Duct seepage reduction

A method for reducing seepage through a leak in a liquid transporting duct, wherein the leak is defined in terms of its maximum dimension xL and its maximum width in an orthogonal direction yL and the effective size of the leak is given by:

• SL=(xL2+y2L)1/2 1)
• the method comprising:
• a) selecting sealing elements that are substantially planar and have an effective size SE suitable for partially covering the leak, wherein the effective size SE is less than the effective size SL of the leak, where the effective size SE of the sealing element is given by:
• SE=(a2+b2+c2)1/2 2)
• and a, b and c are the dimensions of the sealing elements in mutually orthogonal directions;
• and
• b) introducing a plurality of the selected sealing elements into the liquid being transported within the duct wherein, due to the selection of sealing elements having the effective size SE, a plural number of the selected sealing elements are sufficiently small to be drawn by the pressure differential at the locality of the leak to move over and build up over the leak, to be held to the internal surface of the duct wall over the leak by said pressure differential, to thereby reduce the size of the leak.