A seal

Abstract: A seal for use in replacing an existing fluid-carrying pipe with a replacement pipe comprises a tubular body of a flexible material, the body having a rear portion (52) for connection to the leading end of the replacement pipe and front portion (54) adapted in use to provide a barrier to the flow of fluid along the annular gap between the internal wall of the existing pipe and the external wall of the replacement pipe, the seal also having a membrane (62) serving to prevent the flow of fluid through the bore of the seal, the membrane being puncturable or removable to permit the flow of fluid through the seal.

Description: The invention relates to a seal for use in replacing an existing pipe carrying fluid. FR-A-1342949 is directed to an element which serves to form a gas-tight closure in a hole in a wall and permits an electrical element or the like to pass through it (by piercing a membrane) while insulating or isolating the element from the surrounding surface of the hole. The element is shaped to be push-fitted into the hole in the wall where a flange engages the surface of the wall. According to one aspect of the present invention there is provided a seal for use in replacing an existing fluid-carrying pipe with a replacement pipe, the seal comprising a tubular body of a flexible material the body having a rear portion attached to the leading end of the replacement pipe and a front portion adapted in use to provide a barrier to the flow of fluid along the annular gap between the internal wall of the existing pipe and the external wall of the replacement pipe, the seal also having a membrane serving to prevent the flow of fluid through the bore of the seal, the membrane being puncturable or removable to permit the flow of fluid through the seal. According to another aspect of the present invention, there is provided a seal for use in replacing an existing fluid-carrying pipe with a replacement pipe, the seal comprising a tubular body of a flexible material, the body having a rear portion for connection to the leading end of the replacement pipe and a front portion adapted in use to provide a barrier to the flow of fluid along the annular gap between the internal wall of the existing pipe and the external wall of the replacement pipe, the seal also having a membrane serving to prevent the flow of fluid through the bore of the seal, the membrane being puncturable or removable to permit the flow of fluid through the seal, the body having an aperture linking the bore of the seal to its external surface. According to yet another aspect of the present invention, we provide a seal for use in replacing an existing fluid-carrying pipe with a replacement pipe, the seal comprising a tubular body of a flexible material, the body having a rear portion for connection to the leading end of the replacement pipe and a front portion adapted in use to provide a barrier to the flow of fluid along the annular gap between the internal wall of the existing pipe and the external wall of the replacement pipe, the seal also having a membrane serving to prevent the flow of fluid through the bore of the seal, the membrane being puncturable or removable to permit the flow of fluid through the seal, the front portion having a plurality of vanes, disposed around its external wall, the vanes providing the barrier to the flow of fluid along the annular gap. Embodiments of the invention are hereinafter described, by way of example, with reference to the accompanying drawings in which:- Figure 1 is a side view of one form of a seal to be used with a replacement service pipe in a method for replacing pipes, Figure 2 is a front view of the seal shown in Figure 1; Figure 3 is a sectional view along lines III-III of Figure 2 taken from above and to one side of the seal; Figure 4 shows the seal after attachment to the leading end of a replacement gas service pipe and about to be inserted into one end of the existing gas service pipe; Figure 5 shows a side view in section of a seal with the membrane at the rear end of the seal; and Figure 6 shows a side view of another form of the seal. Referring to Figures 1 to 3 the seal 50 for use in replacement may be a moulding of a synthetic resin material such as polyethylene, and comprises a tubular body 51 having a rear portion 52 for insertion into the leading end of a replacement gas service pipe 18 and a front portion 54. The rear portion 52 is provided with several circumferentially arranged tooth-like elements 55 serving to engage and grip the internal wall of the replacement pipe 18 when the portion 52 is push-fitted into the leading end of that pipe. The external diameter of the portion 52 is so selected that, in use, the portion 52 forms a gas-tight fit with the internal wall of a replacement pipe 22 as shown Figure 4. In use, however the outer surface of the rear portion 52 may be coated with a suitable settable adhesive so that the portion 52 adheres firmly to the internal wall of the replacement pipe 18 upon insertion thereinto. The replacement pipe 18 itself is also made of a synthetic resin material preferably polyethylene, so allowing the seal to be heat fused onto the replacement pipe 18 as an alternative to adhesive. The front portion 54 comprises several spaced annular vanes 56 to 60 which are generally radially directed and disposed at a spacing from each other along the outer wall of the seal. As shown the diameter of the vanes increases in the direction from the front end of the seal to the point at which the rear portion 52 of the seal begins. The rearmost vane 60 forms an abuttment for the circumferential front edge of the replacement pipe 18 as shown in Figure 4. In use, one or more and preferably all the vanes are so dimensioned as to provide a barrier to the flow of gas along any annular gap which would, in use, upon insertion of the seal be formed between the body 52 of the seal and the internal wall of the existing gas service pipe. The seal is also provided at its front end with a membrane 62 closing off the bore of the seal body 52, wherein in use to prevent the flow of gas into and through the body 52 of the seal until the membrane 62 is punctured, detached or broken in some way. In the embodiment shown in Figure 5 the membrane 62 is located at the rear end of the seal otherwise the seal is similar in form to that previously described. In the embodiment shown in Figure 5, the front portion 54 of the seal has a thicker wall 63 than that shown in Figures 1 to 5 so that there is formed between the front and rear portions an annular shoulder 64 rearwardly of the last of the vanes 60. Because of this the radial extent of the vanes 56 to 60 in the seal in Figure 6 is foreshortened in comparison to the radial extent of the vanes in the seal in Figures 1 to 5 so that the overall radial dimension of area bounded by each vane remains unchanged. In addition extending radially through the wall of the front portion 54 of the seal at a point disposed between the last vane 60 and the shoulder 64 is an aperture 65 for purposes described in our published European patent application No. 406377. In use, as shown the front end of the replacement service pipe 18 is caused to abut against the shoulder 64. After the rear portion 52 of the seal has been push fitted onto the end of the service pipe 18, the seal is heat fused thereto or is affixed thereto by adhesive. A method of replacing an existing gas service pipe with a replacement pipe using the seal is described in our published European patent application No. 406377.

Claims: A seal for use in replacing an existing fluid-carrying pipe with a replacement pipe, the seal comprising a tubular body (51) of a flexible material, the body (51) having a rear portion (52) attached to the leading end of the replacement pipe (18) and a front portion (54) adapted in use to provide a barrier to the flow of fluid along the annular gap between the internal wall of the existing pipe (63) and the external wall of the replacement pipe (18), the seal (50) also having a membrane (62) serving to prevent the flow of fluid through the bore of the seal (50), the membrane (62) being puncturable or removable to permit the flow of fluid through the seal (50). A seal as claimed in claim 1, characterised in that the seal (50), is heat-fused to one end of the pipe (18). A seal for use in replacing an existing fluid-carrying pipe with a replacement pipe, the seal comprising a tubular body (51) of a flexible material, the body (51) having a rear portion (52) for connection to the leading end of the replacement pipe (18) and a front portion (54) adapted in use to provide a barrier to the flow of fluid along the annular gap between the internal wall of the existing pipe (63) and the external wall of the replacement pipe (18), the seal (50) also having a membrane (62) serving to prevent the flow of fluid through the bore of the seal (50), the membrane (62) being puncturable or removable to permit the flow of fluid through the seal (50), characterised in that the body (51) has an aperture (65) linking the bore of the seal to its external surface. A seal as claimed in any of claims 1 to 3, in which the front portion has at least one annular vane (56, 57, 58, 59, 60) disposed around its external wall, the or at least one of the vanes providing the barrier to the flow of fluid along the annular gap. A seal as claimed in claim 4, characterised in that there are a plurality of vanes (56, 57, 58, 59, 60), the diameter of the vanes increasing in the direction from the front end (54) of the seal (50) to the rear end (52). A seal for use in replacing an existing fluid-carrying pipe with a replacement pipe, the seal comprising a tubular body (51) of a flexible material, the body (51) having a rear portion (52) for connection to the leading end of the replacement pipe (18) and a front portion (54) adapted in use to provide a barrier to the flow of fluid along the annular gap between the internal wall of the existing pipe (63) and the external wall of the replacement pipe (18), the seal (50) also having a membrane (62) serving to prevent the flow of fluid through the bore of the seal (50), the membrane (62) being puncturable or removable to permit the flow of fluid through the seal (50), characterised in that the front portion (54) has a plurality of vanes (56, 57, 58, 59, 60) disposed around its external wall, the vanes providing the barrier to the flow of fluid along the annular gap. A seal as claimed in claim 6, characterised in that the diameter of the vanes (56, 57, 58, 59, 60) increases in the direction from the front end (54) of the seal (50) to the rear end (52). A seal as claimed in any of the preceding claims, characterised in that the membrane (62) is located at the front end (54) of the seal (50). A seal as claimed in any of the preceding claims, characterised in that the seal (50) is of polyethylene. A seal as claimed in any of the preceding claims, characterised in that the seal (50) is a moulding.

Inventors: ASHCROFT IAN, BENNETT ROBERT NEAL, HICKS MICHAEL, LAMB RICHARD, NIXON KEITH, PARKES ADRIAN SYDNEY, SMITH JOHN PHILIP, TAYLOR JOHN, ASHCROFT, IAN, BENNETT, ROBERT NEAL, HICKS, MICHAEL, LAMB, RICHARD, NIXON, KEITH, PARKES, ADRIAN SYDNEY, SMITH, JOHN PHILIP, TAYLOR, JOHN
Applicants: BRITISH GAS PLC
Application year: 1989
Main classification: F16L7
IPC codes: F16L55, F16L7