DE2707799A1 - METHOD OF LAYING PIPING FOR HOT OR COLD MEDIA - Google Patents

Abstract

In the case of long-distance lines being laid directly in the ground for hot or cooled, fluid or gaseous heat media, insulating pipe sections are laid in a dug-out trench and are connected to one another in a sealing manner there at their ends. The insulating pipe sections consist of an inner heat-medium pipe and of an outer protective jacket pipe. An insulating jacket is foamed into the intermediate space, which insulating jacket produces a force-fitting bond between the two pipes. In consequence, expansion forces of the heat-medium pipe are transmitted uniformly to the exterior via the insulating jacket and the outer jacket pipe, over the entire length, and, in a reverse manner, the friction forces between the earth and the jacket pipe are likewise transmitted uniformly inwards to the heat-medium pipe over the entire line length. In consequence, lines of any desired length can be laid without any fixing points.

Description

PROCEDURE FOR LAYING ROIIR LINES FOR

ICE OR COLD MEDIA The invention relates to a method for laying long-distance lines for hot or cooled media, which lines laid in a row directly in the ground and sealed there with their ends interconnected insulating pipe sections exist, each of which has an inner Has heat transfer tube, which is surrounded all around by an insulating jacket in an outer, protective jacket pipe runs.

The application of the method according to the invention extends in general on the laying of long-distance pipeline systems, in particular for district heating, by means of prefabricated insulated pipe sections of, for example, manufacturing lengths from 6 to 12 m, which are welded together in or next to a prepared trench and be laid in the trench, preferably in a compacted sand bed, so that they can move continuously guided practically only in the longitudinal direction.

The previous version of pre-insulated pipe sections in which the insulation is chosen and applied solely from the standpoint of optimal insulation is, only enables the so-called conventional laying technique, according to which for the temperature-related expansion of the heat transfer pipe, which is usually made of steel Fixations and expansion compensators are provided. Are in a pipeline fixed points and compensators are required at regular intervals, whereby for the latter, moreover, mostly concrete manholes have to be created that have a control and enable the maintenance of these pipe elements.

By the Swiss patent no. 533'271 is recently a method has become known in which by the fact that the pipeline for hot Media heated or heated to a temperature above the normal ambient temperature. for cold media to one temperature below the mean ambient temperature is cooled and thereby in the desired position at two or more fixed points is fixed, the installation of expansion compensators can be dispensed with, not but on the installation of so-called fixed points, which are also very complex and in the event of improper and very careful execution, considerable damage being able to lead.

The object of the invention is to provide a method for laying Pipelines for hot or cooled media according to the technology mentioned above to create in which the installation of special fixed points can be dispensed with, which not only enables significant cost savings, but also Frequently occurring errors, damage and malfunctions can be avoided which are based on such fixings have been installed with insufficient care and / or expertise are due.

This object is achieved in the method according to the invention in that that insulating pipe sections are laid in which a force-fit connection from the heat transfer pipe via the insulating jacket to the outer jacket pipe and vice versa is present, and that a pipeline formed from such pipe sections their Ends with simple stretching devices, but without any fixed points in the Is laid in the ground.

The expansion forces of the heat transfer pipe are reduced by the force-fit connection Evenly over the insulating and outer sheath over the entire length of the laid cable The frictional forces between the soil are transferred to the outside and vice versa and jacket pipe, which are taken up by the fixed points in conventional laying must, also evenly inwards over the entire length of the laid cable transferred to the heat transfer pipe and it can be as long as you like in this way Long-distance lines are laid free of fixed points.

The frictional connection of the inner heat transfer pipe via the thermal insulation with the outer jacket tube can preferably be achieved in this way be that a heat transfer pipe made of a steel whose quality is primarily is selected in accordance with the expected temperature stresses, held centered inserted into a jacket tube made of plastic, e.g. hard polyethylene or polypropylene and into the remaining space between the heat transfer pipe and the jacket pipe insulating rigid foam, e.g.

preferably a polyurethane with the required strength is foamed, the jointless both on the outer wall of the heat transfer pipe as also adheres to the inner wall of the outer jacket pipe and the required Verbund guaranteed.

It is advantageous if the one laid in the trench is not yet covered with sand or Soil backfilled pipe pre-tensioned, causing up to a medium temperature from approx. 1300 C commercially available steel pipes can be used for the heat transfer line can.

This biasing effect can be achieved in a number of ways. at Lines for the transport of hot media, for example, purely mechanically Pulling on the two ends of the line, or by preheating the line in front of it Backfilling, for example electrically with the help of trace heating or by warm air or another heated gas or liquid through the Line is directed.

In the case of lines for the transport of cooled media, a negative mechanical preload by applying pressure to the ends of the line or e.g. cooled by subcooling the line with the aid of a gas passed through it Air or a chilled liquid.

Need of course, both for connecting each Pipe sections together in the trench as well as when the non-backfilled ones are prestressed Line at intervals, supports are created, for example, by stones or trestles, which are then created can be removed again when sanding in afterwards.

In order to distribute the tension assigned to the bias as evenly as possible To ensure elongation or contraction, it can be useful to do this temporary support to overcome or reduce friction generated. That can, if not preferred, this friction by pre-tempering with an elevated temperature or to compensate for overcooling, for example by lubricating the when laying slid beneath supports or by supporting the line on roller bearings, by periodically briefly lifting the line from the supports during prestressing or by periodically pulling or pushing on the cable ends during the prestressing.

The management or arrangement of according to the inventive method laid cables can thus be carried out with or without pre-tensioning with free ends, however, in each case simple when introducing the cable ends into buildings Stretching devices, expedient and easiest in the form of angled Expansion legs, should be provided to allow for the residual expansion between pre-tempering and record the operating temperature in the sliding area, which is no longer in the ground lying cable ends is created.

Claims (12)

PATENT CLAIMS Process for laying pipelines for hot or cooled media, which pipelines are lined up directly in the ground laid and interconnected insulating pipe sections exist, each of which has an inner heat transfer tube, which is surrounded all around by an insulating jacket runs in an outer jacket tube, characterized in that insulating tube sections be laid in which a non-positive connection from the heat transfer pipe over the insulating jacket to the outer jacket pipe and vice versa is present, and that a pipe formed from such pipe sections at their ends with simple Expansion devices, but without any fixed points in the ground. 2. The method according to claim 1, characterized in that the laid but the pipeline not yet backfilled with sand or soil is prestressed. 3. The method according to claim 2, characterized in that the bias is generated by preheating. 4. The method according to claim 3, characterized in that for prestressing a hot or cold gas or a hot or cold liquid through the pipe the line is directed. 5. The method according to claim 3, characterized in that the pre-heating the line takes place by means of electrical energy. 6. The method according to claim 2, characterized in that the bias mechanically by pulling on or Press on the ends of the line. 7. The method according to any one of claims 2 to 6, characterized in that that in order to achieve the most uniform possible distribution of the prestressing the pipe expansion or contraction to be effected the bearing friction of the laid, however not yet backfilled pipeline is reduced. 8. The method according to claim 7, characterized in that the supports be lubricated. 9. The method according to claim 7, characterized in that during the pretensioning, the line is periodically lifted briefly from the supports. 10. The method according to claim 7, characterized in that during periodic tensioning at the line ends or pressure at the line ends is exercised. 11. The method according to claim 7, characterized in that the line is supported on roller bearings. 12. The method according to claim 1, characterized in that the ends the line to be angled to form an expansion leg.