IE920671A1

IE920671A1 - Reinforcing strip

Info

Publication number: IE920671A1
Application number: IE067192A
Authority: IE
Inventors: Marc Nys
Original assignee: Bekaert Sa Nv
Priority date: 1991-04-10
Filing date: 1992-03-02
Publication date: 1992-10-21
Also published as: IT1253994B; DE4211044B4; NO921411D0; IE65747B1; FR2675238B1; GB9203628D0; BE1004741A3; ITRM920261A1; NL9200670A; SA92120450B1; NO180329B; LU88092A1; MY108215A; GB2254629A; MX9201600A; GB2254629B; ITRM920261A0; NO921411L; DE4211044A1; NO180329C

Abstract

A reinforcing strip is adapted to be around helically around a cylindrical object such as a pipe (11), adjacent turns of the strip being arranged to partially overlap, the strip comprising longitudinal and transverse elements wherein the longitudinal elements (2-7) are spaced across the strip such that when the strip is wound into the helix, there is substantially even spacing between successive longitudinal elements of the strip, including in regions where adjacent turns of the strip overlap; thus the spacing of wires 6 and 7 in edge region III is such that on winding, wire 2 of opposite edge region II is located so as to give equi-spaced wires. <IMAGE> [DE4211044A1]

Description

REINFORCING STRIP This invention relates to a reinforcing strip to be wound helically around an object, e.g. for use in reinforcing a coating applied to a cylindrical object, such as a pipe, in which the reinforcing strip consists of longitudinal and transverse elements. The invention is particularly but not exclusively, concerned with such a strip in which the elements are of wire, welded together to form a mesh.

It is sometimes necessary to apply a heavy coating of concrete or the like to pipes for underwater use, for example oil pipelines, to counteract their buoyancy.

Such heavy coatings require reinforcement to enable them to withstand the forces they encounter in use.

From U.S. patents 4,033,387 and 4,134,197, it is already known to use for this purpose a reinforcing strip of welded wire mesh as mentioned above. These reinforcing strips are marketed by N.V. Bekaert S.A. under the name ARMAPIPE (Trade Mark). In a particular embodiment of this known reinforcing strip, all longitudinal wires of the welded mesh are equally deformed and evenly distributed across the reinforcing strip .

In winding such a reinforcing strip around a pipe or during the embedding of such a strip in the coating while the coating is being applied to the pipe, it is in most cases desirable that the successive windings of a layer of reinforcing strip should partially overlap one another. Thus, there is formed a helix with successive turns overlapping.

In the use of the reinforcing strips known up to the present, in which the longitudinal wires are evenly distributed across the strip, there is the disadvantage that, in winding the strip with partial overlapping of - 2 the adjacent successive windings, the distribution of J the reinforcing material over the length of the pipe or the coating is uneven.

Viewed from one aspect, the present invention provides a helically wound reinforcing strip in which adjacent turns partially overlap, the strip comprising longitudinal and transverse elements, wherein the longitudinal elements are spaced across the strip in such a manner that along the length of the helix in an axis parallel direction, there is a substantially even spacing between successive longitudinal elements of the strip, including in regions where adjacent turns of the strip overlap.

Preferably the strip has a longitudinal central region and two longitudinal side regions, there being a plurality of longitudinal elements in the central region which are substantially evenly spaced in the transverse direction, and longitudinal elements in the side regions which are arranged, in the transverse direction, so as to provide spaces which receive the elements in the side regions of adjacent overlapped turns of the strip in such a manner that across two overlapped side regions the spacing between adjacent longitudinal elements is substantially the same as the spacing between the longitudinal elements in the central region.

In a preferred embodiment, each side region of the strip includes a plurality of longitudinal elements whose spacing in the transverse direction is substantially twice that of the longitudinal elements in the central region.

Preferably, each side region of the strip includes a plurality of longitudinal elements whose spacing in the transverse direction is substantially the same as that of the longitudinal elements in the central region, each side region further including a space which in the transverse direction has a width substantially equal to the spacing between the longitudinal elements in the central region multiplied by (l + n) where n is the J number of said longitudinal elements in the side region.

Each side region of the strip may, in a preferred embodiment, consist of two longitudinal elements.

In a preferred design, the strip is provided in the form of a welded wire mesh the longitudinal wires of which are preferably uniformly deformed.

The strip may be wound as a reinforcement around a cylindrical object such as a pipe, and may be embedded in a coating applied to the cylindrical object.

Viewed from another aspect, the present invention provides a reinforcing strip adapted to be wound into a helix in which adjacent turns partially overlap, the strip comprising longitudinal and transverse elements, wherein the longitudinal elements are spaced across the strip in such a manner that when the strip is wound into the helix along the length of the helix in an axis parallel direction, there is a substantially even spacing between successive longitudinal elements of the strip, including in regions where adjacent turns of the strip overlap.

Embodiments of the invention will now be described by way of example only, and with reference to the accompanying drawings, wherein: Figure 1 shows a part of a first embodiment of a reinforcing strip according to the invention; Figure 2 shows a part of a second embodiment of a reinforcing strip according to the invention; Figure 3 shows a part of a third embodiment of a reinforcing strip according to the invention; and Figure 4 shows a longitudinal cross-section through half of a part of a pipe with a coating applied to it and a reinforcing strip embedded in this coating according to Figure 3.

Figure 1 shows a part of a first embodiment of a reinforcing strip 1 according to the invention. The reinforcing strip 1 consists of seven longitudinal wires - 4 2-8 with transverse wires 10 welded to them substantially at right angles and at a regular spacing from one another. By preference, the longitudinal wires 2-8 are uniformly deformed. The longitudinal wires 2-8 can however also be straight wires. Three regions are distinguished across the breadth of the reinforcing strip 1: regions I, II and III, or a central region I, a lower side region II and an upper side region III. The central region I contains three evenly spaced longitudinal wires 4, 5 and 6, at for example, a distance of one inch or 25.4 mm apart. It is clear that the central region I can contain more or less than three longitudinal wires. The characteristic feature of the central region I is that the distance between adjacent longitudinal wires is equal or that the longitudinal wires in the central region I are attached at a unit distance from one another. The longitudinal wires 4, 5 and 6 are thus evenly spaced across the strip in the central region I.

The lower side region II and the upper side region III each contain three longitudinal wires: 2, 3 and 4 and 6, 7 and 8, respectively. The distance between adjacent longitudinal wires in these side regions II and III is not equal. Thus the distance between the longitudinal wires 2 and 3 (7 and 8) is substantially one inch or 25.4 mm, while the distance between the longitudinal wires 3 and 4 (6 and 7) amounts to substantially three inches or 76.2 mm.

The characteristic feature of these side regions II and III is that in the overlapping winding of these regions, when strip 1 is being wound around a cylindrical object such as a pipe, it is now possible to ensure that the longitudinal wires are evenly distributed across the overlapping regions II and III and that the distance between adjacent longitudinal wires in these overlapping regions is equal to the distance between adjacent longitudinal wires in the - 5 central region I, or the unit distance. For this purpose it is necessary to make sure that the two longitudinal wires 7, 8 of the upper side region II lie between the longitudinal wires 3, 4 of the lower side region II and that the distance between the adjacent wires 3 and 7 or 4 and 8 of the two side regions is substantially equal to the unit distance or the distance between adjacent longitudinal wires in the central region I.

Figure 2 shows a part of a second embodiment of a reinforcing strip 1 according to the invention. The three regions I, II and III are once more shown: the central region I includes four longitudinal wires 4, 5, and 7, while the side regions II and III include three longitudinal wires, 2, 3 and 4 and 6, 8 and 9 respectively. The distance between adjacent longitudinal wires in the side regions II and III is equal to twice the unit distance or twice the distance between adjacent longitudinal wires in the central region I. When winding so that the side regions II and III overlap, one must now make sure that the longitudinal wires 8 and 9 of the upper side region III lie between the longitudinal wires 2 and 3 and 3 and 4, respectively, of the lower side region II and that the distance between adjacent longitudinal wires of the overlapping regions II, III - for example the distance between the longitudinal wires 2 and 8 - is substantially egual to the unit distance or the distance between adjacent longitudinal wires in the central region I.

Figure 3 shows a part of a preferred embodiment of a reinforcing strip 1 according to the invention. The three regions I, II and III are once more shown; the central region I contains four longitudinal wires 3, 4, and 6, while the side regions II and III contain two longitudinal wires, 2 and 3, and 6 and 7, respectively. The distance between the adjacent longitudinal wires in - 6 side regions II and III is equal to twice the unit J distance or two times the distance between adjacent longitudinal wires in the central region I. By way of example, the dimensions of such a reinforcing strip 1 are given here: the unit distance is 25.4 mm; the diameter of the longitudinal wires is 2.86 mm; the diameter of the transverse wires is 2.00 mm; the distance between the transverse wires is 67 mm and the length of the reinforcing strip or roll 1 is approximately 115 m.

Figure 4 shows a longitudinal cross-section through half of a part of a pipe 11 with a coating 12 applied to it in which a reinforcing strip 1 according to Figure 3 has been placed. As Figure 4 clearly shows, with a minimum overlapping of one unit distance of the lower side region II by the upper side region III of the successive windings of the reinforcing strip 1, an even distribution of the reinforcing material over the length of the pipe 11 is obtained.

In the embodiment of the pipe 11 represented in Figure 4 only one reinforcing strip or reinforcing layer 1 has been placed in the coating 12. It is clear that more such reinforcing layers or reinforcing strips 1 could be placed in the coating 12.

From the embodiments described above, it is clear that when the distance between two adjacent longitudinal wires in certain parts of the side regions II and III is not equal to the unit distance or the distance between adjacent longitudinal wires in the central region I, then this distance is nevertheless equal to an nmultiple of the unit distance, and that with overlapping winding side regions one must always make sure that n-1 longitudinal wires of one of the regions lie between the two longitudinal wires of the other regions that are at an n-multiple distance from one another, such that the distance between adjacent longitudinal wires of the overlapped two regions II and III is then substantially - 7 equal to the unit distance or the distance between J adjacent longitudinal wires in the central region.

Claims

1. A helically wound reinforcing strip in which adjacent turns partially overlap, the strip comprising longitudinal and transverse elements, wherein the longitudinal elements are spaced across the strip in such a manner that along the length of the helix in an axis parallel direction, there is a substantially even spacing between successive longitudinal elements of the strip, including in regions where adjacent turns of the strip overlap.

2. A strip as claimed in claim 1/ having a longitudinal central region and two longitudinal side regions, there being a plurality of longitudinal elements in the central region which are substantially evenly spaced in the transverse direction, and longitudinal elements in the side regions which are arranged, in the transverse direction, so as to provide spaces which receive the elements in the side regions of adjacent overlapped turns of the strip in such a manner that across two overlapped side regions the spacing between adjacent longitudinal elements is substantially the same as the spacing between the longitudinal elements in the central region.

3. A strip as claimed in claim 2, wherein each side region includes a plurality of longitudinal elements whose spacing in the transverse direction is substantially twice that of the longitudinal elements in the central region.

4. A strip as claimed in claim 2, wherein each side region includes a plurality of longitudinal elements whose spacing in the transverse direction is substantially the same as that of the longitudinal elements in the central region, each side region further - 9 including a space which in the transverse direction has a width substantially equal to the spacing between the longitudinal elements in the central region multiplied by (1 + n) where n is the number of said longitudinal elements in the side region.

5. A strip as claimed in claim 4, wherein each side region consists of two longitudinal elements.

6. A strip as claimed in any preceding claim, in the form of a welded wire mesh.

7. A strip as claimed in claim 6,' wherein the longitudinal wires are uniformly deformed.

8. A strip as claimed in any preceding claim, wound as a reinforcement around a cylindrical object.

9. A strip as claimed in claim 8, embedded in a coating applied to the cylindrical object.

10. A strip as claimed in claim 9, wherein the cylindrical object is a pipe.

11. A reinforcing strip adapted to be wound into a helix in which adjacent turns partially overlap, the strip comprising longitudinal and transverse elements, wherein the longitudinal elements are spaced across the strip in such a manner that when the strip is wound into the helix along the length of the helix in an axis parallel direction, there is a substantially even spacing between successive longitudinal elements of the strip, including in regions where adjacent turns of the strip overlap.

12. A strip as claimed in claim 11, having a longitudinal central region and two longitudinal side - 10 regions, there being a plurality of longitudinal elements in the central region which are substantially evenly spaced in the transverse direction, and longitudinal elements in the side regions which are arranged, in the transverse direction, so as to provide spaces which are adapted to receive the elements in the side regions of adjacent overlapped turns of the strip, when wound into the helix, in such a manner that across two overlapped side regions the spacing between adjacent longitudinal elements is substantially the same as the spacing between the longitudinal elements in the central region.

13. A strip as claimed in claim 12, wherein each side region includes a plurality of longitudinal elements whose spacing in the transverse direction is substantially twice that of the longitudinal elements in the central region.

14. A strip as claimed in claim 12, wherein each side region includes a plurality of longitudinal elements whose spacing in the transverse direction is substantially the same as that of the longitudinal element in the central region, each side region further including a space which in the transverse direction has a width substantially equal to the spacing between the longitudinal elements in the central region multiplied by (1 + n) where n is-the number of said longitudinal elements in the side region.

15. A strip as claimed in claim 14, wherein each side region consists of two longitudinal elements.

16. A strip as claimed in any of claims 11 to 15 in the form of a welded wire mesh. - 11

17. A strip as claimed in claim 16, wherein the J longitudinal wires are uniformly deformed.

18. A reinforcing strip substantially as hereinbefore described with reference to Figure 1; or Figure 2; or Figures 3 and 4 of the accompanying drawings.