District-heating line and a method of manufacturing the same

• US 4,288,653 A
• Filed: 03/17/1980
• Issued: 09/08/1981
• Est. Priority Date: 06/18/1979
• Status: Expired due to Term

• Current Assignee: Hans Blom, Leif Wiberg
• Original Assignee: Hans Blom, Leif Wiberg
• Inventors: Blom, Hans, Wiberg, Leif
• Primary Examiner(s): Askin, Laramie E.
• Application Number:
  US06/130,725
• Time in Patent Office: 540 Days
• Field of Search: 174/11 R, 174/47, 174/96, 174/98, 174/110 F, 73/40.5 R, 73/49.1, 137/551, 138/33, 138/103, 138/104, 165/11 R, 200/61.04, 200/61.05, 219/301, 237/13, 324/52, 324/61 R, 324/65 R, 338/34, 338/35, 340/604, 340/605, 361/49, 29/433, 29/825, 156/47, 156/51, 156/56, 264/46.5, 264/229, 264/238
• US Class Current: 174/47
• CPC Class Codes: F16L 59/143 Pre-insulated pipes
• CPC Class Codes: Y10T 137/8158 With indicator, register, recorder, alarm or inspection means
• CPC Class Codes: Y10T 29/49838 by stringing

Abstract

A district-heating line comprising an inner metal tube intended for the transfer of heating medium and encircled by an insulating layer of foamed plastic. Arranged around the insulating layer is a protective tube. To enable an alarm to be given in the event of a fault in the line, there is fixedly mounted on the outer cylindrical surface of the metal tube, an elongated block which carries at least one alarm conductor, said conductor being grouted in a fixed position in an associated channel in the block by the foamed plastic insulating material. In this way, the alarm conductor can be fixed at a given distance from the metal tube, to facilitate the localizing of a fault.

Claims

1. A district heating line of the kind including an inner metal tube for transporting a heat transfer medium, an insulating layer of foam-plastic material arranged around the metal tube, a moisture impenetrable protective tube surrounding said foam-plastic layer, at least one electrical conductor formed as part of an electrical circuit, elongated blocks mounted on and affixed to the inner metal tube along the length of the tube, said blocks being made of electrically insulating material and having extending along the length thereof at least one radially outwardly opening channel with the channels on adjacent blocks aligned with one another, said channels being dimensioned to accommodate said electrical conductor and position it at a fixed distance from the outer cylindrical surface of the inner metal tube, and means securing said electrical conductor in said channels at said fixed distance from the outer cylindrical surface of the inner metal tube.

2. The district heating line of claim 1 in which the elongated blocks are made of a foam-plastic material.

3. The district heating line of claim 1 in which said electrical conductor is stretched when accommodated in said channels.

4. A method of manufacturing a district heating line including the steps of forming elongated blocks each having at least one axially extending radially outwardly opening channel dimensioned to receive at least one electrical conductor, attaching a plurality of said elongated blocks to the outer surface of a metal tube with the channels of adjacent blocks in alignment, positioning at least one electrical conductor in the aligned channels and securing said conductor at a fixed distance from said elongated metal tube, arranging a protective tube around and coaxial with the metal tube and elongated blocks, and pouring a hardenable foamable plastic material in the annular chamber between the metal tube and the protective tube.