GB421324A - Improvements in and relating to the localisation of leaks in pipe lines - Google Patents

Abstract

421,324. Locating leaks in pipes &c. ENFIELD CABLE WORKS, Ltd., 296, High Holborn, London, and O'DUFFY, D. A., 9, Bagshot Road, Bush Hill Park, Middlesex. May 3, 1934, No. 13433. [Class 99 (ii)] A leak in a pipe line or cable a, containing a liquid b such as a mineral oil and having a make-up feed reservoir c at one end, is localized by injecting at a tapping d another liquid, such as a solution of 1-5 per cent rosin in mineral oil, which differs from the first by an easily distinguishable property and forms a column e capable of travelling within the pipe line. If the leak is at a point f<1> say, the column e will be carried towards it by oil from the reservoir c, but if it is at a point f<2> on the opposite side of the tapping d it will remain stationary, and this travelling or stationary condition of the injected column is determined by chemical or physical analysis of a sample or samples of the oil drawn from the said tapping after a predetermined period of time. The invention is also applicable to a pipe line containing a gas, e.g., nitrogen, a different gas, but one such as air having a density approximating to that of nitrogen to reduce diffusion to a minimum, being injected into the pipe. For testing a short section where the leak is known to be, and when it is not desired to make several tappings for injection purposes, one or more columns of gas may be injected at some suitable point outside the section and pushed along known distances by admitting make-up gas to one end in known volumes and withdrawing equal volumes at the opposite end. After the section has been left for a time the composition of the gas at any point along the section can be determined, and hence the position of the leak, by sampling at the point of injection or the withdrawal end of section ; alternatively the positions of the test columns are determined by withdrawing the whole gas column from the section and analyzing samples at definite intervals. The latter method may also be used for oil-filled pipes, but in this case the make-up feed must be maintained in operation.