GB1588714A

GB1588714A - Isolating pipes from one another

Info

Publication number: GB1588714A
Application number: GB2108876A
Authority: GB
Original assignee: Avon Rubber PLC
Current assignee: Avon Protection PLC
Priority date: 1977-08-22
Filing date: 1977-08-22
Publication date: 1981-04-29

Description

(54) IMPROVEMENTS IN OR RELATING TO ISOLATING PIPES FROM ONE ANOTHER (71) We, AVON LIPPIATT HOBBS LIMITED, a British Company, of Penn Place, Rickmansworth, Hertfordshire, 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 be particularly described in and by the following statement: The invention relates to isolating pipes from one another and especially to isolating a branch pipe from a main pipe containing fluid.

The invention provides a method of isolating a branch pipe from a main pipe containing fluid, comprising forming an opening in the branch pipe without allowing the fluid to escape into the surroundings, inserting a sealant material into the branch pipe through the opening so as to form a fluid-tight seal in that pipe, and severing the branch pipe at a position such as to leave the remaining portion of the branch pipe connected to the main pipe sealed from the exterior by at least a portion of the sealant material.

The method of the invention is especially advantageous when applied in connection with domestic gas supply for disconnecting branch pipes or service pipes from main gas pipes. The method of the invention makes it possible to disconnect branch pipes or service pipes from mains gas pipes while gas is flowing through the mains pipe.

The sealant material may be, for example, a suitable grease, paste or putty. It may be a material obtained by mixing together two or more components prior to insertion, which material cures or sets with time, for example, a two part closed cell foam such as that used for cavity wall insulation, or it may be a material that cures or sets on reaching ambient temperature the material being maintained in a flowable condition for insertion by the application of heat or a reduction in temperature. The amount of sealant material required to give a fluid-tight seal will depend on the pressure difference across it and the co-efficient of friction between the sealant material and the internal surface of the pipe.

When the fluid within the pipes is a gas at a pressure greater than atmospheric. pres- sure, as, for-example, in the case mentioned above of domestic gas supply, the opening in the branch pipe is advantageously formed by enclosing the area of the branch pipe in which the opening is to be made under a cover secured to the branch pipe in a fluidtight manner and drilling a hole through the wall of the branch pipe under the cover. A drilling tool for drilling the hole may, and if it is wished to withdraw the drilling tool completely after formation of the opening, advantageously, extend through valve means provided to give access to the area of the branch pipe beneath the cover, the drilling tool blocking the valve means so as to prevent the escape of fluid. After forming the hole, the drill may then be withdrawn through the valve means into a tubular member which it blocks so as to prevent the escape of fluid until the valve means is closed. A so-called "under pressure" drilling rig may be used for this purpose, the rig having a base which forms at least a part of the said cover. The cover may be secured to the branch pipe by means, for example, of a securing chain, or by means of pads clamped together around the branch pipe.

When the opening is formed by drilling a hole through the wall under a cover as referred to above, the sealant material is preferably inserted into the branch pipe through the cover, the cover being provided with valve means to allow the sealant material to be so inserted without allowing fluid to escape, and the cover remaining in position until the fluid-tight seal is formed. The valve means for insertion of the sealant material may be the valve means provided for the drilling tool, if this is first withdrawn, or it may be additional valve means.

The sealant material is advantageously inserted into the branch pipe so that it forms the fluid-tight seal in the branch pipe between the main pipe and the opening. In this case the cover may be removed after the fluid-tight seal is formed and before the branch pipe is severed. After the branch pipe is severed, the sealant material may provide a satisfactory seal between the interior of the main pipe and the surroundings on its own. Alternatively, however, a plug, for example, of a rubber or a foamed plastics material, may be inserted in the severed end, displacing the sealant material down the branch pipe, if necessary.

The opening may be formed in the branch pipe at a position adjacent to the mains pipe so that the portion of the branch pipe remaining connected to the main pipe after severing is relatively short. It may, however, be desired to shorten the length of the remaining portion of the branch pipe further, and when a plug has been inserted into the severed end of the branch pipe this may be achieved by ramming the plug down the branch pipe towards the main pipe and cutting off a further portion of the branch pipe leaving the interior of the main pipe still sealed from the surroundings by at least a portion of the plug and/or the sealant material. The plug may be rammed down the branch pipe to such an extent that a portion of the sealant material or all of it is displaced into the main pipe. In this manner, the length of the branch pipe remaining connected to the main pipe may be reduced to a short stub.

The portion of the branch pipe remaining on the main pipe after severing and, if desired, further reduction in length, may, if it is to be left permanently, be encapsulated in a suitable encapsulant material. In the case of a service pipe connected to a mains gas pipe, the service pipe may be fitted to the mains pipe by means of a ferrule or similar fitment. The entire ferrule or similar fitment together with the remaining portion of the service pipe is then preferably encapsulated.

As an alternative to encapsulation, where, for example, the branch pipe is a service pipe screwed into the main pipe, either directly or by means of a fitment screwed into the main pipe, the portion of the branch pipe remaining on the main pipe after severing may be removed by securing a cover to the main pipe over the branch pipe in a fluid-tight manner so as to form a fluid-tight enclosure, removing the branch pipe from the main pipe within the enclosure and inserting in its place a plug or a fitment to which a new service pipe can be secured. As with the cover secured to the branch pipe for the formation of the opening, the cover secured to the main pipe may be provided at least in part by the base of a so-called "under pressure" drilling rig, the drilling tool having been removed.

Conventional extractor and carrier tools may be inserted into the enclosure for removing the remaining portion or stub of the branch pipe and inserting a plug or fitment. To operate the extractor, it must generally be brought into exact alignment with the stub which it can then engage and be rotated to unscrew the stub from the main pipe. Similarly, the carrier tool must generally be brought into exact alignment with the opening left on removal of the stub in order to insert the plug or fitment. This exact alignment is often difficult to achieve.

Advantageously, a flexible sleeve is provided, which is secured at one end to the cover and into which an operator inserts his arm, the sleeve being secured to his arm, and the cover is provided with valve means to enable the operator to gain manual access through the sleeve to the remaining portion of the branch pipe for manually removing it and replacing it with a plug or fitment. The sleeve is preferably of bellows construction.

The flexible sleeve secured to the operator's arm makes it possible to prevent the escape of fluid to the surroundings when the valve means is opened, and the operator can carry out the removal of the branch pipe and the insertion of a plug or fitment by hand, the valve means being closed before he withdraws his arm from the sleeve.

With the method of the invention, it is also possible to form a fluid-tight seal in the portion of the branch pipe severed from the main pipe. This may be achieved by inserting a quantity of the sealant material into the branch pipe such that the branch pipe can be severed at a position which leaves sufficient material on each side to seal each severed end of the branch pipe.

A method of isolating a branch pipe from a main pipe containing fluid in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figures 1 to 4 show some of the different arrangements of pipes on which the method of the invention can be carried out; Figure 5 shows a step in the method of the invention; Figure 6 shows the apparatus shown in Figure 5 on a larger scale; Figures 7 to 10 show further steps in the method of the invention Figures 11 and 12 show the same steps as Figures 5 to 7 but using different apparatus; Figures 13 and 14 show a further step in the method of the invention; and Figure 15 shows apparatus for use in an alternative step to that shown in Figures 13 and 14; and Figure 16 shows apparatus for use in an alternative step to that shown in Figures 13, 14 and 15.

Referring to the accompanying drawings and initially to Figures 1 to 4 which show some of the different ways in which service pipes for domestic gas supply are connected to mains gas pipes and on which the method of the invention can be carried out, the same reference numerals being used for the same parts. In Figure 1, a straight service pipe 1 is connected to a mains pipe 2 containing gas at a pressure greater than atmospheric pressure by means of a screwed nipple 3. Figure 2 shows a service pipe 1 having a right angle bend connected to a mains pipe 2 also by a screwed nipple 3. In Figure 3 the service pipe 1 is screwed into a ferrule 4 which is in turn screwed into the mains pipe 2 and in Figure 4 the ferrule 4 is shown connected to the mains pipe 2 by means of a split collar 4a. In all these cases the method of the invention can be applied.

Referring to Figure 5, an under pressure drilling rig indicated generally by the reference numeral 5 is first secured to the service pipe 1 at a position adjacent to the mains pipe 2 by means of a U-bolt 6. The drilling rig 5, which can be seen in more detail in Figures 6 and 7, has a base 5a, which covers an area of the service pipe 1 in which a hole is to be made and is held in gas-tight engagement with the outer surface of the pipe 1 to form a gas-tight enclosure. The drilling rig 5 also comprises a main valve Sb which can be opened and closed by a handle Sc to provide access to the enclosure, and a tubular member Sd on the side of the valve Sb remote from the service pipe 1. The tubular member 5d is of the same internal diameter as the opening in the valve 5b so that the valve functions as a so-called "full-way" valve. The valve 5b may be a gate valve, a ball valve or a sliding plate valve. A drilling tool (not shown) of an external diameter such that it makes a sliding fit with the tubular member Sd and the valve Sb can be inserted through the tubular member and valve into the enclosure and a hole drilled in the service ipe 1. The drilling tool blocks the valve 5b so that gas cannot escape into the surroundings while the hole is being formed.

After formation of the hole the drilling tool may be withdrawn into the tubular member 5d so that it still prevents the escape of gas to the surroundings, and the valve 5b can then be closed.

In the form of apparatus shown in Figs. 5, 6 and 7 the drilling rig 5 is provided with an injection port 7 having an auxiliary valve 8 which also functions as a "full-way" valve.

To the valve 8 can be attached a feed-tube 9a of a pressure gun 9. Alternatively, the feed tube 9a may be inserted through the injection port 7 into the pipe 1 as indicated in broken lines in Figure 7. The pressure gun 9 comprises a cylinder 10 and a ram 11 and is supplied with a sealant material 12 in a suitable flowable form which, on movement of the ram 11 down the cylinder 10, is forced into the enclosure and from there into the pipe 1, or directly into the pipe 1 via the feed tube 9a.

The sealant material 12 may be a grease, paste or putty. It may be a material obtained by mixing together two or more components prior to insertion into the service pipe 1, which material cures or sets with time, for example, a two part closed cell foam such as that used for cavity wall insulation, or it may be a material that cures or sets on reaching ambient temperature, the material being maintained in a flowable condition for insertion by the application of heat or a reduction in temperature.

A sufficient quantity of the sealant material 12 is injected into the pipe 1 so that it completely blocks the pipe 1 and forms a gas-tight seal in the pipe 1. The drilling rig 5 is then removed and the service pipe 1 is severed at a position such as to leave a sufficient quantity of the material 12 in the end portion of the service pipe 1 connected to the main pipe 2 as to give a gas-tight seal between the mains pipe 2 and the exterior as can be seen in Figure 8. The quantity of the sealant material 12 required will depend on the pressure of the gas in the mains pipe 2 and the coefficient of friction between the sealant material 12 and the internal surface of the pipe 1.

A satisfactory seal may be given by the sealant material 12 on its own but, if desired, a plug 13 of rubber or a foamed plastics material may be driven down the portion of the pipe 1 remaining on the mains pipe 2 so as to force the sealant material 12 down the pipe 1 and to displace it into the interior of the mains pipe 2, as shown in Figure 9. A further portion can then be cut off from the service pipe 1 leaving a short stub still secured to the mains pipe 2 sealed by a portion of the plug 13 as can be seen in Figure 10.

A different form of drilling rig to that shown in Figures 5 to 7 is shown in Figure 11. This drilling rig has a base 14 arranged to cover an area of the service pipe 1 in which an opening is to be formed. The base 14 comprises a hollow cylindrical member 15 from the lower end of which extends a plate 16, the plate being secured to the service pipe 1 in a gas-tight manner by means of bolts 17 through clamping pads 18 on each side of the pipe. The cylindrical member 15 is externally screw-threaded for connection to a tubular member 1 9a on one side of an Atlas Copco valve 19 which valve can be opened by means of a handle 20 to allow communication through an opening in the valve between the interior of the cylindrical member 15 and the interior of a hollow cylindrical connector 21 connected to a tubular member 1 9b on the other side of the valve 19. The diameter of the opening in the valve 19 and the internal diameters of the tubular members 19a and 1 9b are the same.

A hole saw 22 on a shank 23 extending along the connector 21 can be inserted through the valve 1 9 and the cylindrical member 15 into engagement with the pipe 2 for forming an opening therein. The hole saw 22 is of such diameter that it makes a sliding fit with the tubular members 1 9a and 19b and the opening in the valve 1 9 so that when it is inserted through the valve and engages the service pipe 1 it blocks the opening in the valve and prevents gas from the service pipe from escaping into the surroundings as the hole is formed. The connector 21 at its upper end is in gas-tight engagement with the shank 23 by means of an annular rubber sealing disc 24 and a sealing nut 25.

After the formation of the opening, the hole saw 22 can be withdrawn into the tubular member 19b, which it blocks preventing the escape of gas until the valve 19 is closed.

The hole saw 22 and the connector 21 can then be completely removed from the valve 19.

As can be seen from Figure 12, a filler body 26 containing sealant material can then be connected to the valve 19. A plunger 27 extends out of the body 26, through a filler cap 28, and can be depressed to expel sealant material out of the filler body through the valve 19 (which is opened for this purpose, the escape of gas being prevented by the sealant material itself) into the pipe 2 to form a fluid-tight seal in a similar manner as described with reference to Figure 7. The same steps are then taken as described with reference to Figures 8 to 10, the drilling rig being removed, the pipe I severed, a plug inserted and driven down the pipe I and a further portion of the pipe 1 cut off leaving a short stub.

When the stage shown in Figure 10 is reached, if the stub of the service pipe 1 is to be left premanently, the stub and plug 13 may then be encapsulated in a suitable encapsulant material 14 by urging a mould containing the encapsulant material against the external surface of the pipe 1 over the stub of the service pipe 1 and the joint between the service pipe 1 and the mains pipe 2, and causing or allowing the encapsulant material to harden. The mould is then removed leaving an encapsulated stub as can be seen in Figure 13.

The stub of the service pipe 1 may be encapsulated instead in the manner shown in Figure 15 which shows a base 29 of a drilling rig secured to the mains pipe 2 over the stub of the service pipe 1. A retainer cap 30 through which extends a screw plunger 31 is secured to the base 29 by means of a bayonet fastening 32. Encapsulant material 33 is placed in the enclosure formed by the base 29 and cap 30 and the plunger 31 depressed it being maintained in its depressed position until the encapsulant material 33 has set. The base 29, cap 30 and plunger 31 are then removed.

In cases where the service pipe 1 is connected to the mains pipe 2 by means of a ferrule or like fitment, the entire fitment and stub are preferably encapsulated as shown in Figure 14.

Instead of leaving the stub of the service pipe 1 permanently in position, it may be desired to remove the stub completely and either insert a plug or a fitment, for exam ple, a so-called "Service T" for the connection of a new service pipe to the mains pipe 2. Thus, instead of encapsulating the stub as shown in Figures 13, 14 and 15, the step may be taken as shown in Figure 16, in which a base 34 of a drilling rig is secured to the mains pipe 2 over the stub by chains 35 so that it covers the stub, the base being provided with a rubber sealing ring 36 to ensure that the base is secured in a gas-tight manner. The base 34 is also provided with a stop gate 37 which can be opened to allow access to the stub or closed to prevent gas escaping from the mains pipe 2 after the stub is removed. To the upper edge of the base 34 is secured, by means of a strap 38, a flexible canvas sleeve 39 of bellows construction, the upper end of the sleeve being provided with an elasticated wrist band 40.

To remove the stub, the operator inserts his arm into the sleeve 39, opens the stop gate 37 and unscrews the stub manually. He then closes the stop gate 37 before removing his arm from the sleeve 39 together with the stub. The wrist band 40 which grips the arm of the operator while he is removing the stub, prevents the escape of gas to the surroundings while the stop gate 37 is open, and only the very small volume of gas within the sleeve can escape when the operator, having closed the gate, removes his arm from the sleeve. To insert a plug or service T, the operator inserts his arm once more into the sleeve 39, opens the stop gate 37 and inserts the plug or service T manually.

After removing his arm from the sleeve 39 he can remove the base 34 from the mains pipe 2. The bellows construction of the sleeve 39 makes it possible for the operator to have freedom of movement within the sleeve and facilitates location of the stub for its removal, and of the opening left by the stub for the insertion of the plug or service T.

WHAT WE CLAIM IS: 1. A method of isolating a branch pipe from a main pipe containing fluid, comprising forming an opening in the branch pipe without allowing the fluid to escape into the surroundings, inserting a sealant material into the branch pipe through the opening so as to form a fluid-tight seal in that pipe, and severing the branch pipe at a position such as to leave the remaining portion of the

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Claims

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along the connector 21 can be inserted through the valve 1 9 and the cylindrical member 15 into engagement with the pipe 2 for forming an opening therein. The hole saw 22 is of such diameter that it makes a sliding fit with the tubular members 1 9a and 19b and the opening in the valve 1 9 so that when it is inserted through the valve and engages the service pipe 1 it blocks the opening in the valve and prevents gas from the service pipe from escaping into the surroundings as the hole is formed. The connector 21 at its upper end is in gas-tight engagement with the shank 23 by means of an annular rubber sealing disc 24 and a sealing nut 25.

After the formation of the opening, the hole saw 22 can be withdrawn into the tubular member 19b, which it blocks preventing the escape of gas until the valve 19 is closed.

The hole saw 22 and the connector 21 can then be completely removed from the valve 19.

As can be seen from Figure 12, a filler body 26 containing sealant material can then be connected to the valve 19. A plunger 27 extends out of the body 26, through a filler cap 28, and can be depressed to expel sealant material out of the filler body through the valve 19 (which is opened for this purpose, the escape of gas being prevented by the sealant material itself) into the pipe 2 to form a fluid-tight seal in a similar manner as described with reference to Figure 7. The same steps are then taken as described with reference to Figures 8 to 10, the drilling rig being removed, the pipe I severed, a plug inserted and driven down the pipe I and a further portion of the pipe 1 cut off leaving a short stub.

When the stage shown in Figure 10 is reached, if the stub of the service pipe 1 is to be left premanently, the stub and plug 13 may then be encapsulated in a suitable encapsulant material 14 by urging a mould containing the encapsulant material against the external surface of the pipe 1 over the stub of the service pipe 1 and the joint between the service pipe 1 and the mains pipe 2, and causing or allowing the encapsulant material to harden. The mould is then removed leaving an encapsulated stub as can be seen in Figure 13.

The stub of the service pipe 1 may be encapsulated instead in the manner shown in Figure 15 which shows a base 29 of a drilling rig secured to the mains pipe 2 over the stub of the service pipe 1. A retainer cap 30 through which extends a screw plunger 31 is secured to the base 29 by means of a bayonet fastening 32. Encapsulant material 33 is placed in the enclosure formed by the base 29 and cap 30 and the plunger 31 depressed it being maintained in its depressed position until the encapsulant material 33 has set. The base 29, cap 30 and plunger 31 are then removed.

In cases where the service pipe 1 is connected to the mains pipe 2 by means of a ferrule or like fitment, the entire fitment and stub are preferably encapsulated as shown in Figure 14.

Instead of leaving the stub of the service pipe 1 permanently in position, it may be desired to remove the stub completely and either insert a plug or a fitment, for exam ple, a so-called "Service T" for the connection of a new service pipe to the mains pipe 2. Thus, instead of encapsulating the stub as shown in Figures 13, 14 and 15, the step may be taken as shown in Figure 16, in which a base 34 of a drilling rig is secured to the mains pipe 2 over the stub by chains 35 so that it covers the stub, the base being provided with a rubber sealing ring 36 to ensure that the base is secured in a gas-tight manner. The base 34 is also provided with a stop gate 37 which can be opened to allow access to the stub or closed to prevent gas escaping from the mains pipe 2 after the stub is removed. To the upper edge of the base 34 is secured, by means of a strap 38, a flexible canvas sleeve 39 of bellows construction, the upper end of the sleeve being provided with an elasticated wrist band 40.

To remove the stub, the operator inserts his arm into the sleeve 39, opens the stop gate 37 and unscrews the stub manually. He then closes the stop gate 37 before removing his arm from the sleeve 39 together with the stub. The wrist band 40 which grips the arm of the operator while he is removing the stub, prevents the escape of gas to the surroundings while the stop gate 37 is open, and only the very small volume of gas within the sleeve can escape when the operator, having closed the gate, removes his arm from the sleeve. To insert a plug or service T, the operator inserts his arm once more into the sleeve 39, opens the stop gate 37 and inserts the plug or service T manually.

After removing his arm from the sleeve 39 he can remove the base 34 from the mains pipe 2. The bellows construction of the sleeve 39 makes it possible for the operator to have freedom of movement within the sleeve and facilitates location of the stub for its removal, and of the opening left by the stub for the insertion of the plug or service T.

WHAT WE CLAIM IS:

1. A method of isolating a branch pipe from a main pipe containing fluid, comprising forming an opening in the branch pipe without allowing the fluid to escape into the surroundings, inserting a sealant material into the branch pipe through the opening so as to form a fluid-tight seal in that pipe, and severing the branch pipe at a position such as to leave the remaining portion of the

branch pipe connected to the mains pipe sealed from the exterior by at least a portion of the sealant material.

2. A method as claimed in claim 1, wherein the sealant material is in the form of a grease, paste or putty.

3. A method as claimed in claim 1, wherein the sealant material is a material obtained by mixing together two or more components prior to insertion, which material cures or sets with time.

4. A method as claimed in claim 1, wherein the sealant material is a material that cures or sets on reaching ambient temperature, the material being maintained in a flowable condition for insertion by the application of heat or a reduction in temperature.

5. A method as claimed in any one of claims 1 to 4, wherein the opening in the branch pipe is formed by enclosing the area of the branch pipe in which the opening is to be made under a cover secured to the branch pipe in a fluid-tight manner and drilling a hole through the wall of the branch pipe under the cover.

6. A method as claimed in claim 5, wherein a drilling tool for drilling the hole extends through valve means provided to give access to the area of the branch pipe beneath the cover, the drilling tool blocking the valve means so as to prevent the escape of fluid, and after forming the hole the drilling tool is withdrawn through the valve means into a tubular member which it blocks so as to prevent the escape of fluid until the valve means is closed.

7. A method as claimed in claim 5 or claim 6, wherein the sealant material means is inserted into the branch pipe through the cover, the cover being provided with valve means to allow the sealant material to be so inserted without allowing fluid to escape, and the cover remaining in position until the fluid-tight seal is formed.

8. A method as claimed in claim 7, when dependent on claim 6, wherein the valve means for the insertion of the sealant material is the valve means provided for the drilling tool, the drilling tool having been withdrawn before the sealant material is inserted.

9. A method as claimed in claim 7 or claim 8, wherein the sealant material is inserted into the branch pipe so that it forms a fluid-tight seal in the branch pipe between the main pipe and the opening, and the cover is removed after the fluid-tight seal is formed and before the branch pipe is severed.

10. A method as claimed in claim 9, wherein after the branch pipe is severed a plug is inserted into the severed end.

11. A method as claimed in claim 10, wherein the plug is rammed down the branch pipe towards the main pipe and a further portion of the branch pipe is cut off leaving the interior of the main pipe still sealed from the surroundings.

12. A method as claimed in any one of claims 1 to 11, wherein the portion of the branch pipe remaining on the main pipe after severing is encapsulated in an encapsulant material.

13. A method as claimed in any one of claims 1 to 11, wherein the portion of the branch pipe remaining on the main pipe after severing is removed by securing a cover to the main pipe over the branch pipe in a fluid-tight manner so as to form a fluidtight enclosure, removing the branch pipe from the main pipe within the enclosure and inserting in its place a plug or fitment.

14. A method as claimed in claim 13, wherein a flexible sleeve is provided, which is secured at one end to the cover and into which the operator inserts his arm, the sleeve being secured to his arm, and the cover is provided with valve means to enable the operator to gain manual access through the sleeve to the remaining portion of the branch pipe for manually removing it and replacing it with a plug or fitment.

15. A method as claimed in claim 14, wherein the sleeve is of bellows construction.

16. A method as claimed in any one of claims 1 to 15, wherein the sealant material is inserted into the branch pipe in such a quantity that the branch pipe can be severed at a position which leaves sufficient material on each side to seal each severed end of the branch pipe.

17. A method substantially as hereinbefore described with reference to the accompaning drawings.

1. A method as claimed in any one of claims 1 to 17, wherein the main pipe is a mains gas pipe and the branch pipe is a service pipe.