Economy In Cleaning Cast Iron Pipe
During the last year there were cleaned in the various cities of the United States enumerated below 100 miles of cast iron and wrought iron water mains of sizes varying from 4 inches to 30 inches in diameter. In some cases the tuberculation, incrustation, or deposit was large, sometimes as much as two or three inches thick on the average. In other cases the conditions were not nearly so bad. the foreign matter sometimes being only one-half inch thick, and considerably scattered. But even in the latter instances the percentage of increase in carrying capacity was very satisfactory, ranging from 14 per cent, upward. In every case the work has met with success and has been a source of profit and gratification to those for whom the cleaning has been done. The following cities and water companies have had water mains cleaned in the last year:
Altoona. Pa.; Altoona. Pa. (Penna. R. R. Co.) : Bellefontaine. O. (C., C., C. & St. Louis R. R.) ; Connellsville, Pa.; Cincinnati, O.; Edmonton. Alberta, Canada: Gettysburg, Pa.; Hartford, Conn.; Hannibal. Mo.; Little Rock, Ark.; Mercer, Pa.; McKees Rocks, Pa. (Pitts. & Lake Erie R. R.) ; Newport, Ky.; Nantucket, Mass.; Paterson. N. J. (Linen Thread Co.) ; Shreveport, La.: St. Louis. Mo.; St. Marys, Pa.: Sherburne, N. Y.; Stroudsburg. Pa.: Sharon, Pa.; Trenton, N. J.; Uniontown, Pa.; Wichita, Kan.
The methods of water-main cleaning; have been improved and new devices for carrying on the work has been added to the already extensive line of apparatus used. This has meant a reduction in the field cost and a corresponding reduction in prices charged for the work. The Cleaning Company has purchased a turbine machine for use under special conditions from Wilhelm Muller, of Germany, under whose patent this machine is made and operated. The illustration herewith shows this machine, which consists of a cutter head constructed for rapid revolution for operation by a water turbine, which is actuated by the water flowing through the main being cleaned. A cable is attached to the rear of the device for retarding the forward motion of the machine and keeping it under control, the finely divided cleanings being washed ahead and out of the main by the flowing water. The cutter head revolves at a high rate of speed, thereby removing all foreign material down to the pipe coating itself, without injury to the coating, which is left intact. This machine has been used quite extensively with great success. On general work, however. the machines used cons st of several heads flexibly connected together, these heads carrying cutting and scraping blades which revolve and cut longitudinally, removing the foreign deposits and incrustation. These latter machines are either pulled through the pipe by means of cables and winches, or forced through by the pressure of the water on flexible pistons attached to the rear of the machines. Briefly stated the cleaning operations are. first, to dig down to the mains to be cleaned in two places, the distance between these holes carrying, according to the size of the main, the pressure maintained on the main, the nature of the incrustation found in the main, and the conditions of the supply. Where there is sufficient water pressure and the condition of the interior of the main warrants it, a self-propelled machine is used, but in other cases, after the cuts are made in the main a cable is passed through the main by means of a cable carrier. After passing this cable through the main, the machine is pulled into the pipe, the pipe made up at that point, and the machine pulled through by means of a windlass, at the same time washing the main of all sediment and cleanings, these being carried to the surface of the street through a riser pipe. After the machine has been pulled through the main, the water is shut down, the riser pipe removed, and the main reconnected. The work has been done at varying costs to the owners of the mains, the cost depending on the size of pipe cleaned, the amount cleaned, and the local conditions, all of which have to be considered when estimates are made. In general, however, the work has been done at costs varying from one-fifth to one-tenth of the cost of relaying or laying new pipe. The outlook for the coming season in this field is particularly bright, for not a few of the large cities throughout the country are planning to go into this work extensively. The cleaning of water mains is progressing beyond the period of experimentation and has proved to be a purely business proposition whereby pumping costs are reduced and the increased carrying capacity and pressure for firefighting prove that this work pays for itself many times over. A great deal could be said of the economy of pipe cleaning. As an instance, the cleaning at Gettysburg, Pa., may be cited, as the work was handled upon a very close margin of saving. There was approximately 15,000 feet of eight-inch pipe to be considered. Pitomcter tests made before the work was arranged for showed that an increase in carrying capacity of 10 per cent, could surely be obtained by cleaning with a possibility of securing a larger increase. With the capacity increased by 10 per cent, the owners could postpone laying a parallel eight-inch line for five years, thereby saving on the investment charge. The saving in pumping expense was calculated from the decrease to be secured in the head pumped against and questions of depreciation of plant considered. It conclusively showed that the owners would save money by having this line cleaned, so the work was done, and pitomcter tests after cleaning showed an increase in capacity of 14 per cent. In now pipe installation work the question of keeping the underground system in good condition at the least expense should be considered. Lines should be laid with as few bends as possible, and such as are necessary should ho of long radius. Instead of one 90-degrec bend, two 15-degree bends can often he used, and this will probably mean a saving of time and expense when cleaning has to be considered. Hatch boxes in manholes should be installed where possible and according to some prearranged plan, so that the lines can be periodically inspected, and the hatch box used for entering and removing cleaning apparatus when cleaning becomes necessary.
Care is needed in the yarning of joints, so that balls or strips of lead arc not formed in the bottom of the pipes, as these obstructions often hold up the cleaning apparatus, causing additional cuts, delays and expense.
Every water works man will probably have to look into this cleaning matter sooner or later, although there may, perhaps, be water which will not eventually cause the mains to become dirty. Engineers tell us that defective pipe coating will allow incrustation to take place, and that soft waters being more commonly acid will cause more of this trouble than hard waters, that both filtered and unfiltered waters will do so, but that more trouble might he expected from surface waters than from ground waters. Filtration will prevent deposits, but. until the long-looked-for “perfect” pipe coating or pipe is discovered cleaning may he necessary sooner or later.