Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/08—Cable junctions
  • H02G15/18—Cable junctions protected by sleeves, e.g. for communication cable
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L47/00—Connecting arrangements or other fittings specially adapted to be made of plastics or to be used with pipes made of plastics
  • F16L47/20—Connecting arrangements or other fittings specially adapted to be made of plastics or to be used with pipes made of plastics based principally on specific properties of plastics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L5/00—Devices for use where pipes, cables or protective tubing pass through walls or partitions
  • F16L5/02—Sealing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16N—LUBRICATING
  • F16N15/00—Lubrication with substances other than oil or grease; Lubrication characterised by the use of particular lubricants in particular apparatus or conditions
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/08—Cable junctions
  • H02G15/18—Cable junctions protected by sleeves, e.g. for communication cable
  • H02G15/182—Cable junctions protected by sleeves, e.g. for communication cable held in expanded condition in radial direction prior to installation

Definitions

• This invention relates to a double wall elastomeric tubular article and to its use in covering an elongate substrate, such as a cable or pipe.
• Double wall tubular article of the type of this invention are disclosed in U.S. Patent No. 4,868,967 to Holt et al and European published patent application EP281,353 to Chang, the entire disclosures of which are incorporated herein by reference.
• a friction reducing means is provided between the walls of the double walled article.
• Particularly preferred friction reducing means are pituitous liquids, such as solutions of high molecular weight polymers.
• the articles are useful for covering substrates such as cables, pipelines or the like. In certain instances it is desirable that only a single layer of elastomeric material be applied over the substrate, for example when the article is used to repair the jacket on a cable subject to abrasion. As taught in U.S. Patent No.4,868,967 and EP281,353, an annular ring cut may be made in the outer wall which can then be unfolded, or slid, into contact with the substrate. It has been found that if a pituitous liquid or silicone oil, as preferred in the prior disclosures, is used, the amount of friction reducing means required to install the article over the substrate results in an undesirably messy application. This is particularly true if the friction reducing means is a pituitous liquid. However, it has been found that if a low viscosity liquid is used, the article is extremely difficult to install and cannot be installed over substrates of different diameters.
• One aspect of this invention comprises a tubular article comprising a double walled tube having a friction reducing means between the two walls of the double wall, the friction reducing means comprising a liquid having dispersed therein particles having an average particle size of about 0.1 to about 1000 microns, the particles being substantially insoluble in the liquid.
• Another aspect of this invention comprises a method of covering an elongate substrate which comprises revolving onto the substrate a tubular article comprising a double walled tube having a friction reducing means between the two wall of the double wall, the friction reducing means comprising a liquid having dispersed therein particles having an average particle size of about 0.1 to about 1000 microns, the particles being substantially insoluble in the liquid.
• Figure la is a perspective view of a first embodiment of the invention comprising a double-walled article
• Figure lb is a transverse cross-sectional view of the article
• Figure lc is an axial cross-sectional view of the article
• Figure 2 illustrates a preferred method of forming the article
• Figure 3a illustrates an initial revolving action
• Figure 3b illustrates subsequent revolving action
• FIG. 3c illustrates the installed article
• a key feature of the article of this invention is the friction reducing means, or lubricant, used between the walls of a double wall tubular article.
• the friction reducing means utilized in the practice of this invention comprises a liquid having insoluble particles dispersed therein .
• the liquid is preferably a low viscosity liquid, for example a liquid having a viscosity of about 1 to about 1000 centistokes, more preferably about 5 to about 500 and most preferable about 5 to about 250 centistokes.
• Preferred liquids are low viscosity liquid silicones, for example dimethyl siloxane, aqueous or glycol solutions of soluble polymers, mineral oils, vegetable oils, polyols, water, surfactants, liquid high molecular weight alcohols and the like.
• Dispersed in the liquid are particles having an average particle size of about 1 to about 1000 microns.preferably about 50 to about 500 and more preferably about 50 to about 300 microns.
• the particles are preferable solid and should be substantially insoluble in the liquid.
• the particles may be droplets of a second liquid substantially insoluble in the first.
• substantially insoluble means that less than about 50%, preferably less than about 40% and most preferably less that about 30%, of the particulate substance dissolves in the liquid.
• Preferred particles are particulate salts of fatty acids, such as stearic or oleic acid, for example, sodium stearate, etc., PTFE powder, talc, particulate graphite, molybdenum disulfide and the like.
• the particles are preferably present in the friction reducing means in an amount of about 2 to about 40%, more preferably about 5 to about 35 and most preferable about 10- to about 25%, by weight, based on the weight of the liquid.
• the intended use of the article of the invention may restrict the liquid that can be used.
• the liquid selected should have a relatively low vapor pressure at such temperatures.
• a particular instance is the use of the article over a high voltage cable.
• Such cables are intended to operate at about 90°C, but higher temperatures can arise and accessories used in conjunction with such cables are expected to be operable up to 130°C.
• the liquid should have a boiling point of greater than 130°C and preferably its vapor pressure is less than 1 bar at 130°C.
• both the liquid and particles be non-toxic or non-irritating to the person installing the article.
• the amount of friction reducing means required according to the instant invention is significantly less than that required if a pituitous liquid or silicone oil is used in accordance with the teaching of U.S. Patent No. 4,868,353, mentioned above.
• U.S. Patent No. 4,868,967 discloses a double-walled tubular article of the same general type as the article of this invention.
• the tube can be revolved along a substrate by relative sliding motion between the two walls of the double wall, substantially without relative sliding motion between a wall adjacent the substrate and the substrate. This revolving action may cause the walls to stretch, and thus the tube can be installed over substrates of larger dimension than its relaxed dimension, resulting in tight engagement.
• first and second walls of the double wall can be continued such that the first and second walls exchange position and can preferably then return to their original configuration. Such a complete revolution may be achievable only once, although we prefer that it can be continued as many times as desired.
• the article may be revolved along an elongate member and left in any desired position.
• the first and second walls may of course be indistinguishable from one another, except for the fact that at any given time one is an inner wall adjacent the substrate and one is an outer wall overlying the inner wall. Then the portion of wall material that constitutes each wall will continuously change as the revolving action takes place.
• Revolving involves stretching a wall portion as it passes from an inner position, and relaxing another wall portion as it passes from an outer position to an inner position.
• Reference to a first, second, inner or outer wall merely refers to a portion of wall identifiable for the time being by its position and does not imply that it has any structural uniqueness.
• the revolving action may be pictured best perhaps by imagining a longitudinal axial section of the double-walled tube over a cylindrical substrate.
• the tube will appear as a caterpillar-track on either side of the substrate (Caterpillar is a trade mark).
• the tube can progress along the substrate by the caterpillar- tracks revolving. This involves shear between the inner and outer walls constituting the caterpillar-track, and will generally avoid shear between the inner wall and the substrate.
• an outer wall may be cut (which term includes any suitable technique for parting two parts of it) and a resulting separated outer wall portion revolved such that the double walled article becomes (at least in part) a single walled article extended along the substrate.
• the a icle of this invention may be of any length, and it will generally be less than 30 m (100 feet) and more frequently less than 15 m (50 feet).
• articles of this invention are from about 5 cm (2 inches) to about 130 cm (50 inches) in length, and in particular are from 13 cm (5 inches) to 80 cm (30 inches) in length depending on the substrate over which they are to be used.
• the outer diameter of the article similarly can be of any desired size, and typically is less than 125 cm (50 inches) generally less than 50 cm (20 inches), preferably from 2.5 cm (1 inch) to 15 cm (6 inches) depending on intended use.
• the inner diameter is preferably from 0.2 cm- 120 cm, more preferably 0.5 cm-50 cm, especially 1 cm to 10 cm.
• the ratio between the length and outer diameter of the article will also depend on the use to which it is to be put. Preferably that ratio is more than 5, more preferably more than 7, especially more than 8. Typical values are from 5-12. Articles of such shape will tend to buckle (rather than revolve) if subjected to an axial compressive force applied between an outer wall at one extreme end and an inner wall at an opposite extreme end.
• a preferred technique whereby articles of the invention are installed is as follows: the revolving action is at least initiated by applying a shear force between the inner wall at one extreme end (by means for example of an end of a substrate to be covered) and the outer wall at a position a short distance, say less than 7 cm, preferably from 0.5-5 cm, from that same end (by means for example of an installer's hand).
• This technique is particularly relevant to a preferred use of the article where both the inner and outer walls are under tension when the article is installed on the substrate, as is required if an environmental seal is to be reliably achieved.
• Both the inner and outer walls must therefore be expanded as the article is revolved onto the substrate, and that portion of the outer wall which is over the substrate will generally be under greater tension than the remainder that has yet to reach the substrate. This difference in tension will tend to drive any fluid separating the inner and outer walls towards the end of the article yet to reach the substrate, i.e. towards the end of less tension. The inner and outer walls at the end over the substrate will cease to be separated, and friction will bring the revolving action to a stop. Hence the need for an effective friction reducing means.
• the inner and outer walls are each preferably from 0.0025 to 1.3 cms (0.001 to 0.5 inches) thick, more preferably from 0.05 to 0.65 cms (0.02 to 0.25 inches), and most preferably from 0.15 to 0.25 cm (0.05 to 0.1 inch) thick.
• the material comprising the walls should of course be sufficiently flexible that the revolving action may take place, and it preferably has an elongation to break of at least 20%, more preferably at least 40%, especially at least 100%, more especially at least 200%, particularly at least 500%, more particularly at least 700%.
• the degree to which the walls of the article may be stretched will determine the maximum size of substrate over which the article may be installed.
• the outer diameter of the substrate is from 1.0 to 8 times the inner diameter of the article of the invention. Preferred ranges are from 1.1 to 5, especially from 1.1 to 2.5.
• the article can be installed over a substrate of larger size will depend on the tensile stress of the material comprising the walls.
• the article can be installed by hand over substrates having the size ranges given above, using the technique disclosed above whereby a shear force is applied between the end of the article and a position close to that end.
• the material comprising the double-wall will be chosen from at least three considerations. Firstly it must allow the revolving action necessary for installation onto or use along a substrate of a certain size or shape or substrates of a certain range of sizes and shapes.
• the properties of interest here will include flexibility, tensile stress at a chosen elongation, elongation to break and ability to retain the friction- reducing means.
• the second consideration is the functional requirement of the installed product. For example, it may need a certain mechanical strength, abrasion resistance, cut resistance, moisture impermeability, etc. If it is to have an electrical function it may be required to be of high resistivity as an insulator, of low resistivity as a screen or other conductor, of intermediate resistivity as for stress- grading. It may have a certain specific impedance at a certain frequency, it may need anti-tracking properties, or it may need resistance to corrosion under high electrical discharge, etc. Where it is to be used in difficult environments it may need compatibility with certain sealing materials, U.V. resistance, fungal resistance, oxidation resistance, resistance to stress-relaxation, flame resistance, resistance to solvents, or low water up-take, etc.
• the material is preferably an elastomeric material containing appropriate additives to provide the desired properties.
• the material comprises neoprene, EPDM, natural rubber, silicone rubber, styrene/butadiene copolymer rubber, butyl rubber.chlorosulfonated polyethylene or the like.
• the article of this invention can be used to cover any elongate substrate, such as electrical and fiber optic cables, cable splices, damaged cable jackets, pipelines, bus bars, bushings, fuses, elbow connectors and various other electrical connections, electrical wires, pipes and pipe lines, including hose and irrigation pipes, particularly over weld areas and damaged sections, pylons of off-shore oil rigs, flag poles, and other articles of circular or other cross-sectional shapes.
• any elongate substrate such as electrical and fiber optic cables, cable splices, damaged cable jackets, pipelines, bus bars, bushings, fuses, elbow connectors and various other electrical connections, electrical wires, pipes and pipe lines, including hose and irrigation pipes, particularly over weld areas and damaged sections, pylons of off-shore oil rigs, flag poles, and other articles of circular or other cross-sectional shapes.
• the article can be easily installed due to the elastomeric nature of its walls, and when in position it may be cured preventing or restricting further movement.
• a sealing material may be provided between the inner wall and the substrate or between the outer wall and some other object with respect to which movement is to be prevented.
• Such sealing material may be supplied on a surface of the substrate, on a wall of the article or as a discrete component that is positioned as desired during installation of the article.
• the double-walled tube is able to apply a compressive force to a sealing material, forcing it against a substrate, whilst avoiding any shear that would tend to displace it during installation.
• Illustrative sealing materials that may be used with the article for sealing or locking purposes include adhesives, sealants, gels.
• the sealing material may be provided in sheet form (which includes tapes, strips and bands), either alone or on a backing material, which may be wrapped around the substrate.
• a typical article is illustrated in Figures la, lb and lc which provide respectively perspective, transverse cross-sectional and longitudinal cross-sectional views.
• the article 1 comprises an outer wall 2 and an inner wall 3.
• the walls are joined to form a continuous, closed double-walled tubular structure.
• a friction-reducing means 4 is located within the double wall, separating the walls and allowing relative sliding motion between them.
• An article of this invention can be made by a variety of methods. The manner in which it is made is generally not critical.
• a preferred method of manufacture is illustrated in Fig. 2.
• a tube approximately double the desired length of the tubular article is formed by, for example, extrusion.
• the ends 6 and 7 of the tube 5 are folded over until they form an overlap region as illustrated.
• the friction reducing means can be added at this point. Because of the low viscosity of the friction reducing means it has been found to be desirable to mount the tube on a mandrel provided with a longitudinally extending groove. A vacuum can be applied to the groove creating a pocket between the walls. The low viscosity friction means can then be inserted into this pocket.
• the ends 6 and 7 may be secured together, for example by means of an adhesive , forming the continuous wall of the double wall structure.
• the adhesive between the walls of the article can then be cured, generally by placing the article in an oven or, if the friction reducing means is volatile, in an autoclave.
• Another preferred method comprises extruding individual tubes, one of smaller diameter than the other, arranging the tubes in concentric relationship and then bonding the ends of the tubes together.
• an end 9 of the article is expanded to the outer diameter of the substrate and an end of the substrate is inserted into the expanded open end 9 of the article, as shown in Figures 3a and 3b.
• the force on the article will generally be applied at line 10, i.e. close to the applied at position 11. From Figure 3b it can be seen that, for the relative size of substrate and article illustrated, the circumferential tension in the right hand end 9 of the outer wall 2 will be greater than in the left hand end which would cause the friction reducing means 4 to be driven away from where it is needed, were it not for some means to restrict such displacement.
• the article can be used to cover, for example a cable joint.
• the tubular article Before the cables are joined, the tubular article is positioned over one of the cables and axiaily revolved away from the cable end. The cables are then joined and the tubular article is positioned over the joint by applying an opposite axial force relative to the outer wall.
• Figure 3c illustrates, partially in cross-section, article 1 when fully on an elongate substrate.
• Article 1 comprises outer wall 2, inner wall 3 and friction reducing means 4.
• the arrows indicate movement of the outer wall 2 while substrate 8 substantially prevents axial motion of inner wall 3.
• outer wall 2 progressively revolves into contact with the surface of substrate 8 resulting in moving the article 1 in an axial direction from left to right in the drawing.
• Example 1 This example illustrates the use of insoluble particles in a low viscosity liquid as the friction reducing means for a double walled tubular article.
• a tube of neoprene about 18 inches long and having a wall thickness of .12 inch, an internal diameter was positioned on a mandrel and folded over itself.
• a friction reducing means (FRM) in the amounts specified in Table I and consisting of a liquid dimethyl siloxane having a viscosity of 100 centistokes (DC-200, lOOcs commercially available from Dow Corning) and varying amounts of particles of sodium stearate, as designated in Table I, was introduced into the space between the walls.
• the ends of the tube were overlapped and secured together with adhesive to provide a double wall tubular article about 8.5 inches in length.
• the article was placed in an oven to cure the neoprene adhesive.
• Sample articles were installed onto a 1.38 inch diameter mandrel or a 1.76 inch diameter mandrel and the force necessary to revolve the article along the mandrel was measured. The results are shown in Table I.
• This example illustrates the use of insoluble particles in a pituitous liquid as the friction reducing means for a double walled tubular article.
• Example 1 The procedure of Example 1 was repeated using as the friction reducing means (FRM) an aqueous solution of a water soluble high molecular weight polymer (Polywater F from Polywater Corp., of Minnesota) optionally containing particles of polytetrafluoroethylene
• FAM friction reducing means
• Example 3 This example illustrates the heat aging performance of double wall articles containing a liquid/dispersed particle friction reducing means in accordance with this invention.
• Example 1 The procedure of Example 1 was repeated using 1.5 ml of a friction reducing means comprising dispersions of sodium stearate, in the amounts specified in Table III, in dimethyl siloxane having a viscosity of 100 centistokes.
• the articles used were somewhat larger, having an internal diameter of 1.025, the other dimensions being the same as in Example 1.
• Sample articles were installed onto a 1.38 inch diameter mandrel or a 1.76 inch diameter mandrel and the force necessary to revolve the article along the mandrel was measured. The samples were then placed in an oven maintained at 70°C for the times indicated in Table III. The samples were removed from the oven, cooled and the force required to revolve the article along the mandrel was measured. The results are listed in Table III.
• the articles could be readily revolved along the substrate. This demonstrates that the article can be installed over the substrate in use and can be removed if desired, e.g. to modify or repair an underlying cable splice.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)
• Containers And Plastic Fillers For Packaging (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 1991
  • 1991-07-08 ZA ZA915279A patent/ZA915279B/xx unknown
  • 1991-07-26 EP EP91915042A patent/EP0541695A1/en not_active Withdrawn
  • 1991-07-26 AU AU84334/91A patent/AU8433491A/en not_active Withdrawn
  • 1991-07-26 CA CA002087708A patent/CA2087708A1/en not_active Abandoned
  • 1991-07-26 BR BR919106699A patent/BR9106699A/pt not_active Application Discontinuation
  • 1991-07-26 WO PCT/US1991/005311 patent/WO1992002754A1/en not_active Application Discontinuation
• 1993
  • 1993-01-26 FI FI930317A patent/FI930317A/fi not_active Application Discontinuation

Non-Patent Citations (1)

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