Abstract: A method of detecting the presence of moisture adjacent the exterior side of tubes in a pipe system such as a subterranean district heating system of insulated tubes, whereby it is measured or registered whether an electrical conductivity exists between two electric conductors permanently positioned immediately adjacent the tube in supposed dry and electrical insulating but hygroscopic surroundings. Furthermore, a pipe system and a pipe having means for facilitating the use of the said method, these means comprising one or more electrical conductors extending along each pipe embedded in the insulating material surrounding the pipe.

Abstract: A method of providing insulated joints between consecutive lengths of insulated pipes each consisting of at least one fluid conducting pipe surrounded by a layer of heat insulating material and an outer protective tube from which the ends of the conductor pipe or pipes project, whereby two aligned pipe lengths are joined by joining the protruding conductor pipe ends by welding or otherwise, thereafter mounting a tube casing around the space between the adjacent ends of the insulating material, said casing being sealed against the end portions of the protective tubes, then letting a foam producing substance foam up inside the tube casing until the foam flows out through an upper hole in the tube casing, and thereafter closing this hole by means of a stopper, characterised in that the stopper is mounted in the hole before the foam appears therein, the stopper used being adapted so as to close the hole only partially in the first instance and having means operable to completely close the hole, these closing mean

Abstract: A method of establishing pipe systems for hot media, such as subterranean district heating pipe systems, comprising arranging a number of pipe lengths in continuity of each other with a certain spacing between the adjacent ends thereof, and interconnecting these ends by means of relatively short, axially easily compressible conductor elements such as tube bellows, whereafter the pipe lengths are axially expanded by sending a hot medium through the pipe system thus assembled, until the single pipe lengths, at a temperature below the expected maximum operational temperature of the system, have expanded sufficiently to cause the adjacent pipe length ends to abut against each other, whereafter these pipe length ends, by welding, bolting or otherwise, are joined rigidly to each other. Hereby the pipes may be anchored rigidly to their surroundings and be subjected to temperature variations without the lack of thermal movability of the pipes causing unpermissible stress in the pipes.