NZ575638A - Improvements relating to tubular members and/or conduits and/or methods and/or assemblies for joining tubular members - Google Patents

Abstract

A method of joining together tubular members which are substantially comprised of non-corrosion resistant material so as to provide a substantially corrosion-resistant joint by welding, the method comprising the steps of welding a first corrosion-resistant tubular member or sleeve 24 to a first non-corrosion resistant tubular member, so as to form a first corrosion-resistant end piece 27 having a first corrosion-resistant open end, welding a second corrosion-resistant tubular member or sleeve 22 to a second non corrosion-resistant tubular member, so as to form a second corrosion-resistant end piece 26 having a second corrosion-resistant open end, applying a corrosion-protective coating to both the non-corrosion resistant tubular members, positioning the first and second open ends in substantial axial alignment with each other so that the first corrosion resistant end-piece is in contact with the second corrosion-resistant end-piece but not with the second non-corrosion-resistant tubular member and the second corrosion-resistant end-piece is not in contact with the first non-corrosion resistant tubular member, and externally welding the first and second corrosion-resistant end-pieces together using corrosion-resistant welding material 29.

Description

10057422088* ) ;57 5 g 3 8 ;5 ;10 ;15 ;20 25 ;OurRef: KRM001 Patents Form No. 5 ;30 ;COMPLETE SPECIFICATION ;"Improvements in or relating to tubular members and/or conduits and/or methods 35 and/or assemblies for joining tubular members" ;We, Albany Pipe Dreams Limited, a New Zealand company of 43 Wentwoith Park, Albany, Auckland, New Zealand do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to 40 be particularly described in and by the following statement: ;1 ;IMPROVEMENTS IN OR RELATING TO TUBULAR MEMBERS AND/OR CONDUITS AND/OR METHODS AND/OR ASSEMBLIES FOR JOINING TUBULAR MEMBERS ;5 TECHNICAL FIELD ;This invention relates to methods and assemblies for joining together tubular members, such as pipes, where the pipes are substantially comprised of a non-corrosion-resistant material. Where used herein, "non-corrosion-resistant" means a 10 material that is susceptible to substantial corrosion over the normal life of the pipe under normal conditions of use unless coated or otherwise protected and "corrosion-resistant" means not susceptible to substantial corrosion over the normal life of the pipe under normal conditions of use without being coated or otherwise protected and "corrosion-protective" means substantially preventing or reducing corrosion. 15 More particularly but not exclusively the invention relates to methods and assemblies for joining together piping to form pipelines for water reticulation and hydro power systems. ;BACKGROUND ART ;20 Water reticulation and hydro power schemes need to convey large amounts of water for long distances (for example, several or many kilometres). As it is impractical to convey pipes of such length into the remote areas where these pipes are installed, the pipes are manufactured in lengths of 6 to 16 m and connected together to form a pipe line. Typically, particularly when the diameter is larger than about 500 mm, 25 these pipelines are constructed of pipe lengths manufactured from carbon (mild) ;steel. ;The pipes are normally buried but can also be run above ground. In either case there is an issue around corrosion, both on the inside and outside of the pipe, as well as an ;2 ;erosion problem on the inside from water carrying a high silt load. Smaller, especially lower pressure pipelines, are typically manufactured from plastic, which is substantially corrosion-resistant. However, as the pressure increases and/or the pipe diameter increases, a plastic pipe must be made with a thicker wall to provide the necessary strength. For larger pipes the wall thickness necessary to provide an acceptably strong pipe in plastic becomes expensive and impractical to manufacture. Therefore, larger pipes may be made of, for example, stainless steel, which is substantially corrosion-resistant, or carbon (mild) steel, which is substantially non-corrosion-resistant. Large diameter steel pipes can be made which are sufficiently strong but with much thinner walls than the equivalent pipes made of plastic. Mild steel is typically preferred because it is significantly cheaper than stainless steel, and is also stronger, so that the pipes can be made with a reduced wall thickness and are lighter and easier to manufacture. However, the mild steel pipes need to be protected in some manner from corrosion. To prevent corrosion the normal practice is to apply a corrosion-protective coating to the mild steel pipe, for example by painting the inside and outside of the pipe, or coating the metal with cement or zinc (galvanizing). ;These issues are not only restricted to large scale pipes and pipelines but may also occur in smaller pipes and pipelines which are exposed to corrosion. ;Various ways of joining the lengths of pipe together are known. For example, a "coupling" can be used, which is clamped over a pipe at the joint. Alternatively the pipes can be made with socket ends which can be fitted together. However these joints have little resistance to axial movement so must be installed in straight runs with massive thrust blocks fitted at every change of direction. They are also not good at resisting soil movement and can easily breach (break). ;A further alternative is to weld the pipe lengths together. This has the advantage that if buried, the welded pipe generally needs no anchor blocks and is much less likely to be damaged in an earth slip. In the case of an above ground installation, fewer supports are needed. ;A disadvantage with a welded pipeline is that the welding process destroys the corrosion-protective coating near the weld. Unless the coating is repaired, corrosion will soon destroy the pipeline. Also the joint needs to be welded and the coating repaired on the inside as well as the outside of the joint. This can be inconvenient and time-consuming, particularly when the pipe diameter is less than about 1200 mm or access is otherwise difficult or unsafe. Welding in an enclosed space also requires much greater safety precautions. ;US patents 3635498 and 3708864 describe a pipe joining method where the two ends of pipe to be joined are provided with a sleeve that is significantly thinner than the pipes. One pipe end has the sleeve extend beyond the end of the pipe, while the other pipe has the sleeve spaced back away from the pipe end. The two pipe ends are brought together and a weld is made to fuse the pipes ;US patent 4634040 refers to a joining system where a sleeve is placed over the two pipe ends and fillet welds are used at both ends of the sleeve to weld to the pipe. This proposal involves two welding steps "on site". ;US patent 3248134 describes a welded coupling in which external sleeves are used to reinforce weakened areas near the pipe joint resulting from the annealing effect of welding heat. ;US patent 3194936 describes a coupling system with a single external sleeve which is welded in 2 places to join the pipe ends. ;US patent 3439941 describes a welded coupling in which 2 sleeves are provided which interengage with each other, and the entire joint is then welded. The weld bead extends from the inner surface of the pipe right through to the outer surface of 5 the sleeves, fusing all 4 elements of the coupling. ;US patent 4579273 describes a further form of welded connection. ;These patents do not address the need for corrosion resistance or the requirement to 10 recoat after welding. ;While specific reference has been made herein to large scale pipe and pipeline systems, the present invention is not intended to be so restricted and can also be applicable to smaller scale piping systems. ;15 ;It is an object of the present invention to provide methods and assemblies for joining together tubular members, such as pipes, which overcome at least some of the abovementioned problems, or which at least provide the public with a useful choice. ;20 SUMMARY OF THE INVENTION ;In a first broad aspect of the invention there is provided a method of joining together tubular members which are substantially comprised of non-corrosion resistant material, said method comprising the steps of: ;25 welding a first corrosion-resistant tubular member or sleeve to a first non-corrosion- ;resistant tubular member, so as to form a first corrosion-resistant end piece having a first corrosion-resistant open end; ;5 ;welding a second corrosion-resistant tubular member or sleeve to a second non-corrosion-resistant tubular member, so as to form a second corrosion-resistant end piece having a second corrosion-resistant open end; ;applying a corrosion-protective coating to both said non-corrosion resistant tubular members; ;abutting said first and second open ends in substantial axial alignment with each other; and externally welding said first and second corrosion-resistant end-pieces together using corrosion-resistant welding material. ;In a further broad aspect of the invention there is provided a method of joining together tubular members which are substantially comprised of non-corrosion resistant material, said method comprising the steps of: ;welding a corrosion-resistant tubular member to an end of a first non-corrosion-resistant tubular member, so as to form a male end piece; ;positioning a corrosion-resistant sleeve around and projecting from an end of a second non-corrosion-resistant tubular member, and welding said sleeve to said second non-corrosion-resistant tubular member both internally and externally so as to form a female end piece; ;applying a corrosion-protective coating to both said non-corrosion resistant tubular members; ;inserting said male end piece into said female end piece so that said corrosion-resistant sleeve is in contact with said corrosion-resistant tubular member and is not in contact with said first non-corrosion resistant tubular member; and externally welding the end of said sleeve to said corrosion-resistant tubular member using corrosion-resistant welding material. ;In a further broad aspect of the invention there is provided a method of constructing a conduit comprising joining together tubular members according to the methods described above. ;Preferably the conduit is a pipeline. ;Preferably the pipeline is adapted for water reticulation. ;Preferably the pipeline is adapted for use in carriage of water for hydro-electric generation. ;In a further broad aspect of the invention there is provided a conduit constructed by a method broadly as described above. ;According to a further broad aspect of the invention there is provided an assembly for joining together tubular members which are substantially comprised of non-corrosion-resistant material, said assembly comprising; ;a first corrosion-resistant tubular member or sleeve welded to a first non-corrosion resistant tubular member, so as to form a first corrosion-resistant end piece; ;a second corrosion-resistant tubular member or sleeve welded to a second non-corrosion resistant tubular member, so as to form a second corrosion-resistant end piece; ;Preferably said first end piece is a male end piece comprising a first corrosion-resistant tubular member welded to an end of a first non-corrosion resistant tubular member; and said second end piece is a female end piece comprising a corrosion-resistant sleeve positioned around and projecting from an end of a second non-corrosion-resistant tubular member, said sleeve being welded to said second non-corrosion-resistant tubular member both internally and externally. ;Preferably said male end piece is inserted into said female end piece so that said corrosion-resistant sleeve is in contact with said corrosion-resistant tubular member and is not in contact with said first non-corrosion resistant tubular member; and 5 the end of said sleeve is externally welded to said corrosion-resistant tubular member using corrosion-resistant welding material. ;In an alternative preferred embodiment said first end piece is a first male end piece comprising a first corrosion-resistant tubular member welded to an end of a first non-10 corrosion resistant tubular member; and said second end piece is a second male end piece comprising a second corrosion-resistant tubular member welded to an end of a second non-corrosion resistant tubular member. ;In a further alternative preferred embodiment said first end piece is a first female end piece comprising a first corrosion-resistant sleeve positioned around and projecting from an end of a first non-corrosion-resistant tubular member, said first sleeve being welded to said first non-corrosion-resistant tubular member both internally and externally; and said second end piece is a second female end piece comprising a second corrosion-resistant sleeve positioned around and projecting from a second end of a second non-corrosion-resistant tubular member, said second sleeve being welded to said second non-corrosion-resistant tubular member both internally and externally. ;Preferably in any of said assemblies according to the invention said first and second 25 end pieces are abutted together substantially in axial alignment with each other and said corrosion-resistant members or sleeves are welded to one another using corrosion-resistant welding material. ;15 ;20 ;8 ;Preferably in any of said assemblies according to the invention both said non-corrosion-resistant tubular members or sleeves are substantially coated with a corrosion-protective coating. ;According to a further broad aspect of the invention there is provided a tubular member which is substantially comprised of non-corrosion-resistant material adapted to be joined to other such members, comprising: ;a non-corrosion-resistant tubular portion; ;a first end piece comprising a first corrosion-resistant tubular member or sleeve welded to a first end of said non-corrosion-resistant tubular portion; and a second end piece comprising a second corrosion-resistant tubular member or sleeve welded to a second end of said non-corrosion-resistant tubular portion. ;Preferably said first end piece comprises a male end piece comprising a corrosion-resistant tubular member welded to a first end of said non-corrosion-resistant tubular portion; and said second end piece comprises a female end piece comprising a corrosion-resistant sleeve positioned around and projecting from an opposing end of said non-corrosion-resistant tubular portion, said corrosion-resistant sleeve being welded to said non-corrosion resistant tubular portion both internally and externally. ;In an alternative preferred embodiment said first end piece comprises a first female end piece comprising a first corrosion-resistant sleeve positioned around and projecting from a first end of said non-corrosion-resistant tubular portion, said first sleeve being welded to said non-corrosion-resistant tubular portion both internally and externally; and said second end piece comprises a second female end piece comprising a second corrosion-resistant sleeve positioned around and projecting from a second end of said non-corrosion-resistant tubular portion, said second sleeve being welded to said non-corrosion-resistant tubular portion both internally and externally. ;In an alternative preferred embodiment said first end piece comprises a first male end piece comprising a corrosion-resistant tubular member welded to a first end of said non-corrosion-resistant tubular portion; and 5 said second end piece comprises a second male end piece comprising a corrosion- ;resistant tubular member welded to a first end of said non-corrosion-resistant tubular portion. ;Preferably in any of the above aspects or embodiments of tubular members in 10 accordance with the invention said non-corrosion-resistant tubular portion is substantially coated with a corrosion-protective coating. ;According to a further broad aspect of the invention there is provided a conduit comprising a plurality of tubular members broadly as described wherein said first and 15 second end pieces of adjacent said tubular members are abutted together substantially in axial alignment with each other; and welded together using corrosion-resistant welding material. ;According to a further broad aspect of the invention there is provided a conduit ;20 comprising a plurality of assemblies broadly as described wherein said first and second end pieces of adjacent said tubular members are abutted together substantially in axial alignment with each other; and welded together using corrosion-resistant welding material. ;25 According to a further broad aspect of the invention there is provided a conduit comprising a plurality of interconnected tubular members, in which a first said interconnected tubular member comprises: ;a first non-corrosion-resistant tubular portion; and ;10 ;a male end piece comprising a corrosion-resistant tubular member welded to a first end of said first non-corrosion-resistant tubular portion; and an adjacent interconnected tubular member comprises: ;a second non-corrosion-resistant tubular portion; and a female end piece comprising a corrosion-resistant sleeve positioned around and projecting from an opposing end of said non-corrosion-resistant tubular portion; ;said sleeve being welded to said second non-corrosion-resistant tubular portion both internally and externally; ;said first and second non-corrosion-resistant tubular portions being substantially coated with a corrosion-protective coating, while said corrosion-resistant tubular member and sleeve substantially lack said coating; ;wherein the male end piece is inserted into the female end piece so as to bring into close association the end of said corrosion-resistant sleeve and said corrosion-resistant tubular member and so that said corrosion-resistant sleeve is in contact with said corrosion-resistant tubular member and is not in contact with said first non-corrosion resistant tubular member; and the end of each said sleeve is externally welded to the associated said corrosion-resistant tubular member using corrosion-resistant welding material. ;Preferably according to any of these aspects relating to a conduit, the conduit is a pipeline. ;Preferably the pipeline is adapted for water reticulation. ;Preferably or in the alternative the pipeline is adapted for carriage of water for hydroelectric generation. ;Preferably in each or any of the above aspects the non-corrosion-resistant tubular members are comprised of carbon (mild) steel. ;11 ;Preferably in each or any of the above aspects or embodiments the corrosion-resistant tubular members or sleeves are comprised of stainless steel. ;Preferably in each or any of the above aspects or embodiments the corrosion-resistant tubular members or sleeves are substantially not coated with a corrosion-protective coating. ;BRIEF DESCRIPTION OF THE DRAWINGS ;Preferred embodiments of the invention will now be illustrated, by way of example only, with reference to the accompanying drawings in which: ;Figure 1: illustrates a partial section of a male end piece and a female end piece of a tubular member, such as a pipe, in accordance with the invention; Figure 2: illustrates a partial section of a male end piece as shown in ;Figure 1 inserted into a female end piece as shown in Figure 1; ;Figure 3: illustrates a partial section of a completed joint utilising a male and female end piece as shown in Figures 1 and 2 in accordance with the invention Figure 4: illustrates a partial section of two male end pieces of a tubular member, such as a pipe, in accordance with the invention; ;Figure 5: illustrates a partial section of two male end pieces as shown in ;Figure 4, abutted together; ;Figure 6: illustrates a partial section of a completed joint utilising 2 male end pieces as shown in Figures 4 and 5 in accordance with the invention. ;Figure 7: illustrates a partial section of two male end pieces of a tubular member, such as a pipe, in accordance with one embodiment of the invention, one of the male end pieces being coned or belled; ;12 ;Figure 8: illustrates a partial section of two male end pieces as shown in ;Figure 7, positioned for joining; ;Figure 9: illustrates a partial section of a completed joint using 2 male end pieces as shown in Figures 7 and 8 in accordance with the invention. ;DETAILED DESCRIPTION OF THE DRAWINGS ;Referring to figure 1, in a first preferred embodiment of the first broad aspect of the invention there is provided a first non-corrosion-resistant tubular member 1, such as a pipe or fitting (such as a bend) of carbon (mild) steel, having an end 2. A corrosion-resistant tubular member 3, such as a length of stainless steel pipe, of similar diameter but shorter length than member 1, has an end 4. In accordance with the invention, ends 2 and 4 are abutted and the end 4 of the corrosion-resistant member 3 is butt welded 5 to the end 2 of the non-corrosion-resistant member 1, in such a manner that the walls of the two members are aligned, to form a male end piece. ;Referring now to the other end of the assembly illustrated in Figure 1, there is further provided a second non-corrosion-resistant tubular member 7 such as a pipe or fitting (such as a bend) of carbon (mild) steel, having an end 8. A corrosion-resistant sleeve 9, which may for example be a length of stainless steel pipe, having an internal diameter such as to fit snugly over the member 7, is positioned around and projecting from the end 8 of the member 7. The sleeve 9 has a projecting end 10. The sleeve 9 is welded in place both internally and externally with a double fillet weld 11a, 11 b, to form a female end piece 12. ;Generally the hoop stress in the pipe determines the wall thickness as the longitudinal stress is half of the hoop stress. That implies that a fillet weld with a leg length equal to the thickness of the sleeve 9 is normally adequate for the expected loads. Should that not be the case - as when the support interval is ;13 ;unusually large - the fillet weld size can be increased by increasing the wall thickness of the sleeve 9. ;The stainless steel members and sleeves may suitably be manufactured from flat bar stock, rolled into an appropriate sized ring, and butt welded together at the ends to form a ring. To aid assembly in the field the sleeve 9 could be formed by rolling as a shallow cone which would facilitate insertion of the male end piece. ;The physical properties of the stainless steel used for the end pieces can often be different to the carbon steel properties - usually they are lower (weaker) than the carbon steel. The difference in these physical properties can be compensated for by increasing the wall thickness of the stainless steel portions. ;The welding material used for the welds between the corrosion-resistant members or sleeves and the non-corrosion-resistant members may itself be corrosion-resistant, for example stainless steel, or non-corrosion-resistant, for example , carbon steel. ;When the stainless steel ends are completely welded in place, a corrosion-protective coating 13, such as paint or galvanizing, as is known to those skilled in the art, is applied. Generally, the corrosion-resistant member 3 and sleeve 9 are left uncoated. If the welds between the corrosion-resistant sleeve or member and the non-corrosion-resistant members are made of non-corrosion-resistant material, for example, carbon steel, or are otherwise susceptible to corrosion, then they should also be coated with the corrosion-protective coating 13. For example, a carbon steel filler material may be used for the weld, which is non-corrosion-resistant. In this case the weld as well as the non-corrosion-resistant sleeve and member should be covered in the coating process, so as to prevent contact with the atmosphere resulting in corrosion. ;Alternatively, a corrosion-resistant material may be used for the weld, such as stainless steel filler wire. However, in the case of welding carbon steel to stainless steel using stainless steel filler wire, the weld would still be vulnerable to corrosion due to the additional carbon in the carbon steel with which the weld is in contact, as will be apparent to those skilled in the art. Therefore the weld should also be coated with the corrosion-protective coating in these circumstances. ;Up to this point, the assembly may be manufactured in accordance with the method of the invention, in a workshop or factory situation. For example, multiple tubular members, such as pipes and fittings, may be manufactured, having at one end of each such member a male end piece 6 and at the opposite end a female end piece 12. Tubular members may also be manufactured having two male end pieces 6, one at each end, or two female end pieces 12, one at each end, according to the requirements of the particular pipeline. ;The manufactured pieces may then be transported to a field location where a pipeline is to be assembled. ;Referring now to Figure 2, in use according to a first preferred embodiment of the invention, a joint is assembled by inserting male end piece 6 into female end piece 12 so that projecting end 10 of sleeve 9 does not extend past weld 5. Thus at the joint the two corrosion-resistant portions, member 3 and sleeve 9, are in contact with each other and sleeve 9 is not in contact with non-corrosion-resistant member 1. ;Referring now to Figure 3, the joint is completed by a single external weld 14, which may suitably be a fillet weld using corrosion-resistant welding material, for example stainless steel wire, welding together the projecting end 10 of sleeve 9 ;15 ;and the corrosion-resistant member 3. Typically in the field, this step may be performed in a trench or on support saddles. ;The joining weld 14 is performed only on the corrosion-resistant end members and/or sleeves. As these do not require a corrosion-resistant coating, they are generally left uncoated during manufacture. If any coating has been applied during manufacture, it will be damaged by the weld, but as the pieces being welded are themselves corrosion-resistant, this damage has no deleterious effect on the overall corrosion-resistance of the assembly and does not require repair. ;Referring now to Figures 4-6, in an embodiment of a further broad aspect of the invention, there is provided a tubular member 20 having a portion 21 which is substantially comprised of non-corrosion-resistant material such as mild steel. A first corrosion-resistant tubular member 22, such as a length of stainless steel pipe, which may preferably be substantially shorter than but of similar diameter to non-corrosion-resistant member 21 is welded, suitably using a butt weld, to a first end 23 of the non-corrosion-resistant tubular portion 21, so that the interior of the pipes are substantially aligned. A similar second corrosion-resistant-member 24, such as a further relatively short length of stainless steel pipe, is welded to the opposite end 25 of non-corrosion-resistant portion 21. Thus the member 21 is provided with two substantially similar end pieces, which may both be termed male end-pieces, indicated generally by arrows 26 and 27. ;After the end pieces have been assembled and welding completed, the non-corrosion-resistant portion 21 is then substantially coated with a corrosion-resistant protective coating 28. Again, generally the first and second corrosion-resistant tubular members will not be coated, as that would be unnecessary and wasteful of coating material. However, the welds should be coated if vulnerable to corrosion due to the nature of the materials used, as described above. ;16 ;In use as illustrated in Figures 5 and 6, the open ends of end pieces 26 and 27 from two adjacent lengths of pipe 21 a,b may be joined together by being abutted together in substantial axial alignment, and then welded together using a single externally applied butt weld 29 using a corrosion-resistant weld material. ;A male-male joint as described may be preferred in instances where a higher axial load is anticipated, in particular where it is preferred that the load path be straight to better resist axial loads. For example, when an unsupported length of pipe must cross a gap, such as above a river or gully, the bending loads on the unsupported pipe give rise to an axial compression load on one side of the pipe and axial tension load on the other side. The male to male joint offers a better load path in these circumstances. ;On the other hand, in most instances where the axial load is small, the male-female joint is preferred as it is tolerant of small misalignments and even allows for a small amount of change of direction at the joint, enabling better alignment with the land contour. It also is easier to weld together the male-female joint, as the ends of the pipe are held in position and the fillet weld is easier to apply. ;In a further embodiment of a male-male joint as illustrated in Figures 7 to 9, a first male end piece 6 is formed as described above by butt welding 5 the end 4 of the corrosion-resistant member 3 to the end 2 of the non-corrosion-resistant member 1. Second male end piece indicated generally by arrow 30 is formed in a similar manner but is belled or coned slightly. When the two end pieces 6 and 30 are brought together as shown in Figure 8, first end piece 6 fits slightly inside belled or coned end piece 30. The external corrosion-resistant weld 31 is then made between the corrosion-resistant belled end 32 of the second end piece 30 and the outside of the first male end piece 6. Although this technique may result in some loss of ;17 ;tolerance for angular variation at the joint, it can offer advantages of being quicker to put together, allowing an easier weld, and using relatively small amounts of stainless steel at the joint. This embodiment may be particularly useful for straight runs of pipeline. ;5 ;A female-female joint, in which two female end pieces 12 assembled according to the invention as previously described are abutted in substantial axial alignment and corrosion-resistant sleeves 9 are welded together using a corrosion-resistant welding materia!, is also possible and envisaged within the scope of the invention, should it 10 be desirable in a particular pipeline arrangement. ;It will be appreciated that no internal welding, or internal or external coating repair work is required, and yet the joints whether male-female or male-male are entirely protected from corrosion, as all wetted surfaces are either of corrosion 15 resistant material or are coated with a corrosion-protective coating which has not been damaged by subsequent welding. ;A plurality of tubular members and fittings such as bends, may thus be fitted together according to the method of the invention to form a robust and corrosion 20 protected pipeline. A complete pipeline may be assembled using a mixture of male- ;female and male-male joints as required, and using such combination of members having a male and female end-piece, or two male end pieces, or two female end-pieces, as are required. ;25 Where in the foregoing reference has been made to integers or components having known equivalents, then such equivalents are herein incorporated as if individually set forth. ;18 ;Accordingly, it will be appreciated that changes may be made to the above described embodiments of the invention without departing from the principles taught herein. ;Additional advantages of the present invention will become apparent for those skilled 5 in the art after considering the principles in particular form as discussed and illustrated. Thus, it will be understood that the invention is not limited to the particular embodiments described or illustrated, but is intended to cover all alterations or modifications which are within the scope of the appended claims. ;19 ;RECEIVED at IPONZ on 15 February 2010 *

Claims (38)

1. A method of joining together tubular members which are substantially comprised of non-corrosion resistant material so as to provide a substantially corrosion-resistant joint by welding, said method comprising the steps of: welding a first corrosion-resistant tubular member or sleeve to a first non-corrosion-resistant tubular member, so as to form a first corrosion-resistant end piece having a first corrosion-resistant open end; welding a second corrosion-resistant tubular member or sleeve to a second non-corrosion-resistant tubular member, so as to form a second corrosion-resistant end piece having a second corrosion-resistant open end; applying a corrosion-protective coating to both said non-corrosion resistant tubular members; positioning said first and second open ends in substantial axial alignment with each other so that said first corrosion resistant end-piece is in contact with said second corrosion-resistant end-piece but not with said second non-corrosion-resistant tubular member and said second corrosion-resistant end-piece is not in contact with said first non-corrosion resistant tubular member; and externally welding said first and second corrosion-resistant end-pieces together using corrosion-resistant welding material.

2. A method as claimed in Claim 1 of joining together tubular members which are substantially comprised of non-corrosion resistant material so as to provide a substantially corrosion-resistant joint, said method comprising the steps of: welding a corrosion-resistant tubular member to an end of a first non-corrosion-resistant tubular member, so as to form a male end piece; positioning a corrosion-resistant sleeve around and projecting from an end of a second non-corrosion-resistant tubular member, and welding said sleeve to said second non-corrosion-resistant tubular member both internally and externally so as to form a female end piece; RECEIVED at IPONZ on 15 February 2010 applying a corrosion-protective coating to both said non-corrosion resistant tubular members; inserting said male end piece into said female end piece so that said corrosion-resistant sleeve is in contact with said corrosion-resistant tubular member and is not in contact with said first non-corrosion resistant tubular member; and externally welding the end of said sleeve to said corrosion-resistant tubular member using corrosion-resistant welding material.

3. A method of constructing a conduit comprising joining together tubular members according to the method as claimed in Claim 1 or Claim 2.

4. A method as claimed in Claim 3 wherein said conduit is a pipeline.

5. A method as claimed in Claim 4 wherein said pipeline is adapted for water reticulation.

6. A method as claimed in Claim 4 wherein said pipeline is adapted for use in carriage of water for hydro-electric generation.

7. A method as claimed in any one of Claims 1 -6 wherein said non-corrosion-resistant tubular members are comprised of carbon (mild) steel.

8. A method as claimed in any one of Claims 1-7 wherein said corrosion-resistant tubular members or sleeves are comprised of stainless steel.

9. A method as claimed in any one of Claims 1-8 wherein said corrosion-resistant tubular members or sleeves are substantially not coated with a corrosion-protective coating.

10. An assembly for joining together tubular members which are substantially comprised of non-corrosion-resistant material according to a method as claimed in any one of Claims 1 to 9, said assembly comprising; 21 RECEIVED at IPONZ on 15 February 2010 a first corrosion-resistant tubular member or sleeve welded to a first non-corrosion resistant tubular member, so as to form a first corrosion-resistant end piece; a second corrosion-resistant tubular member or sleeve welded to a second non-corrosion resistant tubular member, so as to form a second corrosion-resistant end piece.

11. An assembly as claimed in Claim 10 wherein: said first end piece is a male end piece comprising a first corrosion-resistant tubular member welded to an end of a first non-corrosion resistant tubular member; and said second end piece is a female end piece comprising a corrosion-resistant sleeve positioned around and projecting from an end of a second non-corrosion-resistant tubular member, said sleeve being welded to said second non-corrosion-resistant tubular member both internally and externally.

12. An assembly as claimed in Claim 10 wherein: said first end piece is a first male end piece comprising a first corrosion-resistant tubular member welded to an end of a first non-corrosion resistant tubular member; and said second end piece is a second male end piece comprising a second corrosion-resistant tubular member welded to an end of a second non-corrosion resistant tubular member.

13. An assembly as claimed in Claim 10 wherein: said first end piece is a first female end piece comprising a first corrosion-resistant sleeve positioned around and projecting from an end of a first non-corrosion-resistant tubular member, said first sleeve being welded to said first non-corrosion-resistant tubular member both internally and externally; and said second end piece is a second female end piece comprising a second corrosion-resistant sleeve positioned around and projecting from a second end of a second non-corrosion-resistant tubular member, said second sleeve being welded to said second non-corrosion-resistant tubular member both internally and externally. 22 RECEIVED at IPONZ on 15 February 2010

14. An assembly as claimed in any one of Claims 10 to 13 wherein said first and second end pieces are abutted together substantially in axial alignment with each other and said corrosion-resistant members or sleeves are welded to one another using corrosion-resistant welding material.

15. An assembly as claimed in Claim 11 wherein said male end piece is inserted into said female end piece so that said corrosion-resistant sleeve is in contact with said corrosion-resistant tubular member and is not in contact with said first non-corrosion resistant tubular member; and the end of said sleeve is externally welded to said corrosion-resistant tubular member using corrosion-resistant welding material.

16. An assembly as claimed in any one of Claims 10 to 15 wherein both said non-corrosion-resistant tubular members or sleeves are substantially coated with a corrosion-protective coating.

17. An assembly as claimed in any one of Claims 10 to 16 wherein said non-corrosion-resistant tubular members or portions are comprised of carbon (mild) steel.

18. An assembly as claimed in any one of Claims 10 to 17 wherein said corrosion-resistant tubular members or portions or sleeve*? are comprised of stainless steel.

19. An assembly as claimed in any one of Claims 10 to 18 wherein said corrosion-resistant tubular members or portions or sleeves are substantially not coated with a corrosion-protective coating.

20. A tubular member which is substantially comprised of non-corrosion-resistant material adapted to be joined to other such members according to a method as claimed in any one of Claims 1 to 9, comprising: a non-corrosion-resistant tubular portion; 23 RECEIVED at IPONZ on 15 February 2010 a first end piece comprising a first corrosin-resistant tubular member or sleeve welded to a first end of said non-corrosion-resiscant tubular portion; and a second end piece comprising a second corrosion-resistant tubular member or sleeve welded to a second end of said non-corrosion-resistant tubular portion.

21 .A tubular member as claimed in Claim 20 wherein said first end piece comprises a male end piece comprising a corrosion-resistant tubular member welded to a first end of said non-corrosion-resistant tubular portion; and said second end piece comprises a female end piece comprising a corrosion-resistant sleeve positioned around and projecting from an opposing end of said non-corrosion-resistant tubular portion, said corrosion-resistant sleeve being welded to said non-corrosion resistant tubular portion both internally and externally.

22. A tubular member as claimed in Claim 20 wherein said first end piece comprises a first female end piece comprising a first corrosion-resistant sleeve positioned around and projecting from a first end of said non-corrosion-resistant tubular portion, said first sleeve being welded to said non-corrosion-resistant tubular portion both internally and externally; and said second end piece comprises a second female end piece comprising a second corrosion-resistant sleeve positioned around and projecting from a second end of said non-corrosion-resistant tubular portion, said second sleeve being welded to said non-corrosion-resistant tubular portion both internally and externally.

23. A tubular member as claimed in Claim 20 wherein said first end piece comprises a first male end piece comprising a corrosion-resistant tubular member welded to a first end of said non-corrosion-resistant tubular portion; and said second end piece comprises a second male end piece comprising a corrosion-resistant tubular member welded to a first end of said non-corrosion-resistant tubular portion. 24 RECEIVED at IPONZ on 15 February 2010

24. A tubular member as claimed in any one of claims 20 to 23 wherein said non-corrosion-resistant tubular portion is substantially coated with a corrosion-protective coating.

25. A tubular member as claimed in any one oi claims 20 to 24 wherein said non-corrosion-resistant tubular members or portions are comprised of carbon (mild) steel.

26. A tubular member as claimed in any one of claims 20 to 25 wherein said corrosion-resistant tubular members or portions or sleeves are comprised of stainless steel.

27. A tubular member as claimed in any one of claims 20 to 26 wherein said corrosion-resistant tubular members or portions or sleeves are substantially not coated with a corrosion-protective coating.

28. A conduit comprising a plurality of tubular members as claimed in any one of Claims 20 to 27 wherein said first and second end pieces of adjacent said tubular members are abutted together substantially in axial alignment with each other; and welded together using corrosion-resistant welding material.

29. A conduit comprising a plurality of assemblies as claimed in any one of Claims 10 to 19 wherein said first and second end pieces of adjacent said tubular members are abutted together substantially in axial alignment with each other; and welded together using corrosion-resistant welding material.

30. A conduit comprising a plurality of interconnected tubular members as claimed in any one of Claims 20 to 29, in which a first said interconnected tubular member comprises: a first non-corrosion-resistant tubular portion; and a male end piece comprising a corrosion-resistant tubular member welded to a first end of said first non-corrosion-resistant tubular portion; and an adjacent interconnected tubular member comprises: 25 RECEIVED at IPONZ on 15 February 2010 <i a second non-corrosion-resistant tubular portion; and a female end piece comprir-ing a corrosion-resistant sleeve positioned around and projecting from an opposing end of said non-corrosion-resistant tubular portion; said sleeve being welded to said second non-corrosion-resistant tubular portion both internally and externally; said first and second non-corrosion-resistant tubular portions being substantially coated with a corrosion-protective coating, while said corrosion-resistant tubular member and sleeve substantially lack said coating; wherein the male end piece is inserted into the female end piece so as to bring into close association the end of said corrosion-resistant sleeve and said corrosion-resistant tubular member and so that said corrosion-resistant sleeve is in contact with said corrosion-resistant tubular member and is not in contact with said first non-corrosion resistant tubular member; and the end of each said sleeve is externally welded to the associated said corrosion-resistant tubular member using corrosion-resistant welding material.

31. A conduit produced by a method as claimed in any one of Claims 1 to 9.

32. A conduit as claimed in any one of Claims 29 to 31 which is a pipeline.

33. A pipeline as claimed in Claim 32 which is adapted for water reticulation.

34. A pipeline as claimed in Claim 32 which is adapted for carriage of water for hydroelectric generation.

35. A method substantially as herein described with reference to any one of the drawings.

36. An assembly substantially as herein described with reference to any one of the drawings. 26 RECEIVED at IPONZ on 15 February 2010

37. A tubular member substantially as herein described with reference to any one of the drawings.

38. A conduit substantially as herein described with reference to any one of the drawings. ALBANY PIPE DREAMS LIMITED By its attorneys Pairman IP 27