GB1012442A - Improvements in or relating to pipeline cleaning methods and apparatus - Google Patents

Abstract

1,012,442. Abrasive blasting. KLEAN KOTE Inc. May 22, 1962, No. 19696/62. Heading B3D. A method of cleaning a long pipe-line in situ comprises injecting at the inlet of a relatively long primarily horizontal section of the pipe-line a mixture of sand and gas at a velocity sufficient to produce agitation of the sand through the pipe-line section, and venting the gas and sand to the atmosphere through the open outlet end of the pipe-line section. In apparatus for carrying out the method, Figs. 1-3, a mixture of sand and air or other gas is delivered from a sand supply container 10 through hoses 12 to a head 14 to which air or other gas is supplied to introduce the mixture into the pipe-line P. The container 10 is a metal tank mounted-by uprights 16 on skids 18 which enable it to be readily moved. The vessel is charged with sand through inlets 20 having closures 22. Pipes 26 extending through the top of the vessel terminate above the bottom of the vessel and are held by collars 48 on the opposite arms of a bracket 44. The hoses 12 pass through the pipes 26. Air from a compressor 60 is supplied, under the control of valves 78, to vertically adjustable jets 64 in the bottom of the vessel, whereby sand is carried upwardly through the hoses 12. Each pipe 26 has openings 50, 52 extending through the hose 12 and located above the level of the sand in the vessel. Air from the compressor 60 is supplied, under the control of valve 62a, to a pipe 56 having its outlet 58 above the sand level, whereby the vessel is pressurized and air flows through the openings 50, 52 into the hoses 12. The head 14 includes a hollow casing 80 having an outlet connection 84 for securing to the inlet end of the pipe-line. Pipes 88 extending through end wall 86 into the casing contain flexible hoses 90; the sand-air mixture is delivered from the hoses 12 to the hoses 90 under the control of valves 12a. Air from a compressor 98 is supplied, under the control of valves 100, to pipes 92 extending through the wall 86, their discharge ends being near the wall 86 and remote from the discharge ends of the hoses 90. Disposed in front of the discharge ends of the pipes 92 are baffles 94 inclined so that the air from the pipes 92 is given a swirling motion in the casing 80 to cause a gyratory movement of the free ends of hoses 90. For large diameter pipe-lines carrying natural gas, the gas under pressure in the pipe-line may be used as a motivating force. In this arrangement, Figs. 4-6, gas from a manifold 117 passes through valve 121 to a manifold 122 and thence through a pipe 124 containing a valve 124a to jets 152, 153, 154, whereby sand in a container 130 is blown up pipes 147, 148, 149. These have near their upper ends openings 156 and gas from the manifold 122 passes through a pipe 123 containing a valve 123a into the upper part of the container 130. The sand-gas mixture from the pipes 147, 148, 149 passes through pipes 141, 142, 143 containing valves 144, 145, 146, to a head 113. The pipes 141, 142, 143 extend through the rear plate 139 of the head 113 and are equally spaced about a circle having a diameter somewhat less than that of the pipe-line 110 being cleaned. Gas from the manifold 117 passes through valve 120 to a manifold 125 and thence through pipes 126, 127, 128, 129 containing valves 126a, 127a, 128a, 129a to the head 113. The pipes 126, 127, 128, 129 extend through the rear plate 139 of the head 113 and are equally spaced about a circle having a diameter substantially equal to that of the pipe-line being cleaned. Baffles 140 within the head 113 cause the gas to travel in a spiral path in the rear portion 138 of the head which is joined by a frusto-conical section 137 to a front portion 135 having an internal diameter similar to that of the pipe-line being cleaned. When cleaning, the pipe-line 110 is preliminarily cleared by purging with gas; to effect this, the head 113 is connected to the pipe-line and valves 120, 126a,127a,128a,129a opened. After a suitable period, the head 113 is disconnected and a pig 160 having cup-like rubber washers 160a is inserted in the end of the line. The head 113 is then re-connected to the pipe-line to drive the pig through the line to clear any debris or fluid and to ensure that there are no air pockets. Sand blasting is then performed. For this, the valve 121 is opened to supply gas to the container 130 so that sand passes to the head 113,- and the valve 120 is opened to admit gas to the head 113 to drive the sand through the pipe-line; the gas pressure to the container 130 is maintained greater than the gas pressure to the head. A given charge of sand is admitted to the line during a short period of time as determined by the inlet pressures, the sand supply being then cut off by operating valve 121 while the gas drive is continued to propel the charge of sand through the pipe-line to the outlet. The valve 120 is then closed and the pipe-line allowed to return to atmospheric pressure. The sand blasting is repeated as often as necessary to clean the pipe-line to a bright surface polished to a smooth finish. To clear any sand or dust a cleaning pig 161 having fine wires forming a brush is used.