Verfahren zum Verlegen von ein erhitztes Medium fuehrenden Rohrleitungen in vertieftem Erdreich sowie dafuer zu verwendende Isoliervorsatzschale

摘要

1325788 Buried and insulated pipes I QUASSOWSKI-KEMPF 3 Aug 1971 [7 Aug 1970] 36436/71 Heading F2P A pipe is insulated by a covering formed from a plurality of insulating shells which co-operate to completely surround the pipe along substantially its whole length, the shells having at least on the inside a coating of bituminiferous material and a resistance to temperature of above 180‹ C., and an embedding substance covering the pipe along substantially its whole length, the embedding substance containing bitumen and a heat retaining aggregate and filler, the embedding substance having a greater coefficient of thermal conductivity than the shells and being of greater thickness than the shells. A method of laying such a pipe may incorporate the lagging steps before or after the introduction of the pipe into the ground. Thus sections of the pipe may be welded together in a trench before lagging, or lagged sections with free ends may be laid in a trench, the ends welded, and lagging applied to the joint areas. The embedding substance may be contained within a sheet metal case 5. The Shells.-The shells are preferably semicylindrical and include a core having a temperature resistance in excess of 180‹ C. covered with bitumen or asphalt, the covering being preferably between 5 and 15 mm. thick. The shells have a thermal conductivity between 0À04 and 0À07 k.cal./mh.‹C,, and preferably have a density of 300 kg./m3. Shell cores may be of pearlite particles or foam glass particles embedded in a binder such as water glass or high temperature bitumen and may be dried at 300‹ C. Alternatively the shells may be of foam glass. The Embedding Material (6).-This may be of bitumen with a filler aggregate of higher thermal conductivity than the shells 4. The filleraggregate may be cork, and the bitumen may incorporate a light asphalt, the mixture being cast at about 200‹ C. The material has a thermal conductivity of approximately 0À1 k cal./mh.‹C. Clamps (not shown) may engage outwardly facing grooves 511 in the casing 5 to prevent distortion during casting of material 6. Operation.-When the pipes convey hot fluid the coating of bituminous material on the inside of the shells 4 melts and allows movement of the pipes as they expand. Any voids left between pipe and shells may be filled by more bituminous material flowing in between the joins of the shells. The shells have good enough insulation to prevent the embedding substance 6 from losing its integrity.