FI57837B - SAETTING THE LAWGING AV ROER ELLER LEDNINGAR I MARKEN - Google Patents

Description

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Sweden-Sverige (SE) 13318/71 (71) Granges Essem Aktiebolag, 721 88 Västeräs, Sweden-Sverige (SE) (72) Filip Bertil Thyberger, Västeräs, Kurt Olle Ragnvald Lindström, Västeräs, Sweden-Sverige (SE) (7l ) Oy Borenius & Co Ab (5l) A way to lower pipes or wires to the ground - Sätt vid läggning av rör eller ledningar i Marken

The invention relates to a method of laying pipes or conduits in the ground for dispensing flowing media having an arbitrary temperature.

When laying pipes or lines on the ground, e.g. for distributing district heat from a heating center to different consumption points, the pipes have hitherto usually been laid so that they can move freely in their longitudinal direction in the ducts, drums or the like in which they are placed. As a result, it has been necessary to place in the distribution system some kind of expansion compensation device to control the effects of temperature fluctuations normally occurring in such heating systems.

The most popular devices to smooth out enlargement are the so-called expansion loops or expansion sleeves. Neither of these devices is particularly well suited for use in district heating distribution systems. The use of an expansion loop results in the construction of a number of additional bends or arcs in the system, which cause an additional flow resistance to the medium distributed in the system. In addition to the disadvantage caused by the increased flow resistance, the bending loop must be positioned so that it can move freely. For this reason, special cavities must be provided in the ground when lowering district heating systems, which causes considerable additional costs of 2,57837 when the system is built. In order to avoid the above-mentioned disadvantages, some solutions have been tried in the past, e.g. the use of metal pipe bellows. By using such bellows structures, it is possible to avoid making special cavities in the ground, but instead no reduction in the flow resistance of the medium is achieved.

In order to keep the basic costs of district heating systems as low as possible, both methods have been used in parallel in the same equipment to smooth the longitudinal movements of the pipes, whereby the choice between alternatives is decided on the basis of pipe dimensions and placement.

When constructing mains, which, due to their large dimensions, are usually lowered into pre-cast, deck-covered ducts, the use of expansion loops incurs only a small additional cost, as the space required by these loops can easily be arranged during the casting of said ducts. Due to the high wall thickness of the pipes used in the mains, it is almost impossible to produce bellows with sufficient mobility and strength. In the case of smaller-length pipes, bellows are suitably used, since the pipes are often lowered in groups into a protective housing of etemite or plastic. In this way, the casting of special wells or the like for expansion loops is avoided. The bellows, on the other hand, can be installed in the available space mainly in the manner set forth in U.S. Patent No. 3,250,297.

When laying district heating pipes, for example in the villa area, it is possible to do without both expansion loops and bellows, because the distances between the buildings are very short and the wires are routed through the buildings. In this case, it can be allowed that the longitudinal movement of the pipes can be smoothed in those arcs, etc., which are fitted to the building. However, running wires through buildings should generally be avoided because it is not always possible to enter buildings for inspection or maintenance and repair, and in addition, running wires in a building requires a considerable amount of space.

To prevent heat from leaking from the pipes, these are insulated with some suitable insulating material. Thick mains to be laid in ducts 57837 3 are usually insulated by hand after the different pipe lengths have been calculated And welded together. Either housings or pipes are questionably isolated from the smaller pipes placed in the enclosures, however, a combination of these methods is usually used for best results, as it is possible to use pipes which are pre-insulated along their entire length, except for the zones near the ends. Both methods use tubes of limited length to facilitate their transport. For this reason, numerous joints have to be welded, each of which requires a considerable amount of manual work, as it is difficult to weld around the pipes in tight spaces and at the same time obtain welds of acceptable quality.

When laying pipes in protective enclosures, the pipes must also be insulated after welding and the enclosures must be connected in such a way that moisture cannot penetrate the insulation. Special extension elements are usually used for this purpose.

Manual work associated with invoicing incurs significant costs. Moreover, since such an approach requires high accuracy in connection with angular deviations of the pipes in order to avoid additional stresses in the pipes and casings, the trench made for the pipes must be precisely leveled.

Branching the pipe in the above cases requires a device that compensates for the movements caused by variations in the length of the pipes. This is a factor to be taken into account, especially when calculating district heating systems in areas where the buildings are relatively close to each other and the pipelines for the above reasons are laid outside the buildings, eg under a sidewalk or roadway.

The object of the invention is first and foremost to eliminate the above-mentioned disadvantages and to simplify the work and thus to reduce the cost of setting up district heating systems, especially when calculating smaller pipes.

The invention is mainly characterized in that the pipe or line and the surrounding thermal insulation sheath 4 57837 are placed in corrugated or corrugated curves and then the ditch is filled in a manner known per se.

The invention will be explained in more detail below on the basis of some exemplary embodiments schematically shown in the accompanying drawing. Other features of the invention will be set forth in connection with this disclosure.

Figure 1 is a schematic top view of an alternative according to the invention for solving a conduction problem in a villa area. Figure 2 is a schematic top view of another alternative for solving the pipe-drawing problem in an area with villas or larger settlements. Figure 3 shows a cross-section of pipes used for laying wires. Figure 4 shows a top view of laying pipes in a ditch according to the invention. Fig. 5 shows a top view of an alternative way of laying the pipes, and finally Fig. 6 shows a top view of yet another alternative way of laying the pipes.

In the drawing, in which the corresponding details are denoted by the same reference numerals in the different figures, Figure 1 shows the villa area 10 bounded by streets 11 and 12, on which houses 13, 14, 15 are built. from a heating center which distributes heat to these heat consuming houses 13, 14, 15 by means of a transfer means via a circulating system.

Heat distribution from the heating center or heating plant takes place along the main lines, represented here by lines 16, 17 laid in the street 11, of which line 16 acts as a supply line for circulating medium in the distribution system and another line 17 acts as a return line. Suitable locations for the main lines are connection points 18, 19 for connecting smaller distribution lines 20,21. These lead to different consumption points represented here by houses 13, 14,15.

Main lines 16, 17 and lines 20,21 are normally lowered to the ground under the pavement or possibly the carriageway. The cables are preferably laid under the pavement, as this will minimize traffic disruption during cable repair and maintenance work.

57837 5

In the villa area shown in Figure 1, the house-specific heating systems of the different houses 13,14,1b are connected to the lines 20,21 on the street 12 by branch lines 22,23,24,25,26,27 so that the transfer medium flows from the main line 16 at the branch point 21 to the line 21 for further supply. , 24,27 to the heat exchangers in the houses 13,14,15, after which the medium returns to the heating center or heating plant via the distribution line 20 and the main line 17 of the branch lines 26,25,22.

To reduce the number of junctions, the system shown in Figure 2 can be used, where the number 28 generally refers to the residential area bounded by streets 29.30 and on which houses 31,32,33,34,35 are built. The main lines 16,17 are lowered to the street 30, and the branches 38,39 are connected at the branch points 36,37, which in some cases may have the same dimensions as the main lines for connecting the distribution point or intermediate heat exchanger 40 to the distribution system. From this distribution point or intermediate heat exchanger, lines 41 ... 50 go directly to different buildings 31,32,33,34,35. This system has the greatest advantage in connection with group buildings, whereby a special intermediate heat exchanger 40 is constructed so as to provide a secondary system for the distribution of heat between the buildings and the intermediate heat exchanger.

In the district heating systems described in connection with Figures 1 and 2, the distribution lines 20,21, the branch lines 22 ... 27 and the lines 41 ... 50 have been calculated by applying the features of the invention, without which all the previously unsuitable and uneconomical expansion loops and expansion sleeves. To achieve this, pre-insulated pipes have been used, which have been delivered from the factory in large lengths. When calculating, pipe sections so long are cut off that the various connection points can be connected to each other. In this case, pipe lengths longer than the distances between the respective connection points are cut off, after which the pipe sections are calculated as corrugated curves as shown in Figures 1 and 2. The required length of the pipe sections is easily calculated after determining the amount of bending of the corrugated curves, which must be adjusted so that the variations in the length of the inner pipe fit within the outer insulating layer 53 surrounding the inner pipe 51 shown in section.

6 57837

The tubes 51 are suitably made of metal, after which a soft, relatively flexible thermal insulation layer 52 is placed around the tube, which in turn is surrounded by a tight and partially load-bearing outer sheath 53 of plastic or the like. The soft, relatively resilient layer 52 must then have such properties that, when the pipe is lowered to the ground and covered with the filling mass, it allows the inner pipe 51 to move radially inside the outer jacket 53 without appreciably changing the shape of this jacket.

When lowering the pipes, straight ditches 54 can be made as shown in Fig. 4 and then the pipes 55,56 can be lowered into these ditches, suitably on a substrate of sand or the like, to reduce the stresses on the pipes in case of displacement in the soil. This method is in itself both comfortable and simple, but its disadvantage is that the freely lowered tubes move relatively easily and lose their desired shape. To avoid this, another alternative is to make a ditch for the pipes shaped as shown in Figure 5, this ditch 54 also being made substantially in the same way as the corrugated ducts 55 and 56. However, as the interlocking ditches 54 may be difficult to make for smaller pipes 55, 56 in which the distances between the corrugation points of these pipes are short, according to yet another alternative shown in Fig. 6, the pipes 55,56 can best be lowered into a wide straight trench 54 to the bottom of which guides 57, e.g. pins, plates or the like, are attached so that these tubes 55,56, when lowered next to these conductors 57, acquire the desired curved shape and, moreover, remain in place. The tubes 55,56 need not be located lying at the bottom of the trench 54 so that their corrugations are substantially horizontal, but the guides 57 may also be located in the lateral planes 58,59 of the trench 54, with the corrugations being substantially vertical.

The method of laying pipes for dispensing transfer media according to the invention is not limited to the above-mentioned systems, but this method can be applied to any piping in which it is desired to compensate for length variations in pipes or lines caused by temperature variations. The only limiting factor is that the dimensions of the pipes must be such that they can be practically bent and lowered 7 57837 corrugated.

In order to lay the pipes as economically as possible, the pipe material must be available in remarkably large uniform lengths. The pipes are therefore delivered wound in such a way that they can be lowered using as few joints as possible.

However, since the method of laying pipes according to the invention is applicable to dimensions of the inner pipe 51 with a diameter of up to 70 mm, the pipe material cannot always be supplied wound, because such large pipe diameters would require diameters such that the coils could not be transported by car or train. When using such pipe dimensions, e.g.

^ the same mode of transport as for larger plastic pipes, namely by placing the pipes on interconnected vehicle units and allowing the movements of the pipes during transport to be agreed between these different units, which is possible due to the flexibility of the pipes.

The pipe-laying method according to the invention greatly simplifies the construction of distribution systems, e.g. for heat, because pre-insulated pipes can be used in large lengths, thus avoiding the numerous welding seams required hitherto and the associated insulation at least at the joints. Moreover, since no complex equipment requiring monitoring and maintenance is required to compensate for the variable length, additional economic advantages are obtained compared to previously used systems.

The invention is not limited to the embodiments described above and shown in the drawing, but the invention can be varied in many ways within the scope of the following claims.