A METAL PIPE AS WELL AS A METHOD AND PLANT FOR ITS PRODUCTION

Abstract: A metal pipe, preferably of steel, which is resistant corrosion, inside with respect to the conveyed medium and outside with respect to its surroundings, comprises a comparatively thin-walled core (1), a plurality of strips (2) which are highly tensioned and helically wound in layers, one layer crossing the other, each layer being joined to the underlying one, e.g. by means of welding, and, externally a comparatively thin casing (3) a plant for producing such pipe, comprising an arrangement of three co-acting operational stations, first a unit (Figs. 1 and 2) for producing a pipe core (1) from a strip wound on a reel (13), thereafter a second station comprising a plurality of winding units (4) (Figs. 3-6) for applying highly tensioned strip on the outside of the pipe core (1), welded to the pipe core and to underlying layers of strip, and finally a unit (Figs. 7 and 8) for providing the outmost layer of strip (2) with a sealing casing (3) from a strip (39) mounted on a reel. Method for producing such pipes with adjustable length.

Description: A metal pipe as well as a method and plant for its production The present invention relates to a metal pipe, preferably of steel, the inside of which has the ability to resist corrosion from the conveyed medium, while its outside has the ability to withstand corrosion from its surroundings, and a plant and a met- hod for producing such a pipe on site to a reasonable cost and in any desired length of strip material wound into coils. The pipe, method and plant for producing it have been given the form and the characterizing features apparent from the attach¬ ed patent claims. The invention is illustrated by the accompanying drawings, on which Fig. 1 is a side view of an apparatus nown per se, incorpo¬ rated in the plant for producing a pipe core with a seam weld, Fig. 2 is a plan view of the apparatus in Fig. 1, Fig. 3 is a side view of an arrangement coming after the apparatus in Figs. 1 and 2, having four units, each of which cross-lays strip on the pipe core, Fig. is a plan view of the arrangement in Fig. 3 » Fig. 5 is a cross section through one of the winding or lay- ing units shown in Fig. 3, Fig. 6 is a somewhat displaced cross section of the same winding unit as in Fig. 5» Fig. 7 is a side view of an apparatus incorporated in the final section of the plant for covering the pipe with a casing having a seam weld, and Fig. 8 is a plan view of the same apparatus as shown in Fig. 7. A strip 10 of material resistant to the liquid to be conveyed is pulled from a reel 13 by a pair of coacting rolls 11,12 and is formed by this pair of rolls 11,12, of which one, 11, has a con¬ cave and the other, 12, a convex configuration, to a trough with arcuate bottom cross section. The edges of the trough are pressed by a second pair of rolls l with a concave configuration until OWPI -ft, 1PO the edges meet and the trough is given a cirular, cylindrical form by a third, concave roll pair 15. Immediately after the ro pair 15, the edges now abutting each other are welded together means of a welding head 16, and the weld is caused to pass a kn means 17 to check that it is homogeneous and fault-free. The now ready pipe core 1, moving axially with a velocity controlled by the roll pairs 11,12 and 1^,15 passes through a plurality of winding units 18 (only four are shown on Fig. 3 and h) . Each of these winding units 18 comprises a frame k carryin an annular track 19 concentrically surrounding the pipe core 1 a in which a rotor 5 with at least three arms is arranged, such t it is enabled to rotate about the pipe core 1, bearing against t track 19 with rollers 21 mounted at the ends of its arms 20. The rotor 5 is provided with two obliquely, outwardly directed arms 22, at the free ends of which a shaft 8 is rotatably mounted. T shaft 8 carries a reel 6 rigidly mounted thereto for a strip 2. The shaft 8 is rigidly attached at right angles to a disc 23 dis posed for coaction with at least one pair of brake blocks ≥ , The rotor 5 rotatably supports a plurality (three rollers being shown on Fig. 5) of rollers 25, arranged to lie with sprin bras against the strip 2 wound onto the pipe core from the reel by the winding unit 18. The rotors 5 of the different, winding un l8 are arranged to rotate synchronously at such a rate that the wound-on turns of strip will abut with their edges against each other. The rotor 5 can suitably be provided with a seam welding head 7 with a device 27 or continuous supply of welding wire 25 and with a plurality of protective gas cylinders 29. The stand k can suitably be provided with a holder 30 for a spot welding uni 31 coacting with a plurality of spot welding heads 32. The rotors 5 of the winding units 18 are driven, e.g. from common shaft 33, with teeth Jk meshing with a gear ring 35 attac ed to the rotor 5« The winding units are suitably provided with flanged wheels 36, arranged to roll along rails 38 laid on a substructure 37 su porting the apparatus, so that the distance between them can be adjusted in response to the width of strip used. After the winding units 18, the plant is provided with a unit (Figs. 7 and 8) for providing the outermos strip layer with a longitudinally welded casing of a material which is resistant to the surrounding medium, e.g. sea water. This unit comprises a reel 39 for a strip kO and a plurality of roll pairs l arranged for pulling the strip -0 from the reel 39 and bending it round the outermost strip layer, and a welding head k2 for longitudinally welding the mutually abutting edges t of the strip θ, and means -3 for checking the homogenity of the weld. The plant described above functions in the following mode. The strip 10, coiled up on the reel 13, is pulled off from the reel by the roll pair 11,12 and is formed into a substantially U-shaped trough. The edge portions of the trough are formed byv the roll pair <lA,15 into a continuous cylinder, which is provided with a longitudinal weld by means of the welding head 16, the homogenit of the weld being checked by means 17, and the thin-walled pipe core 1 thus obtained is taken through the winding units 18. The end of the band 32 of the first winding unit 18 is attached to the pipe core 1 by means of at least one spot weld, and the rotor of the winding unit 18 is caused to rotate with a speed relative to the axial movement of the pipe core 1, such that the edges of the wound-on strip 2 will lie against each other. The tension of the strip 2 is regulated by the brake blocks 2 acting on the disc 23 such that said tension is just under that which would ca-uεe defor- mation of the cylindrical cross section of the pipe core 1 by means of spot welds applied at εutable spacing. With larger pipe dia¬ meters it has been found advantageous to heat the strip 2 during winding, so that the thermal contraction on cooling increases the strip tension. When the strip end of the first winding unit 18 reaches the other winding unit 18, the strip 2 of the latter is attached to the first strip on the outside by means of spot welding. The rotor 5 of the second windiung unit 18 is caused to rotate in the oppo¬ site direction to that of the first one, so that the turns of the strips 2 will cross each other, etc. ' + until the wound-on layers of strip have given the pipe desired siiffnes and strength. If it is desired to give the pipe extra safety with respect to leakage of conveyed material, the abutting strip edges in one or more of th layers can be welded together with a continuous seam weld. The ready-wound pipe is finally provided with a sealing cas ing provided with an axial seam weld in the same way as for the pipe core 1. When the pipe ia to be produced and laid at sea, it has bee found advantageous to mount the whole plant on a carrage, which means of wheels or glide cushions is displaceable from aft to fo of a vessel synchronously with the pipe production, for being co paratively rapidly moved aft, when it has reached the fore, in co junction with the produced pipe length being thrust out aft over the vessel while the latter is moved a corresponding distance for wards, by means of cables to a plurality of anchors, for example.

Claims: Claims 1. Metal pipe, preferably of steel, the inside of which is re¬ sistant to corrosion from the conveyed medium, while its outside is resistant to corrosion from its surroundings, CHARACTERIZED.^ the combination of: a) an inner, comparatively thin-walled pipe core (l):, b) a plurality of strip layers (2) disposed outside this pipe core (1) helically crossing each other in a mode known per se; and c) a comparatively thin-walled protective casing (3) disposed on the outside of said layers. 2. Pipe as claimed in claim 1, CHARACTERIZED by the combination: a) that the pipe core (l) is produced from a material resistant to corrosion from the conveyed material; b) that the strips (2) are tightly tenεioned and joined to the nearest under-lying layer (l or 2) at suitable spacing, e.g. by means of welds; and c) that the protective casing (3) is produced from a material resistant to the effect of its surroundings. / 3« A plant for producing metal pipe, preferably steel pipe, in accordance with patent claim 1 or 2, the inside of the pipe being resistant to corrosion from the conveyed medium, while its outside is resistant to corrosion from its surroundings, CHARACTERIZED in that it comprises a unit (Figs. 1 and 2) for continuously producting, from a strip (10) coiled on a reel (13), a thin-walled, longitudinally welded pipe core (1) and feeding it to the next unit; an arrangement of units (Figs. 3-6) for applying layers of rein¬ forcing strip (2) on the outside of the pipe core (1); and a unit (Figs. 7 and 8) for disposing a sealing, longitudinally welded protective casing (3) outside the reinforcing strips (2). k. A plant as claimed in claim 3, CHARACTERIZED in that the arrangement of units for providing reinforcing strips (2) on the outside of the pipe core (l) comprises a plurality of stands (4) mounted along and round the pipe core (1), each stand carrying annular means (35) disposed for concentrically surrounding the pipe core (1) and for being enabled to rotate about the core and to accompany a rotor (5) on the inside of said means, said rotor carrying a reel (6) with a strip (2) coiled thereon, and welding means (7) for attaching the wound-on strip (2) to the pipe core (1) or an underlaying strip layer from the reel (6). 5. A plant as claimed in claim , CHARACTERIZED in that all the annular means (35) are disposed for synchronous rotation and that all the strips (2) are equally as.wide. 6. A plant as claimed in claim 5, CHARACTERIZED in that alter- nate annular means (35) rotate clockwise, while the means in between rotate anti-clockwise. 7. A plant as claimed in claim 4, CHARACTERIZED in that the annular means (35) are disposed for rotation at a βpeed such that the wound-on turns of band (2) will abut each other edge to edge. 8. A plant as claimed in claim , CHARACTERIZED in that the stand portions (22) carrying the reels (6) are provided with mean for positioning them such that the shafts (8) of the reels (6) will be perpendicular to the winding-off direction of the strips (2). 9. A plant as claimed in claim -, CHARACTERIZED in that it com¬ prises means (9) carried by the stands (b) for giving the strips (2) an increased temperature immediately prior to their being wound on to the substructure. 10. A plant as claimed in claim -, CHARACTERIZED in that the uni of which it is comprised are mounted on a common carriage which b means of wheels or glide cushions is displaceable along a track. 11. A method of producing a metal pipe, preferably a steel pipe in accordance with claim 1, the inside of which is resistant to corrosion from the conveyed medium, while its outside is resistan to corrosion from its surrounding, CHARACTERIZED in that a plural ty of strips (2) wound onto reels (6) are attached by their ends to a pip~e core (1) or to a previously applied strip layer, subse¬ quent to which the reels (6) are caused to rotate planetarily and in alternate directions around the pipe core (1), while the pipe core (1) is given an axial movement with such a speed that the strips (2) will be wound onto the core (1) helically and edge to edge. -gUREA OMPI 12. A method as claimed in claim 11, CHARACTERIZED in that the rotation of the reels (6) is braked about their own shafts, so that the wound-on strips (2) will be severely tensioned. 13. A method as claimed in claim 11 or 12, CHARACTERIZED in that the strips (2) are fixed mutually and relative to the pipe core (1) by means of welds at suitable spacing. OMPI

Inventors: BRUNDIN H
Applicants: BRUNDIN H, STALLARHOLMENS FOERVALTNINGS A, STALLARHOLMENS FOERVALTNINGS AB
Application year: 1979
Main classification: F16L9
IPC codes: B21C37, F16L9