AU2008202558A1

AU2008202558A1 - Method and Apparatus for the In-situ Repair of Conduits

Info

Publication number: AU2008202558A1
Application number: AU2008202558A
Authority: AU
Inventors: David Richard Harrington
Original assignee: Sideliner Enterprises Pty Ltd
Current assignee: Sideliner Enterprises Pty Ltd
Priority date: 2007-06-22
Filing date: 2008-06-11
Publication date: 2009-01-15

Description

1 JUN 2008

ORIGINAL

Australia Patents Act 1990 Complete Specification for the Invention Entitled METHOD AND APPARATUS FOR THE IN-SITU REPAIR OF CONDUITS The invention is described in the following statement: 00 2 l METHOD AND APPARATUS FOR THE IN-SITU REPAIR OF

CONDUITS

This invention relates generally to methods and apparatus for the 00 in-situ repair of conduits, such as sewers, drains, water mains and the like.

In particular, it relates to such methods employing settable resinimpregnated pre-forms which are expanded into place in a zone of a conduit to be repaired using an inflatable form.

It is common for conduits which are buried, pass beneath structures, are incorporated into buildings or are otherwise difficult of access to require repair. Under such circumstances, so-called 'No Dig' or 'Trenchless Technology' techniques are now almost universally employed to repair them in-situ. An extensive and diverse range of methods has been proposed for the in-situ repair of such conduits. Of these, the most common is one in which a pre-form of a suitable absorbent reinforcement material is impregnated with a settable resin, placed upon an expandable form, positioned in a zone of a conduit to be repaired, expanded into intimate contact with the inner wall of the conduit using the inflatable form and maintained in that state until the settable resin has cured. The inflatable form is then removed, leaving the cured pre-form in place bonded to the inner surface of the conduit. Properly performed, the resultant repair is smooth and has minimal effect upon flow efficiency.

In the case where a conduit requires repair of only a discrete zone, an inflatable mandrel may be employed, towed into position with a settable resin-impregnated pre-form fixed to its outer surface. Once 00 3 positioned, the mandrel is inflated using fluid pressure and may be heated

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to accelerate curing of the settable resin. When the settable resin has cured, the mandrel is removed leaving the cured repair bonded to the inner 00 surface of the conduit. An example of this method is that taught by Fisco in US 5,628,345. Where longer lengths require repair, and particularly in r conduits of larger diameter, the weight of a mandrel and settable resin- 00 impregnated preform becomes excessive and it is common for the preform to be made with an impervious surface and, following impregnation with settable resin, to be everted into position using fluid pressure, pressure being maintained to keep the pre-form in intimate contact with the inner surface of the conduit until the settable resin has cured. Heat may be used to accelerate curing of the settable resin. When the settable resin has cured, the ends of the pre-form are cut out to restore flow. An example of this method is that taught by Warren in US 6,827,526 in which the resin-impregnated pre-form is everted by air pressure in a launcher vessel, from which the pre-form is dispensed. This method is normally used in conduits of smaller diameter. Where conduits of larger diameter are to be repaired, fluid pressure in the form of a head of water is employed. An example of this method is that taught by Wood in US 4,064,211. In a variation of the second method, a settable resinimpregnated pre-form is winched into a conduit to be repaired and an impervious tubular form is everted into it using fluid pressure. The everting form acts to expand the pre-form into intimate contact with the inner wall of the conduit, pressure being maintained to keep the pre-form 00 4 in intimate contact with the inner surface of the conduit until the settable ;Z resin has cured. Following curing of the pre-form, the everting form is left in place bonded to the pre-form and the ends of preform and sleeve are cut 00 out to restore flow. An example of this method is that taught by Wood in US 4,786,345. In another variation, a settable resin-impregnated pre-form for repair of a discrete zone of a conduit is fixed to a flexible, impervious 00 sleeve and everted from a launcher vessel to transport the pre-form into the conduit and locate it in the zone to be repaired. Eversion of the sleeve brings the pre-form into intimate contact with the repair zone, pressure being maintained to keep the pre-form in intimate contact with the inner surface of the conduit until the settable resin has cured. Following curing of the pre-form, the sleeve is de-everted and removed from the conduit, leaving the cured pre-form in place bonded to the inner surface of the conduit. An example of this method is that taught by Harrington in US 6,619,886.

While all of the above methods are well known and proven, they do not provide a satisfactory repair method for the very large number of smaller defects which arise in conduits of small diameter in a typical metropolitan sewerage or drainage system. Generally speaking, the methods outlined above are operated with special equipment which may require a high level of skill and judgement in its use. The equipment is often expensive, large and heavy, requiring multiple personnel and support vehicles for its operation.

The object of the present invention is to provide a method and apparatus (a system) for the efficient repair of localised defects in conduits

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of relatively smaller diameter; which has relatively low capital and operating costs; which requires only a relatively low level of skill and 00 judgement for its operation; which is light and compact; and which requires only minimal support in terms of personnel and vehicles.

Importantly, the apparatus of the system must also be sufficiently 00 expansive to accommodate a range of conduit diameters; must be sufficiently flexible to accommodate the sharp directional and crosssectional changes which may occur in conduits of relatively smaller diameter; and must have provisions to ensure that the apparatus may be reliably removed from a conduit upon completion of a repair.

According to the present invention, a localised defect in a conduit is repaired by impregnating a suitably shaped pre-form of a suitable reinforcement material with a suitable settable resin, positioning it on an inflatable mandrel, locating the mandrel in the conduit zone to be repaired, inflating the mandrel to bring the settable resin-impregnated pre-form into intimate contact with the inner surface of the conduit, maintaining inflation of the mandrel until the settable resin has cured, and deflating the mandrel and removing it from the conduit leaving the cured repair in place bonded to the inner wall of the conduit. To accommodate the directional and cross-sectional changes common in a typical metropolitan sewerage or drainage system, the mandrel is made such that, in its deflated state, it is small in diameter in relation to a conduit to be repaired and fully flexible.

The repair pre-form is optionally made in tubular form and slid over the 00 6 ~mandrel or in flat form and wrapped around the mandrel. The repair preform is optionally impregnated with settable resin on or off the mandrel.

The use of a tubular pre-form impregnated on or off the mandrel is 00 generally easier and more convenient than using a pre-form separately impregnated flat and then wrapping it around the mandrel. This is an important point, as the ambient-curing resins normally used with the repair 00 system generally have a short pot life. It is frequently more convenient to impregnate a tubular pre-form on the mandrel as this results in less inadvertent resin transfer and mess. Where on-mandrel impregnation is used, retaining bridles (see following) may be tied prior to impregnation by an operator with clean hands. A release shroud of a material to which the settable resin adheres poorly is positioned between the mandrel and the settable resin-impregnated pre-form. The release shroud is fixed to the leading end of the mandrel (leading in the sense of direction of entry into a conduit to be repaired) and, following curing of the repair, the mandrel is deflated and withdrawn in the reverse direction by a cable attached to its trailing end. This causes the release shroud to evert and peel cleanly away from the repair, ensuring a reliable release. Common industry practice is to secure resin-impregnated pre-forms on inflatable mandrels using frangible ties, elastic bands or the like. It is well known in the industry that pre-forms secured in this way may become displaced and, particularly when traversing bends, may actually be completely detached from mandrels. To more securely retain the settable resin-impregnated pre-form on the mandrel during its positioning in a conduit, retaining bridles of a 00 7 Ssuitable material are attached to the leading end of the mandrel and to the inside surface of the leading edge of the resin-impregnated pre-form. The bridles are attached to the pre-form using a hot-melt glue gun and, during 00 removal of the mandrel from the conduit, peel away from the cured repair.

To assist in positioning the resin-impregnated pre-form on the mandrel, C1 self-adhesive patches of the hooked part of the Velcro® attachment system 00 are fixed to the outer surface of the release shroud at the trailing or at both extremities of the pre-form, the hooks engaging the fibrous material of the pre-form. The inflatable body of the mandrel is optionally made of a suitable elastic material or of a non-elastic material, the inflation of which is limited by a non-elastic sizing sleeve. The end fittings of the mandrel and their methods of fixing to the inflatable body optionally have several configurations. A positioning carriage is optionally used in positioning the mandrel and resin-impregnated pre-form in a conduit to be repaired.

The various aspects of the present invention will be more readily understood by reference to the following description of preferred embodiments given in relation to the accompanying drawings in which: Figure 1 is a longitudinal cross-sectional view of the leading end of said inflatable mandrel showing a first method of fixing said inflatable body to said end fitting; Figure 2 is a longitudinal cross-sectional view of the leading end of said inflatable mandrel showing a second method of fixing said inflatable body to said end fitting; Figure 3 is a side view of the leading end of an inflatable Smandrel of larger diameter with a settable resin-impregnated preform fixed to it; Figure 4 is a transverse cross-sectional view on A-A of the 00 configuration depicted at Figure 3; C 5 Figure 5 is a partially exploded view depicting the use of a CIpositioning carriage to transport into a conduit a larger mandrel 00 with a settable resin-impregnated pre-form fixed to it; With reference to Figure 1, an inflatable mandrel 1 for use in the repair of smaller conduits of a typical diameter in the range 50 to 150 millimetres comprises leading end fitting (leading in the sense of direction of entry into a conduit to be repaired) 2, trailing end fitting (not shown) and inflatable body 3, the ends of which are sealingly bonded to shanks 14 of said end fittings. Said trailing end fitting is identical with said leading end fitting, with the addition of an air hose connection fitting (depicted as 15 in Figure To reduce weight said end fittings are preferably made hollow with the edges of their inner ends made rounded or chamfered to minimise the possibility of chafing or pinching damage to said inflatable body. Release shroud 4 extends axially to cover more than the full length of said inflatable body, in the preferred embodiment, its leading end being fixed to said leading end fitting by several turns of duct tape or other suitable self-adhesive, strip material (depicted as 5 in the Figure). In an alternative embodiment, said leading end of said release shroud is fixed to said leading end fitting by means of a suitable clamping band (depicted as in the Figure). In the preferred embodiment, the trailing (free) end of 00 9 said release shroud is secured in place with suitable frangible tie means,

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said tie means taking the form of a self-adhesive paper tape, such as masking tape, or a ribbon or cord of a suitable weak material. In an 00 alternative embodiment, said trailing end of said release shroud is left free and unattached. In the preferred embodiment, said release shroud is a 0 disposable item having an inflated diameter equal to or slightly less than 00 that of the finished internal diameter of the repair to be effected and a new one is installed on said inflatable mandrel in preparation for each said repair. Said inflatable body is made from a suitable elastic polymer and is able to be safely inflated to 300% of its deflated diameter. Choker ring 6 is positioned immediately adjacent the inner ends of said end fittings and acts to constrict said inflatable body at point 13, thereby preventing its bonded part from peeling away from said end fittings during inflation.

Pre-form 7 is positioned over said release shroud and is supported in position by retaining bridles 8 tied to cable attachment fitting 9 fixed to the nose of said leading end fitting, said retaining bridles being fixed to the inner surface of the leading edge of said pre-form using a hot-melt glue gun at points 10. In the said diameter range, three retaining bridles are normally provided. To provide more positive location of said pre-form on said release shroud, in the preferred embodiment, a plurality of selfadhesive patches of the hooked part of the Velcro® attachment system (not shown) are fixed to the outer surface of said release shroud in the position of the trailing extremity of said pre-form, the hooks acting to engage the inner, fibrous surface of said pre-form and thereby to locate 00 said pre-form on said release shroud. Where the nature of said inner ;Z surface of said pre-form is such that said Velcro® patches attach poorly to it, a smear of a suitable peelable adhesive is applied to said Velcro® to improve adhesion. In an alternative embodiment, said self-adhesive 00 patches of the hooked part of the Velcro® attachment system are fixed to tthe outer surface of said release shroud in the positions of both extremities 00 of said pre-form. In the preferred embodiment, the leading end of said impregnated pre-form is stabilised using suitable frangible tie means, said tie means taking the form of a self-adhesive paper tape, such as masking tape, or a ribbon or cord of a suitable weak material. Said tie means act to prevent said leading edge from being displaced either inwardly or outwardly during transit of a conduit.

Cable attachment fittings 9 are strongly fixed to the noses of both said leading and trailing end fittings and, in operation, have attached to them a cable employed to winch said mandrel and said settable resinimpregnated pre-form into position in a conduit to be repaired and a cable employed to withdraw said mandrel from said conduit following completion of a repair. An internally positioned anti-elongation cable (not shown) is provided in all said mandrels in which said inflatable body is made from an elastomeric material. Said anti-elongation cable optionally takes the form of a chain or multi-strand wire cable fixed to both leading and training end fittings and acts to prevent elastic extension of said mandrel during inflation. In the preferred embodiment (not shown), threaded shanks 11 of said cable attachment fittings are extended to 00 11 Sprotrude into the interior of said end fittings, the ends of said anti- ;Z elongation cable are swaged into threaded terminal fittings (not shown) which are screwed and tightened onto said extended threaded shanks. To 00ensure that said inflatable body is inflated evenly and consistently over all Vt') tt 5 of its parts, said anti-elongation cable is made with slack in the range 100 O to 150 millimetres per metre of length. Without said slack, said inflatable 00 Sbody may experience axial ballooning at its ends during inflation. In the preferred embodiment of said mandrel, said inflatable body is made from a suitable elastic polymer material ranging in thickness from 2.0 millimetres to 8.0 millimetres and of a normal maximum length of three metres. In preferred embodiments for use in conduits in the same diameter range, said inflatable body is made from any of synthetic rubber, butadiene,

GRS,

butyl, E P rubber, Hypalon, Neoprene, Nitrile, polysulfide, fluorocarbon, fluorosilicone, silicone, urethane or polyalkylene oxide polymer.

Mandrels of the present invention incorporating elastomeric inflatable bodies are normally inflated to pressures in the range 100 to 250 kPa. In the preferred embodiment, said release shroud is made in tubular form from a suitable light, thin, flexible sheet polymer material including low, medium or high molecular weight polyethylene or similar cross-linked polymer material in the thickness range 0.15 to 1 millimetre and tolerating an elastic extension of 20 per cent in the approximate temperature range to 40 0 C. Making said release shroud in tubular form ensures its eversion in a controlled and orderly manner during removal of a mandrel following completion of a repair. Where said release shroud is not made 00 12 from a material to which said settable resins adhere only weakly, to aid in its said peeling detachment from said cured repair, the outer surface of said release shroud is optionally treated with a suitable release agent 00 including, talcum, natural waxes, silicone waxes or suitable mineral or non-mineral oils or greases. In the preferred embodiment, said preform is made in the following thickness ranges: 00 CONDUIT DIAMETER (MM) PRE-FORM THICKNESS (MM) 50-100 2 to 3 100 200 2 to 200 300 3 to 6 Said preform is optionally made in single or multiple-layered material. In the preferred embodiment, for repairs in conduits up to 150mm in diameter, said preform is made from a single thickness of knitted pile material ranging in thickness from two to five millimetres and tolerating an elastic extension of up to 20 per cent. In the preferred embodiment, said pre-forms for repairs in conduits in this size range are made in tubular form having the same diameter as a conduit to be repaired, or smaller in the range 10% to 20%, and are impregnated with said settable resin on said release shroud prior to or following its positioning on said inflatable mandrel. The general procedure for impregnation is described in relation to Figure 3. Said retaining bridles are attached to said pre-form prior to its impregnation and then tied to said leading end cable attachment fitting following positioning of said release shroud and pre-form on said mandrel. For repairs in conduits of larger diameter, said pre-form is made 00 13 t~in the thickness range five millimetres to 10 millimetres and optionally includes layers of knitted pile material, woven reinforcement material or needled felt, said layers being fused, bonded or quilted together. Such 00 material is made in flat sheet form, is separately impregnated in its flat t' 5 state and then wrapped around said inflatable mandrel on which said C1release shroud has been previously installed and secured in wrapped form 00 Sby suitable frangible ties, elastic bands or the like. The general procedure for impregnation is described in relation to Figure 3. Said retaining bridles are fixed to the inner surface of the leading edge of said pre-form prior to its impregnation.

With reference to Figure 2, because of the difficulty of replacing in the field an inflatable body which has been bonded to said mandrel, in an alternative embodiment, the ends of said inflatable body are slipped over shanks 14 of said end fittings and secured in place by collar 12 swaged over them. Flanges 16 at the outer ends of swaged collars 12 are captured in grooves 17 and thereby act to retain said swaged collars on said end fittings. Neckings 18 of said swaged collars positioned immediately adjacent the inner ends of said end fittings act to constrict said inflatable body at points 13, thereby minimising any tendency of said inflatable body to pull away from shanks 14 of said end fittings during inflation. In an alternative embodiment, collar 12 is made simply cylindrical without necking 18 and a choker ring (such as that depicted as 6 in Figure 1) is positioned immediately adjacent the inner end of said end fitting to constrict said inflatable body at that point and preventing its being urged 00 14 Sinjuriously against the inner end of said collar during inflation.

With reference to Figures 3 and 4, in an inflatable mandrel intended for repairing conduits in the diameter range 150 to 600 00 millimetres, inflatable body 20 is made from a strong, flexible, non-elastic sheet material considerably larger in diameter than the shanks (not shown) 0 of end fittings 23 and are sealingly attached to said shanks by clamping bands 19. In the preferred embodiment, said end fittings are made hollow, fabricated from a suitable sheet metal material, said shanks preferably being ribbed, grooved or otherwise shaped to promote adhesion and sealing to them of said ends of said inflatable body. Prior to the tightening of clamping bands 19, said inflatable body is provided with one or more circumferentially-arranged folds 25 (edge of one fold depicted as 24 in Figure 3) which permit said inflatable body in its folded form to approximate the diameter of said shanks of said end fittings. In the preferred embodiment, said inflatable body is made from a thin, strong, flexible, impervious material, such as seamless, polyvinylchloride layflat hose. In alternative embodiments, said inflatable body material is fabricated from a suitable sheet material with sewn or fused and taped seams. Said inflatable body can be made with a diameter considerably larger than that of said end fittings and, to limit its inflated diameter to that required for the repair of a conduit of a particular diameter, a non-elastic sizing sleeve 21 is positioned over it. During inflation, the inflated diameter of said inflatable body is limited to that permitted by said sizing sleeve. In the preferred embodiment, said sizing sleeve is made from any 00 strong, flexible, non-elastic fabric, including canvas and calico, and covers

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c, the full length of said inflatable body. Said sizing sleeve is optionally left with its ends unsecured and retained in place by said impregnated pre- 00 form which is provided with positive retaining means on said release t 5 shroud. In the preferred embodiment, the ends of said sizing sleeve are (secured to said end fittings by several turns of duct tape or other self- 00 adhesive tape. Where said ends of said sizing sleeve are so secured, sufficient free length is allowed to prevent said sizing sleeve from inhibiting the axial expansion of said inflatable form during its inflation.

In the preferred embodiment, release shroud 4 in the form described previously is installed over said sizing sleeve in the manner described previously and its leading edge secured in place on leading end fitting 23 by the application of several turns of duct tape or similar self-adhesive, waterproof, strip film material (depicted as 5 in the Figure). In an alternative embodiment, the leading edge of said release shroud is secured in place on said end fitting by means of a suitable clamping band (depicted as 5a in the Figure). In the preferred embodiment, the trailing end of said release shroud is secured in place with suitable frangible tie means, said tie means taking the form of a self-adhesive paper tape, such as masking tape, or a ribbon or cord of a suitable weak material. Said Velcro® patches (typical positions indicated as 22) are fixed to said release shroud following measuring and cutting of pre-form 7 as indicated previously, those positioned at the leading edge of said pre-form being optional. In the preferred embodiment, a tubular said pre-form is slid over and 00 16 Spositioned on said release shroud and impregnated in-situ. Said impregnation process comprises pouring a measured quantity of said settable resin into the annular space between said pre-form and said 00 release shroud and then employing suitable means to knead, squeeze or t' 5 roll said pre-form to ensure an even distribution of resin throughout its thickness. Additional resin is applied as required to the exterior of said 00 pre-form using a suitable brush. A particular advantage of said system is the fact that, in the case of smaller repairs, an even distribution of resin can be achieved throughout the thickness of said pre-form merely by operator hand action. Upon completion of impregnation, said release sleeve and said impregnated pre-form are installed on said inflatable mandrel. In an alternative embodiment, said release shroud and said pre-form are installed on said inflatable mandrel prior to impregnation of said pre-form.

In another alternative embodiment (particularly in the case of larger repairs), a flat said pre-form is impregnated in its flat state (using a roller, if necessary, to achieve an even distribution of said settable resin), wrapped around said release shroud which has previously been installed on said inflatable mandrel and retained in its wrapped form by suitable frangible ties, elastic bands or the like. Two or more retaining bridles 8 are attached to said pre-form prior to its impregnation and tied to cable attachment fitting 9 following positioning of said pre-form on said release shroud. Said patches of Velcro® material engage the fibrous inner surface of said preform as it is positioned on said release shroud. In the preferred embodiment, the leading end of said impregnated pre-form is stabilised 00 17 using suitable frangible tie means, said tie means taking the form of a selfadhesive paper tape, such as masking tape, or a ribbon or cord of a suitable weak material. Said tie means act to prevent said leading edge from being 00 displaced either inwardly or outwardly during transit of a conduit. In an t' 5 alternative embodiment, said leading end of said impregnated pre-form is left unsecured. In an alternative embodiment (not shown) end fittings 23 00 are made in cylindrical form with a plurality of curved, forward or rearwardly-projecting rod members to guide said inflatable mandrel through directional changes in a conduit. Although not essential in said inflatable mandrels incorporating non-elastic inflatable bodies, in the preferred embodiment, an internally positioned anti-elongation cable (not shown) in the form previously described is normally provided in all said inflatable mandrels of larger diameter. Said anti-elongation cable acts to reduce the stress imposed upon the points of attachment of said inflatable body to said shanks of said end fittings during inflation. In said inflatable mandrels incorporating non-elastic inflatable bodies, said inflatable bodies may be made with a diameter of up to 200% of that of said end fittings.

For example, in the preferred embodiment, a said inflatable mandrel for the repair of a conduit having a diameter of 600 millimetres has end fittings of a diameter of 375 millimetres. Typical inflation pressures of said inflatable mandrels of larger diameter vary from 80 kPa at 150 millimetres diameter to 40 kPa at 600 millimetres diameter. In the preferred embodiment, four said retaining bridles are used in said inflatable mandrels in the diameter range 150 to 300 millimetres. At 00 18 Sgreater diameters than 300 millimetres, five or six said retaining bridles ;Z are used.

With reference to Figure 5, where a said inflatable mandrel 23 and 00 settable resin-impregnated pre-form 7 which are longer, of larger diameter 5 and heavier are to be carried for some distance into a conduit, it is often convenient to utilise a positioning carriage 26. Said positioning carriage is 00 provided with wheels 27 of small diameter and is shaped to ride low in a conduit. Said positioning carriage is towed into position by tension applied to cable 30 and withdrawn by tension applied to cable 31. Said inflatable mandrel and impregnated pre-form sits on release apron 34, said release apron being folded double with upper and lower runs joined at fold 36 positioned at the leading end and with transverse bar 35 being fixed across the trailing end of said lower run. Tension applied to cable 32 acts to restrain said lower run of said release apron from displacement from said positioning carriage during displacement of said inflatable mandrel and said impregnated pre-form from said positioning carriage. A suitable lubricant is optionally provided between said upper and lower runs of said release apron to facilitate their independent movement. A suitable weak, peelable adhesive is optionally provided between the lower surface of said release apron and the upper surface of said positioning carriage and acts to secure said release apron in place. Said inflatable mandrel together with said impregnated pre-form is displaced from said positioning carriage by tension applied to cable 28, said upper run of said release apron sliding across said lower run, cables 31 and 32 being secured to maintain the 00 19 positions of said positioning carriage and said lower run of said release apron during said displacement. In an alternative embodiment, cables 31 and 32 are made common. In an alternative embodiment, said positioning 00 carriage is displaced from beneath said inflatable mandrel and said t' 5 impregnated pre-form by tension applied to cables 31 and 32 while cable (28 is secured to maintain the position of said inflatable mandrel and said 00 pre-form. Following displacement of said inflatable mandrel and said impregnated pre-form, said positioning carriage is removed from said conduit by tension applied to cable 31 and said repair effected in the manner described. Said mandrel in inflated by a flow of air or other fluid through line 33.

Following completion of a repair, said mandrel is deflated and withdrawn in the reverse direction from said conduit by tension applied to cable 29 attached to its trailing end. This causes said release shroud to evert and peel cleanly away from said cured repair, ensuring a reliable release.

Said settable resins are formulated to provide a reasonable safe working time and to cure without heating.

In addition to a vehicle and closed-circuit television equipment for surveying, the present invention requires only a winch and compressed air source for its operation. Resin measurement, mixing and impregnation means are simple.

The apparatus described is light and compact and can be operated reliably by one or two personnel with minimal training and minimal 00 support equipment. Said inflatable mandrel is fully flexible and carrying -s said impregnated pre-form, can be substantially smaller in diameter than a conduit to be repaired. It is thus able to readily negotiate the sharp 00 changes in direction and cross-sectional area which may occur in conduits l 5 of relatively smaller diameter. The action of said release shroud ensures C~i that the apparatus may be reliably removed from a conduit upon 00 completion of a repair. The capital and operating costs of the apparatus are low.

Claims

1. Apparatus for the installation of formed-in-situ repairs in pipes and conduits of smaller diameter including: 00 for working in pipes or conduits in the diameter range to 150 millimetres, end fittings which are fixed to and sealingly close the ends of an elastic inflatable body 00 capable of being safely inflated to 300% of its deflated diameter; for working in pipes and conduits in the diameter range 150 to 600 millimetres, end fittings which are fixed to and sealingly close the ends of a non-elastic inflatable body capable of being safely inflated to 200% of the diameter of said end fittings; cable attachment fittings fixed to the ends of said end fittings; an air hose connection fitting fixed to said end fitting which trails during insertion of said apparatus into a pipe or conduit; an air supply hose connecting said hose connection fitting to a source of compressed air; cables connecting said cable attachment fittings to towing means; in apparatus incorporating said elastic inflatable body, an anti-elongation cable the ends of which are strongly 00 22 Elconnected to the interiors of said end fittings; optionally in apparatus incorporating said non-elastic inflatable body, an anti-elongation cable the ends of which 00are strongly connected to the interiors of said end fittings; in apparatus incorporating said non-elastic inflatable body, a non-elastic sizing sleeve which covers the full length of 00 Ssaid non-elastic inflatable body and limits the degree of its inflation; a release shroud fixed to said end fitting which leads during insertion of said apparatus into a pipe or conduit and which extends over the full length of said elastic or non-elastic inflatable body and said non-elastic sizing sleeve where employed; a settable resin-impregnated pre-form of a suitable reinforcement material placed on said release shroud and secured in various ways; a plurality of retaining bridles fixed to the leading end inner surface of said settable resin-impregnated pre-form and tied to said leading end cable attachment fitting; frangible or strippable means temporarily securing the trailing end of said release shroud to said elastic or non- elastic inflatable body and securing the leading and trailing ends of said settable resin-impregnated pre-form to said release shroud. 00 23 Apparatus according to Claim 1 in which said end fittings are made hollow for weight reduction purposes.

3. Apparatus according to Claim 1 in which said release shroud is 00 fixed to said leading end fitting using adhesive tape.

4. Apparatus according to Claim 1 in which said release shroud is cifixed to said leading end fitting using a clamping band. 00 Apparatus according to Claim 1 in which the trailing end of said release shroud is temporarily secured to said inflatable body using frangible tie means.

6. Apparatus according to Claim 5 in which said frangible tie means take the form of a self-adhesive paper tape, such as making tape, or a ribbon or cord of a suitable weak material.

7. Apparatus according to Claim 1 in which said release shroud is made from a light, thin, flexible sheet polymer material in the thickness range 0.15 to 1 millimetre.

8. Apparatus according to Claim 7 in which the material of said release shroud is low, medium or high molecular weight polyethylene or other cross-linked polymer material.

9. Apparatus according to Claim 1 in which said release shroud will tolerate an elastic extension of 20% in the approximate temperature range 5°C to 40 0 C. Apparatus according to Claim 1 in which the trailing end of said release shroud is left free and unsecured.

11. Apparatus according to Claim 1 in which said release shroud is 00 24 la disposable item. c 12. Apparatus according to Claim 1 in which said release shroud has an inflated or expanded diameter equal to or slightly less 00 than the finished internal diameter of a repair to be effected.

13. Apparatus according to Claim 1 in which said release shroud is N treated with a release agent. 00

14. Apparatus according to Claim 13 in which said release agent takes the form of talcum, natural waxes, silicone waxes or suitable mineral or non-mineral oils and greases.

15. Apparatus according to Claim 1 in which said elastic inflatable body is made from a suitable elastic polymer.

16. Apparatus according to Claim 15 in which said elastic polymer is any of synthetic rubber, butadiene, GRS, butyl, E P rubber, Hypalon, Neoprene, Nitrile, polysulfide, fluorocarbon, fluorosilicone, silicone, urethane or polyalkene oxide polymer.

17. Apparatus according to Claim 1 in which said inflatable body is normally inflated to pressures in the range 100 to 250 kPa.

18. Apparatus according to Claim 1 in which said elastic inflatable body is made with a thickness in the range 2 to 8 millimetres.

19. Apparatus according to Claim 1 in which the normal length of said elastic inflatable body is three metres. Apparatus according to Claim 1 in which the ends of said inflatable elastic body are sealingly bonded to the shanks of said end fittings. 00 Lb

21. Apparatus according to Claim 1 in which the ends of said ;Z inflatable elastic body are sealingly fixed to the shanks of said end fittings by swageable collars swaged over them. 00

22. Apparatus according to Claim 21 in which each said swaged collar has a necking adjacent the inner ends of its said shank CI which prevent peeling away of said inflatable body from said 00 shank.

23. Apparatus according to Claim 1 in which said anti-elongation cable takes the form of chain or multi-strand wire cable.

24. Apparatus according to Claim 1 in which said anti-elongation cable is made with slack in the range 100 to 150 millimetres per metre of length. Apparatus according to Claim 1 in which a choker ring is positioned on the ends of said elastic inflatable body immediately adjacent the inner ends of said shanks of said end fittings to prevent peeling away of said inflatable body from said shanks.

26. Apparatus according to Claim 1 in which said retaining bridles are fixed to the leading end inner surface of said settable resin- impregnated pre-form using a hot-melt glue gun.

27. Apparatus according to Claim 1 in which said retaining bridles are attached to said settable resin-impregnated pre-form prior to its impregnation.

28. Apparatus according to Claim 1 in which three said retaining bridles are employed in effecting repairs in pipe and conduits in ;Z the diameter range 50 to 150 millimetres, four said retaining bridles are employed in the diameter range 150 to 300 00 millimetres and five or six said retaining bridles are employed in diameters greater than 300 millimetres. C 29. Apparatus according to Claim 1 in which a plurality of self- 00 adhesive patches of the hooked part of the Velcro® attachment system are fixed to the outer surface of said release shroud to engage and temporarily secure in place the trailing end of said resin-impregnated pre-form. Apparatus according to Claim 29 in which a small amount of peelable adhesive is applied to said Velcro® patches to improve adhesion to the inner surface of said resin-impregnated pre- form.

31. Apparatus according to Claim 1 in which a plurality of self- adhesive patches of the hooked part of the Velcro® attachment system are optionally fixed to the outer surface of said release shroud to also engage and temporarily secure in place the leading end of said resin-impregnated pre-form.

32. Apparatus according to Claim 31 in which a small amount of peelable adhesive is applied to said Velcro® patches to improve adhesion to the inner surface of said resin-impregnated pre- form.

33. Apparatus according to Claim 1 in which said non-elastic 00 27 Sinflatable body is made from a thin, strong, flexible, impervious material.

34. Apparatus according to Claim 33 in which the material of said 00 non-elastic inflatable body is seamless polyvinylchloride layflat hose. Apparatus according to Claim 1 in which said non-elastic 00 inflatable body is fabricated from a suitable sheet material with fused or sewn and taped seams.

36. Apparatus according to Claim 1 in which said non-elastic inflatable body is provided with one or more circumferentially- arranged folds.

37. Apparatus according to Claim 1 in which said non-elastic inflatable body is inflated to pressures ranging from 80 kPa at 150 millimetres diameter to 40 kPa at 600 millimetres diameter.

38. Apparatus according to Claim 1 in which said non-elastic sizing sleeve is made from a strong, flexible, non-elastic fabric.

39. Apparatus according to Claim 38 in which the material of said non-elastic sizing sleeve includes canvas and calico. Apparatus according to Claim 1 in which the ends of said non- elastic sizing sleeve are left unsecured.

41. Apparatus according to Claim 1 in which the ends of said non- elastic sizing sleeve are secured to said end fittings with self- adhesive tape.

42. Apparatus according to Claim 41 in which said non-elastic 00 28 Ssizing sleeve is left with sufficient free length to not inhibit axial expansion of said inflatable form during its inflation.

43. Apparatus according to Claim 1 in which said end fittings of 00 larger diameter are fabricated from sheet metal. 5 44. Apparatus according to Claim 43 in which said end fittings ,Iincorporate a plurality of curved, forwardly or rearwardly- 00 projecting rod members for guiding purposes. Apparatus according to Claim 1 in which said settable resin- impregnated pre-form for use in conduits up to 150 millimetres in diameter is made from a single thickness of knitted pile material ranging in thickness from 2 to 5 millimetres and tolerating an elastic extension of up to

46. Apparatus according to Claim 1 in which said pre-form is made tubular with a diameter equal to that of the pipe or conduit to be repaired or smaller in the range 10 to

47. Apparatus according to Claim 1 in which said pre-form is installed on said release shroud prior to its impregnation said with settable resin.

48. Apparatus according to Claim 1 in which said settable resin- impregnated pre-form for use in conduits in the diameter range 100 to 300 millimetres is optionally made from one or more layers of knitted pile material, woven reinforcement material or needled felt fused, bonded or quilted together.

49. Apparatus according to Claim 48 in which the total thickness of M 00 29 said pre-form material is in the range 2 to 6 millimetres. Apparatus according to Claim 1 in which said settable resin- impregnated pre-form is impregnated flat and then installed on 00 said release shroud and secured with frangible ties, elastic bands or the like.

51. Apparatus according to Claim 1 in which a positioning carriage 00 Sis employed to transport said settable resin-impregnated pre- form on said inflatable form into a pipe or conduit to be repaired.

52. Apparatus according to Claim 51 in which cables are employed to draw said positioning carriage into and from said pipe or conduit and to secure or manipulate said settable resin- impregnated pre-form and said inflatable form.

53. Apparatus according to Claim 51 in which a folded release apron is provided between said resin impregnated pre-form and the upper surface of said carriage.

54. Apparatus according to Claim 53 in which the fold of said release apron is positioned at the leading edge of said carriage and the free end edge of the lower run of said release apron is connecting to a trailing cable. Apparatus according to Claim 53 in which a suitable lubricant is provided between the upper and lower runs of said release apron.

56. Apparatus according to Claim 53 in which a suitable weak, 00 Speelable adhesive is optionally provided between the lower surface of the lower run of aid release apron and the upper surface of said positioning carriage. 00 57. A method for the installation of formed-in-situ repairs in pipes and conduits of smaller diameter including: N for working in pipes or conduits in the diameter range 00 to 150 millimetres, fixing end fittings to sealingly close the ends of an elastic inflatable body capable of being safely inflated to 300% of its deflated diameter; for working in pipes and conduits in the diameter range 150 to 600 millimetres, fixing end fittings to sealingly close the ends of a non-elastic inflatable body capable of being safely inflated to 200% of the diameter of said end fittings; fixing cable attachment fittings to the ends of said end fittings; fixing an air hose connection fitting to said end fitting which trails during insertion of said apparatus into a pipe or conduit to be repaired; connecting a supply hose from a source of compressed air to said hose connection fitting; connecting cables to said cable attachment fittings and leading them out to forwardly and rearwardly-located towing means; 00 31 S(g) in apparatus incorporating said non-elastic inflatable body, installing a non-elastic sizing sleeve which covers the full length of said non-elastic inflatable body and limits the 00 degree of its inflation; fixing a release shroud to said end fitting which leads C during insertion of said apparatus into a pipe or conduit 00 and which extends over the full length of said elastic or non-elastic inflatable body and said non-elastic sizing sleeve where employed; optionally temporarily securing the trailing end of said release shroud to said trailing end fitting with frangible or strippable securing means; fixing pads of the hooked part of theVelcro® attachment fittings to said release shroud in positions in which they will be beneath the leading and trailing ends of said settable resin-impregnated pre-form; fixing a plurality of retaining bridles to the leading end inner surface of said pre-form prior to its impregnation with settable resin; installing said pre-form on said release shroud optionally prior to or following its impregnation with said settable resin; (mn) securing said settable resin-impregnated pre-form to said release shroud with frangible or strippable securing 00 32 means, elastic bands or the like; ;Z tying said retaining bridles to said leading end cable attachment fitting; 00 using said cable attached to the leading said end fitting to draw said inflatable form and said settable resin- impregnated pre-form, followed by said air supply hose 00 and said trailing cable, into position in said pipe or conduit; inflating said inflatable form to bring said settable resin- impregnated pre-form into intimate contact with the inner wall surface of said pipe or conduit; maintaining the inflation of said inflatable form until said settable resin is properly cured; deflating said inflatable form; using said cable attached to the trailing said end fitting to draw said inflatable form out of said pipe or conduit, said release shroud everting and peeling cleanly away from said cured, resin-impregnated pre-form during said withdrawal.

58. A method for the installation of formed-in-situ repairs in pipes and conduits of smaller diameter including: placing a folded release apron on a positioning carriage with its fold positioned at the end which leads during entry into a pipe or conduit to be repaired; 00 33 placing an inflatable form and settable resin-impregnated pre-form on said positioning carriage; connecting cables to the end fittings of said inflatable 00 form, the ends of said positioning carriage and the free end of the lower run of said release apron and leading 00 them out as appropriate to forwardly and rearwardly- 00 positioned winch means; connecting a hose from a source of compressed air to one said end fitting of said inflatable form; using said forwardly directed cables to draw said positioning carriage, said inflatable form and said settable resin-impregnated pre-form into position in said pipe or conduit to be repaired, trailing said rearwardly directed cables and said air hose behind it; using said forwardly-directed or rearwardly directed cables, as appropriate, to displace said positioning carriage from beneath said inflatable form and said settable resin-impregnated pre-form or to displace said inflatable form and said settable resin-impregnated pre- form from said positioning carriage, said release apron everting during said displacement; withdrawing said positioning carriage from said pipe or conduit, together with said release apron and cables attached to both; 00 34 t" inflating said inflatable form to bring said settable resin- impregnated pre-form into intimate contact with the inner wall surface of said pipe or conduit; 00 maintaining the inflation of said inflatable form until (N 5 said settable resin is properly cured; 00 deflating said inflatable form; using said cable attached to the trailing said end fitting to draw said inflatable form out of said pipe or conduit, said release shroud everting and peeling cleanly away from said cured, resin-impregnated pre-form during said withdrawal.