WO2013007998A1

WO2013007998A1 - Multi-component work-piece and tool

Info

Publication number: WO2013007998A1
Application number: PCT/GB2012/051616
Authority: WO
Inventors: Nigel Davison; Ryan LANGLEY; Nick ASPEY
Original assignee: Express Engineering (Thompson) Ltd
Priority date: 2011-07-08
Filing date: 2012-07-09
Publication date: 2013-01-17
Also published as: GB201111711D0; GB2492596B; GB2492596A; GB201212161D0

Abstract

A method of manufacturing a multi-piece component comprises the steps of: mounting a work-piece blank (1) in a machine tool; machining a profile of a multi-piece component from the work-piece blank (1), the profile defining at least some individual pieces of the multi-piece component, all the pieces of the multi-piece component being attached together; mounting a clamp (10) on the work-piece, the clamp (10) being attached to at least two pieces (4,6) of the multi-piece component defined in profile; machining the profile to separate at least one of the pieces (4) from the profile, said separated piece (4) being support by the clamp (10); and removing the clamp (10).

Description

Multi-Component Work-Piece and Tool

Field of the Invention

The present invention relates to a multi-component work-piece, a method of manufacturing such a component and a tool for use in the method of manufacture.

Background of the Invention

Swivel flanges are widely used in the process industry sector. Such flanges allow adjacent components to be connected together when there is slight mis-alignment between those components.

A pipe having swivel flanges at each end thereof, known in the industry as a double ended swivel flange pipe comprises a pipe section, at each end of the pipe a flange support, and two flanges which are arranged on the pipe section and to abut against at least a part of the flange. The double ended swivel flange pipe is connected to an adjacent pipe by means of fasteners that are passed through the flange. The fasteners draw opposing faces of the flange supports into sealing abutment with each other.

There are a number of problems associated with swivel flanges of the prior art. First, they are formed of multiple pieces which are assembled together and then welded. The flanges are held on to the component by the flange supports and hence must be mounted on the pipe before the flange supports are attached thereto by welding. As well as being time consuming, the process of welding potentially introduces both distortion and weakness into the structure. The introduction of distortion means that the multi-piece component cannot be manufactured to such tight tolerances as would be possible if the welding step were omitted. Further, the likelihood of weaknesses being introduced into the component by welding means that the component is in general made with a greater safety factor, meaning that more material is used and the component is heavier than would be the case if welds could be avoided.

The fact that the multi-piece component is fabricated from a number of pieces means that each individual piece must carry its own documentation. This procedure is time consuming and carries with it an excessive administrative burden. In manufacturing the above described multi-piece component of the prior art a steel tube is machined to form a central pipe section having a circular cross-section of constant outside diameter, and flange supports at each end thereof, which include a first part having an outside diameter greater than that of the central pipe section and a second part having an outside diameter greater than that of the first part. Once machined, one flange support is cut off. Two flanges that are machined from other pieces of stainless steel tube are then slid on to the central pipe section. One of the flanges is shaped to sit on and be supported by the flange support at one end of the pipe section. The other flange is shaped to sit on and be supported by the flange support at the other end of the pipe section. The freed flange support is then welded back on to the end of the central pipe section. It is the re-connecting of one of the flange supports by welding that is likely to introduce distortion and weakness into the multi-piece component.

The swivel flange described above is one type of retained flange. The problem described above may be found in other areas of manufacture where a multi-piece component includes a retained element. The invention described below is therefore not limited to swivel flanges used in pipelines. Further, the invention described below is not limited to components manufactured of steel Components could be manufactured of other metals or metal alloys, plastics or other materials.

It would therefore be desirable to manufacture a multi-piece component in which at least one of the pieces is mounted on another piece between the ends thereof, without the necessity to weld or otherwise attach together separated pieces of the multi-piece component.

It would be desirable to manufacture a multi-piece component from a single piece of material. In this way the multi-piece component may be regarded as a one component rather than a number of different components, and may therefore need only be subjected to a single set of tests and carry a single set of documentation.

Summary of the Invention

According to a first aspect of the invention there is provided a method of manufacturing a multi- piece component comprising the steps of: i) Mounting a work-piece blank in a machine tool;

ii) Machining a profile of a multi-piece component from the work-piece blank, the profile defining at least some individual pieces of the multi-piece component, all the pieces of the multi-piece component being attached together;

iii) Mounting a clamp on the work-piece, the clamp being attached to at least two pieces of the multi-piece component defined in profile;

iv) Machining the profile to separate at least one of the pieces from the profile, said

separated piece being support by the clamp; and

v) Removing the clamp.

The method may include at least one further step of machining the work-piece with the clamp mounted thereon and supporting the separated at least one piece of the multi-piece component.

The method may include mounting two or more clamps on the work-piece, each clamp being attached to at least two pieces of the multi-piece component defined in profile.

Step ii of the method advantageously includes the step of machining bores, which may be through bores, in one of the pieces of the multi-piece component. The bores may be bores configured for use in final installation of the multi-piece component. Step iii of the method advantageously includes the step of attaching the clamp to the piece defined in profile including bores formed in step ii of the method by fasteners engaging with the bores and the clamp. Such fasteners may be bolts or pins.

Step ii may include the step of removing material from the centre of the work-piece.

Alternatively, where removal of material from the centre of the work-piece is required, this may form part of removing material from the centre of the work piece may be performed between steps iii and iv, if machining involves rotating the work-piece, for example machining using a lathe, or after step iv or v if the work-piece remains stationary in machining, for example drilling or reaming.

According to a second aspect of the invention there is provided a multi-piece component comprising a first piece comprising at least one section of a first diameter the at least one section bounded by spaced apart elements of greater dimension than the first diameter and at least one second piece mounted on but separated from the at least one first section and retained thereon between the spaced apart elements, wherein the at least one second piece consists of a continuous element extending around the first section, the continuous element being free from joints.

Preferably, the spaced apart elements have diameters greater than the first diameter.

Advantageously, at least one of the spaced apart elements comprises a flange seat and the second piece comprises a flange.

Advantageously, the multi-piece component is a swivel flange connector pipe and the second piece of the multi-piece component is a flange. The swivel flange connector pipe may be single or double ended. In a double ended swivel flange connector, two second pieces are mounted on the first section, each second piece comprising a flange.

At least one of the spaced apart elements may comprise a flange seat. In the case of double ended swivel flange, each spaced apart element may comprise a flange seat.

According to a third aspect of the invention there is provided a tool for use in the method of manufacture of a multi-piece component, the tool comprising a clamp, the clamp comprising at least two parts, fastening means to attach together the at least two parts, attachment means for attaching the clamp to a piece of a multi-piece component and a support surface adapted to sit on and be supported by another piece of the multi-piece component.

The fastening means may comprise at least one bore in each of the at least two parts, wherein at least one bore of one of the at least two parts aligns with at least one bore of an adjacent one of the at least two parts, when the at least two parts are attached together. The fastening means may include an element adapted for insertion into the aligned bores. Such an element may be a bolt, a screw, a pin, a peg or a clip. At least one of the bores may be threaded. The element may be threaded and may co-operate with threads of an at least one bore, or the threaded portion of the element may extend beyond the bore and a nut may be attached thereto.

The at least two parts of the clamp may be attached together by a hinge. In one embodiment the at least two parts of the clamp are attached together at one side by a hinge and at the other by fastening means.

The fastening means may include a hinge. Advantageously, the fastening means includes a lever pivotally attached to one of the at least two parts, and a clasp pivotally attached to the lever, the axes of the pivots being offset with respect to one another, and an adjacent one of the at least two parts may include a slot adapted to receive a part of the clasp.

Preferably, the attachment means for attaching the clamp to a piece of the multi-piece component includes a bore, said bore in use being aligned with a bore in the piece of the multi-piece component, and an element for insertion into the aligned bores. The element may be a bolt, a screw, a pin, a peg or a clip. At least one of the said bores may be threaded. The element may be threaded and may co-operate with threads of an at least one bore, or the threaded portion of the element may extend beyond the bore and a nut may be attached thereto.

The attachment means may comprise a plurality of bores, each lying on at a different distance from the centre of the clamp. This allows the same clamp to be used to secure pieces of a multi-piece component having different sizes. The machine tool operator when attaching the clamp aligns a bore in the piece that is to be supported by the clamp with the appropriate bore in the attachment means. In place of a plurality of bores, the attachment means may include a slot, the slot providing for an element such as a bolt to be aligned with a bore in the piece to which the clamp is to attach lying at any distance from the centre of the clamp between the ends of the slot.

The clamp may include a peripherally located lip extending in the axial direction of the clamp. A lip element may form part of each of the at least two parts of the clamp. In use, the lip at least partially encapsulates the piece of the multi-piece component to which it is attached. Brief Description of the Drawings

In the drawings which illustrate preferred embodiments of the invention and are by way of example:

Figure 1 illustrates side and end views and an isometric projection of a work-piece blank pre- machining;

Figure 2 illustrates side and end views of and a cross-section on A-A of the work-piece of Figure 1 machined to a rough profile having a single end flange;

Figure 3 illustrates side and end views of and a cross-section on A-A of the work-piece of Figure 1 machined to a rough profile having end flanges at both ends thereof;

Figure 4 illustrates a partially machined work-piece having single end flange;

Figure 5 illustrates a partially machined work-piece having end flanges at both ends thereof;

Figure 6 illustrates the partially machined work-piece of Figure 4 with a clamp attached to the flange thereof;

Figure 7 illustrates the partially machined work-piece of Figure 5 with clamps attached to each of the flanges thereof;

Figure 8 illustrates the partially machine work-piece of Figures 4 and 6 with the flange released from the work-piece and clamped;

Figure 9 illustrates the partially machined work-piece of Figures 5 and 7 with the flanges released from the work-piece and clamped;

Figure 10 illustrates a multi-piece component having two end flanges, the end flanges clamped by a first type of clamp; Figure 11 illustrates a multi-piece component having two end flanges, the end flanges clamped by a second type of clamp;

Figure 12 illustrates a multi-piece component having two end flanges, the end flanges clamped by a third type of clamp;

Figure 13 illustrates the finished multi-piece component having two end flanges;

Figure 14 illustrates a finished multi-piece component having two end flanges, one of the end flanges attached to a pipeline;

Figure 15 illustrates a finished multi-piece component having two end flanges, one of the end flanges attached to a pipeline and the other to another pipeline component;

Figure 16 illustrates the partially machined multi-piece component of Figure 4 with the end flange released;

Figure 17 illustrates the partially machined multi-piece component of Figure 5 with both end flanges released;

Figure 18 illustrates a first type of clamp;

Figure 19 illustrates a second type of clamp;

Figure 20 illustrates a third type of clamp;

Figure 21 illustrates a fourth type of clamp; and

Figure 22 illustrates a fifth type of clamp. Detailed Description of the Preferred Embodiments

The first stage of a method of manufacture of a multi-piece component according to the invention will now be described with reference to Figure 1 to 5. Figure 1 illustrates a blank work-piece 1 from which the multi-piece component is formed. In the illustrated example, the work-piece 1 comprises a first part 2 of a first diameter and a second part 3 of a second diameter. The work-piece may be cast or pre-machined into the shape illustrated from a section of bar.

Figure 2 illustrates the work-piece 1 after a step in the machining method of the invention. As can be seen, a rough profile of an end flange 4 and a flange seat 5 have been formed by removing material from the work-piece 1. This would typically be done using a lathe. This step in the machining method creates a central section 6 of the work piece, which in the illustrated example has an outside diameter less than that of the flange 4, flange seat 5 and a fixed end flange 8 formed from the second part 3. As can be seen from the section on A- A, the flange 4 is attached to the central section 6 by means of a web 4a.

Figure 3 illustrates the work-piece 1 but machined to form swivel flanges at each end thereof, rather than just one end as in Figure 2. The work-piece 1 is therefore machined to form two swivel flanges 4, 7 mounted on the central section 6 and between flange seats 5, 9, which in the finished multi- component work piece co-operate with respective flanges 4, 7. At this stage in the manufacturing process the flanges 4, 7 remain attached to the central section 6 by webs 4a, 7a.

Figures 4 and 5 illustrate the next step in the manufacturing method for the work piece in which a plurality of bores 4b, 7b are formed in the flanges extending axially therethrough. Also, in this part of the manufacturing method the flange seats 5, 9 are machined to provide surfaces 5a-5c and 9a-9c upon which the flanges 4, 7 sit in use. In the case of the multi-piece component illustrated in Figure 4, the flange seat 5 and the fixed end flange 8 are machined in the respective ends of the work-piece 1. At this stage in the process the centre of the work-piece 1 remains solid. The fixed end flange 8 provides bores 8a and indents 8b each for co-operation with an another component to attach the end flange 8 thereto. The flanges 4, 7 must be released from the work-piece 1 in order for the multi-component work- piece to function as a swivel flange, the flanges 4, 7 being connected to the work-piece 1 by webs 4a, 7a respectively. In order to achieve this, the method of the invention involves the step of attaching a clamp to the flange 4, 7, the clamp being configured to rotate with the work-piece when attached to the unreleased flange. The clamp may be attached to the work-piece to rotate therewith, or with respect thereto, when connected to the released flange. What is essential for safe working is that the released flange is constrained against radial movement with respect to the longitudinal axis of the work-piece 1. Preferably, the clamp is attached to the work-piece to rotate therewith.

Referring now to Figures 6 to 9, these figures illustrate the work-piece 1 with a clamp 10 (described in greater detail with reference to Figure 20) secured to the flange 4, 7 and mounted on the central section 6. The clamp 10 is attached to the flange 4, 7 by means of bolts 11 extending through bores 4b, 7b and secured by nuts 12. The clamp 10 is formed of two clamp halves 10a, 0b which are joined by a hinge 0c on one side. The clamp 0 is mounted on the work-piece 1 by pivoting one of the halves 0a, 0b with respect to the other, placing the two halves about the central section 6 and bringing the two halves together. On the opposite side to the hinge each clamp half 0a, 0b is a part of a fastening means Od, which is adapted to fasten the two halves 0a, 0b together. Each clamp half 0a, 0b includes a slot to receive a bolt 11. Having placed and closed the clamp 0 about the central section 6, and before fully fastening the fastening means, the operator aligns each slot 12 with a bore 4b, 7b and passes a bolt through the aligned bore and slot. The operator then proceeds to fully fasten the fastening means Od and to attach and tighten the nut 2 on to the bolt 11.

Each clamp half 0a, 0b provides an inner semi-circular surface Oe of substantially the same diameter as the outside diameter of the central section 6. When the fastening means Od is fully fastened, there is sufficient friction between the inner surfaces of the clamp halves and the outer surface of the central section 6 that the clamp is fixed with respect to the central section 6 irrespective of whether the flange 4, 7 to which the clamp is connected is a part of or released from the work-piece . With the clamp 0 in place the work-piece 1 may be machined safely to remove the web 4a, 7a and hence release the flange from the work piece, as shown in Figures 8 and 9. In the absence of the clamp, as the thickness of the web 4a, 7a decreases during the machining process, the flange 4, 7 would become unstable with respect to the central section 6. At this point further machining would be unsafe.

Figures 16 and 17 illustrate partially machined multi-piece components after the step of machining away the webs 4a, 7a to release the flanges 4, 7 from the central section 6. To machine out the centre of the work-piece 1 , the released flanges 4, 7 may need to be clamped to the central section. This may be preferable even when the centre of the work-piece 1 is to be removed without rotating the said work-piece, for example by drilling or reaming. Further, the flanges 4, 7 may need to be secured with respect to the central section 6 for other reasons, such as during transportation of the multi-piece component, or during assembly of the multi-piece component into a structure of which the multi-piece component forms a part.

Figures 18 to 22 illustrate different embodiments of clamp, and Figures 10 to 12 illustrate some of those clamps in use.

Referring first to Figure 18, the clamp 20 comprises clamping halves 20a, 20b. Each clamp half 20a, 20b includes a semi-circular inner surface 20e the diameter of which is selected to match the external diameter of a central section 6 of a work-piece 1. Each clamping half 20a, 20b is provided with part of a fastening means 20d, which in the illustrated example comprise bores 20d' and 20d" located on respective sides of the clamping half 20a, 20b. The bores 20d' of the clamping half 20a align with bores 20d" of the clamping half 20b, the bores 20d" being counter-sunk to receive the head of a bolt passed through aligned bores 20d', 20d". The bores 20d' may be threaded and bolts engaged with the threads thereof, or the bores may not be threaded and a nut attached to the end of a bolt protruding through the bore 20d'.

Each clamping half 20a, 20b comprises a back plate 21 that is substantially semi-circular in its peripheral shape. Portions 22 are cut away from each clamping half 20a, 20b to provide access to the fastening means 20d. A lip element 23 extends outward from curved peripheral edge of the back plate 21. Where the back plate 21 is cut away to provide access to the fastening means 20d, the lip element 23 is also cut away. A bore 24 is provided in each clamping half 20a, 20b to secure the clamp 20 to a flange of the work-piece 1.

Figure 10 illustrates the clamp 18 securing flanges 4, 7 on a work-piece 1. To attach the clamp 20 to the flange, the two clamping halves 20a, 20b are presented up to the central section 6 of the work piece 1, the bores 20d', 20d" aligned, bolts 25 inserted therein and at least partially fastened. The bores 24 are aligned with a bore 4b, 7b in the flange 4, 7 and a bolt 11 inserted into the aligned bores. The bore 24 may be threaded, in which case a nut need not be provided on the bolt 11. When the clamp 20 is attached to a flange 4, 7, the lip elements 23 extend over and partially encapsulate the flange. As will be appreciated from the drawings of Figure 10, the work-piece 1 has been machined such that flanges 4, 7 are released from the central section 6. In Figure 10 the centre of the work-piece has been machined to include an axial bore 6a such that the multi-piece component may form part of a pipe line.

Figure 19 illustrates a second embodiment of clamp 30. Again the clamp comprises two clamping halves 30a, 30b joined by fastening means 30d. The fastening means 30d comprises a clasp 30e movable between two positions attached to the clamping half 30a, and a slot 35 configured to engage with the with the clasp 30e.

Each clamping half 30a, 30b is provided with a bore 34 for attachment of the clamp 30 to a flange by aligning the bore 34 with a bore 4b, 7b of a flange and passing a bolt 11 therethrough. As with the first embodiment of the clamp, each clamping half 30a, 30b is provided with a lip 33 which partially encapsulates the flange when the clamp 30 is attached thereto. The clasp 30e is pivotally attached to a lever 30f at pivot point 30g, with the lever 30f being pivotally attached to the clamping half 30a at pivot point 30h. The pivot point 30g of the clasp is off set with respect to the pivot point 30h. By moving the lever 30f towards the clamping half 30b, the clasp 30e may be engaged with the slot 35. Moving the lever 30f back towards the clamping half 30a tightens the fastening means 30d to fasten the two clamping halves together about a central section 6 of a work-piece 1. As can be seen from the front view of the clamp 30 in Figure 19, the corners of each clamping half 30a, 30b are provided with a chamfer 36 at the point where the curved peripheral edge intersects with the straight peripheral edge of the clamping half 30a, 30b. In this way, to attach the clamp 30 on to a work piece it is not necessary to disassemble the clamp completely. The lever 30f on one side may be pivoted away from the edge of the clamping half, thereby slackening off the clasp 30e attached thereto. In such a configuration the clamping halves 30a, 30b may move apart from one another by a small distance. The clasp 30e to the other side would be released completely (see the clasp 30e on the right hand side in the front view of Figure 19. The chamfered edges 36 allow the clamping halves 30a, 30b to pivot with respect to one another.

A lip element 33 extends outward from curved peripheral edge of the back plate 31. The lip element is cut away to provide access to the fastening means 30d.

Figure 11 illustrates a multi-piece component with flanges fastened in place with clamps 30 of the type illustrated in Figure 19. The lips 33 of clamp 30 engage the flanges 4, 7. The bores 34 are aligned with bores 4b, 7b and a bolt passed therethrough to enhance the attachment of clamp 30 to the flange 4, 7.

The work-piece 1 in the drawings begins as a solid element. However, the work-piece 1 could begin as a pipe.

Figure 20 illustrates in detail the embodiment of clamp 0 shown in use in Figures 6 to 9 described above, and also in Figure 2.

The clamp 0 comprises clamping halves 0a, 0b. The clamping halves 0a, 0b are connected together by a pivot 0c to one side of the clamp and a fastening means 1 Od to the other, the fastening means comprising bores Of which are aligned to receive a bolt Og to fasten the clamping halves 0a, 0b together. The bores Of of the clamping half 0a may be threaded to receive the threaded bolt Og or a nut may be provided to attach to the bolt Og to thereby tightened the fastening means Od and secure the clamp 0 in position.

Each clamping half 0a, 0b includes a semi-circular portion Oh with a flange Oi extending therefrom, the slot 3 being situated in the flange Oi. The opposing internal faces of the slot 3 include a plurality of spaced apart protrusions 13a which act as positioning guides, The slots 13 could be plain slots without the protrusions 13a.

Figure 12 illustrates a multi-piece component where the flanges 4, 7 are attached to clamps 10. One of the advantages of the clamps 10 is that the slots 13 allow the same clamp to be used with flanges of different diameters, whereas with the type of clamp 20 or 30 a different dimension of clamp is required for each different diameter of flange. With the clamp 10, the bolt 11 is moved in the slot 3 such that it is aligned with a bore 4b, 7b and then inserted into the bore.

Figure 21 illustrates another alternative embodiment of a clamp 40, which is similar to the clamp 20 illustrated in Figure 8, the difference being that the clamp includes a collar 46. The collar 46 is a separate part and is formed in two halves, 46a, 46b. The collar halves 46a, 46b are held on to the work piece by the clamp 40 and provide for the same clamp to be used with work pieces of differing diameters, by the provision of collars 46 of differing thickness.

Figure 22 illustrates another alternative embodiment of a clamp 50, which is similar to the clamp illustrated in Figure 9, the difference being that the clamp includes a collar 56. The collar 56 is a separate part and is formed in two halves 56a, 56b. The collar halves 56a, 56b are held on to the work pieces by the clamp 50 and provide for the same clamp to be used with work pieces of differing diameters, by the provision of collars 56 of differing thickness.

Figures 3 to 5 illustrate a finished multi-piece component and finished multi-piece components in use. Referring first to Figure 3, the flanges 4, 7 have bores 4b, 7b around their periphery for attachment of the flange 4, 7 to another object, and the flanges are released from the central section 6 of the work-piece . The central section 6 has been machined internally as required for the purpose of the component. The ends of the work-piece 1 have been machined to form flange supports 5, 8.

In Figure 14 a double ended swivel flange pipe 70 is connected to a flexible pipe 71. The flexible pipe 71 is provided with an end flange 72 which includes bores 72b for alignment with bores 7b of the flange 7. In Figure 15, a single ended swivel flange pipe 80 is shown attached by flange 4 to another component 81 of a pipeline. The other end of the pipe is connected to a flexible pipe.

The invention provides: a method for the manufacture of multi-piece components including retained elements without the requirement for any parts of the component to be removed and re-attached by a joining technique during manufacture; a clamp for use in the performance of the method of the invention, the clamp securing a component released from a work piece during manufacture; and a multi- piece component including at least one element situated between the ends of and retained on the component. The invention increases the strength of the component as compared with components where joining techniques such as welding are used and therefore allows a multi-piece component to be manufactured with less material. This may reduce manufacturing and transport costs. Further, by manufacturing the multi-piece component from a single work-piece and without separating elements therefrom and re-joining them, the multi-piece component of the invention may be regarded as a single component and therefore may be certified as a single component and therefore may need only a single set of documentation.

Multi-piece components including retained elements formed without the requirement for any parts of the components to be removed and re-attached by a joining technique have applications in many fields. For example, in any pipeline application where captured flanges or captured components are deployed the multi-piece component of the invention could find utility. In the oil and gas industry, in pipelines, drill pipes, well head and Christmas tree applications.

Claims

1. A method of manufacturing a multi-piece component comprising the steps of: i) Mounting a work-piece blank in a machine tool;

separated piece being support by the clamp; and

v) Removing the clamp.

2. A method of manufacturing according to Claim 1, including at least one further step of

machining the work-piece with the clamp mounted thereon and supporting the separated at least one piece of the multi-piece component.

3. A method of manufacturing according to Claim 1 or 2, including mounting two or more clamps on the work-piece, each clamp being attached to at least two pieces of the multi-piece component defined in profile.

4. A method of manufacturing according to any preceding claim, wherein step ii of the method includes the step of machining bores in one of the pieces of the multi-piece component.

5. A method of manufacturing according to Claim 4, wherein the bores are configured for use in final installation of the multi-piece component.

6. A method of manufacturing according to Claim 4 or 5, wherein step iii of the method includes the step of attaching the clamp to the piece defined in profile including bores formed in step ii of the method by fasteners engaging with the bores and the clamp.

7. A method of manufacturing according to any preceding claim, wherein step ii includes the step of removing material from the centre of the work-piece.

8. A method of manufacturing according to any of Claims 1 to 6, including a step involving removal of material from the centre of the work-piece, said step of removing material from the centre of the work-piece being performed between steps iii and iv.

9. A method of manufacturing according to any of Claims 1 to 6, including a step involving

removal of material from the centre of the work-piece, said step of removing material from the centre of the work-piece being performed after step iv or v.

0. A multi-piece component comprising a first piece including at least one section of a first diameter the at least one section bounded by spaced apart elements of greater dimension than the first diameter and at least one second piece mounted on but separated from the at least one first section and retained thereon between the spaced apart elements, wherein the at least one second piece consists of a continuous element extending around the first section, the continuous element being free from joints.

. A multi-piece component according to Claim 0, wherein the spaced apart elements have diameters greater than the first diameter.

12. A multi-piece component according to Claim 10 or , wherein at least one of the spaced apart elements comprises a flange seat and the second piece comprises a flange.

3. A multi-piece component according to any of Claims 0 to 2, wherein the multi-piece

component is a swivel flange connector pipe and the second piece of the multi-piece component is a flange.

4. A multi-piece component according to Claim 3, wherein the swivel flange connector pipe is single or double ended.

5. A multi-piece component according to Claim 4, wherein in a double ended swivel flange connector, two second pieces are mounted on the first section, each second piece comprising a flange.

16. A multi-piece component according to any of Claims 10 to 15, wherein at least one of the spaced apart elements comprises a flange seat.

7. A multi-piece component according to Claim 5 or 16, wherein in a double ended swivel flange, each spaced apart element comprises a flange seat.

18. A tool for use in the method of manufacture of a multi-piece component of Claims 1 to 9, the tool comprising a clamp, the clamp comprising at least two parts, fastening means to releasably attach the at least two parts together, attachment means for attaching the clamp to a piece of a multi-piece component and a support surface adapted to sit on and be supported by another piece of the multi-piece component.

19. A tool according to Claim 18, wherein the fastening means comprises at least one bore in each of the at least two parts, wherein at least one bore of one of the at least two parts aligns with at least one bore of an adjacent one of the at least two parts, when the at least two parts are attached together.

20. A tool according to Claim 18 or 19, wherein the fastening means includes an element adapted for insertion into the aligned bores.

21. A tool according to any of Claims 18 to 20, wherein at least one of the said at least one bores is threaded.

22. A tool according to Claim 20 or 21, wherein the element is threaded and is adapted to co-operate with threads of an at least one bore, or the threaded portion of the element extends beyond the bore and a nut may be attached thereto.

23. A tool according to any of Claims 18 to 22, wherein at least two parts of the clamp are attached together by a hinge.

24. A tool according to Claim 23, wherein the at least two parts of the clamp are attached together at one side by a hinge and at the other by fastening means.

25. A tool according to any of Claims 18 to 24, wherein the fastening means includes a hinge.

26. A tool according to Claim 25, wherein the fastening means includes a lever pivotally attached to one of the at least two parts, and a clasp pivotally attached to the lever, the axes of the pivots being offset with respect to one another.

27. A tool according to Claim 26, wherein an adjacent one of the at least two parts includes a slot adapted to receive a part of the clasp.

28. A tool according to any of Claims 18 to 28, wherein the attachment means for attaching the clamp to a piece of the multi-piece component includes a bore, said bore in use being aligned with a bore in the piece of the multi-piece component, and an element for insertion into the aligned bores.

29. A tool according to any of Claims 18 to 28, wherein the attachment means comprises a plurality of bores, each lying on at a different distance from the centre of the clamp, or a slot extending in a radial direction.

30. A tool according to any of Claims 18 to 29, wherein the clamp includes a peripherally located lip extending in the axial direction of the clamp.

31. A tool according to Claim 30, wherein the lip element forms part of each of the at least two parts of the clamp.

32. A tool according to any of Claims 18 to 31, further comprising a collar, the collar configured to sit between a work-piece and the clamp.

33. A tool according to Claim 32, the tool including a plurality of collars, each having a different thickness.