Monitoring Squeeze Pressure of Track Tensioners

Abstract

A tensioner system holds back elongate products such as subsea pipelines being laid into water. The system comprises at least one endless circulatory track and an array of rollers supporting the track. Each of the rollers of the array is mounted for rotation around a respective shaft. At least one of the shafts comprises a load pin that is arranged to sense loads applied to the surrounding roller in directions normal to an axis of rotation of that roller.

Claims

1-18. (canceled)

19. A tensioner system for holding back elongate products being laid into water, the system comprising: at least one endless circulatory track; and an array of rollers supporting the or each track, each of the rollers of the array being mounted for rotation on a respective shaft; wherein: two or more of the shafts each comprise a respective load pin that is arranged to sense loads applied to a surrounding roller of the array in directions normal to an axis of rotation of that roller; the load pins feed respective load signals to a processor; the shafts are supported by a chassis structure; and each load pin is fixed relative to the chassis structure.

20. The system of claim 19, wherein the or each load pin extends between mutually spaced walls of the chassis structure and protrudes outwardly beyond interfaces between the surrounding roller and the walls, at opposed ends of that roller.

21. The system of claim 20, wherein the or each load pin comprises circumferential grooves aligned with the interfaces between the surrounding roller and the walls.

22. The system of claim 20, wherein the or each load pin comprises strain gauges aligned with the interfaces between the surrounding roller and the walls.

23. The system of claim 22, wherein the strain gauges are disposed within a bore that extends longitudinally along the each load pin.

24. The system of claim 19, wherein the or each load pin is hard-wired to a processor that is arranged to process load signals from the load pin and to output the processed signals to a tensioner control system.

25. The system of claim 24, wherein the processor is integrated with, or hard-wired to, the tensioner control system.

26. The system of claim 19, wherein the or each track is mounted on a frame that incorporates one or more additional load pins arranged to sense loads applied to the frame.

27. A method of monitoring a tensioner system when holding back elongate products being laid into water, the method comprising: sensing individual loads applied to an array of multiple rollers that supports and extends along an endless circulatory track, the loads being applied in directions normal to an axis of rotation of that roller, wherein the loads are sensed and a respective load signal is produced by a load pin on which each roller is mounted for rotation; and advancing the track while each roller rotates and each load pin remains in fixed relation to a supporting chassis structure.

28. The method of claim 27, comprising applying shear forces to the or each load pin by virtue of flame applied to a central portion of the load pin and opposing forces applied to end portions of the load pin.

29. The method of claim 28, wherein the force applied to the central portion of the each load pin is applied by the surrounding roller.

30. The method of claim 28, wherein the opposing forces applied to the end portions of the each load pin are applied by mutually spaced supporting formations.

31. The method of claim 27, comprising conveying load signals from the or each load pin to a processor through a wired connection, processing the load signals and outputting the processed signals to a tensioner control system.

32. The method of claim 31, comprising outputting the processed signals to the tensioner control system through a wired connection.

33. The method of claim 27, comprising recording the individual loads to determine a distribution of squeeze forces along the track.

34. The method of claim 27, comprising recording the individual loads to determine deviations in the outer diameter of a product passing through the tensioner system while being laid.

35. An installation vessel comprising the tensioner system of claim 19.

Description

[0052] To put the invention into its context, reference has already been made to FIGS. 1 to 3 of the accompanying drawings, in which:

[0053] FIG. 1 is a schematic side view of a conventional tensioner track supported by a chassis that is mounted to a support structure via hydraulic cylinders, and further includes a graph of typical squeeze force distribution along the length of the track;

[0054] FIG. 2 is a schematic detail side view of opposed tensioner tracks of a tensioner of the invention, shown gripping a pipeline between their respective series of pads; and

[0055] FIG. 3 is a schematic enlarged detail view of one of the tensioner tracks shown in FIG. 2, showing loads and reaction forces acting on the tracks via the pads and supporting rollers.

[0056] In order that the invention may be more readily understood, reference will now be made, by way of example, to the remainder of the accompanying drawings in which:

[0057] FIG. 4 is a perspective view corresponding to FIG. 3;

[0058] FIG. 5 is a part-sectional exploded perspective view corresponding to FIG. 4;

[0059] FIG. 6 is an exploded perspective view corresponding to FIG. 5 but showing further detail of the rollers;

[0060] FIG. 7 is a longitudinal sectional view of one of the rollers surrounding a load pin in accordance with the invention;

[0061] FIG. 8 is a schematic side view of the load pin within the roller of FIG. 7, connected to a sensing and control circuit; and

[0062] FIG. 9 is a perspective view of a tensioner showing possible locations for auxiliary load pins.

[0063] Referring now to FIGS. 4 to 6 of the drawings, a tensioner comprises a track body 32 that supports an array of rollers 30. The rollers 30 of the array, in turn, support a track 10 that comprises a chain of articulated links 24, each having a back plate 28 that supports a respective pad 26.

[0064] The invention may be used with a variety of tensioner track designs depending on the diameter of the elongate product being laid and its stiffness, structure and composition, in particular whether a pipeline is rigid or flexible. For example, a V-shaped pad assembly, in which each back plate carries two pads in intersecting planes, is common and may be an alternative to a discrete or unique pad on each back plate.

[0065] The rollers 30 of the array turn on parallel and co-planar axes around respective pins, axles or shafts 34 that serve as spindles. The rollers 30 are tubular, each defining a central lumen that receives one of the shafts 34 coaxially. FIG. 6 shows alternating ones of the rollers 30 in outline to show the shafts 34 extending within them.

[0066] As can be seen in FIGS. 4 and 6, the shafts 34 are supported at their opposed ends by mutually-spaced, parallel walls 36 of the track body 32. The shafts 34 extend orthogonally with respect to the walls 36 to bridge the gap between the walls 36. FIGS. 5 and 6 show that each of the walls 36 is penetrated by a corresponding array of holes 38 that serve as sockets to receive respective ends of the shafts 34.

[0067] The walls 36 are exemplified here by continuous walls 36 that are integral with the track body 32. However, the walls could be interrupted by gaps to form longitudinally-successive wall sections or wall portions, each supporting one end or both ends of the shafts 34. Also, the wall sections could be discrete components that are fixed to the track body 32.

[0068] The length of each shaft 34 slightly exceeds the spacing between the walls 36 of the track body 32. Consequently, each end of each shaft 34 fits into and extends through a respective one of the holes 38 in the walls 36.

[0069] FIG. 7 shows that, in accordance with the invention, at least one of the shafts 34 may contain, or be replaced by, a load pin 40.

[0070] The load pin 40 is fixed relative to the track body 32 such that the associated roller 30 turns around and relative to the load pin 40. Thus, the shape of the load pin 40 is rotationally symmetrical about a central longitudinal axis 42 that also serves as the axis of rotation of the roller 30 that surrounds the load pin 40.

[0071] The load pin 40 is cylindrical with constant circular cross-section along its length, save for circumferential grooves 44 that encircle the load pin 40 inboard of its ends, in planes orthogonal to the central longitudinal axis 42. A central portion 40A of the load pin 40, inboard of the grooves 44, extends between the parallel walls 36 of the track body 32 and supports the surrounding roller 30.

[0072] The length of the load pin 40 exceeds the spacing between the parallel walls 36 of the track body 32. End portions 40B of the load pin 40 protruding from opposed ends of the surrounding roller 30, outboard of the grooves 44, extend longitudinally outwardly through the holes 38 in the walls 36 and are fixed to the track body 32 by socket formations 46.

[0073] The grooves 44 of the load pin 40 are aligned longitudinally with the interface between the inner sides of the walls 36 and the outer ends of the roller 30. The grooves 44 define shear planes and concentrate shear forces acting on the load pin 40 in use, in directions orthogonal or normal to the central longitudinal axis 42. Those shear forces arise from squeeze forces that act on the end portions 40B of the load pin 40 via the walls 36 of the track body and the corresponding reaction force that acts on the central portion 40A of the load pin 40 via the surrounding roller 30.

[0074] A narrow bore 48 extends longitudinally through the load pin 40, centred on the central longitudinal axis 42. The bore 48 accommodates strain gauges 50 in longitudinal alignment with the grooves 44. The strain gauges 50 are positioned and arranged to sense shear deformation of the load pin 40 around the grooves 44, and hence to produce load signals that indicate the squeeze force applied by that particular roller 30.

[0075] FIG. 8 shows a circuit 52 that connects the strain gauges 50 of the load pin 40 to a processor 54 for processing load signals from the strain gauges 50. The processor 54 outputs processed signals to a tensioner control system 56 that, in turn, responds to those signals and/or provides corresponding outputs, such as displays and alarms, to system supervisors. The circuit 52 further comprises a source 58 of electrical power that powers the processor 54 and applies a voltage across the strain gauges 50. Advantageously, the strain gauges 50 can be hard-wired to other components of the circuit 52 because the load pin 40 can remain stationary while the roller 30 rotates about the load pin 40. The other components of the circuit 52 can also be hard-wired to each other, or signals could be communicated between them wirelessly.

[0076] Conveniently, the strain gauges 50 of two or more load pins 40 of an array of rollers 30 can feed signals to a single processor 54.

[0077] Turning finally to FIG. 9, this shows a tensioner system 60 with four tracks 10 in mutually-opposed pairs, the tracks 10 being equi-angularly spaced around a vertical firing line. One or more of the tracks 10 may be equipped with at least one load pin 40 in its array of supporting rollers 30 as described above.

[0078] The tracks 10 are supported by a frame 62. The circles in FIG. 9 show possible locations where additional pins could be mounted on the frame 62 to provide alternative load measurements for the purpose of validation or verification of the overall squeeze force.

[0079] Secondary locking and reaction pins such as these on the frame 62 may be adopted to measure the squeeze force, and for alternative confirmation purposes. In particular, acquiring load measurements from secondary pins may be used for validation of load measurements acquired using the abovementioned methodology involving load pins 40 placed within supporting rollers 30.