Bending restrictor

Abstract

Bend restrictor comprising at least one pipe section and at least one clamp section wherein the pipe section comprises an outward facing flange at each end, the pipe section is split in the longitudinal direction into at least two parts, wherein the clamp section comprises an inward facing flange at each end and a pipe shaped middle section therebetween, wherein the clamp section is split in the longitudinal direction into at least two parts, wherein said parts are connectable through bolt connections, and wherein each inward facing flange is adapted to receive the outward facing flange of a pipe section.

Claims

1. A bend restrictor comprising: at least one pipe section, and at least one clamp section, wherein the pipe section comprises an outward facing flange at each end, the pipe section is split in the longitudinal direction into at least two parts, wherein the clamp section comprises an inward facing flange at each end and a pipe shaped middle section therebetween, wherein the clamp section is split in the longitudinal direction into at least two parts, wherein said parts are connectable through bolt connections, or through locking pin connections or through straps and wherein each inward facing flange is adapted to receive the outward facing flange of a pipe section, wherein the at least two parts of the clamp section comprises through holes adapted to receive a bolt, and wherein the at least two parts of the clamp section comprises axial extending tongues comprising the through holes adapted to receive said bolt.

2. The bend restrictor according to claim 1, wherein the outer diameter of the pipe shaped middle section of the clamp section is equivalent to the outer diameter of the pipe section between the outward facing flanges.

3. The bend restrictor according to claim 1, wherein the clamp section comprises a radial extension at each end, wherein each radial extension comprises the inward facing flange.

4. The bend restrictor according to claim 1, wherein the bend restrictor is made of metal and each section, preferably each part, comprises a sacrificial anode.

5. The bend restrictor according to claim 4, wherein the sacrificial anode(s) of the clamp section is arranged on the pipe shaped middle section of the clamp section.

6. The bend restrictor according to claim 1, wherein the bend restrictor is made of PUR or composite material.

7. The bend restrictor according to claim 1, wherein the maximum outer diameter of the clamp section is unchanged by the axial extending tongues.

8. The bend restrictor according to claim 1, wherein the clamp section has an axial length of 0.2 to 10 times the axial length of the pipe section.

9. The bend restrictor according to claim 1, wherein the clamp section has an axial length of 0.2 to 1.5 times the axial length of the pipe section.

10. The bend restrictor according to claim 1, wherein the clamp section has an axial length of 2 to 10 times the axial length of the pipe section.

11. The bend restrictor according to claim 3, wherein the axial length of the pipe section is adapted to the axial length of the radial extensions of the clamp section, such that when the bend restrictor is in a bend position the radial extensions of two clamp sections connected to the same pipe section are brought in direct, force transferring contact.

12. The bend restrictor according to claim 1, wherein the parts of the pipe section comprises through holes adapted to receive a bolt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will now be described in further details with reference to the enclosed drawings. A person skilled in the art will appreciate that different features illustrated in different embodiments may be combined to provide further embodiments of the present invention.

(2) FIG. 1a is a schematic cross-sectional view of a prior art bed restrictor.

(3) FIG. 1b illustrates the clamp and the pipe section of the prior art bed restrictor.

(4) FIG. 2a is a schematic cross-sectional view of a first embodiment of the invention.

(5) FIG. 2b illustrates the clamp and the pipe section of the first embodiment of FIG. 2a.

(6) FIG. 3a is a schematic cross-sectional view of a second embodiment of the invention.

(7) FIG. 3b illustrates the clamp and the pipe section of the second embodiment of the bed restrictor.

(8) FIG. 4 illustrates a bend restrictor according to the first embodiment.

(9) FIG. 5 illustrates a pipe section according to the first embodiment of the bend restrictor.

(10) FIG. 6 illustrates a clamp according to the first embodiment of the bend restrictor.

(11) FIG. 7 shows half a bend restrictor according to a third embodiment.

PRINCIPAL DESCRIPTION OF THE INVENTION

(12) A prior art bend restrictor is illustrated on FIGS. 1a and 1b. The end section 15 is connected to an equipment wall 10. A pipe section 18 is connected to the end section 15 with a clamp 16. The end section 15 comprises an outward extending flange at the end extending from the equipment wall 10. The pipe section 18 also comprises outward extending flanges 19 at each end thereof. The clamp 16 comprises one inward facing flange 14 adapted to receive the outward facing extending flanges of two pipe sections or the end section 15 and the first pipe section. The cable to be protected by the bend restrictor is not shown in the schematic representation, but the longitudinal open passage therethrough is easily visible. In the schematic illustration it is also not visible that each pipe section and each clamp are longitudinal split in at least two sections. In this prior art solution, the clamps have a very limited contribution to the length of the bend restrictor.

(13) The prior art bend restrictor on FIG. 1a comprises three pipe sections and four clamps. If these are split in half the bend restrictor comprises fourteen pieces. These pieces are, if designed as in NO320897, connected with twenty-eight bolts.

(14) A weak point of the prior art bend restrictor is at the position of the first clamped, marked with an asterisk (*). Three elements are connected at this point. The inward facing flange of the clamp is designed such that a limited movement of the outward flange of the first pipe section in relation to the outward flange of the end section is possible such that a limiting bending of the bend restrictor and the cable arranged therein is made possible. The outward flange of the pipe section at * is often the weakest point of the bend resistor.

(15) FIGS. 2a and 2b illustrate a first embodiment of the present invention using the same schematic method of illustration. The pipe section 28 is similar to the prior art pipe section, in one aspect of the embodiment the pipe sections are split in the longitudinal direction, but assembled without bolt connections or similar elements. Instead the two or more pieces of the pipe section are kept in place by the clamps.

(16) The clamp 26 has a new design. The clamp 26 comprise a longitudinal pipe shaped middle section 22 with a diameter similar to the diameter of the main part of the pipe section 28. At each end the clamp 26 comprises a radial extension 21 with an inward facing flange 24, 24′. Compared to the prior art the bend restrictor of FIG. 2a comprises no point where two pipe sections are directly connected within the same inward facing flange, in that the inward facing flanges are separated by the pipe shaped middle section 22. The effect of the separation is that the weak spot of the prior art solution is removed and the bending forces are distributed between the two ends of the first clamp 26 connected to the end section 15. The position * of the first pipe section flange is moved further away from the equipment wall 10, which increases bending moment capacity.

(17) The design of the clamp further provides for the clamp to contribute considerably to the length of the bend restrictor. The bend restrictor illustrated on figure has a similar length as the prior art bend restrictor of FIG. 1a but comprises considerable less parts. The bend restrictor on FIG. 2a comprises one pipe section and two clamps, which makes six pieces if they are split in two. If only the clamps include bolts, only eight bolts are required for the assembling of the illustrated bend restrictor. The design allows for a reduction from fourteen to six pieces and from 28 to eight bolts. In use the bend restrictor will normally have a considerable greater length and the reduction in number of parts will be even more dramatic.

(18) If the bend restrictor is prepared in steel for installation in moist climate including submerged in water the parts have to be protected from corrosion to obtain a reasonable life span. For this purpose, it is known to install sacrificial anodes on each part or element. In the prior art solution anodes on the external surface of the clamps increases the external diameter of the bend restrictor. Further, due to the difference in outer diameter between the central part of the pipe section and the clamp of the prior art, the curvature of the surface on which the anodes are attached is different and two different types of anodes adapted to the two surface curvatures are required. In the design according to the present invention the outer diameter of the central part of the pipe section is identical to the outer diameter of the middle section of the clamp. Anodes with the same adapted curvature can there be attached to the surface of both types of elements, which simplifies the number of different parts. Additionally, arrangement of the anode on the middle section of the clamp has the effect that the anode does not increase the over all diameter of the bend restrictor and the anode is also less exposed to external forces.

(19) FIGS. 3a and 3b illustrates a second embodiment of the present invention using the same schematic illustration. In this embodiment the clamp 26 is similar to the clamp of FIG. 2a. However, the pipe sections 128 are reduced in length. This embodiment may to some extend limit the number of parts compared to the prior art solution. The solution can be prepared without bolt connections between the parts of the longitudinal split pipe sections. Also, the increase in the bending moment capacity due to movement of the weak point further away from the wall 10 is achieved in this embodiment. With the second embodiment a further increase in bending moment capacity is obtained due to the fact that with this design the radial extending sections 21 of two adjacent clamps 26 can interact directly and transfer compression forces directly between the clamps without interacting with the pipe section 128 connected by the two clamps.

(20) FIG. 4 shows a bend restrictor according to the first embodiment in further detail. In this illustration the bend restrictor is prepared of steel. A number of pipe sections 28 are connected with clamps 28 arranged therebetween. The longitudinal split 27 of the clamp into parts is visible. Sacrificial anodes 31 are arranged on each part. In full electrical contact between the clamp parts can be obtained it will sufficient with one anode on each clamp. Sacrificial anodes 30 are arranged on the surface of the pipe sections 28. In this drawing the longitudinal split in the pipe sections is not visible and therefore only one anode on each pipe section is visible. However, unless full electrical contact between the split parts of the pipe section can be obtained an anode is arranged on each part. The pipe sections can rotate freely when no bending forces are pressing the outward flange against the surface of the inward facing flange of the clamp.

(21) FIG. 5 illustrates a pipe section 28 according to the first embodiment. Here the longitudinal split 27 between the parts 28a and 28b is visible. Outward extending flanges 29 and 29′ are arranged at the ends. A sacrificial anode 30 is arranged on the main surface of part 28a. A similar anode is arranged on the part 28b, although not visible in on the drawing.

(22) FIG. 6 illustrates a clamp 26 according to the first embodiment. The clamp 26 is split in the longitudinal direction into two parts 26a and 26b along the line 25. On the surface of the middle section 22 an anode 31 is arranged. The clamp comprises extended sections 21, 21′ at each end. Inside the extended section 21 an inward facing flange 24 is arranged. The clamp parts 26a and 26b are kept together by bolts 40. In the disclosed embodiment the bolts 40 are arranged in axial extending tongues 23a, 23b with trough holes. Alternatively, the through holes for arranging the bolts could be arranged within the wall of the extended section.

(23) FIG. 7 illustrates a longitudinal split bend restrictor according to the second embodiment of the present invention. The shorter pipe section parts 128a and 128b are arranged at the opposite ends of the clamp part 126. The outward extending flange 129 of pipe section part 128b is arranged within the inward facing flange 124 of the clamp part 126. The illustrated embodiment is preferably made of polyurethane (PUR) or a polymer composite material. Through holes for connecting clamp parts are not shown on FIG. 7 but could be arranged in the extended section 121.

(24) When the bend restrictor is bend the end surface 132 of the clamp part 126 will be brought in contact with the end surface of a clamp section arranged around flange 129′. The bending force is thereby transferred directly from one clamp section to the next section and the force of the pipe section is reduced and possibly eliminated.