GB1311017A - Method and apparatus for blocking pressure pipes - Google Patents

Abstract

1311017 Stopping pipes GAS COUNCIL 16 Dec 1971 [16 Dec 1970] 59742/70 Heading F2P In a method of temporarily blocking the bore of a pipe 2 carrying a pressurized fluid, for example for repair or inspection, an expansible, flexible sealing member 6 is inserted through a hole 37 in the pipe wall upstream of a rigid support device 5 which is inserted into the pipe bore, preferably through a further hole 9. Pressure boxes 10, 56 are sealingly mounted on the pipe as shown where the holes 9, 37 are to be drilled, gate valves 13 being provided to seal the lower part of the boxes so that the drilling apparatus may be removed through the upper sections of the boxes and to allow the seal and support members 6, 5 to be inserted. The support device 5 depends from a tube 8 and comprises an elongate support plate 23 and a number of movable plates 28 rotatably mounted on the plate 23 at their centres by bevel gears (27, 31) (Fig. 3, not shown). The plates 26 are rotated, by rotation of the tube 8, from an in-line disposition when the support 5 is inserted through the hole 9 to fan out across the bore thus providing a rigid support for the expansible seal 6. Flanges 22, 55 on the tube 8 seal the hole 9 and locate the device 5 in the pipe so that the axis of rotation of the plates 28 coincides with the bore axis. The seal 6 may comprise an inflatable bag carried on a flexible tube 34 which passes through a guide tube 36 threadedly engaged with a collar at the top of the pressure box 56 (Fig. 4, not shown). An arcuate depending finger 44 guides the bag 6 into position prior to inflation. Most of the fluid which may seep past the bag seal 6 is directed out of the pipe by a tube 51 which carries a further sealing bag 7 inserted through another hole 63. If the fluid is inflammable the tube 51 is connected to a flame trap. Any fluid which enters the tube 8 is extracted at an outlet 53. A section of the pipe 2 may be isolated and by-passed by erecting a similar arrangement, in mirror-image fashion to that shown, at a second downstream location on the pipe. Fluid is directed through the tube 36 via an enclosure 45 to a by-pass pipe 50 and the fluid re-enters the pipe downstream through the second seal arrangement. A tube 48 connects the enclosure 45 and the upper section 15 of the pressure box 10 to equalize the pressure under the control of a stop-cock 49.