AU581720B2 - Protection of pipe means in a splash zone on a rig construction at sea - Google Patents

Description

IMPROVEMENTS IN OR RELATING TO THE PROTECTION OF PIPE MEANS IN A SPLASH ZONE ON A RIG CONSTRUCTION AT SEA.

This invention relates to the protection of pipe means in a splash zone on a rig construction or similar installation at sea.

In rig constructions or other installations at sea, the so-called splash zone constitutes a parti¬ cularly exposed region on the rig, the pipes and trunks in the splash zone being particularly exposed to corrosion-promoting and other influences, partially as a consequence of the influences of sea and air and partially as a consequence of the effects of the beating of the waves, attacks of marine overgrowth etc. A particular problem arises as a consequence of the often narrow intermediate spaces which are found be¬ tween pipes and trunks thrust together or adjacent, something which involves large problems for ready access. Hitherto, one has been obliged to effect cleaning, inspection and application of protective medium by means of divers in the regions which are submerged in the sea and, in the regions which are located above or just at sea level, in a more con¬ ventional manner by means of personnel placed in scaffolds or at similar work locations. Work domes or boxes have also been employed in which work personnel are received in a chamber which borders up to the pipe or the trunk. Such personnel-receiving work domes or boxes are, on the other hand, difficult to employ in the regions where the associated trunk thrusts tightly up to other construction members of the rig. In addition, such boxes can be difficult to complete to provide totally suitable work zones for personnel.

With the present invention, the objective is to avoid the afore-mentioned problems by carrying out corrosion protection and other protective attempts in a rational and proper manner, without using divers or personnel received in work domes or boxes.

Accordingly, the present invention resides in an arrangement for use in the protection of pipe means in a splash zone on a rig construction at sea comprising: (a) a container made up of at least two parts for assembly around said pipe means and having a length which spans both exposed and submerged portions of said pipe means, said container and said pipe means defining therebetween an annular chamber which is closed below and open above and has a breadth which is limited rela¬ tive to its length, and said container being sealed at its lower end against said pipe means;

(b) a first carriage means adapted for movement in said annular chamber around the axis of said pipe means; (c) means for guiding and supporting said first carriage means;

(d) a second carriage means guided and supported by said first carriage means and adapted for movement along the latter in a direction axially of said pipe means,said second carriage means comprising holder means for the replaceable mounting of equipment designed for remotely •controlled cleaning and^" inspection of the surface of the pipe means and the application of protective medium thereto; and (e) means enabling operation of said equipment and extending from an upper portion to a lower portion of said annular chamber.

The invention also includes a method of using the arrangement of the last preceding paragraph which com- prises:

(a) assembling the at least two parts of the container around the pipe means; (b) draining the annular chamber defined between the container and said pipe means; and

(c) actuating the first and second carriage means to move the first carriage means around the pipe means and to move the second carriage means axially of the latter while simultaneously actuating the equipment replace- ably mounted on the holder means of the second carriage means via the operation-enabling means for said equip¬ ment. By a) employing a container chamber with a strongly limited breadth dimension, b) effecting cleaning, in¬ spection and application of protective medium by remote control and c) employing a carriage device which is moveable in the axial direction and peripheral direction of the chamber to support necessary equipment,it has been made possible to effect the protection with a minimal need for space and in a manner involving little danger and, at the same time, with the possibility for effective control of the protective work. If desired, the protective work can be carried out on external work platforms or, if necessary,effected and overseen from a position on the deck of the installation.

By employing a container of limited breadth, a chamber is available with a relatively low volume in spite of the relatively large length of the chamber. It is then posssible to effect cleaning, inspection and application of protective medium in a controlled atmos¬ phere, that is to say under regulatable temperature and regulatable air humidity conditions, the volume in the chamber being able to be exchanged, as required,, in a relatively easy manner.

Alternatively, the chamber of said container may have an open end at its upper end and also at its lower end or only at its lower end. This is a practical solution in case of using the apparatus for removing growth, corrotion material etc. from the pipe or trunk surrounded by said chamber. In addition, it is also possible to use a chamber with-closed upper and lower ends in order to use the apparatus in completely submerged condition.

In order to achieve a relatively rapid and effec- tive cleaning, inspection and application of protective medium, it is preferred that the first and second carriage means constitute a coherent unit comprising two equivalent unit portions arranged one on each oppo¬ site side of the container. Desirably, the equivalent unit portions are arranged to bear or thrust against each other at upper and lower positions in the container.

From a pure construction point of view, it is preferred that each equivalent unit portion includes first and second carriage assemblies, said first carriage assembly comprising rigid frame means with an upper set of wheels mounted to run on a roller track at the upper edge of the container and with a lower set of wheels providing lateral supporting abutment against a circularly curved guide rail at the lower end of the container, said frame means comprising elongate bracing members between said upper and lower sets of wheels and upper and lower wheel support members for carrying said respective sets of wheels, parallel guide means arranged between said wheel support members as well as parallel to and between said bracing members for separate con¬ trol of said second carriage assembly which comprises a plate adapted to have the equipment replaceably mounted thereon and to be displaced in relatively close proxi¬ mity to the inner wall of the container. The guide means preferably pass through opposite end portions of the second carriage assembly.

In order that the invention can be more clearly understood, convenient embodiments thereof will now be described, by way of example, with reference to the accompanying drawings in which:

Fig. 1 is a side view of an arrangement in use on a rig trunk and seen from the side, Fig. 2 is a vertical section of a container and associated carriage means,

Fig. 3 is a horizontal section of the arrangement of Fig. 2, Fig. 4 is a perspective view at the upper end of the container illustrating an alternative form of fastening for the arrangement, and

Fig. 5 is a plan of the fastening of Fig. 4. Referring to Fig. 1, a vertically extending rig trunk 10 is illustrated in the so-called splash zone, that is to say the rig trunk 10 is shown at 10b sub¬ merged below sea level 11 and at 10a above sea level 11. In this region, the rig trunk 10 is surrounded by a box-forming cylindrical container 12 or case which is provided with an upwardly opening, upper end 13 and a closed, lower end 14. The container 12 is carried in a support yoke 15 which is divided into two parts along a vertical plane separately fixable to the rig trunk 10 by means of clamp means 16 at the central portion 17 of the support yoke.

The container 12 is designed as a two-part con¬ struction, that is to say a construction which is divided into two similar half portions 12a and 12b (Fig. 1 and 2) extending axially along dividing lines. Each half portion 12a and 12b can, if desired, be divided up, in addition, into several parts along radi¬ ally extending dividing lines. he container can have, for example, a length of 10-13 m.

During assembly, the half portions 12a and 12b are mounted one after the other in place on the rig trunk 10, they being suspended from the support yoke 15 and thereafter tightened together against each other and, at the same time, against the rig trunk 10 by means of an upper tightening means 18 and a lower tightening means 19 and preferably one or more inter¬ mediate tightening means 20.

In an alternative embodiment (not shown) the con- tainer may be open in both upper and lower ends thereof. It is most convenient that remotely controlled closing means are located at both upper and lower ends of the container in order to close one or both ends thereof as need may be. This enables the container to have a more flexible application. In other words, the con¬ tainer may be used for different application in partly or in completely submerged condition with a closed off chamber surrounding the pipe or trunk. In addition, the container can be used in an efficient manner for specific cleaning applications with an open lower end, allowing the cleaned off material to be discharged directly through the lower end thereof into the surrounding body of sea. As shown in Fig. 3, the half portions 12a and 12b thrust sideways against each other via a V-shaped sealing means 21 and an equivalent V-shaped seal-forming stop 22. This arrangement of V-shaped sealing means and V-shaped stop is arranged along longitudinal vertical edges of the half portions 12a,12b as well as along horizontal, lower edges of the half portions. At the mutual jointing, the sealing means 21 and the stops 22 form combined control means and sealing means.

At lower ends of the half portions 12a, 12b, a bottom portion 23 extends over into a duct profile

24 lying radially innermost which is designed with a semi-circular arcuate contour with the duct opening 24a facing towards the rig trunk 10. Inside the opening 24a of the duct profile 24, there is received a packing member 25 which forms a yielding seal against the rig trunk 10. At the ends, the packing member can be securely connected, with a sealing means 21 at the one edge and with a stop 22 at the opposite edge.

The tightening means 18, 19 and 20 are preferably hydraulically driven, split-up annular tightening means which can be submerged along the container to the respective fastening level by means of hoist lines (not) shown), in order to tighten together the container half portions into specific container portions which are locally extra braced.

Bottom portion 23 of the container half portions extends horizontally inwards towards the duct profile 24. The bottom portion 23 and the duct profile 24 are braced relative to each other with a series of triangu¬ lar plates 26. Just above the bottom portion 23 at the outer wall of the container, there is fixed, via radi- ally extending support arms 27, a circularly curved rail 28. The rail 28 is formed of a plate piece which has the lower portion of the rail 28 arranged at a certain height above the bottom portion 23 and which has the upper porticn f the rail 28 projecting a distance upwards above the support arms 27.

A first carriage 30 is equipped with a pair of upper support wheels 32 and 32 which are rotated about horizontal wheel axes 3a and 32a and which rest against a roller track 33 on the top of the container 12. A set of lower support wheels or support rollers 34, 35, 36 which are rotated about vertical roller axes 34a, 35a, 36a respectively thrust against the inside and outside of the rail 28. The upper pair of support wheels 32, 32 with an associated support plate 37 is connected, via a pair of rigid control rods 39, 40 to the lower set of support rollers 34, 35, 36 with an associated support plate 38. In an intermediate space between the support plates 37 and 38 and between the control rods 39, 40, there are fixed guide-forming means 41, 42 between the support plates 37, 38, These guide- forming means 41, 42 are formed of somewhat elastic means, such as chains or wires or can, for example, be formed of rigid means, such as rigid pipes.

On the guide means, 41, 42, there are slidably mounted a second carriage 43 or a slide which by means of a pair of guide sleeves 44, 45 engage with their respective associated guide means 41 and 42. The slide of the carriage 43, which in itself has a certain weight or supports special weight elements, is raised and lowered along the guide means 41, 42 via a support wire 46 and a winch 47 fastened to the upper support plate 37 of the carriage 30. The carriage 30 moves along the roller track 23 in a suspended condition with control and support along the rail 28 and is for- wardly driven in the peripheral direction of the con¬ tainer 12 by means of a drive motor 48 which is fastened to the support plate 37 and which engages with a drive gear wheel 49 (Fig. 11) with a gear wheel rim 50 just below the roller track 33 at the upper end of the container 12.

From the deck of the rig there are suspended two segregated.work platforms 51, that is to say one for each container -half portion 12a, 12b.

In the illustrated embodiment (see Fig. 3), there is shown, on each of the container half portions 12a and 12b, a corresponding carriage 30. Each carriage 30 is equipped with an associated slide or carriage 43 and with an associated winch 47 and drive motor 48. Each carriage unit 30, 43 can, during mounting of the container half portions 12a and 12b on the rig trunk, already be mounted in place on the associated con- tainer half portion in certain accurately established positions in the container half portions. When the con¬ tainer half portions are pushed together against each other for mutual sealing and for sealing against the rig trunk, cooperating support means 52, 53 on the carriage units (above as well as below in the container 12) can jointly thrust against each other for mutual repelling and controlling of the carriage units rela¬ tive to each other in the peripheral direction of the container. The carriage units 30, 43 are adapted to move backwards and forwards over curved lengths each of about 180 (for example, approximately 190°) so that the carriage units collectively can cover the whole periphery of the rig trunk. By means of the vertically moveable carriage 43, the carriage units can collec¬ tively cover the rig trunk over the whole vertical dimension of the container. On the slide or the carriage 43, there are fastenable on a fastening plate 43a, via associated fastening means 54, different types of the treating apparatus and control apparatuses, for example, cleaning equipment in the form of a sand blast nozzle or the like, control equipment in the form of TV camera or similar visual aid means including headlight or similar illuminating means and equipment for the appli¬ cation of protective medium, for example, in the form of paint roller with associated nozzle for the supply of protective medium to the paint roller or, if desired, directly to the surface which is to be supplied with protective agent. Said treatment apparatuses or control apparatuses can be mounted and used after the other as required.

After the container is emptied of water (draining by means of suction conduit and associated pump) and necessary equipment is mounted on the support plate 43a, provision is made for the carriage units 30, 43 to be operated by remote control either from the plat¬ form 51 or from a control room on the deck of the rig. To the carriage 30, that is to say parallel to the con¬ trol rods 39, 40, there can be fastened associated electrical leads or medium hoses or pipes for the supply of different media to the equipment on the slide or the carriage 43. If desired, the control rods 39. 40 can themselves form medium supply pipes between the bottom of the container and the top. In addition or instead, there can be fastened to the carriage 30 a rigid suction pipe or a suction hose which has its lower outlet arranged just above the bottom portion 23 of the container 12. This suction pipe or this suction hose can be used alternately for the removal of water from internal chambers of the container just after the mutual jointing of the two container half portions 12a, 12b and for the removal of cleaning medium (sand par¬ ticles or the like) and detached coating particles, excess corrosion protective medium or the like. If de- sired, there can be arranged a suitable hose or a suitable pipe for the supply of hot (preferably also dry) air or gas to the bottom portion of the container for heating and drying untreated and treated surfaces of the rig trunk in order to obtain a desired air humidity and a desired air temperature in internal chambers of the container 12.

With the present invention, the objective is to effect a treatment and a visual control together with applying corrosion protective medium or another protec- tive medium on dried portions of a rig trunk or similar construction parts in a simple and risk-free manner by remote controland with minimum demands on space. In this connection, provision is made for the con¬ tainer 12 to be designed with an internal chamber of relatively small volume, but nevertheless with an effective utilisation of the limited volume of the chamber. Provision is made for the fastening plate 43a of the slide or carriage 43 for the mounting of appropriate equipment, to be arranged as tightly as possible up to the inner wall of the container 12 without necessarily contacting this so that the greatest possible space can be obtained for said treatment equip¬ ment and control equipment. In this connection, guide sleeves and associates guide means of the slide or carriage are arranged laterally displaced relative to the intermediate fastening plate 43a while the control rods 39, 40 are further displaced sideways away from the slide or the carriage 43 but, nevertheless, not further away than that the control rods 39, 40 can, if necessary, form stops for guide sleeves of the slide or the carriage 43 or other suitable support means during displacement of the slide or the carriage along the guide means 41, 42.

The said limited volume within the internal chamber of the container involves the advantage that the volume is relatively easy to empty and fill and in addition is easy to control in connection with airing so as to provide drier treatment surfaces and humidity- regulatable or temperature-regulatable atmosphere in a ready manner, the chamber being able to be blown through by air or gas which is supplied to the lower end of the chamber or which can be sucked through by sucking in air or gas from the lower end of the chamber. Simultaneously with the afore-mentioned air or gas exchange, there can be obtained, as a consequence of the narrow passage in the container, an effective flow along the outer surface of the rig trunk.

In the present embodiment, there is illustrated the solution in connection with the treatment and con¬ trol of the rig trunk for application of corrosion pro¬ tective medium. However, the solution can also be em- ployed for application of another protective medium which is to be applied outside the treated surface of the rig trunk. The container can, for example, be used with advantage in connection with the application of a layer of rubber or a similar protective layer outside the rig trunk. For example, such a coating can be applied in sections of plate material around the rig trunk with a vertical joint in each section and with a horizontal joint between each pair of sections, to form a freely sitting stocking which can slide down- wards along the rig trunk gradually as subsequent sections are jointed on. The stocking can, if necessary, be carried below by the carriage units 30, 43 via suit¬ able support equipment on the fastening plate 43a. Alternatively, the stocking can be supported indepen- dently of the carriage units 30, 43 via suitable support equipment (not shown) while the carriage units can be equipped for the application of or jointing to- gether of the plate-formed coating. Finally the inter¬ mediate space between the rig trunk and the stocking can be filled with suitable filler material, such as a fluid medium of two or several components which on hardening expands to a certain limited extent.

As an example, the inner wall of the container 12 can be arranged at a distance from the outer wall of the pipe trunk of 15 cm since such a distance can be sufficient to receive the above-described equipment. At the same time, such a limited distance will give a minimal volume in the container and the container will be able to be easily arranged at locations which other¬ wise can be accessible with difficulty with other equipment. In Figs.' 4 and 5, there is illustrated an alter¬ native embodiment where a support and guide device 60 for the carriage 30 is fixed, independently of the con¬ tainer, directly to the pipe or trunk 10. The support and guide device is made in the form of two half por- tions 60a, 60b which are clamped together against each other around the pipe or trunk 10 by means of clamp bolts 61, 62 in opposite bracket portions 63, 64 of the two half portions 60a, 60b.

By the solution shown there is the possibility of supporting the carriage 30 in an accurate manner without vibrations and movements which otherwise can exert pressure on the container during use as a consequence of the impact of waves against the con¬ tainer, In addition, by arranging the carriage 30 at a level above the upper edge of the container there results, furthermore, an easily available access to the second carriage and equipment which is mounted on the latter.

With the construction illustrated in Figs. 4 and 5, there can be employed, in a manner corresponding to that shown in Fig. 2, a lower support for the carriage 30 on a guide at the bottom of the container. Alter- natively, there can be utilised a lower support (not shown^') fixed directly to the pipe or trunk independent of the container.

Claims (9)

1. Arrangement for use in the protection of pipes or trunks in a splash zone on a rig construction at sea which comprises a container made up of at least two parts for assembly around the pipe or trunk and having a length which spans both exposed and submerged portions of said pipe or trunk, said con¬ tainer and said pipe or trunk defining therebetween an annular chamber which is open below and above or closed at one or both ends thereof, characterised in that said container (12) is sealable at its lower and/ or upper end(s) against the pipe or trunk (10) and the annular chamber has a breadth which is limited rela¬ tive to its length, and in that said arrangement com¬ prises a first carriage component (30) adapted for movement in said annnular chamber around the axis of the pipe or trunk (10); a guide and support assembly (12, 28, 33; 60, 60a, 60b) for said first carriage component; a second carriage component (43) guided and supported by the first carriage component and adapted for movement along the latter in a direction axially of the pipe or trunk, said second carriage component comprising a holder (43a) for the replace¬ able mounting of equipment designed for remotely controlled cleaning and inspection of the surface of the pipe or trunk and the application of protective medium thereto; and parts (39, 40) enabling operation of said equipment and which pass from an upper por¬ tion to a lower portion of said annular chamber.

2. Arrangement according to claim 1, characterised in that the guide and support assembly for the first carriage component (30) is mounted at upper (33) and lower (28) ends of the container (12).

3. Arrangement according to claim 1, characterised in that the guide and support assembly (60, 60a, 60b) for the first carriage component (30) is carried by the pipe or trunk (10) in a region between the upper edge of the container (12) and an upper fastening for the container on the pipe or trunk.

4. Arrangement according to claim 1, characterised in that the first and second carriage components (30, 43) constitute a coherent unit comprising two equivalent unit portions arranged one on each opposite side of the container.

5. Arrangement according to claim 4, characterised in that the equivalent unit portions are arranged to bear against each other at upper and lower positions in the container.

6. Arrangement according to claim 4 or 5, charac¬ terised in that each equivalent unit portion includes first and second carriage assemblies, said first carriage assembly (30) comprising a rigid frame (37-40) with an upper set of wheels (31, 32) mounted to run on a roller track either carried by the pipe or trunk (10) in the region between the upper edge of the con¬ tainer and an upper fastening for the container on the pipe or trunk or disposed at the upper edge of the container (12) and with a lower set of wheel (34, 35, 36) providing lateral supporting abutment against a circularly curved guide rail (28) at the lower end of the container, said frame (37, 40) comprising elongate bracing members (39, 40) between said upper and lower sets of wheels and upper and lower wheel support members (37, 38) for carrying said respective sets of wheels, parallel guide members (41, 42) arranged between said wheel support members as well as parallel to and between said bracing members for separate control of the second carriage assembly (43) which comprises a plate (43a) adapted to have the equipment replaceably mounted thereon and to be displaced in relatively close proximity to the inner wall of the container (12).

7. Arrangement according to claim 6, characterised in that the guide members (41, 42) pass through opposite end portions of the second carriage assembly (43).

8. Arrangement according to any of claim 1 to 7, characterised in that the parts (39, 40) enabling operation of the equipment are mounted on the first carriage component (30) and are electrical leads and/or medium supply hoses.

9. Method of using the arrangement of claim 1, charaterised by assembling the at least two parts of the container (12) around the pipe or trunk (10); draining the annular chamber defined between the container (12) and the pipe or trunk (10); and actuating the first and second carriage components (30, 43) to move the first carriage component (30) around the pipe or trunk and to move the second carriage component (43) axially of the latter while simultaneously actuating the equipment replaceably mounted on the holder (43a) of the second component (43) via the parts (39, 40) enabling operation of said equipment.