Show A TOUGH engineering PROBLEM the coolgardie Cool gardie gardle project proposes the delivery of gallons of water per day at a point in the mining regions of australia miles from the reservoir in the mountains near the coast where it Is impounded to force t through h rough a pipe line for this long distance not only must its friction be overcome but it has to be actually raised a total vert icle lele distance of 1830 feet further the district through which the pipe line passes laa desert whose soil is impregnated with salts which ate are said to be so corros ivre to iron that it is deemed calest not to bury the pipe in the ground at all another reason for laving having it exposed is that in a pipe line of such great length avoidance of leaks is essential in an ordinary pipe line leaks a thousandth part of its flow in a mile the loss may be a trifling matter yet evert even so small a loss lose in a pipe line of this length would amount to nearly a third of its flow in the arid and desert through which this pipe line passes it is thought that the soil might absorb small leaks so that they would not show at all on the surface of the ground it if the pipe were buried facility of ins inspection therefore to Is another important reason tor for keeping the oie pipe above ground instead of burying it besides this the ordinary reasons for burying water pipes to get them out ot of the way and keep them from freezing in the winter do not obtain at all in the region over which this pipe line will pass and as the cost of excavation and back filling a treche miles long will be saved by placing the pipe on the surface the decision not to bury it seems on the whole a wise one the one great difficulty which is to be involved in keeping th thu pipe on the surface is the necessity ot of providing for and contraction in an ordinary continuous steel conduit buried in the earth in a temperate climate the extremes of temperature of water passing through it all will probably not exceed 35 degrees turning now to the coolgardie Cool gardie gardle conduit to be laid unprotected on the surface of the ground and with a distance dia tance between pumping catl abati ons as great as seventy five or eighty miles it Is evident that chat the water confined from evaporation and exposed in a steel pipe to the fierce rays of the australian sun may reach a high temperature in its passage from one pumping oration elation or to the next which in the case of the long eat conduits will require nearly three days the english engineers estimate the range of temperature which will occur in the fhe pipe line at 75 degrees and wes hould think this rather an underestimate it will be seen at once that with such a range ot temperature internal strains would be set up in t the 11 e pipe which might become so great as to cause movement and leakage at the circumferential joints expansion joints therefore are essential to the safety ot of the pipe and the english engineers propose that such joints shall be placed at intervals of about feet for the whole length of the conduit which would make hakea a total of about expansion joints in the length of the conduit the engineering problem presented then and one which we need hardly say is without precedent is the design of an expansion joint tor for a pipe of from twenty six to thirty one inches diameter which shall provide for a motion reaching five eighths of an inch which shall sustain pressure reaching pounds per square inch which shall be and remain tight with little or no attention and which shall be as nearly as possible a permanent part of the pipe line |