WO1997048535A1

WO1997048535A1 - Pipe coating apparatus

Info

Publication number: WO1997048535A1
Application number: PCT/GB1996/001424
Authority: WO
Inventors: Douglas Thomas Mullen; Alan Gregory Lane
Original assignee: Bredero Price Services Limited
Priority date: 1996-06-19
Filing date: 1996-06-19
Publication date: 1997-12-24

Abstract

In the application of an anti-buoyancy coating to a pipe, the positioning of a sheer transfer device around the pipe as the coating is being applied is controlled by a device comprising an arm (55) provided with a plurality of roller means (85) and means (70) to controllably bring said roller means into contact with the periphery of said cage.

Description

Pipe Coating Apparatus

This invention is concerned with coating of pipes of the type used m subterranean or submerged pipelines for the recovery of oil, gas, slurries or the like pipeable materials from a subterranean well. In particular it is concerned with pipes in which a steel pipe section is coated with an anti corrosion coating and then a concrete aggregate anti-buoyancy coating (hereinafter referred to as a concrete coating) is applied. Such pipes normally include a mechanical shear transfer device in the form of a wire winding or caging applied around the anti-corrosion coating prior to the application of the concrete coating. This opposes the tendency of the concrete coating to slip or jump off the anti-corrosion coated pipe during laying operations which can impose considerable bending stresses upon the pipe, leading to loss of coating integrity.

Pipe coating methods addressing the problems of effectively applying a concrete coating to a pipe treated with an anti-corrosion coating are described, for example, in the following earlier patents: US-A-3 955 600, GB-A-1 504

051,

GB-A-1 504 052, GB-B-2 088 992, GB-B-2 101 499 and EP-B-0 380 474.

In a typical coating method uniform lengths of steel pipe are accumulated for coating and each in turn is lifted e.g. by overhead crane onto a bogie for individual coating treatment during which the length of pipe is caused to rotate about its longitudinal axis and passed longitudinally past a concrete coating station wherein concrete/aggregate is caused to impinge upon the rotating pipe thereby building up a thickness of concrete on the pipe to form a coating. Such a concrete coating can also be applied by other methods. The term "concrete" is used herein for brevity and convenience but will be understood by those versed in this art as referring to any weight coating consisting of a high density material delivered as a plastic mass for coating purposes, and which after coating forms a hardened coating. Preferred weight or anti-buoyancy coatings may be applied to a thickness of from about 40 mm to 150 mm or more and have a typical density of from 2165 to 3215 kg/m by choosing appropriate mixtures of cement, sand and iron ore

Problems exist in the coating of pipes incorporating the wire caging type of shear transfer device. In order to locate the cage concentrically about the longitudinal axis of a pipe section it is necessary to employ a multitude of bracing elements between the cage and the pipe. These

"spacers" are normally manufactured from a plastics material and serve to hold the cage at the optimum distance from the pipe surface prior to it becoming encased in the concrete coating. However during the concrete coating process the pipe/caging assembly is subjected to, among others, severe rotational forces which can cause the pipe and cage to rotate about different axes. If the cage is not positioned accurately during the coating operation the subsequent properties of the coating will be impaired. Hence a great number of spacers are required to maintain the optimum spacing of the cage from the pipe. Typically about 360 spacers are required for a 10 metre length pipe section and thus the installation of the cage upon the pipe is a time consuming, labour intensive and therefore expensive, operation.

It is an object of the present invention to obviate or mitigate at least some of the aforementioned disadvantages.

Accordingly there is provided a device to promote the location of a cylindrical wire cage concentrically about the longitudinal axis of a rotating tubular article comprising an adjustable arm provided with a plurality of roller means and means to controllably bring said roller means into contact with the periphery of said cage.

Preferably the means of bringing the plurality of rollers into contact with the perimeter of the cage comprises a claw device consisting essentially of at least two articulated arms attached to a support, said arms being actuable between an open and a closed (cage-contacting) position by at least two eccentrically mounted pistons.

The roller means may comprise cylindrical rollers, disc rollers or combinations thereof, which are freely rotatable on suitable bearings, but at least one such roller device may be controlled e.g. with braking means. Preferably the respective roller means are individually adjustable to provide for "best fit" pressure loading points for the cage size to be constrained around the pipe. It will be understood that the device is suitable for use with a range of pipe (and corresponding cage) diameters.

The plurality of roller means may be individually attached to the arms by frames incorporating at least one spring, said spring serving to constrain the movement of said frames, and hence said rollers, relative to the arms.

An embodiment of the present invention will now be described with reference to the following drawings in which

Figures 1 and 2 show a three dimensional representation of typical pipe coating plant;

Figure 3 shows a reproduction of a photograph detailing a spacer;

Figure 4 shows an end view of a cage location device in accordance with the present invention;

Figure 5 shows a schematic representation of the interaction between a roller and a cage;

Figure 6 shows a partially cut-away view of a roller biasing unit. Referring firstly to Figs. 1 and 2 there is shown a typical pipe coating plant comprising means for supporting a pipe section 5 surrounded by a wire cage 10, a concrete delivery station 15 and transport bogies 20. The pipe 5 is fitted with the cage 10 prior to being loaded, e.g. by crane, onto a set of bogies 20. Said bogies 20 serve to convey the pipe 5 past the delivery station 15 at the required speed and to impart the necessary axial rotation to the pipe 5. Concrete is fed from hopper 25 onto conveyor 30 which carries it to a set of delivery rollers 35. The rollers 35 deliver the concrete onto the surface of the rotating pipe at a flow rate in the region of 120 kg/s . Any concrete which does not adhere to the surface of the pipe 10 is scavenged from below the delivery station 15 and returned to the hopper 25. Once the pipe has fully passed the coating station 15 and received the desired thickness of coating 40 it is removed for appropriate curing/storage (not shown) .

Referring now to Fig. 3 shows a typical spacer 45 of the type used to locate the cage 10 relative to the pipe 5 prior to coating.

Turning now to Fig. 4, there is shown a cage location device 50 in accordance with the present invention in an engaged position. The device 50 is composed chiefly of two arms 55 attached to a carrying member 60 by pinned links 65. Said links 65 define a fulcrum about which the arms 55 can rotate. Rotation of the arms 55 is achieved by the extension and retraction of actuation pistons 70 mounted on an upright 75 atop the carrying member 60. The cross beam/arm assembly shown in the end view presented in Fig. 4 is actuable as a claw device and effectively serves, in use, to define a circumferential peripheral pressure applicator to hold the cage 10 about the pipe 5. The inner portion of each arm 55 adjacent to the cage 10 is substantially concave 80 and located around the periphery of said concave portion 80 are a plurality of adjustable spring biased rollers 85.

In use, the location device 50 is situated at the entry to a delivery station and is initially in an open disengaged position with the actuation pistons 70 retracted (not shown) . Pipe/cage assemblies are fabricated substantially as described hereinbefore, the main difference being that a vastly reduced number of spacers are employed to locate the cage 10 around the pipe 5. Typically for a 10 metre length pipe a spacer reduction from 360 to 20 can be achieved. The pipe cage assembly is then transferred onto the transport bogies and rotated in the normal manner. Upon reaching the entrance to the delivery station the location device 50 is activated either by manual command or by an automatic position sensing system. Actuation pistons 70 extend causing arms 55 to rotate about pinned links 65 and said arms 55 continue to rotate until the rollers 85 are brought into contact with the rotating cage 10. Said rollers exert sufficient force upon the cage 10 to position it concentrically about the axis of rotation of the pipe 5 immediately prior to the coating operation.

The rollers 85 remain in contact with the cage 10, keeping it in the correct position for the majority of the coating process. The pistons 70 retract, and the rollers subsequently break contact with the cage 10, immediately prior to the coating of the tail section of the pipe 5 to allow clearance for the support bogie. By the time the location device 50 is thus disengaged, sufficient concrete is present upon the pipe 5 ahead of the tail section to hold the cage 10 in the correct position. With the actuation pistons 70 retracted, the location device 50 is ready to receive the next pipe 5 to be coated.

Referring now to Fig. 5 there is shown a schematic representation of an individual roller 85 interacting with the outer surface of a cage 10. In the interests of longevity the individual rollers 85 are preferably manufactured from a hard plastics material such as polyurethane. Displacement means along an axis perpendicular to the cage axis of rotation 95 allow the distance between the roller 85 and rotational axis 95 to be varied as depicted by arrow 90. This feature allows the locating device 50 to accommodate a range of pipe and cage 10 diameters. The roller 85 can also be rotated 100 about said perpendicular axis thereby, in conjunction perpendicular movement 95, allowing each roller 85 to be "fine tuned" and exert the optimum force upon the cage 10 for the given operating conditions.

Fig. 6 shows one embodiment of a means of attaching a roller 85 to an arm 55 incorporating spring biasing means. The use of a spring 105 allows the roller 85 to maintain contact with the cage whilst compensating for any irregularities present in the shape or surface configuration of the cage. The roller 85 is attached via an axle 110 to a frame 115 which is supported within the arm 55 by bushes 120. The frame 115 is restrained from free movement relative to the arm 55 by a threaded bar 125 which at one extremity holds a coil spring 105 in compression against the arm 55. The threaded bar 125 is connected to the frame 115 by a lock nut 130 thereby allowing the initial displacement of the roller 85 from, and its travel relative to, the arm 55 to be varied. As detailed before the whole assembly can be rotated 100 to provide the best performance for the given operating conditions.

It should be understood that the embodiment of the invention described hereinbefore is given by way of example only, and whilst representing the best mode for performing the invention currently known is not meant to limit the scope thereof in any way.

Claims

1. A device to promote the location of a cylindrical wire cage concentrically about the longitudinal axis of a rotating tubular article comprising an adjustable arm (55) provided with a plurality of roller means (85) and means (70) to controllably bring said roller means into contact with the periphery of said cage.

2. A device as claimed in claim 1 wherein the means of bringing the plurality of roller means into contact with the perimeter of the cage comprises a claw device consisting essentially of at least two articulated arms attached to a support (60) , said arms being actuable between an open and a closed (cage-contacting) position by at least two pistons (70) .

3. A device as claimed in claim 1 or claim 2 wherein the roller means comprise cylindrical rollers, disc rollers or combinations thereof, which are freely rotatable on suitable bearings.

4. A device as claimed in claim 3 wherein the roller means are individually adjustable to provide for "best fit" pressure loading points for the cage size to be constrained around the pipe.

5. A device as claimed in any preceding claim wherein the rotation of at least some of the roller means is controllable e.g. by braking means.

6. A device as claimed in any preceding claim wherein the plurality of roller means are individually attached to the arms by frames (115) incorporating at least one spring

(105) , said spring serving to constrain the movement of said frames, and hence said rollers, relative to the arms.

7. A device as claimed in claim 6 wherein movement of the frames relative to the arms is adjustable.

8. A device substantially as hereinbefore described with reference to figures 4, 5 and 6.

9. A method of applying a weight-coating to pipes using a concrete coating plant comprising selecting a pipe section for coating, providing a wire cage concentrically around a pipe section, providing means for supporting the pipe section for coating purposes, presenting the pipe section for coating at a concrete delivery station, arranging a device as claimed in any one of claims 1 to 8 to control the location of the cage about the pipe during coating, conveying the pipe section past the delivery station at the required speed whilst imparting the necessary axial rotation to the pipe, and applying concrete to the conveyed pipe.

10. A method according to claim 9 wherein the device for controlling the location of the cage about the pipe during coating is activated by position sensing means to enable automatic operation of the coating plant.