CA1046960A - Method of repairing leaks in pipelines carrying fluent medium and means for use in the method - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method of sealing a leak in a pipe wherein a bandage soaked in synthetic resin is wrapped around the portion of the pipe whereat the leak is located. A vent in the bandage allows escape of the leaking medium whilst the bandage is setting hard and eventually the vent is sealed to complete the repair of the leak. There is also provided a kit f or the effective carrying out of the method.

Description

This inventiorl relal:c~ to an imE)roved rnethod of repairing 1 leaks ln pipe9 carrying fluent mediurn and Ineans for use in the method.

It is well known that when a leak occurs in a pipeline carrying, for example, combustible gaseous medium such as natural or town gas, then a potentially dangerous situation has arisen. Frequentl~, the leak will be su~h as not normally to justify replacement of the pipeline section in which the leak exists, but in actual fact in practice this is what happens, as heretofore efficient leak repairing methods have not been available. The most common location in a pipeline for a leak to occur, is at a joint, and leaks at joints are even more difficult to repair than when the leak occurs in the pipeline between joints.

Furthermore, the problem of repairing the leak in a pipeline is increased when the pipeline carries a fluent ~ medium which is under pressure, and clearly the greater the ;~ pressure, then the greater the difficulty in making an effective repair.

The present invention seeks to overcome this problem, and in accordance with the method,a leak in a pipeline is repaired by wrapping around the pipe a flexible wrapping - or bandage consisting of or including resin absorbent material, said wrapping including a vent means firmly secured thereto providing an easy access route for the medium leaking from the joint, the method further including soaking the absorbent material in curable resin before or after application

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, of the wrappin~, allowing or effecting curing of the resin, 1 and Einally sealiny said vent.

The wrapping preferably comprises a layer of resin ab~orbent material and a stretchable plastics material film to which the vent means is sealingly secured.

Upon initial wrapping of the pipeline, usually at a joint the medium leaks freely through the vent means, 50 that the leaking medium does not tend to force its way past ~he resin soaked layers, and eventually the vent is sealed when the resin has cured sufficiently.

Preferably, the absorbent material is fibrous felt, and it is preferred that the stretchable plastics sheet is of polyurethane of a thickness of the order of 60 thousandths of an inch. The vent means may be a short length of tubing which passes through a hole in the wrapping and is bonded in an air tight manner to the film by means of polyurethane resin, which is also used for soaking the absorbent layers.

Prefera~ly also, the method inc:Ludes applying a second layer of stretchable plastics material over the wrapping after it has been applied to the pipe and before the resin on the absorbent material is cured, the plastics material being selected so as to bond to such resin as it cures.

The invention also provides a wrapping or bandage for use in the method, said wrapping consisting of or including resin absorbent material, and a vent means firmly secured thereto ~3~

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Eor providincJ an easy acce~s route for medium leaking from 1 a pipe joillL arourld which the wrappiny is wrapped.

The wrapping or bandage preferably comprises a layer o~
resin absorbent material and a stretchable plastics material filrn to which the vent means is secured.

Preferably, the wrapping is contained in a package which is compartmentalised, the wrapping being in one compartment and another compartment containing resin in which the absorbent material is to be soaked, said compartments being normally separate but capable of being interconnected so that the resin is Eree to flow into contact with the wrapping.

; The package may include a third compartment containing a hardener for the resin, said compartment being normally separate Erom the other two, but being connectable with the compartment containing the resin, to intermix with the resin and start it curing before bringing the resin into contact with the wrapping.

The package may be a flexiblQ sach~t divided into the compartments by removable clips or the like, being in one example complimentary pairs of strip plastics material.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:-' :
Figure 1 is an elongated section elevation of part of a wrapping according to the embodiment.

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Figure 2 is a pe~specti1~e view of the components of a kit, 1 including a wrapping as shown in Fig. 1 for the repairing of a leak in a pipe joint;

Figure 3 an~i 3A respectively are sectional elevations of the package of the kit shown in Fig. 2; and the detail ringed in Fig.3; and Figs. 4 to 12 illustrate respectively, and in perspective view, the steps involved in applying the wrapping to a leaking pipe joint.

Referring to the drawings, and firstly to Figure 1, a wrapping for use in the invention is shown in section, and will be seen to comprise a layer o~ stretchable plasticis film 10, in this case a polyurethane film of a thickness of approximately 60 thousandths of an inch. On one side of the film 10 is an absorbent layer 12, this absorbent layer in this example being of polypropylene felt. A vent in the form of a short cylindrical bush 16 having a liner 16A passes completely through the laminate as shown, and is bonded to the film 10 and also to the felt layer 12 by means of polyurethane resin indicated by reference numeral 18. The film 10 and felt 12 are held between a spring clip 13 and a collar 15 integral with bush 16 and a felt disc 17 is placed over collar 15 as shown. The polyurethane resin which is also applied at the outer and inner edges of disc 17, serves not only to anchor the sleeve 16 to the laminate, but also effects a gas tight seal at the sleeve 16.
~ ,' Fig.2 shows a kit which is for use in repairing a leak at a pipe joint such as ii5 illustrated generally by the reference numeral x in Fig. 4r The kit comprises a package 20 of which .

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a sectional elevatiorl is illustrated in Fiy. 3 and in detail 1 in Fiy. 3A, and this package contains the wrapping described with reference to Fig. l. The packaye 20 is in fact a sealed sachet or bag of a three layer material comprisiny nylon -surlin - polythene~ Transversely of the length of the bag the sides are clipped together by means of plastic clips 22 so that in fact the bag is divided into three separate compartments 24, 26 and 28. Compartment 24 contains the wrapping of Fig. 1 whilst compartment 26 contains the resin to be applied to the wrapping and compartment 28 contains a hardener for the resin in compartment 26. The resin system it will be appreciated is a two part system, and in actual fact is a polyurethane resin -system. The ckips 22 serva to keep the resin parts separate and out of contact with the bandage in compartment 24 until ; such times as the wrapping is to be used, when the clips 22 are removed and the two parts of the resin system allowed to ; intermix and to soak the wrapping as will be explained hereinafter The surlin of the bag gives the bag a puncture proof property, and the polythene which is the inner layer is inert to the resin catalyst or hardener contained in compartment 28.

For some hardeners, the compartment 28 is lined with a sleeve of metal foil or the like the ends being sealed closed by clips 22, to stop the ingress of moisture to such an extent as to cause contamination of the hardener.

In addition, the kit contains a collar 30 for fitting round pipe joint X as will be explainedF an abrasive cleaning strip ~ 32 for cleaning th0 pipe joint prior to application of the ; 30 _~_ - ~ -.
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wrappincJ, a ~eaLlncJ plu~J 3~ for sea1ing the v~nt means, a wrapping strlp 36 of polyurethane ~ilrn, elastic bandc 3~
has been rlpplied, yJoves ~0 for the operators use, and a knife 42 for slitiny the bag 20 at the approE~riate tirne as will be explainedO

Fig. 3 shows a section through the bag 20 the hardener and resin being indicated at 44 and 46. The compaxtments 24, 26 and 28 are formed by clipping the faces of the bag together by means of the clipping arrangement shown in Fig. 3. This comprises a plastics material strip of U section 48 and an inner strip 50 which fits in the U section, trapping the layers of the bag 20 therebetween and effectively sealing the compartments 28, 26 and 24 one from an other. In order to interconnect the compartments, it is simply a matter of removing the clipping arrangement 22 either by sliding the strips 48 and 50 one relative to another, or by springing off strip 48.

The collar 30 is of the same felt material as the layer 12, and is moulded to rigid form by the soaking of the f01t in polyurethane resin, and moulding the collar to shape, allowing the resin to cure.

The felt material used for the layer 12, and collar 30is a needle felt.

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In order to repair a pipe joint, the joint region is first of all cleaned using the abrasiv~ strip 32 as shown in Fig. 4. It will be noticed in this figure than an excavation ,......

around th~ pip~- jo:int llas been showrl to ena~le acces.C; ~hereto 1 by an operator.

Referrl.ng now to ~;-ig. 5, the collar 30 i8 showrl in position.
It is to be noted that the col]ar is split, the ends are sprung apart to allow it to be positioned as shown, and eventually the ends are held adjacent by means of the elastic bands 38. It is to be noted that the collar is designed to leave a gap 52 into which the vent tube 16 can fit in the subsequent application of the wrapping. The purpose of the collar 30 is to maintain a leakage path to the vent tube 16 and also to provide a more suitable profile for supporting the wrapping.

Fig. 6 illustrates the next stage of the method. The operator removes the clip 22 of the package 20 separating compartments 28 and 26 to allow the two parts of the polyurethane resin system to mix, and indeed he promotes the mixing by raising and lowering the respective ends of the now enlarged compar~ment 26 and 28 as illustrated in Fig. 6. ~his mixing process is continued approximately for 1 minute.

After the completion of the mixing of the two parts of the resin system, the other clip 22 is removed and the mixed resin is allowed to pass into contact with and to soak the wrapping in the compartment 24. The operator at t~is stage kneads the resin mix into intimate contact with as much of the wrapping as he can. In any case, the needle felt is extremely absorbent and will soak up the resin mix effectively .

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wetting out all ot the wrappiny.

Upon compLetic)rl of this step, the operator now uses knif~
42 to slit open the bag 20 as illustrated inFig. 7, whilst -the bay lies horizontally on the ground. This exposes the wr~pping as shown in Fig. 7 and he unfolds the wrapping at one end and folds it into concertina fashion at the other end so that he can grip the folded end as shown in Fig. 8.
He then holds up the wrapping in suspended manner as shown in FigO 9 with the vent tube 16 nearer the top and short edge of the wrapping which as will be appreciated is of rectangular form.

The operator now applies the soaked wrapping to the pipe joint with the collar 30 already attached as shown in Fig. 5, p~sitioning the vent tube 16 in the gap 52. The collar 30 is located so that one of the shorter ends, the end which the operator is shown holding in Fig. 10, will lie on top of the pipeline. ~his end he opens out so that the film 10 is exposed, the layer 12 being folded back. The other end he now places in overlapping relationship with the film 10 thereby to complete the wrapping of the joint, and finally the folded over end of layer 12 is placed into overlapping relationship with said other end to complete the ( wrapping.

1' ~he wrapping strip 36 is now applied over the wrapping as shown in Fig~ 12. In applying the wrapping strip, the operator can take this over the vent tube 16 provided he continues to puncture the wrapping strip at the vent tube to permit ; 30 the continued escape o the fluent gaseous medium being ~ _9_ :, : ., . : : :
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carri~d by the pipeline, avoidiny the build up o~ internal 1 pressure on the joint. ~he wrapping strip i5 applied initially to the smaller dialneter of th~ pipe joint.

When the resin has cured sufficiently, the liner 16A is removed from the tube 16 to expose the clean inner surface of the tube 16 and this is eventually plugged using the plug 34 in order to complete the repair. The plug 34 maybe cemented and/or hammered or ~orced in to the position.
It is to be noted that the wrapping strip is applied to the wrapping whilst the resin is still tacky, and being of a polyurethane film, will firmly anchor and bond to the wrapping in the final joint repair.

By emboclying a polyurethane film in the wrapping there is providecl the advantage that the leaking gas will not tend to permiate through the wrapping as a hole, but will flow towards the outlet tube 16.
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The outlet tube 16 and its liner and in addition the plug 34 will preferably be of plastics material, and certainly ; the tube 16 should be such as to bond firmly and in an air tight manner to the film lO and preferably also to the felt 12.

Although it will normally be desirable first of all to clean the outside of the pipeline where this is rouyh and uneven, or pitted or the likeO in other cases initial preparation of the pipeline surface may not be necessary.
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The method i~ cheap and efficient, and can be carried out 1 very quickly by unskilled lahour~ The results are extremely ~ncouraging, and it i~ to be noted that other resins, felt and plastics film materiaL can be u~ed without departing from the scope of the invention.

Although the embodiment of the invention described has illustrated the repair of a leak in a pipeline at a pipe joint, it is to be understood that the method can be applied at other locations in the pipeline other than at joints.

; Instead of using polyurethane felt it may be of advantage to use polypropylene felt and it has been found that the plastics film 10 can be made 40 to 60 microns thickness.
Furthermore, instead of snapping plug 34 into position, it may be screwed into position closing tube 16. The kit ; may be provided with a primer to be applied to the cleaned pipe surface prior to the application thereto of the bandage in order to improve the bonding of the wrapping to the pipe. The collar 30 is an alternative arrangement , may be of cardboard material.

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Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of repairing a leak in a pipeline carrying fluent medium under pressure comprising wrapping around the pipeline in the region of the leak a flexible bandage of resin absorbent material provided with an integral vent means, the method further including soaking the absorbent material in curable resin so that the resin seals the leak to the extent that the leaking fluent medium escapes through the vent means, allowing or effecting curing of the resin, and finally sealing said vent means.

2. A method according to claim 1 wherein the bandage comprises a layer of resin absorbent material and a layer of a stretchable plastics material film to which the vent means is sealingly secured, the method including wrapping the bandage round the pipeline so that the ends overlap and one end is placed between the layers of the other end in applying the bandage to the pipeline.

3. A method according to claim 2, wherein the method is used for curing a leak at a pipe joint and prior to the application of the bandage a support collar is placed round the joint to support the bandage, said collar being split so as to leave a gap between the ends thereof into which the vent means is located.

4. A method according to claim 1, wherein the resin is applied to the bandage by connecting a first compartment of a sealed, flexible envelope containing a quantity of the resin with another compartment of the sealed, flexible envelope containing the bandage, and by manipulating the envelope manually and thoroughly effectively to impregnate the bandage

Claim 4 continued:
with the resin, prior to opening the envelope and application of the bandage to the pipeline.

5. A method according to claim 4, wherein a hardener is applied to the resin by connecting a third compartment in the envelope containing the predetermined quantity of the hardener with the first compartment prior to connecting the first compartment to the second compartment.

6. A flexible bandage for use in the method according to claim 1, said bandage comprising resin absorbent material, an integral vent means for providing an escape route for fluent medium escaping from a leak in a pipeline at a region thereof around which the bandage is to be wrapped.

7. A bandage according to claim 6 comprising a layer of said resin absorbent material and a layer of stretchable plastics material film to which the vent means is sealingly secured.

8. A bandage according to claim 7, wherein the film is of polyurethane and is bonded in an air-tight manner to the vent means by polyurethane resin, said vent means comprising a short tube passing through the bandage.

9. A bandage according to claim 8, wherein the short tube has a fitted liner which lines the interior surface of the tube to prevent such interior surface from becoming contaminated with resin, and which is removable from the tube prior to the sealing of same.