Classifications

• • 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
  • F16L59/00—Thermal insulation in general
  • F16L59/14—Arrangements for the insulation of pipes or pipe systems
  • F16L59/16—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like
  • F16L59/18—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like adapted for joints
  • F16L59/20—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like adapted for joints for non-disconnectable joints
• • 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
  • F16L59/00—Thermal insulation in general
  • F16L59/14—Arrangements for the insulation of pipes or pipe systems

Definitions

• the present invention relates to a tube for trans ⁇ porting fluids thermally insulated from the ambient, comprising an inner casing adapted to guide fluids, an insulating layer arranged therearound and a casing im- parting strength to the tube.
• Such tubes are generally known, for instance in the form of tubes which are applied in for instance district heating.
• the inner casing has a relatively great thickness; the inner casing is dimen ⁇ sioned to contain the fluids for transporting, to absorb the pressure at which the fluid is transported, to absorb mechanical loads during fitting of the tube and to absorb mechanical loads while the tube is in place, which mechanical loads are largely generated by the thermal stresses generated as a result of the heat of the fluid for transporting. It is also possible that mechanical forces are exerted on the inner casing by the ambient, for instance the soil in which the tube is placed. In short, the inner casing is adapted to impart strength to the tube.
• the function of the insulating layer requires no further explanation in this case. Further arranged is a relatively thin outer casing which is usually manu- factured from plastic and which only serves to seal the insulating layer from influences from the environment. These prior art tubes result in a number of draw ⁇ backs, wherein one of the most important is the fact that as a result of changes in the temperature of the trans- ported fluid the inner casing is exposed to mechanical stresses of thermal origin. These stresses cause ex ⁇ pansion or shrinkage in different directions, wherein the radial direction does not generally represent a problem because this can be absorbed by the insulating layer.
• the object of the present invention is to provide a tube wherein the above stated drawbacks are avoided.
• a tube system for transport of fluids thermally insulated from the ambient comprising: an inner casing adapted to guide fluids, an insulating layer arranged therearound and an outer casing imparting strength to the tube system.
• This however relates to a tube system which is only suitable for laboratory applications.
• the object of the invention is to provide such a tube system which is suitable for transport over long distances without much flow loss.
• the insulating layer is fixed to the inner casing and the outer casing such that longitudinal forces exerted by the inner casing are transferred by the insulating layer to the outer casing.
• the outer casing is not or hardly subject to temperature changes relative to the surrounding ground due to its insulated arrangement, which likewise brings about only small stresses.
• a further advantage of the present invention lies in the fact that the outer casing is the most robust com ⁇ ponent, so that handling of such tubes takes place more easily than handling of prior art tubes and the danger of pipe fracture due to excavation operations is also significantly lower.
• Yet another advantage of the invention lies in the fact that a greater freedom of dimensioning results from the wide availability of tubes of different diameter and thickness.
• the present invention also relates to a sleeve for mutually connecting tube pieces according to the in ⁇ vention, wherein a particularly attractive form of the outer casing can be obtained by applying internal rings in the sleeve and external rings on the tube pieces.
• the invention further relates to a method for laying a pipe consisting of pieces of tube according to the invention, wherein the tube pieces are placed in their position in a trench and mutually connected, whereafter the trench is filled without interposing of heating.
• figure 1 shows a partly broken away perspective view of a tube according to the invention
• figure 2 shows a sectional view of a weld of tubes according to the present invention
• figure 3 is a detailed sectional view of the weld of an inner tube according to a first embodiment
• figure 4 is a detailed sectional view of the weld of the inner casing according to a second embodiment
• figure 5 shows a sectional view of a transition element between prior art tubes and tubes forming part of the invention according to the first embodiment
• figure 6 is a view corresponding with figure 5 of a further embodiment of such a transition piece
• figure 7 shows a partly broken away perspective view of pipes forming part of a district heating system.
• Shown in figure 1 is a tube piece 1 formed by an inner casing 2 manufactured from a thin material, around which an insulating layer 3 is arranged which is sealed on its outside by an outer casing 4.
• the inner casing 2 is manufactured from thin plastic, for instance polyetherimide, while it is also possible for inner casing 2 to be manufactured from a metal, for instance steel, stainless steel or aluminium.
• the insulating layer 3 is manuf tured from known insulating material, for instance PUR foam.
• an insulating layer with an increased density for instance a PUR foam with an increased density, is preferably used to be able to absorb the in this case extra-great internal pressures due to the transport of fluids.
• the plastic inner casing mainly performs the function of watertight seal.
• collars 5 are arranged with a U-shaped cross section. These also serve during manufacture of the tubes as fixation elements for mutual fixing of inner casing 2 and outer casing 4. These collars 5 can for instance be manufactured from plastic or from the same material as the inner or outer casing. They can be connected to the relevant casings for instance by means of a glue connection. These collars 5 can be adapted to transfer longitudinal forces.
• the inner casing 2 protrudes in axial sense relative to collar 5 and outer casing 4.
• the outer casing is optionally provided with a coating to prevent corrosion.
• FIG 2 a weld between two such tube pieces according to the invention. Going from inside to outside, which also designates the working sequence, the inner casings 2 are first mutually connected, for in ⁇ stance as in the present case of metal inner casings 2 , by a weld 6. Thereafter the space between collars 5 and outer casings 4 are filled with an insulating material, for instance mineral wool, an insulating plastic or filling pieces of other insulating material. A sleeve 8 is subsequently placed round the thus manufactured weld.
• an insulating material for instance mineral wool, an insulating plastic or filling pieces of other insulating material.
• This sleeve is preferably manufactured from steel, wherein it is possible that sleeve 8 cane be divided so that it consists of two halves which are mutually connected for instance by means of hinges, although it is also possible for sleeve 8 to be formed is integrally and be pushed round one of the tubes before the tube pieces are mutually attached.
• This curing mass 9 can once again be formed by a curing plastic, but can also be formed by for instance concrete.
• a peripherally extending ring 10 is fixed to the outside of each of the casings 4.
• This ring 10 can be continuous as in the present case but may also be dis ⁇ continuous and formed for instance by separate pieces.
• the inside of sleeve 8 is provided with corresponding rings 11.
• the rings 11 serve to increase the transfer of forces.
• the r ⁇ ngs 11 are placed outward relative to rings 10. This has the advantage that when concrete is used as mass 9 particularly good use is made of the properties of concrete, since in that case the concrete is mainly under strain of pressure between rings 10 and 11.
• Figure 3 shows a preferred embodiment of a connection between the internal casing 2 of different tube pieces.
• One of the internal casings 2 is herein provided with a connecting sleeve 12 of the first embodiment which is fixed thereto, for instance by means of a weld 6, while the inner casing associated with the other tube piece is connected to a connecting sleeve 13 of the second type.
• Both connecting sleeves 12,13 are formed at their free end such that they fit mutually. They can herein be mutually fixed by for instance a glued seam 35.
• FIG 4 The embodiment shown in figure 4 is however only applicable with plastic inner casings 2.
• a sleeve 15 which is provided with a heating wire 14 and which is pushed round the two inner casings 2 for mutual connection and wherein a connection is formed by feeding a current through the heating wire 14, whereby the relevant part of sleeve 15 and a corresponding part of the outside of inner casing 2 melt and a joint is formed.
• the invention is however most certainly not limited to said forms of mutual connection; it is very well possible to apply other forms of connection, for instance by mechanical connecting means such as clamps, bolts or glues.
• a transition piece 16 which is suitable to form a connection between a tube piece according to the present invention 1 with a metal inner tube and a prior art tube piece 17 and for connecting accessories such as valves or manifolds, which initially will certainly be more easily obtainable generally than valves or accessories for the system described in the present application.
• the prior art tube piece 17 com ⁇ prises an inner tube 18 of substantial thickness, an insulating layer 19 and an outer tube 20 of substantial thickness. In many situation this outer tube 20 is manufactured from plastic.
• the transition piece 16 is formed by an inner casing 21 of a first small thickness, which thickness sub ⁇ stantially corresponds with that of the inner casing 2 and a casing piece 22 welded thereto of greater thickness, for instance a thickness lying between the thickness of inner casing 2 and that of inner casing 18. It is possible to make use of a larger number of intermediate steps.
• the casing pieces 21,22 are mutually connected by welds 23 and also connected by welds 23 to the relevant inner casings 2 respectively 18.
• a separate insulating layer 7 to fill the space between the inner casing and the outer casing, while a separate outer casing 24 is applied which consists for instance of two parts and which is connectable by means of welding, shrinking or glueing to outer casing 2 respectively 20.
• Figure 6 shows an embodiment wherein a flange connection 36 is applied as connection between a tube piece 1 with plastic inner tube 2 according to the invention and a prior art tube piece 17 and for connecting accessories such as valves or manifolds, which initially will certainly be more easily obtainable generally than valves or accessories for the system described in the present application.
• a transition piece 25 which comprises a metal inner casing 26, the diameter and thickness of which correspond with those of the prior art tube pie 17 and which is connected thereto by means of a weld 13.
• the transition piece contains a metal outer casing 27 over a part of its length. Inner casing 26 and outer casing 27 are connected via welds to flange 28.
• the space between inner casing 26, outer casing 27 and flange 28 is provided with an insulation material 3.
• the connection between the outer casing 27 of the transition piece according to the invention and the outer casing 20 of the prior art tube piece is effected by means of the outer casing 24 under which is situated an insulating filling piece 7.
• the inner casing 2 of the tube piece according to the invention is provided with a plastic flange 29, while outer casing 4 is provided with a metal flange 30.
• Flanges 28,29 and 30 are connectable by means of a bolt connection 31.
• a flange connection is used as connection between a tube part 1 with an aluminium inner tube 2 according to the invention and a prior art tube piece 17 likewise comprises a transition piece 25.
• the inner casing 2 of the tube piece according to the invention is now provided however with an aluminium flange 29. Between flanges 28,29 and 29,30 are applied gaskets 32 which electrically separate the contact potentials of the materials.
• This latter embodiment is more particularly suitable for connecting accessories such as valves or manifolds, which initially will certainly be more easily obtainable generally than valves or accessories for the system described in the present application.
• figure 7 shows a portion of a district heating system which is formed by two tubes 33,34 which are used for feed respectively as return pipe for a fluid, for instance water or steam for a district heating system.
• a fluid for instance water or steam for a district heating system.
• the pressures applied herein generally lie in the order of magnitude of 10 to 15 bar, so that the inner tube must also be dimensioned for this purpose.
• the inner casing is manufactured from metal, for instance steel, since steel has a better resistance to a relatively high temperature than plastic, while for the return pipe 34 plastic can suffice; this results in a cost saving.
• Another advantage of the present invention lies in the fact that, as a result of the strength-imparting construction being present on the outside, said tube construction can be easily pressed, for instance when making tunnel pressings and borings under roads or under waterways. This results in a considerable cost saving since fewer excavation operations then have to be carried out or pressing or drilling of the casing tubes is no longer necessary.
• Another advantage lies in the fact that the tube pieces can be placed more easily; welding of the thin inner tube can be performed more easily and rapidly than welding of the thick inner tube which was heretofore customary and which also had to be examined with an X-ray device for checking purposes. The application of modern techniques, for instance glueing and the robust concrete sleeve connection, results in even more attractive embodiments.
• the option is herewith also formed of mutually connecting a plurality of such tube pieces, which are normally supplied in lengths of about 16 m, before they are placed in position,- it is after all easier to process the tube pieces when they are lying free than when they are placed in a trench and access is usually more difficult.
• Another advantage lies in the fact that the diameter of the thin inner tube and the insulation thickness can be chosen in optimum manner. It can be envisaged that transport of hot fluids over large distances can best take place in a manner where the diameter and degree of insulation are properly geared to each other. This in contrast to the prior art tubes wherein standardized tube dimensions are used.
• Another advantage lies in the fact that the glass fibre cable 38 with associated measuring unit forming part of the tube system of the invention enables heat loss measurement in the tube system during operation and also serves as leakage detection. It will be apparent that the invention is not limited to the shown embodiments.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Thermal Insulation (AREA)
• Rigid Pipes And Flexible Pipes (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=19762617

Family Applications (1)

Country Status (5)

Families Citing this family (2)

Family Cites Families (9)

• 1996
  • 1996-04-04 NL NL1002786A patent/NL1002786C2/nl not_active IP Right Cessation
• 1997
  • 1997-04-03 PL PL97329856A patent/PL329856A1/xx unknown
  • 1997-04-03 EP EP97914660A patent/EP0890057A1/de not_active Ceased
  • 1997-04-03 AU AU21810/97A patent/AU2181097A/en not_active Abandoned
  • 1997-04-03 WO PCT/NL1997/000168 patent/WO1997038258A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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