GB1145295A - Pipe units for conduit systems - Google Patents

Abstract

1,145,295. Preventing leakage of pipes. RICWIL (U.K.) Ltd. 20 May, 1966, No. 42333/68. Divided out of 1,145,294. Heading F2P. A pipe unit comprises a pipe 10 for carrying a fluid e.g. steam or hot water, and which is covered with a layer of insulation 12, e.g. glass fibre or asbestos and, a surrounding gas-tight tubular metal casing 14 which has end plates 22, 23 sealed around the pipe 10, one of the end plates e.g. as shown the end plate 23, having an opening, such as 45, connected to a tube 50 leading to a source of pressure gas 61, the tube ineluding a relief valve 54, a pressure regulator 62 for reducing the pressure of gas from the source to give a lower pressure to the casing 14, and a pressure sensitive valve arrangement 55-57 whereby, if the pressure in the casing drops below a predetermined value, gas is allowed to flow from the source to the casing provided the supply pressure is above the predetermined value, but gas is prevented from flowing from the casing if the supply pressure is below this predetermined value. The pipes 10 of the units are connected together at man-holes, not shown, in underground conduit systems leading e.g. from a central heating plant, each unit having a number of annular pipe supports 16 which are made e.g. of concrete and have through passages at 19. The tube 50 includes a relief valve 54, and a check valve 57, and a pressure switch 55 which has two electrical contacts which are set at the maximum and minimum pressure levels desired, the switch controlling a solenoid operated valve 56. Pressure gauges 58, 59 respectively record the pressures in the tube 50 and in the source of pressure gas 61. Each unit includes internal and external sacrificial anodes 28, 40 which are made e.g. of aluminium and which are electrically connected to the casing by metal straps 42, 67. The casing 14 is covered by a protective layer of asphalt felt material.