageously, the splice according to the present invention has a relatively small diameter. Typically, the diameter is maximally less than 1.7 times the diameter of the rope having the biggest diameter (and thus of both ropes if the first and second ropes have the same diameter). In preferred embodiments, the diameter of the splice is maximally less than 1.6 times, for example maximally in the range of 1.5 to 1.55 times the diameter of the rope having the biggest diameter (and thus of both ropes if the first and second ropes have the same diameter).

[0033] In a typical embodiment, the first and / or second tapered sections each independently have an overall splice length of less than 40 times, preferably less than 30 times, more preferably less than 25 times, most preferably about 20 times the diameter of the first and / or second rope.

[0034] The splice according to the present invention is particularly suitable to splice synthetic ropes and ropes based on high performance fibers. High performance fibers are known in the art for their high tenacities and low stretch (elongation at break). High performance fibers which preferably have a tenacity of at least 15 g / denier, more preferably at least 20 g / denier. The tenacities of commonly used fibers are known in the field; see for instance Handbook of Fibre Rope Technology by H. A. McKenna, J. W. S. Hearle and N. O’Hear, 2004, Woodhead Publishing Ltd. The high- performance fibers are preferably also characterized by a low elongation at break (typically lower than 3.5%). This is another favorable property for application in hoisting ropes, in particular deep-water ropes. Examples of high-performance fibers are fibers based on ultra- high molecular weight polyethylene (UHMWPE, e.g. available under the trade names Dyneema™ and Spectra™), (para-)aramids (e.g. available under the trade names Twaron™, Kevlar™ and Technora™), liquid crystal aromatic polyester (e.g. available under the trade name Vectran™), carbon- fibers and the like. The fibers may additionally comprise an overlay finish, as is for instance the case for Dyneema™ fibers comprising XBO which are available from Avient Corporation, USA.

[0035] The splice according to the present invention is particularly suitable to repair a damaged rope on site. Accordingly, in a particular embodiment, the first and second rope comprise an equal number of strands. In another embodiment, the first and second rope comprise a different number of strands.

[0036] Preferably, the first and second ropes each comprises 4 to 24 strands, preferably 12 strands. Each of these strands may be directly based on (twisted) yarns, but they may also be based on sub-strands (e.g. on three strands each). The first and second ropes may accordingly be a 12 strands rope or a 12x3 strand rope for example. Such ropes are commercially available as LANKOSDEEP-TW and LANKOSDEEP AHC from Lankhorst Euronete Portugal, S.A. The ropes may comprise a jacket, but this is not preferred.

[0037] A further aspect of the invention is directed to a method for providing the spliced synthetic rope. Said method comprises the steps of: i. aligning the first and the second rope and determining the splice center; ii. preparing the tails of the first and the second rope for splicing, comprising unraveling said tails until the splice center; iii. providing the first helical section by tucking one or more strands of the first rope in a helical pattern into the second rope; iv. providing the second helical section by tucking one or more strands of the second rope in a helical pattern into the first rope; v. providing the first tapered section by tucking one or more strands of the first rope in a helical pattern into the second rope and by cutting out part of the strand volume during said tucking. vi. providing the second tapered section by tucking one or more stands of the second rope in a helical pattern into the first rope and by cutting out part of the strand volume during said tucking; For the sake of clarity, the chronological order of the steps (ii-v) do not necessarily have to be carried out in the order as written above. Although typically, both ropes are first both unraveled and then both halves of the splice are constructed, it may be appreciated that first one halve or a part thereof is constructed before the other rope is unraveled. In addition, typically, first one halve of the splice is constructed followed by the construction of the other. Therefore, a typical chronological is step ii, followed by step iii and v, followed by step iv and vi or step ii, followed by step iv and vi, followed by step iii and v.

[0038] In step ii, the tails of the first and second rope are unraveled, typically up to the strand level of the ropes, meaning that the strands are not individually unraveled to separate yarns or sub-strand. In particular embodiments wherein the first and second ropes have a number of strands that lack a suitable common factor, as described herein-above, step ii comprises unraveling the tails of the first and second rope up to the yarn or sub-strand level, following by reconstructing the yarns into new strands. Unraveling up to the yarn level herein means that the strands are individually unraveled. It may be appreciated that unraveling may comprise unbraiding, unlaying and / or untwisting, depending on the original construction of the particular rope.

[0039] In case the diameters of the first and second rope are different, step ii further may further comprise adjusting the volume of one rope, typically of the thickest rope, as described herein-above, to match the strength of the other rope, and preferably the diameter of the other rope.

[0040] In a preferred embodiment, step iii comprises the steps of: iiia. bundling and optionally twisting together, preferably twisting together in a same lay direction as the individual strand orientation, two or more neighboring strands of the first rope; iiib. tucking the bundled and optionally twisted strands in a helical pattern into the second rope.

[0041] And similarly for step iv, which preferably comprises the steps of: iva. bundling and optionally twisting together, preferably twisting together in a same lay direction as the individual strand orientation, two or more neighboring strands of the second rope; ivb. tucking the bundled and optionally twisted strands in a helical pattern into the first rope.

[0042] Figures 1-6 illustrate a particular embodiment of the method for providing the spice rope with a 12 strand first and second rope.

[0043] Figures 1A illustrates step ii of unbraiding the rope’s tails up to the splice center as determined in step i (not shown). Figure IB illustrates marrying the strands by positioning four left-handed twisted strands alternate in opposite direction (uninterrupted lines), doing the same for the neighboring four right-handed twisted strands (dotted lines) and continuing this until all (24) strands are position in the same manner.

[0044] Figures 2A illustrates optional further steps of marking the first rope at sites BB and AA and the second rope at sites A and B. The first and second helical sections will run from the splice center to sites A and AA respectively, and each have a length of 40 times the diameter of the first rope (which in this case equals the diameter of the second rope). The first and second tapered sections will run from the sites A and AA to sites B and BB respectively, and each have a length of at least 10 times the diameter of the first rope (which equals the diameter of the second rope). Figures 2B illustrates the yet further preparative steps of labelling the individual strands. Left-hand and right-hand twisted strands of the second rope are labeled LHS#-A and RHS#-A respectively, while left-hand and right-hand twisted strands of the first rope are labeled LHS#-B and RHS#-B respectively. These optional steps as illustrated in Figures 2A and 2B are included in this description for the sake of clarity. However, in practice, these preparative steps may be skipped by an experienced splicer.

[0045] Figures 3A-3C illustrate the optional steps of twisting together two neighboring strands of the second rope (step iv-b) in a same lay direction as the individual strand orientation (similar to Lang lay).

[0046] Figures 4A-4C illustrate the construction of the second helical section in step iv, that comprise tucking the bundled and optionally twisted strands of the second rope in a helical pattern into the first rope. As illustrated in Figure 4A, the set of bundled and twisted strands labelled RHS1 / 2-A follows the closest position strand in the first rope and the set is tucked into a left-hand helical pattern (following the over two and under two pattern) in the construction of the first rope until site AA is reached. Thus, as illustrated, the tucking comprises tucking the strands of the second rope respectively at least 10 times, preferably at least 15 over two and under two or more strands of the first rope in a helical pattern following the closest position strand of said second rope respectively with a handedness that is contrary to the handedness of the strands that are being tucked. Similarly, illustrated in Figure 4B, the set of bundled and twisted strands labelled LHS1 / 2-A follows the closest position strand in the first rope and the set is tucked into a left-hand helical pattern (following the over two and under two pattern) in the construction of the first rope until site AA is reached. This is to be continued for the other strands as well (Figure 4C).

[0047] Figures 5A-5C illustrate the construction of the second tapered section in step vi, that comprises providing the second tapered section by tucking one or more stands of the second rope in a helical pattern into the first rope and cutting out part of the strand volume during said tucking. As illustrated in Figure 5 A, about 1 / 3 of the original total strand volume of the set of bundled and twisted strands labelled RHS1 / 2-A is cut out and this set is further tucked into the first rope construction following the same helical pattern as in step iv, as illustrated in Figure 4A. When approaching mark BB, until one more tuck can be made, again about 1 / 3 of the original strand volume is cut out and the final tuck is made. Figure 5B shows the similar procedure for the set of bundled and twisted strands labelled RHS1 / 2-A. This is to be continued for the other strands as well (Figure 5C).

[0048] The above steps iv and vi are to be repeated for the strands of the first rope LHS-1B to LHS-6B and RHS-1B to RHS-6B as well. The resulting splice, before the remaining splice end tails are cut off, is illustrated in Figures 6A-6C. After the splice is bedded in, the remaining splice end tails can be cut off along the rope body. Figure 6A schematically illustrates the entire splice, as also depicted in the photographic Figure 6B. Figure 6C schematically shows a portion of the helical section.

[0049] The spliced rope of the present invention is particularly suitable for CBOS applications such as hoisting and lifting under various conditions. For instance, for lifting load over long distances, of a few hundred meters to several kilometers or for marine and offshore for deep water mooring, deepwater lifting and the like. Hence, a particular aspect of the present invention is the use of the spliced rope of the present invention for these applications. An aspect is according a method comprising using the spliced rope of the present invention in CBOS applications. Another aspect is a method comprising lifting and / or mooring, preferably deep-water mooring and / or deep-water lifting, of a load and / or vessel with the spliced rope of the present invention.

[0050] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and / or" includes any and all combinations of one or more of the associated listed items. It will be understood that the terms "comprises" and / or "comprising" specify the presence of stated features but do not preclude the presence or addition of one or more other features.

[0051] For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

[0052] The invention can be illustrated by the following non-limiting examples.

[0053] Example 1:

[0054] A braided rope produced from a high-performance fiber, Dyneema DM20 XBO from Avient, with a nominal diameter of 28 mm, a specified MBF of 545 kN and a 12x3 construction was spliced using the current invention. In particular, the tails were unraveled until strand level at a length of 75 times the rope diameter (abbreviated as xd’). Next, strands bundled and twisted together in pairs, the resulting sets of strands were tucked in in a helical pattern over a length of 40xd (in both directions) and then tapered in two steps of 1 / 3 of the fiber volume and tucked over a length of 20xd in a helical pattern (in both directions.) The overall spliced length was about 120xd.

[0055] Figures 6B and 6C show the splices obtained, respectively in its entirety and a part of its helical section.

[0056] Three tensile test samples were produced from this rope with a splice as described in the current invention which was placed in the middle of the tensile test sample. The tensile test showed an average breaking force of 571 kN, or an efficiency higher than 100 %. Example 2:

[0057] A braided rope as described in Example 1 was spliced using the splice procedure described in WO 2013 / 134033. The rope was spliced as follows with references in brackets to EP2822887B1 (description is provided for one end, but both ends are spliced in the same manner):

[0058] • rope end strands were divided in 6 rope sets of 2 strands (Fig. 5, page 18);

[0059] • one end is buried in the core of the other end, for a minimal of 6 strands (Fig. 6, page 19);

[0060] • all 6 strand sets are lx tucked under 2 construction strands (Fig. 7, page 20);

[0061] • the strands of 3 sets are tucked 2 times over 1 under 1 construction strand, in a longitudinal direction (Fig. 8, page 21);

[0062] • the strands of the other 3 sets are tucked 3 times, in a helical direction (Fig. 10, page 23);

[0063] • the previous helical spliced strands are now longitudinal tucked for 2 times, over 1 under 1 (Fig. 11, page 24);

[0064] • the previous longitudinal spliced strands are now tucked in a helical direction for 3 tucks (Fig. 14, page 27);

[0065] • all strands are now tucked for 4 times, over one, under one (Fig. 16, page 29);

[0066] • finally, the strands-ends are buried in the core of the construction.

[0067] The resulting spliced rope, as well as the rope obtain in Example 1, were tested in a CBOS test machine with a load applied of 180 kN or 33 % of the MBF and a sheave rotation speed of 1 meter per second and a sheave diameter of 800 mm. The displacement versus rotation cycle plot is included as Figure 7. The rope spliced according to the procedure disclosed in WO 2013 / 134033 identified as Splice A shows a much higher displacement rate taken as the slope of the displacement curve in the steady state regime. The displacement rate for Splice A is more than 10 times the displacement rate of Example 1, which is identified as Splice B. Also, it can be seen from the plot that the time to failure of splice B is significantly higher than that of splice A. This shows the significant improvement in splice stability obtained with this invention versus the state of the art.

[0068] Example 3:

[0069] A braided rope produced from a high-performance fiber, Dyneema DM20 XBO from Avient, with a nominal diameter of 68mm, an MBF of 2912 kN and a 12x3 construction was joined using the splice procedure described in the current invention together with another braided rope produced from a high-performance fiber, Dyneema DM20 XBO from Avient, with a nominal diameter of 88mm, an MBF of 4590 kN and a 12x3 construction. Figure 8 shows the ropes being readied for joining at step i of the procedure here disclosed. The spliced ropes were tested using a standardized splice integrity test according to DNV-RP-E305 with a higher load level applied of 1456 kN which is 50% of the MBF of the weaker rope. The splice held fast for the test which ran for more than 24000 cycles showing an excellent splice stability under this demanding test conditions. After the cyclic test a residual strength test was carried out to ascertain the efficiency of the splice which showed a breaking load of the joined ropes of 3630 kN.

Claims

Claims1. Spliced synthetic rope comprising:- a first rope comprising a first plurality of strands;- a second rope comprising a second plurality of strands; and- a splice connecting the first and second rope, which splice comprises a splice center; wherein the splice comprises at least a helical section that comprises a first and a second helical section, and two tapered sections positioned at either side of the helical section and at either ends of the splice; wherein the first helical section comprises one or more strands of the first rope that are tucked in a hehcal pattern into the second rope and wherein the second helical section comprises one or more strands of the second rope that are tucked in a helical pattern into the first rope; and wherein the tapered sections comprise a first and second tapered section that respectively comprises one or more of strands of the first and second rope that are tucked in a hehcal pattern into the second and first rope respectively, which strands have a decreasing volume in the direction of away from the splice center.

2. Spliced rope according to the previous claim, wherein the strands that are tucked in a helical pattern are bundled in sets of two or more neighboring strands.

3. Spliced rope according to any of the previous claims, wherein the strands that are tucked in a helical pattern are bundled and twisted together in sets of two or more neighboring strands, preferably twisted together in a same lay direction as the individual strand orientation.

4. Spliced rope according to any of the previous claims, wherein the one or more strands of the first rope that are tucked in the first helical section in a helical pattern comprise at least 10, preferably at least 15 helical tucks over and under the strands of the second rope and / or wherein the one or more strands of the second rope that are tucked in the second helical section in a helical pattern comprise at least 10, preferably at least 15 helical tucks over and under the strands of the first rope.

5. Spliced rope according to any of the previous claims, wherein the one or more strands of the first rope that are tucked in the first tapered section in a helical pattern comprise at least 5, preferably at least 7 helical tucks over and under the strands of the second rope and / or wherein the one or more strands of the second rope that are tucked in the second tapered section in a helical pattern comprise at least 5, preferably at least 7 helical tucks over and under strands of the first rope.

6. Spliced rope according to any of the previous claims, wherein the helical patterns in which the one or more strands of the first and second ropes are tucked in the helical and / or tapered sections have an orientation that is opposite to the orientation of the twist of the yarn on which the respective strand is based and optionally opposite to the orientation twist of the sets of two or more neighboring strands that are twisted in accordance with claim 3.

7. Spliced rope according to any of the previous claims wherein one or more strands of the first and second ropes that are tucked in the helical and / or tapered sections in the second and first ropes respectively, each lay against, preferably next to, a respective neighboring strand of the second and first ropes respectively thereby following the original construction pattern of the second and first ropes respectively.

8. Spliced rope according to any of the previous claims, wherein the strands of the first and / or second rope that are tucked in the first and / or second tapered sections have a reducing strand volume in steps of at least 1 / 25, preferably in steps of at least 1 / 10, more preferably in steps of at least 1 / 5, most preferably in steps of at least 1 / 3 of the original strand volume.

9. Spliced rope according to any of the previous claims, wherein the splice has an overall splice length of less than 240 times, preferably less than 180 times, more preferably less than 150 times, most preferably about 125 times the diameter of the first and / or second rope.

10. Spliced rope according to any of the previous claims, wherein the first and / or second helical sections each independently have an overall splice length of less than 80 times, preferably less than 60 times, more preferably less than 55 times the diameter of the first and / or second rope.

11. Spliced rope according to any of the previous claims, wherein the first and / or second tapered sections each independently have an overall splice length of less than 40 times, preferably less than 30 times, more preferably less than 25 times, most preferably about 10 to 20 times the diameter of the first and / or second rope.

12. Spliced rope according to any of the previous claims, wherein the first and second rope independently comprise 4 to 24 strands, preferably 12 strands.

13. Spliced rope according to any of the previous claims, wherein the first and second ropes have the same rope diameter or different rope diameters.

14. Spliced rope according to any of the previous claims, wherein the first and the second ropes have a different individual number of strands.

15. Method for providing a spliced synthetic rope in accordance with the previous claims, said method comprising the steps of: i. aligning the first and the second rope and determining the splice center; ii. unraveling the tails of the first and the second rope until the splice center; iii. providing the first helical section by tucking one or more stands of the first rope in a helical pattern into the second rope; iv. providing the second helical section by tucking one or more stands of the second rope in a helical pattern into the first rope; v. providing the first tapered section by tucking one or more stands of the first rope in a helical pattern into the second rope and by cutting out part of the strand volume during said tucking; vi. providing the second tapered section by tucking one or more stands of the second rope in a helical pattern into the first rope and by cutting out part of the strand volume during said tucking.

16. Method according to claim 15, wherein the first and the second ropes have different rope diameters, and wherein step ii comprises adjusting the volume of the thickest rope, preferably by tapering said rope, to preferably match the strength of the other rope and / or wherein step ii comprises unraveling the tails of the first and the second rope until the splice center up to the yarn or sub-strand level.

17. Method according to any of claims 15-16, wherein step iii comprises the steps of:iiia. bundling and optionally twisting together, preferably twisting together in a same lay direction as the individual strand orientation, two or more neighboring strands of the first rope; iiib. tucking the bundled and optionally twisted strands in a helical pattern into the second rope.

18. Method according to any of claims 15-17, wherein step iv comprises the steps of: iva. bundling and optionally twisting together, preferably twisting together in a same lay direction as the individual strand orientation, two or more neighboring strands of the second rope; ivb. tucking the bundled and optionally twisted strands in a helical pattern into the first rope.

19. Method according to any of claims 15-18, wherein the tucking in steps iii and / or iv comprises tucking the strands of the first and / or second rope respectively at least 10 times, preferably at least 15 over and under the strands of the second and / or first rope respectively, in a helical pattern following the closest position strand of said second and / or first rope respectively, preferably in a helical pattern with a handedness that is contrary to the handedness of the strands that are being tucked.

20. Method according to any of claims 15-19, wherein the tucking in steps v and / or vi comprises tucking the strands of the first and / or second rope respectively at least 5 times, preferably at least 7 over and the strands of the second and / or first rope respectively, in a helical pattern following the closest position strand of said second and / or first rope respectively, preferably in a helical pattern with a handedness that is contrary to the handedness of the strands that are being tucked, more preferably in a helical pattern that is the same as the helical pattern in step iii and / or iv, respectively.

21. Method according to any of claims 15-20, wherein the tucking and cutting in steps v and / or vi comprises cutting out at least 1 / 25 of the original strand volume at the start of the first and / or second tapered section respectively, followed by tucking the remaining strands into the second and / or first rope respectively, followed by one or more additional steps of cutting out at least 1 / 25 of the original strand volume before one more tuck of the remaining strands can be made, followed by tucking the remaining strands into the second and / or first rope respectively, optionally followed by cutting off the remaining strand ends along the rope body.

22. Use of the spliced rope according to any of claims 1-14 in a CBOS application.

23. Use of the spliced rope according claim 22, wherein the CBOS application comprises deep-water mooring, deep-water lifting or the like.

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