GB2182745A

GB2182745A - Improvements relating to methods for sealing joints

Info

Publication number: GB2182745A
Application number: GB08626831A
Authority: GB
Inventors: Bryan Dawson; David William Prowse; John Richard Thorpe
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-11-12
Filing date: 1986-11-10
Publication date: 1987-05-20
Also published as: GB2182745B; GB8626831D0

Abstract

Leaking threads in a pipe joint formed between two pipe fittings 1 and 2 are sealed by injecting a sealant material (preferably of an anerobic type) into the threaded region to fill the gaps in the pipe threads at 8. To achieve this a tapping point 4 is secured about the pipe fitting 1 such as by a strap 5, to secure a gasket 6. A hole 7 is then drilled through the gasket 6 and the pipe fitting 1 down to the pipe threads. A pipe leading from a pump (preferably with a non-return valve) is then attached to the tapping point 4 and the sealant is injected. The tapping point is then sealed off by a plug 9. <IMAGE>

Description

SPECIFICATION Improvements relating to methods for sealing joints This invention is concerned with the sealing of threaded joints. When such a joint is formed, normally a sealing compound is applied to the threads before the two pipe sections are screwed together. However, with time, the sealing material can deteriorate thus enabling a leak to occur through the narrow passages between the threads, especially when the pipe is being used to transmit gases or liquids under high pressure. It is difficult to seal the joint to close off the leak from the outside and if the pipe has to be dismantled so that the sealant material can be re-applied to the threads, the service supplied through the pipe has to be cut off whilst the repair is taking place. This may be impossible or highly undesirable.

It is an object of this invention to provide a means of sealing leaks in pipe threads of a pipe joint which can be carried out effectively without interfering with the service supplied through the pipe.

Accordingly this invention provides a method of sealing leaking pipe threads of a pipe joint without interruption of supply through the pipe, comprising mounting a tapping point on the pipe fitting of the joint, or forming a tapping point in the pipe fitting, drilling a hole through the pipe fitting in alignment with the tapping point to a depth only to the threaded region of the joint, injecting a sealant material through the tapping point and into the threaded passageways formed by the joint and subsequently plugging the drill hole and/or the tapping point.

The provision of a drill hole directly through to the threads of the joint enables a sealant material to be injected under pressure through the tapping point so that the sealant will fill leaky passageways formed in the threaded joint. The pressure of the fluid passing through the pipe assists in causing the sealant material to migrate through the leaky passageways formed through the threaded joint so that adequate sealing is achieved.

It is preferred that the axis of the tapping point and the drill hole should be aligned substantially perpendicularly to the axis of the pipe at the joint, although for certain operations it may be preferable to apply the drill hole at an oblique angle to the axis of the pipe.

The preferred form of sealant is of a fastsetting nature and ideally will be of an anaerobic type. If necessary a cleaning solvent could be injected through the threaded passageways prior to injection of the sealant.

Where the pipe fitting is of too thin a section to allow the tapping point to be formed directly in the wall of the pipe fitting it is preferred that the tapping point should be mounted on the pipe fitting by means of a clamping jig. This clamping jig will ideally incorporate a strap or clamp which is bound around the pipe fitting. Preferably a sealing diaphragm will be clamped between the tapping point and the pipe fitting.

A preferred modification of this method is to provide a tapping point assembly with a non-return valve which will stop the leak both through the drilled hole whilst preparations are being made for an injection and will also stop the sealant material from blowing back out after injection.

The hole drilled through the pipe fitting may with advantage be plugged, after injection of sealant, and removal of the tapping point, with a tapered plug driven into the hole. Ideally plugging of the hole will take place within a few minutes of injection of the sealant. The plug may be copper flashed and will preferably be a flush fit when driven fully home.

Depth setting equipment may be provided to enable the user to ensure that drilling is limited to a depth only down to the threaded region of the joint.

The invention also extends to a tapping point assembly for use in carrying out the method of this invention as hereinbefore defined and comprising a body incorporating a tapped through-passageway and attached to a clamping member for securing about the pipe fitting of the joint to hold the tapping point tightly against the pipe fitting. Preferably the clamping member will also be an adjustable collar or strap.

The invention may be performed in various ways and preferred embodiments thereof will now be described with reference to the accompanying drawings, in which: Figures 1 to 3 illustrate a method of sealing leaking pipe threads in accordance with this invention; Figures 4 and 5 illustrate depth measuring and drilling equipment used in carrying out the method; Figures 6 to 9 show a variety of clamping jigs for holding a tapping point onto a pipe whilst carrying out the method; Figure 10 illustrates parts of a further tapping point assembly of this invention in crosssection; Figures 11 and 12 illustrate an alternative method of sealing leaking pipe threads by tapping directly into a portion of the pipe fitting; Figure 13 is a cross-sectional detail of part of a pipe fitting with a tapping point removed when performing this invention; and Figure 14 illustrates means of plugging the hole drilled in the pipe fitting illustrated in Figure 13.

Referring firstly to Figures 1 to 3, there is shown a pipe joint formed between a pipe fitting 1 and a pipe 2 which are screwed to gether at 3 to form a joint. It is assumed that the sealing material applied to the threads of the joint has failed resulting in leaking of the fluid materials carried through the pipe 2. In order to cure the leak it is proposed that a sealant should be injected into the threaded passageway. As a first step a tapping point 4 is fixed by suitable strapping 5 to the exterior of the pipe fitting 1 so as to trap a sealing gasket 6 between the tapping point 4 and the pipe fitting 1. As shown in Figure 2 a hole 7 is then drilled through the gasket 6 and the pipe fitting 1 just down to the threaded region of the joint with the pipe 2.A pipe leading from a pump is then screwed into the tapping point 4 and a fast-setting anaerobic sealant material is injected so as to fill in gaps between the threads of the pipe fitting 1 and pipe 2 as illustrated at 8 (Figure 3). An anaerobic sealant will set quickly to seal off any leakage paths. The tapping point 4 can then be closed off by a plug 9 or alternatively the tapping point 4 may be removed and the passageway 7 in the pipe fitting 1 will be plugged.

As shown in Figures 4 and 5 drilling and depth measuring equipment will be employed to ensure that the hole 7 is drilled down only to the threaded region 3 of the joint. A depth measuring device 10 will determine the distance from the top of the tapping point 4 to the outer wall of the pipe 2. The depth so measured will then be used to determine the positioning of a setting member 11 (provided with a fixing screw 12) slidably received on a bit 13 of a drill 14. When the setting member 11 reaches the top surface of the tapping point 4 during drilling the tip of the bit 13 should then have broken through to the threaded region 3 of the joint.

Figures 6 to 9 illustrate a number of ways of securing the tapping point 4 to the pipe fitting 2. In the arrangement shown in Figures 6 and 7 the tapping point 4 is integral with collars 15 or 16 which can be held in place either by rotating a screw 17 or fixing the two halves of the collar 16 together by bolts 18. In the arrangement shown in Figure 8 the tapping point 4 forms one link of a chain strap 19 which can be tightened to grip around the pipe fitting 1. This arrangement would be particularly suitable for use with pipework carrying fluids under high pressure and for large size or oddly shaped pipes. The arrangement shown in Figure 9 is somewhat similar to that shown in Figure 7 although the tapping point 4 is received through an opening 20 in a two-part collar 21.The ends 22 of the collar portions incorporate spring-like formations which enable the collar 21 to be gripped tightly about the pipe fitting when bolts 23 are secured.

A further tapping point securing system is illustrated in Figure 10. This incorporates a collar 24 for fixing about a pipe by means of a locking bolt 25. The collar incorporates a tapping point 26 with a gasket 27. After a hole has been drilled into the pipe fitting through the gasket 27 a non-return valve assembly 28 is screwed into the tapping point 29. Thereafter an injection pipe for the sealant can be fitted onto the non-return valve by means of a captive swivel nut 30. The nonreturn valve 28 could be formed from a plastics material and will be cheap enough to be discarded with the clamping collar 24 after the sealant has set in the pipe threads. It will be appreciated that the non-return valve assembly may be employed with the other forms of tapping point illustrated in earlier drawings.

In the arrangement shown in Figure 11 the section of pipe fitting 31 is of sufficient thickness to enable a tapping point 32 to be drilled directly through it with a hole leading down to the threaded region 33. Sealant 34 (Figure 12) can be injected into the threaded region in a manner similar to that described previously and the tapping point will then be closed off by a plug 35.

Figures 13 and 14 illustrate a modified method of sealing a hole created in the pipe 1 using a tapping point. The tapping point has been removed only two minutes or so after injection of the sealant. However, before any significant amount of sealant is lost the drilled hole 7 (or 32) is plugged by a tapered plug 36 which is driven into place as illustrated in Figure 14. The plug 36 is held in place by an interference fit and is also sealed by the sealant 8.

It is recommended that the tapered pins 36 should be made from the same materials as the fittings to prevent future electrolysis if the pipework is buried. Where sparkproof operation is necessary the pins could be copper flashed and driven into position by a bronze hammer. The copper flash would also increase the speed of setting of the anaerobic sealant.

A number of advantages are obtained by closing the drilled hole 7 in this way. Firstly, the tapping point and its mounting clip can be removed within a few minutes so that the fitter does not need to go back many hours later to complete the job once the sealant has set. Furthermore there is then no possibility that someone at a future date could disturb the tapping point and clip without realising that the fitting 1 has been drilled which could then open up a leak path. The tapered plug 36 makes the system safe. Furthermore the joint formed by the fitting 1 and the pipe 2 can be re-used without the fitter needing to know whether the fitting has been drilled and injected. It will be noted from Figure 14 that the tapered pin 36 does not protrude into the threaded area and interfere with the thread, so that the fitting can be unscrewed at a future date if necessary.

The type of sealant employed will be chosen to be one which is suitable for use with the particular fluid passing through the pipework. There are many proprietary types of sealant readily available for various purposes.

It is envisaged that the system could be employed to seal leaking pipe threads of pipe joints for a great variety of services operating at high and low pressures. The great advantage of the method employed is that it enables leaks to be sealed without shutting down a process supplied through the pipe.

Claims

1. A method of sealing leaking pipe threads of a pipe joint without interruption of supply through the pipe, comprising mounting a tapping point on the pipe fitting of the joint, or forming a tapping point in the pipe fitting drilling a hole through the pipe fitting in alignment with the tapping point to a depth only to the threaded region of the joint, injecting a sealant material through the tapping point and into the threaded passageways formed by the joint and subsequently plugging the drill hole and/or the tapping point.

2. A sealing method according to claim 1, wherein the axis of the tapping point and the drill hole is aligned substantially perpendicularly to the axis of the pipe, at the joint.

3. A sealing method according to claim 1 or claim 2, wherein the sealant is of a fast-setting nature.

4. A sealing method according to any one of claims 1 to 3, wherein the sealant is of an anaerobic type.

5. A sealing method according to any one of claims 1 to 4, wherein a cleaning solvent is injected through the threaded passageways prior to injection of the sealant.

6. A sealing method according to any one of claims 1 to 5, wherein the tapping point is mounted on the pipe fitting by means of a clamping jig.

7. A sealing method according to claim 6, wherein the clamping jig incorporates a strap or clamp which is bound around the pipe fitting.

8. A sealing method according to claim 6 or claim 7, wherein a sealing diaphragm is clamped between the tapping point and the pipe fitting.

9. A sealing method according to any one of claims 1 to 8, wherein the tapping point assembly incorporates a non-return valve through which the sealant is injected.

10. A sealing method according to any one of claims 1 to 9, wherein the hole drilled through the pipe fitting is plugged, after injection of the sealant and removal of the tapping point, with a tapered plug driven into the hole.

11. A sealing method according to claim 10, wherein the plugging of the hole takes place within a few minutes of injection of the sealant.

12. A sealing method according to claim 10 or claim 11, wherein the plug is copper flashed.

13. A sealing method according to any one of claims 10 to 12, wherein the plug is driven in so as to be a flush fit when fully home.

14. A sealing method according to any one of claims 1 to 13, wherein depth setting equipment is employed to ensure that drilling is limited to a depth only down to the threaded region of the joint.

15. A sealing method according to claim 1 and substantially as herein described.

16. A tapping point assembly for use in carrying out the method according to any one of claims 1 to 15 and comprising a body incorporating a tapped throughpassageway and attached to a clamping member for securing about the pipe fitting of the joint to hold the tapping point tightly against the pipe fitting.

17. An assembly according to claim 16, wherein the clamping member is an adjustable collar or strap.

18. An assembly according to claim 16 or claim 17 which incorporates a non-return valve.at the inlet of the through-passageway.

19. A tapping point assembly substantially as herein described with reference to the accompanying drawings.