A reversible lining tube for repairing an existing pipeline

Abstract: There is provided a reversible lining tube 20 for repairing an existing pipelinel. Such a lining tube 20 is reversible into the existing pipeline 1 so that its initial inner surface 20b becomes outer surface 20a which adheres to the internal surface of the pipeline 1. In detail, the reversible lining tube includes an elastomer layer 20a and a flock layer 20b, prior to reversal into the existing pipeline 1 the elastomer layer 20a is an outer layer and the flock layer 20b is an inner layer, upon reversal into the existing pipeline 1 the elastomer layer becomes an inner layer and the flock layer becomes an outer layer which adheres to the internal surface of the existing pipeline 1. Alternative embodiments utilise a thread-knitted layer in place of the said flock layer.

Description: The present invention relates to a lining tube for use in repairing an existing pipeline, particularly to a lining tube reversible into an existing underground pipeline such as a gas pipe, water pipe, etc. so that its initial inner surface becomes an outer surface which adheres to the internal surface of the existing pipeline. Such a lining tube is for example known from US-A-4 390 574. Fig. 7 shows a process where a reversible lining tube 6 is reversed into an existing underground pipeline 1 to repair the same. According to the process shown in Fig. 7, at first, a resilient leading pig 3 is introduced into the existing underground pipeline 1. Then, a necessary amount of adhesive agent 5 is introduced into the pipeline 1. Afterwards, one end of a reversible lining tube 6 is fixed at an open end 1a of the pipeline 1 in a manner such that the lining tube 6 may be reversed into the pipeline 1. As shown in Fig. 7, a suction apparatus P is connected to an opposite open end 1b of the pipeline 1, so that a negative pressure may be produced in the pipeline 1 to cause the leading pig 3 and the adhesive agent 5 to move towards the open end 1b of the pipeline 1, thereby enabling the reversible lining tube 6 to be reversed into the pipeline 1. In this way, the initial inner surface of the lining tube 6 becomes its outer surface which adheres to the internal surface of the existing underground pipeline 1. Alternatively, instead of using a suction apparatus P, it is possible to connect a pressurizer apparatus (not shown) to the open end 1a. Then, by operating the pressurizer apparatus, a positive pressure is produced in the pipeline 1 to cause the leading pig 3 and the adhesive agent 5 to move towards the open end 1b of the pipeline 1, thereby enabling the reversible lining tube 6 to be reversed into the pipeline 1. In this way, the initial inner surface of the lining tube 6 becomes its outer surface which adheres to the internal surface of the pipeline 1. The lining tube 6 used in the process shown in Fig. 7 comprises an elastomer layer 10 (for instance, polyurethane layer) and a fabric layer 11 (consisting of laterally arranged threads and longitudinally arranged threads), as illustrated in Fig. 8. Referring again to Fig. 8, when the lining tube 6 comprising the elastomer layer 10 and the fabric layer 11 is reversed into the pipeline 1, the fabric layer 11 becomes an outer layer to absorb the adhesive agent 5 so as to adhere to the internal surface of the pipeline 1. However, since the fabric layer 11 has a considerable thickness and a hardness, it is difficult to reduce the overall thickness and hardness of the lining tube 6. As a result, when the lining tube 6 is reversed in the pipeline 1, it has been found that the reversal of the lining tube 6 in the pipeline 1 is relatively difficult, especially when passing through a bent portion 1c of the pipeline 1. On the other hand, as illustrated in Fig. 9, if a lining tube consisting only of a single layer 10 (elastomer layer) is used in repairing an existing underground pipeline 1, it is found that the reversal of the lining tube in the pipeline 1 is easier than the lining tube shown in Fig. 8, especially when passing through a bent portion 1c of the pipeline 1. However, since the elastomer layer 10 fails to absorb the adhesive agent 5, it has been found that the lining tube shown in Fig. 9 is difficult to adhere to the internal surface of the pipeline 1. Also, since the elastomer layer 10 fails to absorb the adhesive agent 5, an adhesive agent layer 5 formed between the elastomer layer 10 and the pipeline internal wall will become uneven, causing an uneven surface of the lining layer on the pipeline internal wall. SUMMARY OF THE INVENTION An object of the present invention is to provide an improved lining tube for use in repairing an existing pipeline, so as to solve the above-mentioned problems peculiar to the above-mentioned prior arts. According to a first aspect of the present invention, there is provided such a lining tube which is reversible into the existing pipeline so that its initial inner surface becomes an outer surface which adheres to the internal surface of the pipeline. In particular, the reversible lining tube according to the invention includes an elastomer layer and a flock layer, prior to reversal into the existing pipeline the elastomer layer is an outer layer and the flock layer is an inner layer, upon reversal into the existing pipeline the elastomer layer becomes an inner layer and the flock layer becomes an outer layer which adheres to the internal surface of the existing pipeline. In the above improved reversible lining tube according to the present invention, the elastomer layer is preferably a polyurethane layer, a polyester layer, a butyl rubber layer, a polyisobutylene layer, or a polyvinyl chloride layer. The flock layer is preferably a fibre layer which is formed by first coating one surface of the elastomer layer with an adhesive agent and then causing an amount of short fibre to adhere to the adhesive-coated surface of the elastomer layer by virtue of static electricity effect. In detail, said short fibre of the flock layer is preferably an aromatic polyamide fibre, a nylon fibre, a rayon fibre, a Tetoron fibre, a polyester fibre, an acrylic fibre, a vinylon fibre, or a polypropylene fibre. The elastomer layer is preferably a thermoplastic polyurethane elastomer layer. In order that the invention may be illustrated, more easily understood and readily carried into effect by one skilled in this art, embodiments of the invention will now be described purely by way of non-limiting example, with reference to the accompanying drawings, and wherein: Fig. 1a is a longitudinally cut cross sectional view showing a reversible lining tube for repairing an existing pipeline, according to the present invention, Fig. 1b is a perspective view illustrating the reversible lining tube shown in Fig. 1a, Fig. 2 is an explanatory view schematically illustrating a process in which a reversible lining tube shown in Figs. 1a and 1b is used for repairing an existing underground pipeline, Fig. 3 is another explanatory view illustrating in more detail how a reversible lining tube shown in Figs. 1a and 1b is used for repairing an existing underground pipeline, Fig. 7 is an explanatory view schematically illustrating a process in which a conventional lining tube is used for repairing an existing underground pipeline, Fig. 8 is another explanatory view illustrating in more detail how a conventional lining tube is reversed in an existing underground pipeline for repairing the same, and Fig. 9 is a further explanatory view illustrating in more detail how another conventional lining tube is reversed in an existing underground pipeline for repairing the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Figs. 1a and 1b showing a reversible lining tube according to the first aspect of the present invention, a reversible lining tube 20 for repairing an existing underground pipeline has an elastomer layer 20a and a flock layer 20b. Prior to reversal into an existing underground pipeline, the elastomer layer 20a is an outer layer and the flock layer 20b is an inner layer. Upon reversal into the existing underground pipeline, the elastomer layer 20a becomes an inner layer and the flock layer 20b becomes an outer layer which adheres to the internal surface of the existing underground pipeline. The elastomer layer 20a is a polyurethane layer having a predetermined dilation and a tensile strength. Alternatively, the elastomer layer 20a may be a polyester layer, a butyl rubber layer, a polyisobutylene layer, or a polyvinyl chloride layer, provided that they have substantially the same dilation and the same tensile strength as those of the polyurethane layer. In detail, the elastomer layer 20a has a thickness of 0.3 - 1.5 mm. If the thickness of the elastomer layer 20a is less than 0.3 mm, it will be difficult for the reversible lining tube 20 to have a sufficient strength. On the other hand, if the thickness of the elastomer layer 20a is greater than 1.5 mm, there will be a difficulty during reversing movement of the lining tube 20 in an existing pipeline. The flock layer 20b is a fibre layer which is formed by first coating one surface of the elastomer layer 20a with an adhesive agent and then causing an amount of short fibre to adhere to the adhesive-coated surface of the elastomer layer 20a by virtue of static electricity effect. Alternatively, the flock layer 20b may also be formed by spraying (using a pressurized air) the short fibre on to the adhesive-coated surface of the elastomer layer 20a. Here, the short fibre of the flock layer 20b is an aromatic polyamide fibre, a nylon fibre, a rayon fibre, a Tetoron fibre, a polyester fibre, an acrylic fibre, a vinylon fibre, or a polypropylene fibre. Alternatively, the short fibre of the flock layer 20b may also be a semi-synthetic fibre, a synthetic inorganic fibre or a natural fibre. Further, the flock layer 20b has a thickness of 2 mm or less. If the thickness of the flock layer 20b is greater than 2 mm, there will also be a difficulty during the reversing movement of the lining tube 20 in an existing pipeline. Figs, 2 and 3 show an actual operation, a process where a reversible lining tube according to the first aspect of the present invention is reversed into an existing underground pipeline to repair the same. However, in Figs. 2 and 3, the elements which are the same as those in Figs. 7-9 will be represented by the same reference numerals. In Fig. 2, reference numeral 1 represents an existing underground pipeline 1 (such as a gas service pipe) which is to be repaired using the reversible lining tube 20, reference numeral 2 represents a main pipe (such as a gas main buried under ground on road side). In order to perform the repairing operation shown in Fig. 2, the pipeline 1 is cut so as to be separated from the main pipe 2. As shown in Fig. 2, the existing underground pipeline 1 involves several bent portions. A reel apparatus 8, on which flatly folded reversible lining tube 20 is wound, is positioned close to one open end 1a of the pipeline 1. In operation, at first, a resilient leading pig 3 is introduced into the pipeline 1. Then, a necessary amount of adhesive agent 5 is introduced into the pipeline 1. Afterwards, one end of the reversible lining tube 20 is fixed at an open end 1a of the pipeline 1, in a manner such that the lining tube 20 may be reversed into the pipeline 1. Subsequently, a suction apparatus P is connected to an opposite open end 1b of the pipeline 1, so that a negative pressure is produced in the pipeline 1 to cause the leading pig 3 and the adhesive agent 5 to move towards the open end 1b of the pipeline 1, thereby enabling the reversible lining tube 20 to be reversed into the pipeline 1. In this way, the initial inner surface (the flock layer 20b) of the lining tube 20 becomes an outer surface which adheres to the internal surface of the pipeline 1. At this moment, as shown in Fig. 3, since the reversible lining tube 20 is caused to reverse in the pipeline 1 making its reversing/folding portion 20c in contact with the adhesive agent 5, the adhesive agent 5 can coat not only the internal surface of the pipeline 1 but also the reversing/folding portion 20c of the lining tube 20, so that the reversible lining tube 20 may exactly adhere to the internal surface of the pipeline 1 once the flock layer 20b thereof becomes the outer surface in contact with the pipeline internal wall. Referring again to Fig. 3, the reversible lining tube 20, which consists of the elastomer layer 20a and the flock layer 20b in a manner as described above, can easily pass through the bent portion 1c involved in the existing underground pipeline 1. Further, when a lining tube 20 including the elastomer layer 20a and the flock layer 20b is reversed into the pipeline 1, the flock layer 20b becomes the outer surface to absorb the adhesive agent 5, so that the finally formed lining layer (including the elastomer layer 20a and the flock layer 20b) has a uniform thickness on the internal surface of the pipeline 1. Alternatively, similarly to a process described in Fig. 7, instead of using a suction apparatus P, it is also possible to connect a pressurizer apparatus (not shown) to the open end 1a. Then, by operating the pressurizer apparatus, a positive pressure is produced in the pipeline 1 to cause the leading pig 3 and the adhesive agent 5 to move towards the open end 1b of the pipeline 1, thereby enabling the reversible lining tube 20 to be reversed into the pipeline 1. In this way, the initial inner surface (flock layer 20b) of the lining tube 20 becomes its outer surface which adheres to the internal surface of the pipeline 1. In detail, the thermoplastic polyurethane elastomer may be ester polyurethane elastomer such as caprolacton polyurethane elastomer or adipate polyurethane elastomer. that nay be used as a long chain polyol in the caprolacton polyurethane elastomer or adipate polyurethane elastomer, are polyesterdiol such as poly-ε-caprolacton, poly(ethylene adipate), poly(butylene adipate), poly(hexane adipate). On the other hand, the thermoplastic polyurethane elastomer may also be ether polyurethane elastoner. What may be used as a long chain polyol in the ether polyurethane elastomer, may be polyether diol such as polyoxytetramethylene glycol or polypropylene glycol. While the presently preferred embodiments of the this invention have been shown and described above, it is to be understood that these disclosures are for the purpose of illustration.

Claims: A reversible lining tube (20) for repairing an existing pipeline (1), said lining tube (20) being reversible into the existing pipeline (1) so that its initial inner surface (20b) becomes an outer surface which adheres to the internal surface of the pipeline, wherein the reversible tube (20) includes an elastomer layer (20a) and an absorbent layer (20b), prior to reversal into the existing pipeline (1) the elastomer layer (20a) is an outer layer and the absorbent layer (20b) is an inner layer, upon reversal into the existing pipeline (1) the elastomer layer (20a) becomes an inner layer and the absorbent layer (20b) becomes an outer layer which adheres to the internal surface of the existing pipeline (1), characterized in that : said absorbent layer (20b) is a flock layer (20b). A reversible lining tube (20) according to claim 1, wherein the elastomer layer (20a) is a polyurethane layer, a polyester layer, a butyl rubber layer, a polyisobutylene layer, or a polyvinyl chloride layer. A reversible lining tube (20) according to claim 1 or 2, wherein the flock layer (20b) is a fibre layer (20b) which is formed by first coating one surface of the elastomer layer (20a) with an adhesive agent and then causing an amount of short fibre to adhere to the adhesive-coated surface of the elastomer layer (20a) by virtue of static electricity effect. A reversible lining tube (20) according to claim 3, wherein said short fibre of the flock layer (20b) is an aromatic polyamide fibre, a nylon fibre, a rayon fibre, a tetoron fibre, a polyester fibre, an acrylic fibre, a vinylon fibre, or a polypropylene fibre. A reversible lining tube (20) according to any preceding claim, wherein the elastomer layer (20a) has a thickness of 0.3 - 1.5 mm. A reversible lining tube (20) according to any preceding claim, wherein the flock layer (20b) has a thickness of 2 mm or less. A method of repairing or relining an existing pipeline (1) which involves use of a reversible lining tube (20) as claimed in any preceding claim.

Inventors: ITAGAKI MASAAKI, OKABE KAZUKI, TOYODA SHIGERU, YAGI SHUICHI, ITAGAKI, MASAAKI, OKABE, KAZUKI, TOYODA, SHIGERU, YAGI, SHUICHI, Yagi, Shuichi, No. 503 Ekureru daisan Myorenji
Applicants: NISSHIN SPINNING, TOKYO GAS CO LTD, NISSHINBO INDUSTRIES INC., TOKYO GAS CO., LTD.
Application year: 1997
Main classification: F16L55
IPC codes: B32B1, D04B1, B32B5, B32B27, B29L23, B29L9, F16L1, B29C63, F16L55, B29C47