Submarine line clamp assembly

Abstract

A subsea line clamp assembly (1) is provided. The subsea line clamp assembly (1) includes a body (10) having an axis and a clamping member (50), which are assembled in segments around a subsea line (3) and anchored to a subsea anchor (5). The clamping member (50) is movably positioned within the body (10). The inner surface of the body (10) and the outer surface of the clamping member (50) have respective tapered portions as part of teeth (32, 72) arranged to engage with each other. Adjacent teeth (32, 72) may be separated by parallel axial portions. The clamping force on the subsea line (30) can be maintained over the service life of the subsea line (3) despite creep and compression actions that reduce the outer diameter of the line (3).

Description

Technical Field

[0001] This application relates to a subsea line clamp assembly adapted to rigidly secure a submerged line, such as a riser conduit, to a subsea anchor, such as a suction pile.

Background Art

[0002] In the production of oil or gas from a subsea well, the production fluid is generally recovered from the well to the sea surface via a production string housed in a riser extending from the sea surface to the seabed. The riser can generally be connected to a floating production storage and offloading facility (FPSO) at the sea surface and to a subsea manifold, such as a wellhead, by a riser conduit, such as a flowline, at the seabed.

[0003] Patent Document 1, Patent Document 2, and Patent Document 3 disclose clamp assemblies useful for understanding the present invention.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0005] According to the present invention, there is provided a subsea line clamp assembly comprising a body having an axis and a clamp member, the body comprising at least two segments adapted to be assembled around a subsea line, the body having an anchor attachment point adapted to moor the body to a subsea anchor, The clamp member is movable relative to the body and has an outer surface adapted to engage the inner surface of the body and an inner surface adapted to engage the subsea line within the subsea line clamp assembly. The inner surface of the body has at least one first tapered portion. The outer surface of the clamp member has at least one second tapered portion arranged to engage the first tapered portion on the inner surface of the body.

[0006] The subsea line can comprise a conduit such as a riser conduit, for example a conduit adapted to connect to a riser or a flowline or other pipe such as a riser. Optionally, the subsea line can be a cable or other line that does not necessarily comprise a conduit. Optionally, the subsea line can be a tether for a floating installation such as a ship or a floating wind turbine or a wave energy generator.

[0007] Optionally, the tapered portions can form part of a repeating pattern on the body and the clamp member. This pattern can optionally include a serrated pattern formed by teeth. Optionally, each tooth has a first face and a second face. Optionally, each first face is tapered and optionally the tapered portion is formed on the first face. Optionally, each second face is perpendicular to the axis of the body or is tapered at a steeper angle than the first face. Optionally, the first face on the body engages the first face on the clamp member and the first faces on the body and the clamp member optionally face the opposite ends of the subsea line clamp assembly.

[0008] Optionally, each first tapered portion on the body forms part of a tooth and extends radially inwardly towards the clamping member from an outer radial position spaced from the axis of the body to an inner radial position closer to the axis of the body to form a first face that forms the first tapered portion, and a second face that extends radially outwardly so as to return from the inner radial position to the outer radial position with respect to the axis of the body. Optionally, adjacent teeth on each of the bodies are separated by an axially parallel portion of the inner surface of the body arranged parallel to the axis of the body. Optionally, the axially parallel portion extends between adjacent teeth, for example, between a second portion of one tooth and a first portion of an adjacent tooth, and optionally between the end of the first face and the start of the second face. The axially parallel portion is generally on the crest between the teeth that is radially close to the axis of the body, optionally at an inner radial position. Optionally, the teeth of the body are identical.

[0009] Optionally, each second tapered portion on the clamping member forms part of a tooth and extends radially inwardly towards the hole of the clamping assembly from an outer radial position with respect to the axis of the body to an inner radial position closer to the axis to form a first face that forms the tapered portion, and a second face that extends radially outwardly so as to return from the inner radial position to the outer radial position with respect to the axis of the body. Optionally, the second face is perpendicular to the axis. Optionally, adjacent teeth on the clamping member are separated by an axially parallel portion of the clamping member arranged parallel to the axis of the body. Optionally, the axially parallel portion extends between adjacent teeth, for example, between a second portion of one tooth and a first portion of an adjacent tooth, and optionally between the end of the second face and the start of the first face. The axially parallel portion is generally in the valley between the teeth that is radially close to the axis of the body, i.e., at an inner radial position. Optionally, the teeth of the clamping member are identical. Optionally, the axially parallel portions on the body and the clamping member at least partially overlap in the direction along the axis of the body.

[0010] Optionally, the clamp member is movable radially with respect to the body. Optionally, the clamp member is movable axially with respect to the body, optionally in only one direction. Optionally, the clamp member is movable both radially and axially with respect to the body. When the first tapered portion and the second tapered portion engage, the axial movement of the clamp member in the first direction generally biases the clamp member radially with respect to the body, e.g., inwardly from the body, against the subsea line. Optionally, the second surface on the body engages the second surface on the clamp member, and the second surfaces on the body and the clamp member optionally face the opposite ends of the subsea line clamp assembly. Optionally, the engagement of the second surfaces resists the axial movement of the clamp member in the second direction with respect to the body. During the axial movement of the clamp member in the first direction with respect to the body, the sliding of the first tapered surface and the second tapered surface relative to each other biases the inner surface of the clamp member against the outer surface of the subsea line. Optionally, the maximum range of axial movement of the clamp member in the first direction with respect to the body between the first position where the second surface of the tapered portion of the clamp member engages the second surface of the tapered portion of the body and the second position where the second surface of the clamp member is axially most spaced from the second surface of the body corresponds to 5% to 15% (optionally 8% to 12%) of the axial dimension of the first tapered portion and the second tapered portion.

[0011] Optionally, the subsea line clamp assembly is adapted to hold an axial load on the subsea line that exceeds 50 tons, optionally exceeds 100 tons, optionally exceeds 200 tons.

[0012] Optionally, the inner surface of the body has two or more teeth, optionally an array of teeth. Optionally, the tapered portion is annular and extends around at least a portion of the inner surface of the clamping member. Optionally, the inner surface of the body with the first tapered portion is formed on a separate component that is attached to another component and can form the body. Optionally, the outer surface of the clamping member has two or more teeth, optionally an array of teeth. Optionally, the teeth are annular and extend around at least a portion of the outer surface of the clamping member. Optionally, the outer surface of the clamping member with the second tapered portion is formed on a separate component that is attached to another component and can form the clamping member. Optionally, the first tapered portion and the second tapered portion are tapered at the same angle with respect to the axis of the body.

[0013] The radial depth of the tapered portion can be varied for different embodiments. Optionally, the radial depth of at least one of the first tapered portion and the second tapered portion (e.g., the distance between the maximum and minimum radial values of the tapered portion) is greater than the maximum radial deflection of the subsea line over the service life of the subsea line. The outer diameter of the subsea line may decrease as the water depth increases and / or may decrease depending on environmental conditions and / or may naturally decrease over time, e.g., due to creep. The decrease in the outer diameter of the subsea line may be mainly due to the shrinkage of the insulation layer on the outer surface of the riser conduit. A large radial depth of the first tapered portion and the second tapered portion is optionally useful for subsea lines with a high compression coefficient, and a small radial depth is optionally useful for subsea lines made of a rigid material with a low compression coefficient. The maximum range of radial deflection, e.g., the maximum range of the outer diameter of the subsea line over the service life of the subsea line, may be quantifiable or may be known parameters of the material used for the subsea line or its insulation. Optionally, the radial depth of the first tapered portion and the second tapered portion is greater than the maximum predicted shrinkage of the outer diameter of the subsea line over the service life of the subsea line. Optionally, the radial depths of the first tapered portion and the second tapered portion are substantially equal.

[0014] Optionally, the radial force applied to the outer surface of the subsea line by the inner surface of the clamp member is related to the angle of the tapered portion with respect to the axis of the body. Optionally, the angle of the tapered portion with respect to the axis of the body is in the range of 45° to 3°, optionally 25° to 5°, optionally 15° to 10°. In some embodiments, an angle of 3° to 15° is particularly useful.

[0015] Optionally, the axial lengths of the first tapered portion and the second tapered portion are related, optionally in a direction parallel to the axis of the body, to the respective angles of the first tapered portion and the second tapered portion, and optionally to the respective radial depths of the first tapered portion and the second tapered portion. Optionally, the axial lengths of the first tapered portion and the second tapered portion depend on, and are optionally determined by, both the angles and the radial depths of the first tapered portion and the second tapered portion.

[0016] Optionally, the clamp member is segmented. Optionally, the clamp member can comprise three longitudinal segments, although in some cases two may be sufficient. In addition to being divided longitudinally, the clamp member can optionally be divided circumferentially, optionally into two axial sections, optionally into three, four, five or more axial sections. Optionally, the axial lengths of the axial sections of the clamp member are substantially equal. Optionally, each axial section of the clamp member can comprise an integer number of tapered portions, optionally two, three or more tapered portions.

[0017] Optionally, the body can comprise three longitudinal segments, although in some cases two may be sufficient. Also, the body can be divided circumferentially, optionally into two axial sections, optionally into three, four, five or more axial sections. Optionally, the axial lengths of the axial sections of the body are substantially equal. Optionally, each axial section of the body can comprise an integer number of tapered portions, optionally two, three or more tapered portions.

[0018] Optionally, each axial section of the clamp member has the same number of tapered portions as each axial section of the body. Optionally, the axial length of each axial section of the clamp member is shorter than the axial length of each axial section of the body. Optionally, the axial sections of the body are connected to each other by fasteners, optionally bolts. Optionally, each fastener extends over the axial length of the entire body.

[0019] Optionally, the clamp member can be fixed to the body (e.g., one or more body segments) during installation of the clamp assembly over the subsea line, but can be released from the body after installation and can be moved relative to the body during operation. Optionally, the clamp member and the body are divided into the same number of segments in the direction along the axis, and each body segment has a respective clamp member segment. Optionally, the angular dimension of the body segment is larger than that of the clamp member segment. Optionally, the angular dimension of each body segment is larger than that of the respective clamp member segment. Optionally, when the body segments are assembled, the clamp member segments are spaced apart along the axis of the body. Optionally, the body segments are adapted to be fixed to each other by threaded fixtures such as bolts.

[0020] Optionally, the inner surface of the clamp member includes a high-friction material. Optionally, the inner surface of the clamp member is formed or provided with a pattern such as ridges or grooves that increase the coefficient of friction of the inner surface of the clamp member. Optionally, the inner surface of the body and the outer surface of the clamp member are coated or formed with a low-friction material such as PTFE, etc., whereby the friction between the inner surface of the body and the outer surface of the clamp member is lower than the friction between the inner surface of the clamp member and the outer surface of the subsea line.

[0021] Optionally, the outer surface of the clamp member and the inner surface of the body incorporate a stop member that limits the axial movement of the clamp member in a second direction opposite to the first direction. Optionally, the stop member can comprise a second face of teeth.

[0022] Optionally, the clamp member is pre - biased or pre - loaded either after the subsea line has been received within the hole of the clamp assembly and before the subsea line applies an axial load to the clamp assembly, or before the subsea line applies an axial load to the clamp assembly. Optionally, when the clamp member is pre - biased, before the subsea line applies an axial load to the clamp assembly and when there is no large axial load on the clamp assembly, the clamp member applies a radial force, optionally a minimum radial force, to the outer surface of the subsea line.

[0023] Optionally, the clamp member is pre - biased by one or more fixtures, optionally fasteners, optionally bolts. Optionally, the one or more fixtures are axially oriented and optionally urge the clamp member to move axially in a first direction relative to the body. Optionally, by the one or more fixtures, the clamp member applies an increased radial force to the outer surface of the subsea line. Optionally, the one or more fixtures extend axially through an end face of the body and optionally engage an end face of the clamp member. Optionally, one or more openings, optionally circumferentially disposed around the end face of the body, are adapted to receive one or more fixtures for pre - biasing the clamp member.

[0024] Optionally, the inner surface of the body, optionally the inner surface of the body segment, is radially spaced from the outer surface of the subsea line. Optionally, the radial dimension of the clamp member, optionally the radial dimension of the clamp member segment, is equal to or optionally greater than the radial spacing between the body and the subsea line. Optionally, when the radial dimension of the clamp member is greater than the radial dimension of the radial spacing between the body and the subsea line and optionally when the radial dimension of the clamp member is 100% - 110% of the radial spacing between the inner surface of the body and the outer surface of the subsea line, the clamp member is pre - biased.

[0025] Optionally, the body is formed from metal, optionally steel. Optionally, the clamp member is formed from metal, optionally steel. Optionally, the body, or optionally the clamp member, can be formed from a non-metallic material, optionally a composite material, such as a fiber-reinforced plastic or a fiber-reinforced polymer (FRP) or a carbon fiber-reinforced polymer and other composite materials.

[0026] The present invention also provides a subsea line clamp assembly comprising a body and a clamp member. The body has an axis and is divided into segments adapted to be assembled around the subsea line. The body has an anchor attachment point adapted to moor the body to a subsea anchor. The clamp member has an outer surface adapted to engage the inner surface of the body, extending circumferentially around the outer surface of the clamp member, and an inner surface adapted to engage the subsea line within the subsea line clamp assembly. When the subsea line clamp assembly is assembled around the subsea line, at least one segment of the clamp member is movable radially and axially relative to the body. The inner surface of the body has a plurality of first tapered portions. The outer surface of the clamp member has a plurality of second tapered portions arranged to engage the first tapered portions on the inner surface of the body while the clamp member moves relative to the body. The first tapered portion and the second tapered portion face both ends of the subsea line clamp assembly. When the first tapered portion and the second tapered portion engage, the clamp member moves axially in a first direction relative to the body, thereby biasing the inner surface of the clamp member radially inward relative to the body.

[0027] The present invention also provides a method of clamping a subsea line, including the step of assembling a subsea line clamp assembly on the outer surface of the subsea line. The subsea line clamp assembly comprises a body and a clamp member. The body has an axis and is divided into segments adapted to be assembled around a subsea line. The body has an anchor attachment point adapted to moor the body to a subsea anchor. The clamp member has an outer surface adapted to engage an inner surface of the body extending circumferentially around the outer surface of the clamp member, and an inner surface adapted to engage a subsea line within a subsea line clamp assembly. When the subsea line clamp assembly is assembled around the subsea line, at least one segment of the clamp member is movable radially and axially relative to the body. The inner surface of the body has a plurality of first tapered portions. The outer surface of the clamp member has a plurality of second tapered portions arranged to engage the first tapered portions on the inner surface of the body while the clamp member moves relative to the body. The first tapered portion and the second tapered portion face both ends of the subsea line clamp assembly. The friction between the inner surface of the body and the outer surface of the clamp member is lower than the friction between the inner surface of the clamp member and the outer surface of the subsea line. When the first tapered portion and the second tapered portion engage, the clamp member moves axially in a first direction relative to the body, biasing the inner surface of the clamp member radially inwardly relative to the body and against the outer surface of the subsea line.

[0028] One advantage resulting from combining the configurations in some embodiments of the present invention is that, in addition to applying a clamping force onto the subsea line when initially assembled around the subsea line, embodiments of the present assembly are able to stably maintain the clamping force over the service life of the subsea line, despite creep and compression effects acting to reduce the outer diameter of the conduit. The reduction in the outer diameter of the subsea line occurs naturally over time as the outer layer of the insulation material gradually deteriorates or compresses, or as a result of creep due to tension. As this reduction progresses, the first tapered portion and the second tapered portion slide relative to each other, enabling the clamping force to be maintained relatively stably with respect to the outer diameter of the conduit. Thus, even as the outer diameter of the subsea line decreases over its service life, the clamping force does not decrease to the same extent. This advantage enables the performance of the clamp to be stabilized over the service life of the subsea line, reducing the risk of uncontrolled hydrocarbon leakage from connections between the subsea line and manifolds such as pipeline terminations, or through such connections.

[0029] As will be understood by those skilled in the art, the various aspects of the present invention can be implemented alone or in combination with one or more of the other aspects. The various aspects of the present invention can optionally be provided in combination with any one or more of the configurations of any other aspect of the present invention. Also, any configuration described with respect to one aspect can generally be combined alone or together with other configurations in different aspects of the present invention. Any subject matter described herein can be combined with any other subject matter herein to form novel combinations.

[0030] Various aspects of the present invention will be described in detail below with reference to the accompanying drawings. Further other aspects, configurations and advantages of the present invention will be readily apparent from the entire description of the present invention, including the figures showing numerous exemplary aspects and implementations. The present invention is capable of other different embodiments and aspects, and some of its details can be modified in various respects without departing from the scope of the present invention. Therefore, each example in this specification should be understood to have a wide range of applications, and there is no intention to suggest that the scope of the present disclosure, including the claims, is limited to those examples, meaning that it illustrates one possible way of implementing the present invention. Furthermore, the technical terms and expressions used in this specification are for illustrative purposes only and should not be construed as limiting the scope. In particular, unless otherwise stated, the dimensions and numerical values included in this specification are presented as examples showing one possible aspect of the claimed subject matter without being limited to the specific dimensions or values listed herein. All numerical values in the present disclosure are understood to be modified by "about". All singular forms of the elements described in this specification, or any other components, are understood to include their plural forms, and vice versa.

[0031] Terms such as "including", "comprising", "having", "containing", or "involving" and their variations are intended to broadly encompass the subject matter recited thereafter, equivalents, and additional subject matter not recited, and are not intended to exclude other additional elements, components, integers, or steps. Similarly, the term "comprising" is considered synonymous with the terms "including" or "containing" for the purposes of applicable legal requirements. Accordingly, throughout this specification and the claims, unless the context requires otherwise, the word "comprising", or variations such as "comprises" or "comprising", is not to be taken to mean excluding other integers or groups of integers while including the recited integer or group of integers.

[0032] Any discussion of a document, act, material, device, article, etc. is included in this specification solely for the purpose of providing background to the present invention. It is not suggested or indicated that any or all of these matters formed part of the basis of the prior art or were common general knowledge in the field relevant to the present invention.

[0033] In the present disclosure, whenever there is a transitional phrase "comprising" before a composition, element or group of elements, it is understood that the same composition, element or group of elements having a transitional phrase "consisting essentially of", "consisting of", "selected from the group consisting of", "including" or "is" before the listing of the composition, element or group of elements is also contemplated, and vice versa. In the present disclosure, the words "typically" or "optionally" are present in a particular embodiment, which is to be understood as intended to indicate an optional or non-essential configuration of the present invention that can be omitted in other embodiments without departing from the scope of the present invention.

[0034] References to directions and positions such as above and below, and directions such as "up" and "down" should be interpreted by those skilled in the art in the context of the embodiments described for the purpose of indicating the orientation of the configurations shown in the drawings, and should not be construed as limiting the present invention to a literal interpretation of the terms, but rather should be understood by those skilled in the art.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0036] Referring now to the drawings, a first embodiment in which the subsea line clamp assembly 1 is installed is illustrated in FIG. 1a. The subsea line is in the form of a riser conduit or flow line 3 (which may be a separate pipe adapted to connect to the riser 4 or may simply be an extension of the riser 4) and extends along the seabed between a floating production storage and offloading facility (FPSO) and a pipeline end termination (PLET) such as a wellhead. The FPSO may be prone to movement, for example, due to wave action, swell or weather conditions. Generally, even if the FPSO moves towards the PLET, it can be adjusted by the buoyancy section of the riser 4 connecting the flow line 3 to the FPSO. However, if the FPSO moves significantly away from the PLET, the flow line 3 can be stretched, causing tension, strain or even severance of the flow line from the PLET. Thus, movement of the flow line 3 away from the PLET is restricted by the subsea line clamp assembly 1. This subsea line clamp assembly 1 is secured or moored by cables or chains 6a, 6b to one or more (typically two) anchor devices such as the suction piles 5a, 5b seen in FIG. 1b.

[0037] The appearance of the riser clamp assembly 1 according to the first embodiment of the present invention is shown in FIGS. 2a and 2b. The riser clamp assembly 1 generally comprises a cylindrical conduit having a hole 1b with an axis X. As will be explained in more detail below, the riser clamp assembly comprises a body 10 and a clamp member 50 arranged inside the body 10. Only the body 10 is visible in FIGS. 2a and 2b. The body 10 is generally cylindrical and, in this embodiment, comprises three equal longitudinal segments 20a, 20b, 20c as seen in FIG. 2a. The partitions between the segments 20a, 20b, 20c are arranged at approximately equal intervals around the outer periphery of the body 10 and are parallel to the axis X of the hole 1b of the riser assembly 1. In other embodiments, the body 10 may comprise less than three segments, for example only two segments, or there may be more than three segments, and the partitions between the segments need not be regularly spaced around the outer periphery of the body 10 and need not be parallel to the axis X of the hole 1b.

[0038] As shown in FIGS. 2a and 2b, one or more eye plates are arranged on the outer surface 22 of the body 10. In this embodiment, one or more first eye plates 18 are optionally adapted to connect to one or more buoyancy modules 7. The buoyancy module 7 also supports the weight of the riser clamp assembly 1 and optionally the weight of the ends of the cables or chains 6a, 6b closest to the riser assembly 1. In other words, the combined riser clamp assembly 1 and buoyancy module 7 are substantially neutrally buoyant or slightly negatively buoyant, and the buoyancy module optionally prevents the riser clamp assembly 1 from sinking or settling into a substance on the seabed such as mud or sediment.

[0039] Also, in this embodiment, second eye plates 19a, 19b are also arranged on the outer surface 22 of the body 10. The eye plates 19a, 19b are adapted to connect to the chains 6a, 6b that moor the riser clamp assembly 1 to the suction piles 5a, 5b as shown in FIG. 1b.

[0040] As best seen in FIGS. 3a and 3e, the inner surface 23 of the body 10 closest to the FPSO is recessed (e.g., counterbored) along most of the axial length of the body. A radial shoulder 28 is formed on the inner surface 23 of the body 10 adjacent to the end of the body 10 closest to the PLET. In this embodiment, the depth or radial dimension of the shoulder 28 is approximately equal to the wall thickness of the clamp member 50, so the inner diameter of the clamp member 50 is approximately equal to and continuous with the inner diameter of the body 10 adjacent to the recess of the body 10. In other words, in this embodiment, the inner diameter of the hole 1b of the riser clamp assembly 1 is substantially constant along the entire axial length of the riser clamp assembly.

[0041] Each of the outer segments 20a, 20b, 20c of the body 10 (seen in FIG. 3d) is shown in detail in FIGS. 4a - 4d. The inner surface 23 of the recess of each segment 20a, 20b, 20c comprises a plurality of annular tapered portions 30, although one would be sufficient. When the segments 20a, 20b, 20c of the body 10 are assembled as shown in FIGS. 2a and 2b, each tapered portion 30 tapers from the larger inner diameter of the body 10 towards the smaller inner diameter. The maximum inner diameters of the annular tapered portions 30 are all approximately equal, and the minimum inner diameters of the annular tapered portions are also approximately equal. The maximum inner diameter of each tapered portion is disposed immediately adjacent to the minimum inner diameter of the next tapered portion, and vice versa. In this embodiment, the taper of each tapered portion 30 is constant, or in other words, the inner surface of each tapered portion forms a constant angle with respect to the axis X of the hole 1b of the riser clamp assembly 1. Also, in this embodiment, the inner surface 23 also comprises a small optional axially parallel portion 31 (best seen in FIG. 4d) adjacent to the minimum inner diameter of each tapered portion, i.e., at the peak between adjacent teeth. The axially parallel portion 31 can be formed to allow for manufacturing tolerances in the formation of the "peaks" of the minimum inner diameter of each of the annular tapered portions 30 in order to ensure a stable engagement between the tapered portion 30 of the body 10 and the tapered portion 70 of the clamp member 50.

[0042] Thus, the annular tapered portion 30 of the inner surface 23 of each of the main body segments 20a, 20b, 20c forms a series of protrusions or teeth 32 extending radially inward from the inner surface of each main body segment. In this embodiment, the axially parallel portion 31 of the inner surface 23 of the main body segments 20a, b, c is located at the peak between adjacent teeth 32. In this embodiment, the plane 33a perpendicular to the axis of each tooth 32 facing the end 25 of each main body segment 20a, 20b, 20c closest to the PLET is substantially perpendicular to the axis X of the hole 1b (not necessarily exactly perpendicular), and the tapered surface 33b of each radial tooth 32 facing the end 24 of each main body segment closest to the FPSO forms an angle of 3° to 45°, optionally 5° to 25°, and optionally 10° to 15° with respect to the axis X of the hole 1b. In this embodiment, the tapered surface 33b has an angle of 11° with respect to the axis X.

[0043] Each of the inner segments 60a, 60b, 60c of the clamp member 50 (seen in Fig. 3d) is shown in detail in Figs. 5a - 5d. The inner segments 60a, 60b, 60c of the clamp member 50 are generally similar in form to the outer segments 20a, 20b, 20c of the body 10, but the inner segments have a plurality of annular tapered portions 70 on their outer surfaces 62, and these tapered portions are adapted to engage with the annular tapered portions 30 on the inner surfaces 23 of the outer segments 20a, 20b, 20c. Also, in this embodiment, the tapered portions 70 on the outer surfaces 62 of the inner segments 60a, 60b, 60c extend along the entire axial length of each inner segment. Corresponding to the tapered portions 30 of the body segments 20a, 20b, 20c, each tapered portion 70 of the clamp member segments 60a, 60b, 60c includes the large outer diameter of the clamp member 50 and the small outer diameter of the clamp member 50. The maximum outer diameters of the annular tapered portions 70 are all approximately equal, and the minimum outer diameters of the annular tapered portions 70 are also approximately equal. The maximum outer diameter of each tapered portion 70 is disposed immediately adjacent to the minimum outer diameter of the next tapered portion, and vice versa. In this embodiment, the taper of each tapered portion 70 is constant, or in other words, the outer surface of each tapered portion 70 forms a constant angle with respect to the axis X of the hole 1b of the riser clamp assembly 1. In this embodiment, similar to the tapered portions 30 of the outer segments 20a, 20b, 20c of the body 10, the outer surface 62 of each segment 60a, 60b, 60c of the clamp member 60 has a small arbitrary axially parallel portion 71 (best seen in Fig. 5d) adjacent to the minimum outer diameter of each tapered portion, that is, in the valley between adjacent teeth. The axially parallel portion 71 can be formed to allow manufacturing tolerances in the formation of the "valley" of the minimum outer diameter of each of the annular tapered portions 70 to ensure a stable engagement between the tapered portion 30 of the body 10 and the tapered portion 70 of the clamp member 50.More specifically, the manufacturing processes used to form the body segments 20a, 20b, 20c and the clamp member segments 60a, 60b, 60c may be, for example, molding, forging or CNC milling. Depending on this manufacturing process, the peaks of the teeth 32 of the body segments and the valleys of the teeth 72 of the clamp member segments may each be prone to manufacturing errors and / or deviations from the exact design dimensions. Any axially parallel portions 31 of the body segments and any axially parallel portions 71 of the clamp member segments each provide a tolerance for deviations from the exact design dimensions by relaxing the accuracy required at the interface between each peak of the teeth 32 and each valley of the teeth 72. In this embodiment, the axially parallel portions 31, 71 are radially spaced by a radial clearance and allow for deviations at the ends of the peaks without affecting the sliding of the tapered portions relative to each other during use. Without the axially parallel portions 31, 71, any irregularities in the formed teeth 32, 72 would interfere with or limit the uniform engagement between the tapered portion 30 of the body 10 and the tapered portion 70 of the clamp member 50, which could then lead to the body and the clamp member adhering or sticking together as the inner surface 23 of the body and the outer surface 62 of the clamp member move relative to each other axially.

[0044] Thus, the annular tapered portions 70 of the outer surfaces 62 of each of the clamp member segments 60a, 60b, 60c form a series of protrusions or teeth 72 that extend radially outward from the outer surfaces of each of the clamp member segments. In this embodiment, the planes 73a perpendicular to the axis of the holes 1b of each tooth 72 facing the ends 65 of each of the clamp member segments 60a, 60b, 60c closest to the PLET are substantially perpendicular to the axis X of the holes 1b, and the tapered surfaces 73b of each tooth 72 facing the ends 64 of each of the clamp member segments closest to the FPSO form an angle of 3° to 45°, optionally 5° to 25°, and optionally 10° to 15° with respect to the axis X of the holes 1b. In this embodiment, the tapered surface 73b has an angle of 11° with respect to the axis X.

[0045] In this embodiment, since each body segment 20a, 20b, 20c describes an arc of approximately 120 degrees, when the riser clamp assembly 1 is assembled, the body 10 including the body segments 20a, 20b, 20c forms a cylinder having a continuous circumference. In contrast, in this embodiment, each clamp member segment 60a, 60b, 60c describes an arc of less than 120°, for example, 100° to 119°. Therefore, when the riser clamp assembly 1 is first assembled around the marine riser conduit, the clamp member 50 including the clamp member segments 60a, 60b, 60c does not form a cylinder having a continuous circumference, and each clamp member segment is separated from the adjacent clamp member segment by a longitudinal gap between the edge surfaces adjacent in the circumferential direction of the clamp member segment.

[0046] Also, in this embodiment, the teeth 72 of each clamp member segment 60a, 60b, 60c are coated with a low-friction material or a low-friction layer, such as xylan, in order to reduce the friction between the teeth 72 of the clamp member and the teeth 32 of the body segment, respectively. Furthermore, in this embodiment, the inner surface 63 of each clamp member segment 60a, 60b, 60 is coated with a high-friction material or a high-friction layer, such as a rubber layer or a sheet. Alternatively or in addition, the inner surface 63 can be provided with a contoured or patterned surface, such as ridges or grooves, in order to increase the friction between the outer surface of the flow line 3 and the inner surface 63 of the clamp member segment.

[0047] The riser clamp assembly 1 can be assembled around the flow line 3 as follows. The riser clamp assembly 1 is generally attached to the flow line 3 on the deck of a work vessel that deploys, for example, the flow line 3 and the riser 4 before the flow line is lowered to the seabed. However, in some embodiments, the assembly 1 can be retrofitted to an existing subsea line using, for example, an ROV.

[0048] The corresponding segments 20a, 20b, 20c of the body 10 and the corresponding segments 60a, 60b, 60c of the clamp member 50 are first fixed to each other by the installation bolts 40 shown in detail in FIG. 3c. The installation bolts 40 function only to maintain the respective pairs 20a, 60a, 20b, 60b, and 20c, 60c of the body segments and the clamp member segments in proper alignment with each other while the riser clamp assembly 1 is being assembled, and are removed prior to the operation of the riser clamp assembly. In this embodiment, five installation bolts 40 are used to join the respective pairs of the body segments and the clamp member segments, but the number of installation bolts 40 is not limited. As best seen in FIGS. 4b, 4c, and 5c, a series of openings 34 are disposed at substantially equal distances along the axial length of the body segments 20a, 20b, 20c, and a series of corresponding circular recesses 74 are disposed at substantially equal distances along the axial length of the outer surface 62 of the clamp member segments 60a, 60b, 60c. As best illustrated in FIG. 3a, when the respective pairs of the body segments and the clamp member segments are properly oriented relative to each other to assemble the riser clamp assembly 1, the openings 34 and the recesses 74 of the respective pairs of the body segments and the clamp member segments are in alignment with each other. The openings 34 extend radially between the inner surface 22 and the outer surface 23 of each of the body segments 20a, 20b, 20c, while the recesses 74 extend only a short radial distance into the outer surface 62 of each of the clamp member segments 60a, 60b, 60c, as shown in FIG. 3c. Thus, neither the recesses 74 nor the installation bolts 40 penetrate the inner surface 63 of the clamp member segments 60a, 60b, 60c.

[0049] When each pair 20a, 60a, 20b, 60b, and 20c, 60c of the body segment and the clamp member segment are fixed by the installation bolts 40, the body segments 20a, 20b, 20c are assembled to form the complete riser clamp assembly 1. As best seen in FIG. 4b, a series of circular openings 36 are arranged at approximately equal distances along each circumferential edge surface 26a, 26b of each of the body segments 20a, 20b, 20c. In this embodiment, each opening 36 extends into the wall of each body segment in a direction perpendicular to the circumferential edge surfaces 26a, 26b until it joins a corresponding recess 37 in the outer surface 22 of each of the body segments 20a, 20b, 20c, as best seen in FIG. 4c. The body segments 20a, 20b, 20c are assembled by aligning the openings 36 of each circumferential edge surface 26a, 26b of each body segment 20a, 20b, 20c with the openings 36 of the adjacent body segments, and as a result, the body segments 20a, 20b, 20c form a complete cylinder, as best illustrated in FIG. 3a. FIG. 3a shows the riser clamp assembly 1 with one body segment removed for clarity.

[0050] When all of the body segments 20a, 20b, 20c are positioned relative to each other to form a cylinder, fixing bolts or other fasteners (not shown) may be passed through the aligned openings 36 of the adjacent body segments and fixed to clamp the circumferential edge surfaces 26a, 26b of the adjacent body segments to each other.

[0051] As can be best seen in FIGS. 3a and 3d, when assembling the riser clamp assembly 1 in this embodiment as described above, the circumferential edge surfaces 26a, 26b of the adjacent body segments 20a, 20b, 20c contact each other and are clamped together by the fixing bolts. However, the circumferential edge surfaces 66a, 66b of the adjacent clamp member segments 60a, 60b, 60c (which are still fixed to their respective body member segments 20a, 20b, 20c by the installation bolts 40) do not contact each other. In other words, the clamp member segments 60a, 60b, 60c are circumferentially spaced apart from each other by the gaps between the adjacent circumferential edge surfaces 66a, 66b.

[0052] Before the riser clamp assembly 1 is deployed, for example, before the section of the flow line 3 to which the riser clamp assembly is attached is lowered towards the seabed, the installation bolts 40 are removed from the body 10 (however, for example, if the assembly 1 is attached to an existing subsea line, the bolts 40 can be optionally removed underwater). After removing the bolts 40, the clamp member segments 60a, 60b, 60c are no longer fixed to the body segments 20a, 20b, 20c and are free to move relative to the body segments. However, since the inner diameter of the clamp member 50 including the clamp member segments 60a, 60b, 60c is generally approximately equal to the outer diameter of the flow line 3 passing through the hole 1b of the riser clamp assembly 1, the tapered shape of the outer surface 62 of each clamp member segment 60a, 60b, 60c remains in contact with the tapered shape of the inner surface 23 of each body segment 20a, 20b, 20c even after the installation bolts 40 are removed.

[0053] In this embodiment, before the riser clamp assembly 1 is exposed to any axial load from the flow line 3 (and generally before the riser clamp assembly is lowered to the seabed), the clamp member 50 is pre - biased. The purpose of pre - biasing the clamp member 50 is to artificially move the clamp member 50 and the body 10 axially relative to each other by a small amount, so that, then, before there is any actual axial load on the flow line, the clamp member segments 60a, 60b, 60c exert a radial force on the outer surface of the flow line 3. This ensures that the inner surface 63 of the clamp member segment is in complete contact with the outer surface of the flow line 3 and, optionally, reduces the risk that the flow line 3 "slides" relative to the clamp member 50 when the flow line is axially loaded during normal operation.

[0054] In this embodiment, the clamp member 50 is pre - biased by introducing one or more axially movable elements having male threads, generally like bolts (not shown), into axially threaded holes 29 that are circumferentially arranged around the end face 25 (on the shoulder 28) of the body 10, as best seen in FIGS. 3e and 4a. In this embodiment, three holes 29 are equally spaced around the end face 25 of each of the body segments 20a, 20b, 20c, but in other embodiments, there may be fewer or more holes 29. In yet other embodiments, the means for pre - biasing the clamp member 50 may not require an axial hole or screw fixture.

[0055] As best seen in FIG. 3e, the threaded holes 29 extend axially through the shoulder 28 of the body 10 and are radially positioned such that the inner ends of each hole 29 open onto the counterbore portion of the body. Since the radial dimension of the shoulder 28 is approximately equal to the wall thickness of the clamp member 50, the inner ends of each hole 29 are radially aligned with the respective end faces 65 (seen in FIG. 5b) of the clamp member segments 60a, 60b, 60c. Thus, a bolt or tensioner passing through the holes 29 contacts the end face 65 of the clamp member segment and then biases the clamp member segment axially away from the shoulder 28, moving the clamp member 50 axially relative to the body 10, as will be described in more detail below, which is equivalent to axially moving the clamp member relative to the body by the axial load on the flow line 3.

[0056] During operation, the riser clamp assembly 1 first acts to limit and then substantially prevent axial movement of the flow line 3 passing through the riser clamp assembly in a direction towards the FPSO or away from the PLET. The body 10 of the riser clamp assembly 1 surrounds the clamp member segments 60a, 60b, 60c and maintains contact between the inner surface 63 of the clamp member segment and the outer surface of the flow line 3. As described above, in this embodiment, the inner surface of the clamp member segment includes a high friction material or a high friction layer. The high friction material ensures that the flow line 3 is substantially prevented from any movement relative to the clamp member segments 60a, 60b, 60c when an axial load is applied to the flow line 3, such as the axial tension caused by the FPSO moving away from the riser clamp assembly 1. In other words, the flow line 3 must not slide through the clamp member 50.

[0057] Therefore, no matter how the flow line 3 passing through the riser clamp assembly 1 moves axially, the clamp member 50 moves axially relative to the main body 10. The clamp member 50 is prevented from moving axially relative to the main body 10 toward the PLET by the shoulders 28 of the respective main body segments 20a, 20b, 20c that act as stops against the end faces 64 of the respective clamp member segments 60a, 60b, 60c. In addition, the axial vertical planes 73a of the respective teeth 72 on the outer surface 62 of the clamp member segments 60a, 60b, 60c abut against the axial vertical planes 33a of the respective teeth 32 on the inner surface 23 of the main body segments 20a, 20b, 20c, also preventing the clamp member 50 from moving relative to the main body 10 toward the PLET.

[0058] As can be best seen from FIG. 3g, when the clamp member 50 moves axially relative to the main body 10 toward the FPSO, the end faces 64 of the respective clamp member segments 60a, 60b, 60c separate from the shoulders 28 of the respective main body segments 20a, 20b, 20c. Also, the tapered surfaces 73b of the respective teeth 72 on the outer surface 62 of the clamp member segments 60a, 60b, 60c begin to slide axially over the tapered surfaces 33b of the respective teeth 32 on the inner surface 23 of the main body segments 20a, 20b, 20c. As the tapered surfaces 73b, 33b of the corresponding teeth 72, 32 slide axially relative to each other, the clamp member segments 60a, 60b, 60 are also biased radially inward. In other words, as the maximum outer diameter of each annular tapered portion 70 of the outer surface 62 of the clamp member 50 approaches the minimum inner diameter of each annular tapered portion 30 of the inner surface 23 of the main body 10, the clamp member 50 is displaced radially inward away from the inner surface 23 of the main body 10. In FIG. 3g, the degree of compression of the outer surface of the flow line 3 is exaggerated for the sake of illustration.

[0059] When the clamp member segments 60a, 60b, and 60c move radially inward, the circumferential gap between the clamp member segments also decreases. In this embodiment, the initial circumferential gap between the clamp member segments 60a, 60b, and 60c (best seen in FIG. 3d) is sized such that even when the clamp member segments move radially inward to the maximum extent, they are not completely closed. In other words, in this embodiment, the continuous radially inward movement of the clamp member segments is not restricted or prevented by the circumferential edge surfaces 66a, 66b of each clamp member segment that contacts the adjacent clamp member segments. Instead, the radially inward movement of the clamp member segments relative to the body 10 of the clamp member is restricted only by the maximum deflection of the outer surface of the flow line 3 under radial compression.

[0060] When further radially inward movement of the clamp member segments 60a, 60b, and 60c (caused by the flow line 3 moving further axially relative to the riser clamp assembly) begins to be opposed by the reaction of the flow line 3 against being radially compressed, the pressure between the tapered surface 73b of the teeth 72 on the outer surface of the clamp member 50 and the tapered surface 33b of the teeth 32 on the inner surface of the body 10 begins to increase respectively. As the pressure between the corresponding tapered surfaces 73b, 33b of the teeth 72, 32 increases, an axial force in the direction opposite to the axial movement of the clamp member 50 relative to the body 10 is generated between the clamp member 50 and the body 10. When the axial force in the opposite direction generated between the teeth 72 of the clamp member 50 and the teeth 32 of the body 10 balances the axial force of the tension of the flow line 3 passing through the riser clamp assembly 1, the flow line 3 passing through the riser clamp assembly is prevented from moving further axially.

[0061] For example, in response to the FPSO moving further away from the riser clamp assembly 1, when the axial tension in the flow line 3 further increases, the clamp member 50 can move further axially relative to the main body 10. Thereby, the clamp member segments 60a, 60b, 60c move further radially inwards, compressing the flow line 3 more radially. Due to the increase in the reaction of the flow line 3 to the increase in the radially inward force on the flow line, the pressure between the tapered surfaces 73b, 33b of the corresponding teeth 72, 32 further increases, and then the axial force in the opposite directions generated between the teeth 72, 32 increases. When the increased axial force in the opposite direction balances the axial force acting on the flow line 3 again, the flow line 3 is prevented from moving further axially relative to the riser clamp assembly 1.

[0062] In this embodiment, the radial dimensions of the axially perpendicular surfaces 73a, 33a of the teeth 72, 32 are dimensioned such that even when the maximum designed axial load is applied on the flow line 3 and the outer surface of the flow line 3 is deflected maximally radially (including any temporal change in the outer diameter of the flow line 3 due to, for example, the influence of creep and / or aging on the material of the outer surface of the flow line, or due to the temperature of the fluid passing through the flow line), the crests of the corresponding teeth 72, 32 cannot pass through each other axially. In other words, the axially perpendicular surfaces 73a, 33a of the teeth 72, 32 are large enough (e.g., radially deep enough) to ensure that the teeth 72, 32 do not "jump over" each other. Generally, in this embodiment, when the flow line 3 and the clamp member 50 are under the maximum designed axial load relative to the main body 10, the maximum axial separation between the axially perpendicular surface 73a of the corresponding tooth 72 of the clamp member segment and the axially perpendicular surface 33a of the corresponding tooth 32 of the main body segment is 5% - 15% of the axial dimension of each tooth 72, 32. In other embodiments, the maximum distance between the axially perpendicular surfaces 73a, 33a of the corresponding teeth 72, 32 may be larger or smaller than this, for example, less than 5% or 50% or more.

[0063] Conversely, when the axial tension in the flow line 3 decreases, the axial force in the opposite direction between the corresponding teeth 72 of the clamp member 50 and the corresponding teeth 32 of the body 10 (due to the reaction of the flow line 3 against the radial compression applied by the clamp member segments 60a, 60b, 60c at their current radial positions) may become greater than the decreased axial force on the flow line 3. As a result, the clamp member segments 60a, 60b, 60c move axially in the opposite direction and radially outward toward their initial positions until the axial forces acting on the flow line 3 are balanced.

[0064] A second embodiment of the subsea line clamp assembly 101 according to the present invention is shown in FIG. 6a. The second embodiment is generally similar to the first embodiment described above, and like parts are designated by like reference numerals, but incremented by 100. In the second embodiment, the riser clamp assembly includes a body 110 and a clamp member 150 arranged inside the body 110. The body 110 is generally cylindrical, similar to the body 10 of the first embodiment.

[0065] As best seen in FIGS. 6b and 6e and as shown in FIGS. 7a and 7b, when the body is fully assembled, end plates 114a, 114b, 114c are arranged at the axial ends of the body 110, as will be described in more detail below. In this embodiment, each end plate 114a, 114b, 114c includes two large circular axial openings 115 and three small circular axial openings 116, although the exact number of openings 115, 116 is not limited.

[0066] In the second embodiment, the longitudinal segments 120a, 120b, 120c of the main body 110 are modular, and each longitudinal segment, for example 120a, is best seen in FIG. 6d and is further divided into eight axial sections 121a - 121h as shown in detail in FIGS. 8a and 8b. In this embodiment, each of the axial sections 121a - 121h has a substantially equal axial length and includes two tapered portions 130. However, in other embodiments, the axial length of the axial sections may vary, and the number of axial sections may be less than or more than eight. Also, each axial section may include more or less than two tapered portions 130. In this embodiment, each axial section 121 of the main body 110 also has an axially parallel portion 131 adjacent to the end face 124 (i.e., the one closest to the FPSO) of each tapered portion 130, as best seen in FIG. 8a.

[0067] The main body 110 optionally incorporates at least one section 121 that incorporates a first eyeplate 118 (shown in FIGS. 6a and 6b) adapted to optionally connect to one or more buoyancy modules for the reasons previously described with respect to the first embodiment of the subsea line clamp assembly. Also, the main body 110 generally also incorporates at least one (optionally different) section 121 that incorporates second eyeplates 119a, 119b (also shown in FIGS. 6a and 6b), or other anchor attachment points, which are adapted to moor the main body to a subsea anchor or suction pile with a chain or cable.

[0068] In the second embodiment 101, the longitudinal segments 160a, 160b, 160c of the clamp member 150 are also modular and are similarly divided into axial sections as shown in FIGS. 9a and 9b. Thus, for example, the clamp member segment 160a is divided into eight axial sections 161a to 161h as shown in FIG. 6d. In this embodiment, each clamp member axial section 161a to 161h is identical and corresponds to each body axial section 121a to 121h. Also, in this embodiment, each axial section 161 of the clamp member 150 has an axially parallel portion 171 between the tapered portions 170.

[0069] Also, in this embodiment, the axial length of each axial section 161 of the clamp member 150 is generally shorter than the corresponding axial section 121 of the body 120. In other words, when the subsea line clamp assembly 101 is fully assembled, the end faces 124, 125 of each axial section 121 of the body 120 contact (and are clamped against) the corresponding end faces 124, 125 of the adjacent axial sections. In contrast, in this embodiment, the end faces 164, 165 of each axial section 161 of the clamp member 150 are axially spaced from the end faces 164, 165 of the adjacent axial sections. This axial spacing is added to the circumferential spacing that also exists between the circumferential edge faces 166a, 166b of the axial sections 161 of the adjacent longitudinal segments 160a, 160b, 160c as described above in the first embodiment. The axial spacing between adjacent axial sections 161 of the clamp member 150 provides a tolerance for the exact axial dimension of each axial section, allowing for manufacturing errors and / or misalignments from the exact design dimensions, and ensuring that such manufacturing errors do not limit or inhibit the ability of each axial section 161 to move freely axially in response to the flow line 103 moving axially relative to the subsea line clamp assembly 101.

[0070] The second embodiment of the subsea line clamp assembly 101 can be assembled around the flow line 103 in a manner similar to the subsea line clamp assembly 1 of the first embodiment described above. Generally, the axial sections 121a - 121h of each body segment 120a, 120b, 120c are first assembled by aligning the openings 138 that extend axially through the walls of each axial section between the axial edge faces 124, 125 of each axial section. In the second embodiment, it is possible to select the number of axial sections 121a - 121h necessary to constitute the required overall length of the subsea line clamp assembly 101. For example, in applications where it is known that the maximum axial load applied by the flow line 103 is less than a certain threshold, the overall length of the subsea line clamp assembly 101 can be made shorter than another subsea line clamp assembly adapted to a larger axial load and thus composed of fewer axial sections 121a - 121h (i.e., with more axial sections 121). When all the axial sections 121a - 121h are positioned relative to each other to form, for example, the longitudinal segment 120a, an end plate 114a is placed at either axial end of the longitudinal segment 120a, and an axial fixing stud or bolt 139 passes through the opening 115 of the end plate 114a and through each of the aligned openings 138 of the axial sections, and is then fixed by tightening or other means to clamp the axial edge faces 124, 125 of adjacent axial sections together. In this embodiment, the axial fixing bolts 139 are approximately equal to or slightly longer than the full axial length of the body segments 120a, 120b, 120c, and thus each fixing bolt extends between the end faces of the body 110.

[0071] After the longitudinal segments 120a, 120b, 120c of the body 110 are assembled, the corresponding segments 160a, 106b, 160c of the clamp member 150 are fixed to the respective segments 120a, 120b, 120c of the body 110 by the installation bolts 140 in substantially the same manner as in the first embodiment. In this embodiment, for example, each axial section 161a - 161h of the clamp member segment 160a is aligned with the body segment 120a, and as a result, the recesses 174 (best seen in FIGS. 9b and 9c) of each axial section 161a, 161b, 161c are aligned with the respective openings 134 (best seen in FIG. 8a) of, for example, the body segment 160a. Thus, in this embodiment, instead of using five installation bolts 40 to fix the body segment 20a and the clamp member segment 60a in the first example, for example, each installation bolt 140 can be used to fix a single axial section 161a - 161h. In other embodiments, each axial section may be fixed with a plurality of installation bolts 140.

[0072] Next, the body segments 120a, 120b, 120c are assembled in the same manner as in the first embodiment to form a complete subsea line clamp assembly 101. In this embodiment, as shown in FIGS. 8a - 8c, openings 126 are arranged along the circumferential edge surfaces 126a, 126b of each axial section 121 of the body segments 120a, 120b, 120c. Each opening 126 is joined to a corresponding recess 137 on the outer surface of each body segment 120a, 120b, 120c. The assembly of the body segments 120a, 120b, 120c may be such that the openings 136 of each body segment 120a, 120b, 120c are aligned with the openings 136 of the adjacent body segment, and then a fixing bolt or other fastening means (not shown) is passed through the aligned openings 136 of the adjacent body segments to clamp the circumferential edge surfaces 126a, 126b of the adjacent body segments together.

[0073] Alternatively, the subsea line clamp assembly 101 can be assembled by first fixing the axial section 161 of the clamp member 150 to the corresponding axial section 121 of the body 110, then joining the circumferential edge surfaces 126a, 126b of the axial section 121 to form the cylindrical portion of the body 110, and then joining all of such cylindrical portions of the body and end plates 114a, 114b, 114c with the axial fixing bolts 139.

[0074] During operation, the second embodiment of the subsea line clamp assembly 101 functions in a manner similar to the first embodiment described above. The body segments 120a, 120b, 120c of the second embodiment each comprise individual axial sections, but when the body 110 is fully assembled with both axial and radial fixing bolts or other fasteners, this becomes structurally and functionally equivalent to the body 10 of the first embodiment. In contrast, each of the clamp member segments 160a, 160b, 160c of the second embodiment is separated into individual axial sections 161a - 161h, and after removing the temporary installation bolts 140, each axial section of each longitudinal segment of the clamp member 50 can be axially spaced from other adjacent axial sections and its position and orientation can be freely adjusted independently of all other axial sections. This provides an advantage over the integral clamp member segments 60a, 60b, 60c of the first embodiment.

[0075] First, since the clamp member segments 160a, 160b, 160c are not continuous, the outer surface of the flow line 103 is generally not uniformly compressed by the clamp member 150 of the second embodiment. The portions of the flow line 103 in contact with the axial sections 161a - 161h are generally more compressed than the portions of the flow line not in contact with the axial sections of the clamp member segments 160a, 160b, 106c. In other words, the outer diameter of the flow line 103 can be made smaller in the region of the outer surface of the flow line in contact with the axial sections 161a - 161h than in the region aligned with the axial gaps between the sections 161a - 161h. Thus, each axial section 161a - 161h can be slightly embedded in the outer surface of the flow line 103 as compared to the outer surface of the flow line between each of the axial sections 161a - 161h. This can advantageously prevent or further reduce the risk of "slipping" axially between the clamp member 150 and the flow line 103 when the flow line is subjected to an axial load.

[0076] Second, each axial section 161a - 161h can be adjusted independently of adjacent axial sections in terms of its circumferential position and orientation (e.g., pitch and yaw). Thereby, optionally, the clamp member 150 can compensate for local irregularities in the outer diameter and / or stiffness of the outer surface of the flow line 103, which, compared to the clamp member segments 60a, 60b, 60c of the first embodiment, reduces the likelihood of the clamp member 150 adhering or being fixed to the body 110 and also reduces the likelihood of the outer surface of the flow line 103 being overly locally radially compressed.

Claims

Claim 1 A subsea line clamp assembly comprising a body having an axis and a clamping member, wherein the body comprises first and second body segments adapted to be assembled around a subsea line, the body having an anchor attachment point adapted to moor the body to a subsea anchor, the clamping member including at least first and second clamping member segments, the clamping member being movable relative to the body and having an outer surface adapted to engage an inner surface of the body and an inner surface adapted to engage the subsea line within the subsea line clamp assembly, the inner surface of the body having at least one first tapered portion, the outer surface of the clamping member having at least one second tapered portion arranged to engage the first tapered portion on the inner surface of the body, the clamping member and the body being divided into the same number of segments in a direction along the axis, each segment of the body having a corresponding segment of the clamping member, each segment of the body having a larger angular dimension than the corresponding segment of the clamping member, the clamping member and the body being divided into a plurality of axial sections, each axial section of the body having a corresponding axial section of the clamping member, each axial section of the body having a larger axial dimension than the corresponding axial section of the clamping member, at least one end face of each axial section of the clamping member being axially spaced from at least one end face of an adjacent axial section of the clamping member, A subsea line clamp assembly. Claim 2 the clamping member being movable relative to the body in a radial and axial direction, wherein when the first tapered portion and the second tapered portion engage, axial movement of the clamping member relative to the body in a first direction causes the inner surface of the clamping member to be biased radially inwards relative to the body and against the outer surface of the subsea line, the subsea line clamp assembly according to claim 1. Claim 3 The first tapered portion and the second tapered portion face both axial ends of the submarine line clamp assembly according to claim 1 or 2.

4. At least one of the first tapered portions on the body forms a part of a tooth on the body, From an outer radial position on the body spaced from the axis of the body to an inner radial position on the body close to the axis of the body, a first surface on the body extending radially inward toward the clamp member to form the first tapered portion, and a second surface on the body extending radially outward so as to return from the inner radial position on the body to the outer radial position on the body with respect to the axis of the body, having, At least one of the second tapered portions on the clamp member forms a part of a tooth on the clamp member, From an outer radial position on the clamp member with respect to the axis of the body to an inner radial position on the clamp member further spaced from the axis, a first surface on the clamp member extending radially inward toward the body to form the second tapered portion, and a second surface on the clamp member extending radially outward so as to return from the inner radial position on the clamp member to the outer radial position on the clamp member with respect to the axis of the body, the submarine line clamp assembly according to any one of claims 1 to 3.

5. The second surface of each of the teeth on the body and the second surface of each of the teeth on the clamp member are perpendicular to the axis, the submarine line clamp assembly according to claim 4.

6. Each of the teeth on the body and each of the teeth on the clamp member are arranged in a repeating annular array, the submarine line clamp assembly according to claim 4 or 5.

7. The friction between the inner surface of the body and the outer surface of the clamp member is lower than the friction between the inner surface of the clamp member and the outer surface of the submarine line, the submarine line clamp assembly according to any one of claims 1 to 6.

8. The clamp member is axially movable in a first direction with respect to the body, The outer surface of the clamping member and the inner surface of the main body incorporate a stop member that restricts the axial movement of the clamping member in a second direction opposite to the first direction. The subsea line clamp assembly according to any one of claims 1 to 7.

9. The inner surface of the main body has an array of first tapered portions, The first tapered portion is annular and extends around at least a portion of the inner surface of the main body, The outer surface of the clamping member has an array of second tapered portions, The second tapered portion is annular and extends around at least a portion of the outer surface of the clamping member. The subsea line clamp assembly according to any one of claims 1 to 8.

10. The first tapered portion and the second tapered portion are tapered at the same angle with respect to the axis of the main body. The subsea line clamp assembly according to any one of claims 1 to 9.

11. Between the repetitions of the first tapered portion of the main body and the second tapered portion of the clamping member, at least one axially parallel portion is incorporated. The subsea line clamp assembly according to any one of claims 1 to 10.

12. The axially parallel portion of the inner surface of the main body is adjacent to the minimum inner diameter of each of the first tapered portions, The axially parallel portion of the outer surface of the clamping member is adjacent to the minimum outer diameter of each of the second tapered portions. The subsea line clamp assembly according to claim 11.

13. The axially parallel portion is arranged to be radially minimum. The subsea line clamp assembly according to claim 11 or 12.

14. Each of the inner surface of the main body and the outer surface of the clamping member incorporates an axially parallel portion, The respective axially parallel portions on the main body and the clamping member overlap axially in the subsea line clamp assembly, The axially parallel portions that overlap axially on the main body and the clamping member are radially spaced apart from each other by a radial clearance. The subsea line clamp assembly according to any one of claims 1 to 13.

15. The subsea line clamp assembly incorporates an ocean riser conduit disposed within the hole of the subsea line clamp assembly. The subsea line clamp assembly according to any one of claims 1 to 14.

16. A method of clamping the undersea line, including the step of assembling an undersea line clamp assembly on the outer surface of the undersea line, wherein the undersea line clamp assembly includes a main body and a clamp member including segments of at least first and second clamp members, the main body has an axis and is divided into at least first and second segments adapted to be assembled around the undersea line, the main body has an anchor attachment point adapted to moor the main body to a seabed anchor, the clamp member has an outer surface adapted to engage an inner surface of the main body extending circumferentially around the outer surface of the clamp member, and an inner surface adapted to engage the undersea line within the undersea line clamp assembly, the clamp member and the main body are divided into the same number of segments in a direction along the axis, each segment of the main body has a corresponding segment of the clamp member, and each segment of the main body has a larger angular dimension than the corresponding segment of the clamp member, when the undersea line clamp assembly is assembled around the undersea line, at least one segment of the clamp member is movable radially and axially relative to the main body, the inner surface of the main body has a plurality of first tapered portions, the outer surface of the clamp member has a plurality of second tapered portions arranged to engage the first tapered portions on the inner surface of the main body while the clamp member moves relative to the main body, the first tapered portions and the second tapered portions face both ends of the undersea line clamp assembly, the friction between the inner surface of the main body and the outer surface of the clamp member is lower than the friction between the inner surface of the clamp member and the outer surface of the undersea line, when the first tapered portion and the second tapered portion engage, the clamp member moves axially in a first direction relative to the main body, thereby biasing the inner surface of the clamp member radially inward relative to the main body and against the outer surface of the undersea line. The clamp member and the body are divided into a plurality of axial sections, each of the axial sections of the body having an axial section of the clamp member corresponding to each of the axial sections of the body, the axial section of the body having an axial dimension greater than the corresponding one of the axial sections of the clamp member, The method includes the step of axially spacing at least one end face of each of the axial sections of the clamp member from at least one end face of an adjacent axial section of the clamp member. Method.

17. The method according to claim 16, wherein the subsea line is a marine riser conduit.

18. After the step of assembling the subsea line clamp assembly on the outer surface of the subsea line, if the outer diameter of the subsea line decreases, the clamp member slides relative to the body in the first direction to stably maintain the clamping force on the subsea line. The method according to claim 16 or 17.

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