WO1993014335A1

WO1993014335A1 - Inflatable duct seal as environmental sealing

Info

Publication number: WO1993014335A1
Application number: PCT/GB1993/000060
Authority: WO
Inventors: Alain Wambeke; Marc Demesmaeker; Dirk Roosen; Jean-Pierre Wandels
Original assignee: N.V. Raychem S.A.; Raychem Limited
Priority date: 1992-01-17
Filing date: 1993-01-13
Publication date: 1993-07-22
Also published as: CN1083571A; GB9201069D0; AU3357993A

Abstract

A puller having means for gripping a flexible fluid line and means for constricting the line thereby reducing its ability to pass fluid suitable for use in connection with a duct seal or cable splice case, including a flexible hollow member that can be inflated through the fluid line to seal a gap between first and second articles.

Description

I NFLATABLE DUCT SEAL AS ENV I RONMENTAL SEALI NG

The present invention relates to a device for use with a sealing member for environmental sealing of substrates such as cables or pipes, particularly within a duct, or a splice case. This may be done to prevent water, gas or other contaminant from passing along a duct into a manhole etc, or to protect a cable splice from the environment. The invention will be described primarily in terms of an inflatable duct seal, (which term includes "feedthroughs") but the invention is also applicable to other instances of sealing, including splice cases, pipe protection and grommets etc. The device itself comprises a puller that can be used to remove a fluid line, without excessive loss of fluid, from an inflatable seal after it has been inflated through the line.

The reason that a seal (rather than an adhesive bond of no significant thickness) may be required is a disparity in size or shape between the substrate to be sealed and some other object such as a housing within which it lies. For example, a duct may be from several millimetres to several centimetres larger than the cable or other substrate that it carries, an oval cable may lie within a circular duct, or the installed size of a splice case housing may be larger than the spliced cables within it. Also, when a branch-out between two or more cables is to be sealed it will generally be necessary to convert their combined concave cross-section to a convex shape that can be enclosed by, say, a rigid wrap-around or other casing or by half- shells or a dimensionally-recoverable (generally heat-shrinkable) sleeve.

Such seals have usually been formed by the use of a conformable sealing member, for example an O-ring, or the use of a mass of sealant or a hot-melt adhesive. Whilst these seals in general work in a satisfactory manner, problems sometimes occur. For example, by their nature, conformable sealing members have a low modulus and especially where they are used to fill large voids, may have a tendency to creep over extended periods of time. Also, leak paths may occur if it has not been possible to introduce sufficient heat into a hot-melt adhesive to melt it. It is for example difficult to introduce heat into a duct.

Difficulties may also arise due to the materials needed for ducts and cables, which may be incompatible. Cables are often made of polyethylene or lead, and ducts of polyvinyl chloride, steel or cement which may be dirty or crumbly and difficult to clean.

EP 0152696 (Raychem) discloses an assembly for sealing an aperture (such as that between a duct and a cable it carries) which comprises a flexible envelope that is arranged to be wrapped on itself for insertion into the aperture, the envelope having an opening therein for receiving an expansible or expanding filler material, for example a curable foam, for expanding the envelope, a container containing said expansible filler material, and means arranged to connect the container to the envelope to conduct the filler thereto for effecting expansion of the envelope, characterized in that an adhesive or sealant is located on or associated with at least part of the outer surface of the envelope. The disclosure of EP 0152696 is incorporated herein by reference.

Other patent specifications disclosing hollow envelopes for sealing include the following. EP 0100228 (Raychem) discloses a method forming a seal between at least one elongate object and a surface surrounding the or each object, which comprises:

(a) positioning between the object and the surface a flexible envelope containing a void-filling composition which is capable of undergoing a change from a state of lower viscosity to a state of higher viscosity;

(b) deforming at least part of the envelope thereby causing the void-filling composition to conform to the object and to the surface; and

(c) causing said change from lower to higher viscosity.

EP 0210807 (Raychem) discloses a double-walled article, two of which may be used one around the other to form a duct seal, in the form of a tube having a small volume filling of a friction reducing liquid (preferable of high boiling point and low vapour pressure) or solid between its two walls. The article is able to revolve over a substrate by shear between its two walls to provide environmental or electrical protection.

GB 2006890 (Kraftwerk Union) discloses a seal comprising a container formed from resilient plastics sheet and partially filled with a liquid which is provided between a protective tube in a wall and insulation layer around a pipe. The container is of substantially toroidal shape and permits the pipe to move axially and radially whilst maintaining a seal between the insulation layer and the tube.

US 3038732 (Scott and Bond) discloses an inflatable seal bushing for sealing a pipeline casing, which comprises a hollow resilient means having an inflated configuration to match the inside surface of said casing and to contact the outside surface of the pipe of said pipeline, means for introducing a fluid into said hollow resilient means to inflate same, and a plurality of angularly disposed, relatively solid spacer means integral with said hollow resilient means and transverse thereto for centring and supporting said pipe within said casing, each of said spacer means having a passage therethrough for providing liquid communication in the hollow interior of said hollow resilient means.

US 2816575 (Stokes) discloses an apparatus for laying a pipe employing inflated annular sealing rings.

US 3339011 (Ewers Jr. et al) discloses a pneumatically-sealed cable splice case comprising a longitudinally-split sealable cylindrical casing having means within and adjacent to each of its longitudinal ends to retain and space apart a pair of end wall panels each end wall panel including two semi-circular disc portions having rounded outer edges and inner edges including aligned cut-outs therealong. whereby cables may enter said casing through said aligned cutouts, and inflatable seal means confined between each of said pair of panels of said end walls and having openings aligned with said panel openings, said inflatable means being expandable, when so confined, against such cables passed through said end wall openings, characterized in that said end walls are removable from the said means to retain them, and said semi-circular disc portions are pivotally pinned to each other with their cut-outs presented together to form said openings of said panels whereby said semi-circular disc portions may be pivotally opened apart for placement about said conduits.

An inflatable packing device for insertion between mating surfaces of the hub and spigot ends of a pipe joint is disclosed in GB 1077314 (Woodward Iron Company). A hollow-walled sleeve into which fluid is to be injected for heat-insulation of ducts is disclosed in GB 1421960 (Commissariat a l'Energie Atomique).

An inflatable closure member having a sealing material thereof, and used for sealing cables is disclosed in GB 2028601 (Raychem).

US 907136 discloses a packing for pipe joints formed by folding an open mesh fabric and applying a flue etc.

Although various articles have been proposed as inflatable seals, the problem of how to remove any pressure line has not been properly addressed.

We have now devised a device that can if desired combine removal of a pressurization line and closure of that line to reduce loss of pressurizing medium.

Thus, the present invention provides a puller having means for gripping a flexible fluid line and means for constricting the line, preferably by deforming it such as by crushing or pinching, thereby reducing, and preferably eliminating, its ability to pass fluid.

The fluid line may be fixed to the puller or they may be supplied separately and, if desired, be merely loosely associated when in use. It may also, or alternatively, be part of a pressure line or pump or other pressurizing device. The puller, optionally together with the line, may be disposable.

A special puller of this type is useful at least for the following reasons. A fluid line will normally need to be sealed to an inflatable seal if pressurization fluid is not to be lost during inflation, and if the line is not to be blown out of the seal once some pressure has been established. In the past this has been achieved by some complex or expensive attachment device, such as a screw thread or bayonet fixing, which requires for removal some initial rotation or other movement that cannot be caused by the internal pressure. We have found that inflatable sealing members for duct seals and splice cases etc. benefit from simple valves that are of low profile, and preferably substantially flush with the surface of the seal. This usually excludes spring-loaded and ball valves and similar mechanical devices. Indeed, we prefer a simple hole through a wall or between walls of the sealing member that can be sealed by an internal flap, which flap optionally carries a sealing material such as a gel and/or mastic and/or elastomer foam. In the absence of any special mechanical arrangement for retaining a fluid line in the hole, it must be retained by friction between the wall and flap etc or be retained by adhesion to the gel and/or mastic etc. A problem then arises in removing the line when inflation is complete. This problem is exacerbated if the line has a low coefficient of friction, as is preferred if excessive displacement of sealing material is to be avoided when the line is withdrawn. Preferred materials for the line include nylons, and polytetrafluoroethylene which has a very low coefficient of friction. Thus, we found that a puller is desirable to allow it to be withdrawn, generally by hand, from the hole. Furthermore, we found that fluid flow within the line is preferably cut off when the pulling is carried out.

The puller preferably has means for constricting that operates automatically on applying tension to the line. It may have means for holding the line in a configuration (such as one comprising a helix or part thereof) such that on applying tension to the line a first portion thereof (the helix) crosses and applies pressure to a second portion of the line (a further part that doubles back and runs axially through the helix) thereby deforming the second part and causing the constriction.

In this case, we prefer that the puller has a body through which the fluid line can pass such that the second portion of the line is positioned between ends of the body and is in communication (optionally through a wall of a flexible tube within which it lies) with an outer surface of the body; and has means than can locate the first portion of the line around the outer surface and in communication with the second part. Where a helical configuration is used (as mentioned above) the line can pass through the centre of a generally cylindrical body and then be folded back to be wrapped helically around the outside of the body. Part of the helical path can lie in a groove in the body that communicates with the line within the body. Tension in the line on the helical wrap can then crush the line within the body. The non-linear configuration of the line ensures it does not slip through the body. As a result tension can be applied to the line via the body. The exact configuration of the line is not critical. We use the term "helical" loosely and do not wish to be limited to a precise geometrical meaning.

Other mechanical arrangements can be provided by means of which the puller can grip and constrict the line. For example, the puller may have one or more cams, ratchets or other moving parts which may be contained in or comprise at least part of a housing such that on movement of the line through the puller, a moving part is rotated or otherwise moved by the line relative to the puller thereby wedging the line between the moving parts or between a moving part and a housing thereby causing the constriction.

The puller may have means for attachment to a pressure line and/or pump or other pressurization device. Such means for attachment may comprise a screw thread and/or bayonet fixing. Also, or alternatively, the puller may have a pressure regulator.

The invention also provides a kit which comprises

(a) a puller of the invention, and

(b) a flexible hollow sealing member that can be inflated through the fluid line to seal a gap between the first and second articles, such as a cable and a duct or a cable and an outer part of a splice case.

Preferably the sealing member has: a hole through which the fluid line can be inserted to introduce fluid into the member, and

means by which the hole is sealed on withdrawal of the fluid line.

We prefer that the sealing member has means by which the hole is automatically sealed on withdrawal of the fluid line, particularly an internal flap coated with a gel and/or mastic as mentioned above.

A surprising result with sealing members of this type is that we have been able to retain significant pressure for extremely long periods. Testing has indicated that periods of at least 5 years and longer can be achieved without the need for unsuitable prior art valves.

The product may be supplied with the fluid line, which may be referred to as a probe, inserted through the hole. Furthermore, insertion of the probe may be part of the manufacturing process of the sealing member. Such hollow sealing members were subjected to sever mechanical, temperature and pressure testing, and successful results were obtained. In particular, the sealing members were inflated to 50 KPa and tested for leaks for fifteen minutes to measure overall strength, and for 2.8 bar for long-term testing. Helium was used for inflation, and a sophisticated helium gas detector was used to monitor any leaks. We were able to produce an automatically sealing system where passage of helium through the hole used for pressurization was no greater than the background level resulting from mere diffusion through the walls away from the hole. Suitable wall materials (discussed below) can be chosen such that no helium is detectable. The precise nature of the materials and the design of the sealing member can be chosen depending on intended use; the surprising result, however, is that a hole directly through a wall of the member, or between the walls of a lap join etc can automatically seal without the need for expensive valves and all the disadvantages they bring. It is believed that inflatable articles have never previously been used for environmental sealing (particularly in the cable accessories art) where life-times of many years are required without the need for periodic reinflation.

Whilst the exact design of my sealing system will be chosen according to the intended use of the product, we prefer designs incorporating one or both of the following features.

Firstly, an internal flap may be provided across the hole in or between the walls of the member. The flap may seal in response to pressure within the member. The flap preferably comprises a flexible polymeric sheet fixed to a wall of the member such that the probe can pass through the hole and displace the flap, the probe preferably passing between the flap and the wall substantially in the plane of the wall (say at less than 45° to that plane). A sealing material, for example a gel or a mastic, may be provided between the flap and the wall, for example as a coating on the flap. The flap may be bonded or welded to the wall along two lines separated by a small gap (say 5-20 mm), such that the probe can be inserted through the hole in the wall and between the wall and the flap generally along the axis of the channel formed between the two bond or weld lines.

The second design is particularly appropriate where the hole is between overlapping walls of a lap join. (The lap join may arise in formation of the member by forming a tube from a sheet of material.) The hole, which extends the width of the lap join, may decrease in cross-sectional size toward the outside of the sealing member. The hole may therefore have a funnel, or flattened-funnel, shape. A sealing material (preferably a mastic or a gel) may be provided within this funnel-or-other-shaped hole, such that the sealing material is driven by internal pressure to block the hole. The size of the hole and the physical properties and amount of the sealing material may be chosen such that the material does not creep out of the hole to an unacceptable extent. A flap as mentioned above may be used in conjunction with this type of hole.

The sealing material may comprise for example a mastic or a gel. Mastics may be preferred due to their good adhesion to the wall of the sealing member. A seal can therefore remain even on loss of some or all of the internal pressure that forces the flap against the wall. Mastics however have high, generally 100%, compression set and where that is likely to be a problem the mastic may be replaced or supplemented by a gel. For example if the probe is likely to leave a channel in the mastic on withdrawal, a gel could be provided as a supplementary layer between the mastic and the wall, preferably of smaller surface area than (and therefore totally surrounded by) the mastic. A gel may be formed by oil-extension of a polymeric material. The polymeric material may be cross-linked. I prefer that the gel has a hardness at room temperature as determined using a Stevens-Volland Texture Analyser of greater than 45g, particularly greater than 50g especially greater than 60g. It preferably has a stress-relaxation less than 12%, particularly less than 10% and especially less than 8%. Ultimate elongation, also at room temperature, is preferably greater than 60%, especially greater than 1000%, particularly greater than 1400%, as determined according to ASTM D638. Tensile modulus at 100% strain is preferably at least 1.8, more preferably at least 2.2 MPa. In general compression set will be less than 35%, especially less than 25%. Preferred gels are made by extending with an oil block copolymers having hard blocks and rubbery blocks. Examples include triblock copolymers of the styrene-ethylene-butylene-styrene type (such as those known by the Shell Trade Mark Kraton, eg G1650, 1651 and 1652). The amount of block copolymer may be, say from 5 - 35% of the total weight of the gel, preferred amounts being 6 - 15%, especially 8 - 12%. The amount of copolymer, and its molecular weight may be varied to give the desired physical properties such as hardness.

The designs described above will find particular use for environmental protection of supply lines such as pipes and cables particularly telecommunications cables. In particular, they may be used for the formation of duct seals or splice cases. In the case of duct seals, the first article as referred to above will comprise a cable carried by a duct, and the second article will comprise the duct. The duct seal will seal the annular space between the cable and the duct, and serve to prevent contaminants, in particular water, passing along the duct, for example into a manhole or building or other region to be kept dry or clean. Pressure may build up in the duct, and it is therefore desirable that means be provided for restricting movement of the duct seal along the duct in response to a pressure difference across it. To this end, the flexible hollow sealing member preferably can be inflated to seal a gap between first and second articles (for example the cable and duct respectively), and has:

a first surface that will contact the first article, and a second surface that will contact the second article, an average coefficient of friction of the first surface being less than that of the second surface such that the sealing member will not move with respect to the second article under a pressure difference across the member of 35 KPa, and preferably also 70 KPa, whilst allowing movement of the first article relative to the sealing member.

In this way, we allow for movement of the cable (etc) relative to the duct, whilst maintaining the desired seal.

Coefficients of friction can be chosen by varying coatings and supplementary layers on the outer surfaces of the flexible member. For example, we prefer to provide a sealing material, such as a gel or a mastic, or a rubber or other elastomeric foam, on an external surface of the sealing member. Such a sealing material can seal voids between the sealing member and the duct, for example within creases formed in the sealing member when it is wrapped around a cable.

If a mastic is used, a release layer may be desirable in order that the duct seal be easily handled, in particular so that it can be readily inserted into the duct. A thin, flexible polymeric film may be provided on an outwardly-facing surface, for example over a mastic layer. Such a film can allow the mastic to deform to fill voids thereby eliminating leak paths, it can reduce tack facilitating installation, and can have a very high coefficient of friction, particularly to plastics materials such as polyvinyl chloride and polyethylene, typical materials from which cables and ducts are made. Preferred films comprise linear low density polyethylene, such as that known as "cling film". The surface of the sealing member that will face the duct may be covered with such a film to a greater extent (and optionally completely) providing greater friction to the duct than to the cable. The film may have apertures in it, allowing some direct contact between sealing material and first or second surfaces. The film may be provided between two layers of mastic or other sealing material to provide the combined laminate with strength. In that case, apertures in the film allow the two layers to bond to one another directly.

In use, there may be a tendency for a sealing material on the sealing member to be displaced, for example by pressure within a duct. Displacement can be restricted by means such as a strip of foam on a surface of the sealing member that can act, for example, as a dam.

The invention also may be used with a kit of parts for environmentally-sealing a first article such as a cable, which comprises: a second article comprising a substantially rigid housing within which at least part of the first article can be placed, and a sealing member of the invention.

The housing may be blind at one end, one or more sealing members being used to seal a cable entry and exit at the open end. In this way a cable splice may be produced, to seal what is known as a radial distribution point in a telecommunications distribution network. Such design may also be useful for sealing a splice between optical fibre cables. In this case, the housing may contain one or more optical fibre splice organizers. In another design the housing has at least two open ends, allowing production of an in-line (rather than butt) splice case, for copper or fibre cables. Such a housing may be of tubular or wrap¬ around design. Where branching cables are to be sealed, the sealing member may be positioned between branching cables, and between those cables and the housing, or other second article. In general, the member will pass between the branching cables and be wrapped around the branching cables together.

Inflation may be carried out by attaching a probe to a source of pressurizing fluid and (if it is not supplied in place) inserting the probe through the hole in the wall or between walls of the sealing member. The pressurizing fluid is preferably compressible, air or nitrogen or other inert gas being preferred. If a liquid, such as water, is used it will generally be necessary for the sealing member to be stretchable in order that a reserve of pressure be provided to compensate for movement of the first and second surfaces. If the sealing member is stretchable is is likely to be subject to creep or set. I prefer that it have minimal stretch and that a gas be used for inflation.

The probe, when inserted, will provide a path past the internal sealing flap or sealing material allowing the fluid to inflate the sealing member. The sealing member, being flexible, will deform into sealing engagement with the first and second articles, for example by filling an annulus between a cable and a duct within which it lies. A seal can be made inspite of lack of concentricity between duct and cable, and inspite of oval or other awkward cross- sectional shapes of the cable and/or duct. When the desired internal pressure is reached, the probe may be simply withdrawn, allowing the internal pressure automatically to close the hole. Astonishingly, high internal pressures can be achieved and a seal that will last for many years can be made in this way. The probe is preferably held in position prior to and/or during inflation merely by friction and/or by weak adhesion, allowing it easily to be pulled free. There is preferably no mechanical interlocking. The probe is preferably therefore substantially cylindrical at least at the end that enters the sealing member. The probe may comprise metal or a plastics material and may have a low coefficient of friction with the flap, the wall and/or any sealing material between them in order to facilitate removal.

It is desirable that inflation be not too rapid since the sealing member itself, and any sealing material it carries must deform properly into sealing engagement with cable and duct. A hand pump (such as a bicycle pump), an electric pump, a pressurized gas cylinder or other suitable pressurizing means may be used. More powerful pumps may desirably be used with a pressure reducer.

The sealing material or the flap or other means may be delivered on site (or otherwise) by means of a probe, and in particular by means of the probe used for pressurization. Such a probe may have at its end a flap, in a collapsed configuration for example rather like a closed umbrella. In this form it can be inserted through the hole in the sealing member, and on withdrawal of the probe the flap unfolds (for example in the way of opening an umbrella) and becomes deposited on an inner surface of the wall of the member.

In one embodiment, a probe carries a plug at its end which can be forced through the hole in the wall and which is retained within the sealing member on withdrawal of the probe, optionally in the manner described above. The probe has a hole in its wall for supply of air etc, that hole being some short distance away from the end carrying the plug. When the probe is inserted fully into the sealing member, the hole in the probe delivers air into the sealing member. When sufficient pressure is achieved, the probe is withdrawn causing the pressurizing air to escape to ambient, the hole now lying outside the sealing member. Further withdrawal removes the probe completely, leaving the plug behind to seal the hole in the wall.

The sealing member may comprise an envelope wrapped or otherwise positioned around a cable within a duct (for example by sliding it into the duct) and then inflated with any suitable medium, such as air or other gas. The envelope deforms to fill the space between the duct and the cable. Deformation is preferably without significant stretching, say less than 6%, particularly less than 4% in length, and less than 12%, particularly less than 9% in width. Any stretching preferably occurs within a few days of installation, with no subsequent creep. The envelope will generally comprise a single thickness on one side, and two or more thickness on the opposite side (for example at a lap join). The single thickness, which will be the more flexible may usefully face the cable since it will be forced to conform to a smaller diameter and it will buckle or otherwise adapt more easily. The opposite side may face the duct.

The deformation of the envelope may result from the vapour pressure exerted by a high vapour pressure liquid therein. The use of such a liquid, and sealing articles containing such a liquid is inventive in itself, irrespective of the envelope design. Life-time may be even greater when employing such a liquid since loss of its vapour will not result in a pressure reduction so long as there is some liquid left.

In general, the duct seal of the invention may be considered in terms of a pressurizing fluid acting on a moveable wall, either directly or indirectly, the wall preferably being substantially not- stretchable under installation and service conditions. Installation of the duct seal need not, and in general will not, involve heating. This might be advantageous not merely because an awkward method step is avoided, but also because subsequent shrink-back on cooling is avoided. The fact that solidification of a sealing material may be, and generally will be, avoided means that the seal might be more tolerant of movement during service life, and also might mean that shelf-life before use is not a problem. Thus, various problems encountered with prior art duct seals are avoided.

We prefer that the fluid be in contact with the wall of the sealing member, although it need not be and movement of the wall may be brought about by mechanical means interconnecting the wall and some other object directly against which the fluid pressure acts.

The moveable wall preferably forms at least part of a flexible hollow article which preferably contains the fluid. It is possible, however, for the fluid to be located in a reservoir remote from the wall and the substrate, and for it to be in communication with the wall by a pipe. This is not at present preferred since we prefer that sealing be achieved by a self-contained article and that external pipe-work be avoided. The article may be supplied with a container containing a certain amount of fluid, preferably sufficient for one filling, preferably as a kit-of-parts. An example might be a small cylinder of carbon-dioxide, or other gas, such as that used for pressurizing soda syphons.

The wall will in general be preferably flexible, and thus able to conform to substrates of various sizes and/or of irregular or awkward shape. It may comprise at least three layers, for example one serving to retain the fluid, one to provide mechanical strength for example tensional strength against internal pressure, tear- strength or puncture resistance and one layer serving to form a seal to the substrate by accommodating small scale irregularities in the surface of the substrate. To this end the wall may comprise a first layer of metal (or metallized plastics material or metal-coated plastics material) optionally with which the fluid is in contact, and a second strengthening layer such as high density polyethylene, together with a third layer, in direct or indirect face-to-face relation with the first layer, and positioned between the first layer and the substrate. The third layer referred to above may comprise a deformable material such as a rubber or other elastomer or a foam. Other materials may be used as this third layer, for example sealing materials such as sealants, for example as referred to above. We prefer for many uses that no permanent adhesion occur between the sealing member and the duct and cable. In general we prefer that the second layer have a hardness of from 35-85, more preferably 40-80, especially 45-75 shore. The various functions referred to above may, however, be provided by fewer layers, where one layer has two or more functions.

The wall may comprise for example a laminate of a metal film and a layer of plastics material either side. Such plastics layers may allow the wall to be heat-welded to itself to make the envelope. A flap weld or bond, which will be under shear rather than peel when the article is inflated, preferably extends along the length of the sealing member where the sealing member is generally cylindrical. Simple welds that will be in peel may then be formed by hot stamping to close its ends.

Additional layers may be provided for mechanical strength such as oriented, for example biaxially-oriented or two layers of uniaxially oriented, high density polyethylene such as that known by the trade mark Valeron. A possible structure is as follows; the dimension being merely preferred. Copolymer 15 -

Valeron (trade mark) 40 -

Mylar (trade mark) 10 -

Aluminium (as one or more layers) 5 -

Linear low density Polyethylene 0 -

Copolymer 15 -

An alternative structure comprises

"Rayofix" is a terpolymer comprising ethylene butylacrylate, acrylic acid and ethylene groups.

These structures may be varied for example by omitting the mylar or using a different material in its place. Furthermore, each layer may be provided with a coating to aid bonding or welding, for example a polyurethane may be applied and suitable thickness corresponds to 3.7 g/m². The copolymer should allow heat bonding or welding, and may comprise a hot melt adhesive such as one based on ethylene vinyl acetate. Greater thickness of the copolymer (for example up to 200 microns could be used at bond/weld lines for better filling to cover irregularities. Additionally or alternatively a polyamide based adhesive could be used. The structure preferably has an elongation to break of at least 10%, preferably at least 20%. This structure may be used within an envelope for example one comprising a polymer such as an elastomer, such as rubber, optionally reinforced for example with nylon. Alternatively, it may be laminated to such a polymer, or it may be used alone. The additional material may reduce creep. In general, it is merely necessary that sealing contact between the duct wall and the cable or other substrate occur along a line that cuts across any potential leak path, although an area of contact of significant width may be preferred. It may be sufficient, therefore, for a sealing member to have a thin strip of rubber, or other layer such as gel or mastic referred to above, that extends over part only of its surface.

The sealing member preferably comprises a substantially flat (which term includes flattenable, since the article may be set in a curved or similar shape) flexible envelope that can be wrapped around an elongate substrate such as a cable to form an annulus which can be deformed by internal pressure to increase its radial thickness. In this way, an annular gap between a duct and a cable it carries may be sealed.

The sealing member may contain a sheet of material that gives it stiffness or shape, and/or which acts as a release layer preventing its opposing surfaces sticking together, for example during heat bonding or welding of edges during its formation.

We have found surprising success in sealing various shapes of substrate using a sealing member in the form of a flat envelope formed simply by bonding or welding together around their edges one or more initially flat rectangular sheets of material in the way described. Nonetheless, for some purposes it may be desirable to provide a hollow article which has an outwardly-facing convex surface for sealing engagement with an internal surface of a duct etc within which the article is positioned. Such a hollow article may alternatively or additionally have an outwardly-facing concave surface for sealing engagement with a cable or other substrate around which the article is positioned. Such curved surfaces, which might reduce leak paths through avoidance of wrinkles and allow lower internal pressures to be used, may be achieved by thermoforming a flat surface or be formed ab initio by moulding. Nonetheless, the sheet from which the envelope is made may be regarded as substantially flat since it is not in the form of a tube that merely has its ends bonded closed.

The article is preferably of so-called "wrap-around" design, a term well-known in the cable accessories art meaning having the ability to be installed around a cable without access to its ends. (Reference may be made to GB 1155470 which discloses a wrap¬ around sleeve.)

Where a high vapour pressure liquid is to be used, it will be chosen according to the particular substrate to be sealed and to the environment within which it is to be used. In general, the liquid is preferably non-toxic, non-inflammable, non-corrosive to the substrate and to the article containing it, and also has no deleterious effect on any component of the environment now thought to be at risk. The most important properties of the liquid are its boiling point, and vapour pressures over a range of temperatures. We prefer that its boiling point at atmospheric pressure be less than 10°C, more preferable less than 0°C , particularly less than -5°C, although for some uses it could be up to say, 15°C. Its vapour pressure at 0°C is preferably at least 0.25, more preferably at least 0.5, especially at least 0.7 bar gauge. We also prefer that the vapour pressure does not exceed 5 bar gauge, particularly 4 bar especially 3 bar at 25°C more preferably at 20°C. Such properties may be, and preferably are, achieved with a single liquid and its vapour, although mixtures of different components including liquids and gasses such as air may be used. A mixture of a high vapour pressure liquid and a low vapour pressure may be used to achieve a desired pressure. Mixtures may however vary in composition with time as one component preferentially evaporates, unless a suitable azeotrope be found. Suitable liquids include fluorocarbons, marketed under the ICI trade mark Arcton, such as Arcton 134A possibly with Arcton 114. Arcton 134A is CH2FCF3, and Arcton 114 is CHF2CHF2.

The invention is further illustrated by the accompanying drawings, in which:

Figures 1 - 11 show sealing members with which the puller of the invention may be used and figures 12 - 20 show various pullers in more detail.

Figure 1 shows a duct seal in use;

Figures 2A and 2B show formation of a sealing member of the invention;

Figure 3 illustrates an in-line process for making a sealing member as shown in Figure 2;

Figures 4A, 4B and 4C show formation of a second embodiment of sealing member;

Figure 5 illustrates an in-line process for making a sealing member as shown in figure 4;

Figure 6 shows various layers of a sealing member;

Figures 7A, 7B and 7C show use of a probe with a sealing member;

Figures 8 and 9 show ways of installing a sealing flap and plug in a sealing member; Figure 10 shows sealing material used with a sealing member;

Figures 11 A, 11B, 11C, 11D and HE show sealing of a branched cable splice using the sealing member;

Figure 12 shows how the puller is used;

Figure 13 and 14 show a puller in greater detail;

Figures 16 shows a further design of puller;

Figures 17 and 18 show use of a puller with an additional handle;

Figure 19 shows a yet further design of puller; and

Figure 20 shows a puller that can also act as a pressure indicator.

In Figure 1 a sealing member 1 is shown as a duct seal, sealing an annular gap between a cable 2 (the first surface as referred to above) and a duct 3 (the second surface). The sealing member 1 has flexible, and preferably substantially non-stretchable, walls 4 between which a pressurizing fluid such as air is introduced. An outer surface of the walls 4 may be provided with a sealing material 6, such as a mastic, to fill irregularities in the surface of the duct.

Figure 2A shows a way in which a sealing member 1 may be made.

A sheet 7 of material, preferably a laminate, is provided with a hole 8 through which a probe will later be inserted to inflate the sealing member. The hole 8 is covered with a flap 9, a sealing material 10 optionally being provided between the sheet and the flap 9. Next, the sheet 7 is formed into a tube, and a lap join 11 is formed by welding or bonding. In the next step a probe 12 for later pressurization is positioned along the surface of the sheet 7 and into the hole 8. Thus, the product may be supplied with such a probe in place. Alternatively, the probe may be supplied separately. In that case, it may be desirable for some means to be employed in manufacture to prevent a future path for the probe from becoming blocked, or at least to provide indication as to where the probe should later be inserted since the hole 8 will in general not be visible.

After insertion of the probe 12, end seals 13 are made, again by welding or bonding, optionally with folding. The following step involves applying inner sealing material 6 between foam or other dams 14 that restrict its displacement during service. The outer sealing material 15 has been applied in the last step. Such a layer may be covered by a cling film or other suitable very thin and very flexible layer. It may serve to reduce tack, and increase friction. The outer and inner extra layers may be reversed (particularly when employing the funnel design explained in connection with Figure 4 below).

Figure 2B shows positioning of a probe 12 substantially parallel to the surface of the sheet 7.

That sequence of events is shown carried out in-line in figure 3. There the sheet 7 is supplied from a roll 16. A punch 17, or other means, makes hole 8 and flap 9 and sealing material 10 are supplied from rolls and hot-stamped into place. A roll 18 produces the longitudinal lap join 11. Stamps 19 periodically produce transverse hot-welds 13 defining the ends of individual sealing members. Inner sealing material 6 and foam dams 14 are supplied from rolls, and a cutter 20 separates the final individual sealing members 1. They are then packed as shown at 21.

Figure 4A shows a manufacturing technique similar to that shown in figure 2A, except the probe passes between two walls of lap join 11, rather than through a hole 8 through a single wall. A funnel-shaped hole 22 extends through the lap join 11 and contains a sealing material 10. Figures 4B and 4C show in cross-section the way in which probe 12 passes through sealing material 10 in the lap join between walls 4. Pressure 23 within the sealing member acts against the walls 4 which bear against the duct 3 ensuring a good seal. In general, it may be desirable that the hole 8 be positioned such that internal pressure acting on the flap (whether a separate flap as in figure 2A or one wall of a lap join as in figure 4A) urges the flap against the cable or duct.

The in-line process shown in figure 5 corresponds to the method of figure 4 A. A shaped roller 24 may be used to hot- weld or bond the overlapping edges together in a way that leaves periodic funnel-shaped holes between them.

The sealing member 1 of figure 6 is shown in a partial wrapped-around configuration. The reference numbers correspond to those used above. In addition a layer of sealing material 6, such as mastic, is positioned on what will be an inwardly-facing surface that engages a cable.

Figures 7A, 7B and 7C show insertion and withdrawal of a probe 12. The probe has been withdrawn by mere pulling, no unscrewing etc being necessary since it was previously held in place by mere friction or weak adhesion. It is surprising that satisfactory inflation and subsequent sealing can be achieved without a screw or bayonett or other mechanical connection between probe and wall. In figure 7C internal pressure has forced some sealing material 10 through hole 8 ensuring a perfect seal. Further layers may be used over the top of the article as shown, for example a mastic or other sealing material, optionally covered with a thin flexible film. Re¬ entry of a probe for deflation and/or for further pressurization may be possible in some embodiments. This will in general depend on whether the hole is visible and accessible in the installed product.

In figure 8 a flap is inserted into a sealing member, preferably after its manufacture, by means of a probe 12, preferably the probe used for inflation and preferably also as part of the inflating operation. A flap is carried by the probe 12, the flap being in a collapsed configuration as shown at 27. When the probe is slightly withdrawn, as shown in the centre part of the figure, the flap 28 begins to extend. On full withdrawal of the probe the flap 29 is fully extended. The process can be analogous to opening an umbrella.

The pressurizing gas can be seen leaving the probe at 30.

An alternative to the umbrella-like flap of figure 8 is a plug¬ like flap 30 of figure 9. The plug is carried at the end of probe 12, and an opening 31 for egress of air is provided above it. When the probe is fully inserted through hole 8, as shown in the left-hand part of the figure, opening 31 lies within the sealing member. The probe is then withdrawn, initially directing air outside of the sealing member (centre part of the figure), and finally leaving the plug to block the hole (right-hand part of the figure).

A composite sealing material strip, inventive in its own right, is shown in figures 10 , 10B and IOC. Such a strip may be provided on an outer surface of the sealing member, especially in a direction that will be generally circumferential when the sealing member is wrapped around a cable. The sealing strip comprises a mastic or other sealing material 6 between foam or other dams 14 and a thin flexible layer 15 of cling film or other suitable material. The layer 15 may have perforations 32 therethrough and may extend between two layers of mastic, and over an outer surface of the foam dams as shown in figures 10B and IOC.

Figures 11 A, 11B, 11C and 11D show the sealing member used to seal an outlet of a cable splice case 33 housing a branched cable splice. Figure 11 A shows two cables 34 leaving a housing 35. A cross-section near the end of the housing is shown in figures 11B and llC. In figure 11B one sealing member 1 has been wrapped around the two cables, and is shown before inflation. In figure 11C two sealing members 1 are used, one around each cable. The effect of inflating a sealing member is shown in figure 11D. The sealing member can be seen to seal the space between the housing 35 and the cables 34 thus preventing contaminants entering the splice case. (Overlapping layers of the sealing member are shown slightly separated for clarity.) The housing 35 of figure 11D is of the wrap¬ around type, a closure being shown at 36. Figure HE shows the formation of a duct seal or a splice case between cables 34 and a housing 35. Here the sealing member 1 is used around the cables and a core member at the left-hand side of the figure seals gaps at least between the cables. The core member comprises a sealing material such as a mastic between end plates. The end plates can be brought together by a nut and bolt or other driver to displace the sealing material to form the desired seal. Such a core member can be used with a sealing member 1 with or without the puller to be described below.

Figure 12 shows how the puller is used. A duct seal 37 is being inflated between a cable 38 and a duct 39 to provide an environmental seal between them. The duct seal is being inflated by air or other suitable fluid from a pressure source 40 (here a compressed air cylinder, but a pump could be used) via a fluid line 41. The fluid line passes in a helical path around a puller 42 and then through the centre of the puller. The puller is connected by means 43 to a pressure line 44 connected to the source 40. The means 43 may include a tap or valve or pressure regulator. The helical path of the line 41 is maintained by running the line in a helical groove 45 at least part of which is sufficiently deep such that a portion of the line 41 following the helical path is in communication with a portion of line 41 within the centre of the puller. Thus, that portion within the centre can be crushed as tension is applied to line 41 to pull it out of the duct seal 31. The pressure source 40 may include a pressure regulator or tap or valve 46 and a gauge 47.

In figure 13 the path 45 of the line 41 in and around the puller body 42 can be seen more clearly.

Figure 14 shows side and end elevations and a cross-sectional view of a puller, with some dimensions in mm. In general we prefer dimensions to be from 0.5 - 2, more preferable from 0.75 - 1.5 times the value given.

A further design of puller is shown in figures 15 A, 15B, 15C and 15D.

Figures 15 A and 15B show two parts of a puller before and after those parts have been snapped together or otherwise closed.

Figures 15C and 15D are similar, but have the two parts hinged together.

Relative longitudinal movement between the two parts could be allowed for, possibly brought about as the puller as a whole is pulled to tension the line 41. This would constrict the line 41 as desired. The puller has a handle 48 with which it can be gripped.

A yet further design of puller is shown in figure 16, which shows a housing comprising two moveable parts 49, 50 that are clamped around a fluid line 41. More than two such parts 49, 50 may be provided, for example three parts each of up to 120° of arc, or four parts each of up to 90° of arc may be preferred. The various parts may be initially separate and joined together by a mechanical hinge or other device; or they may comprise an integral moulding or other structure and be joined for example by a living hinge. Such a housing is preferably used with a tube 51 and an O-ring or other seal 52. The O-ring is positioned in the housing between the moveable parts 49,50, a fluid line 41 is then inserted, the parts moved together, and the tube 51 then positioned around the closed parts to hold them closed. Figure 16 illustrates four steps of this procedure.

Figures 17 A and 17B show in cross-section, and figures 17C and 17D show in perspective the assembly of a two part puller comprising a body part 53 and a handle 48. A sealing member 54, such as a rubber bush, can be driven down onto the line 41 as the body and handle are brought together.

A similar arrangement is shown in figure 18, but here a sealing disc or washer 55 is used between the body and the handle.

Figure 19 illustrates a puller comprising hinged parts 56 and 57 optionally joined by a living hinge 58. The parts 56 and 57 may be made of any suitable material, and are preferably moulded from polypropylene. A rubber or other tube 59 is positioned within a generally cylindrical passage through the puller. Locking means 60 are provided to hold the two hinged parts together. Pressure applied, for example by hand, forcing the two parts together causes a flange or other means 61 to constrict a fluid line that passes through the tube 59.

Figure 20 shows a puller 42 through which a line 41 passes. The line passes through a rubber tube 59, as in figure 19. The puller of figure 20 has a device 62 for constricting the line 41 which may comprise, for example, any of the devices mentioned above. A feedback device 63 responds to pressure exerted within the line 41 optionally via device 62. Device 63 provides some regulation to or indication of pressure within line 41. Thus, the line can be constricted when a desired pressure is reached. This preferably happens at a pressure of from 2-5, especially 2.5 to 3, particularly about 2.8 bar. A needle or other sensing/control device 64 may be provided at an end of the puller to which a line 44 is connected that leads to a source of pressure. An on/off tap 65 may be provided in this line.

For the avoidance of doubt it is mentioned here that the invention provides various pullers, fluid lines, sealing members, sealing materials and articles, and methods of manufacture and of use concerned with environmental sealing or blocking. In particular, any one or more of the pullers, sealing members, materials, article designs, sealing strips, valves may be selected.

Claims

1. A puller having means for gripping a flexible fluid line and means for constricting the line thereby reducing its ability to pass fluid.

2. A puller according to claim 1, in which the means for constricting operates automatically on applying tension to the line.

3. A puller according to claim 1 or 2, which has means for holding the fluid line in a configuration such that on applying tension to the line a first portion thereof crosses and applies pressure to a second portion thereby deforming the second part causing the constriction.

4. A puller according to claim 3 which has: a body through which the fluid line can pass such that the second portion of the line is positioned between ends of the body and is in communication with an outer surface of the body; and means that can locate the first portion of the line around the outer surface and in communication with the second part.

5. A puller according to claim 4, in which the body contains a flexible tube through which the fluid line can pass and through a wall of which the second part can be deformed.

6. A puller according to any preceding claim, having means for attachment to a pressure line.

7. A puller according to claim 6, in which the means for attachment comprises a screw thread.

8. A puller according to any preceding claim, having a pressure regulator.

9. A puller according to any preceding claim, which has a first and second moving parts such that on movement of the line through the puller, the moving parts are moved by the line relative to one another thereby wedging the line between the moving parts thereby causing the constriction.

10. An article which comprises a puller according to any preceding claim, and said fluid line.

1 1. An article according to claim 10, in which the fluid line has an external surface having a low coefficient of friction.

12. An article according to claim 11, in which the fluid line comprises polytetrafluoroethylene or a nylon.

13. A kit which comprises:

(a) a puller according to any of claims 1-9, and

(b) a flexible hollow sealing member that can be inflated through the fluid line to seal a gap between first and second articles

14. A kit according to claim 13, in which the sealing member has:

a hole through which the fluid line can be inserted to introduce fluid into the member, and

means by which the hole is sealed on withdrawal of the fluid line.

15. A kit according to claim 14, in which the sealing member has means by which the hole is automatically sealed on withdrawal of the fluid line.

16. A kit according to claim 14 or 15, in which the means by which the hole is sealed comprises an internal flap, or comprises two overlapping walls of the member.

17. A kit according to claim 14, 15 or 16, in which a sealing material is provided between the flap and a wall of the member.

18. A kit according to claim 16 or 17 in which the flap comprises a flexible polymeric sheet fixed to a wall of the member such that the fluid line can pass between the flap and the wall substantially in the plane of the wall.

19. A kit according to any of claims 14 - 18, in which the hole is between overlapping walls of a lap join, the hole through the lap join decreasing in cross-sectional size towards the outside of the sealing member, a sealing material being provided within the hole such that it is driven by internal pressure to block the hole.

20. A kit according to claim 17 orl9, in which the sealing material comprises a gel and/or a mastic and/or an elastomer foam.

21. A kit according to any of claims 14-20, in which the sealing member comprises a laminate of a metal and a polymeric material.

22. A kit according to any of claims 14-21, in which the sealing member has:

a first surface that will contact the first article, and

a second surface that will contact the second article,

an average coefficient of friction of the first surface being less than that of the second surface such that the sealing member will not move with respect to the second article under a pressure difference across the member of 35 KPa whilst allowing movement of the first article relative to the sealing member.

23. A kit according to any of claims 14 - 22, in which the sealing member is in the form of an elongate envelope that can be wrapped around a cable.