WOODEN STAVE CONDUITS
Their Use in Ancient and Modern Times.
Specially written for FIRE AND WATER ENGINEERING.
While commonsense shows that iron and steel are in the end the most economical, as they are generally the most serviceable materials for water pipes. yet those of wood have enjoyed and still enjoy a great measure of popularity and success, especially in California and Mexico. Wood pipes are not of today or yesterday. The ancient Egyptians employed them for carrying water; Pliny alludes to them as in use in ancient Rome; the water supply of Constantinople was so conveyed in the early days of the Byzantine Empire, and part of the water the people of that city drink today is furnished by means of such pipes. From 1582 to 1800 Londoners had no other way of receiving their water than through elm logs that had been bored out for the purpose, of which over 400 miles were laid, some very small por tion of which is said to be still in use. Recently, when the waterworks system was being reconstructed in certain districts of the’ British metropolis, a quantity of such pipe was dug up and found to be perfectly sound. In 1799 the Manhattan company was formed by Aaron Burr to supply New York city with water, and the wooden pipes then laid down were in constant use till 1848. when the first Croton aqueduct was built. Many large fragments of these pipes, also, have been dug up of late during the subway work, and all were in excellent preservation. In 1814 Philadelphia bad thirty miles of such pipe in use, some of which may be doing duty today. In 1881 there were still to be found in Detroit, Mich., eighty-four and one-half miles of wood pipes, of which some was laid as late as 1857, and some is even yet utilised. In 1811, at Lynchburg, Va., mains were laid, which were of bored pine logs ten feet long, ten inches in diameter, bored to three inches and bound with iron bands at the joints. When iron mains were substituted thirteen years afterwards, and their predecessors were removed they were in the best of preservation, as were two other joints that were taken up in 1868. Today Toronto, Ont., pumps water from lake Ontario through a wooden pipe of four feet internal diameter, which has been in use for fifty-one years, and is still in good condition. In Boston and most other cities, especially in New England, wooden mains are in use, although they are rapidly being superseded by iron pipe. Denver City, Colo., has nearly too miles of wood-stave pipe in use, and till quite recently continued to lay it. The first of this pipe was laid in 1883, and is now in good condition. Most of Denver’s pipe is made from California redwood, although pine has been used to some extent. Much of the water brought to Denver for domestic use passes through wood pipe. 1’he difficulty, in some cases, the impossibility of making such pipe has been a considerable factor in its disuse. In those districts, however, where greater facilities are on hand, it is now possible to build a wood-stave pipe up to ten feet in diameter, which possesses all the advantages of bored logs, and will also stand a pressure up to 100 pounds per square inch. This is accomplished by the use of California redwood (the Sequoia sempervirens) and the employment of specially constructed machinery, and the use of a patent hardwood tongue for connecting the stave ends. Not only is this wood applicable for waterworks and irrigating schemes, but it has been successfully used in drainage works and mines. As regards the durability of wood pipe, there can be no question, in fact, there is practically no end to the life of wood pipe, when properly built and laid in the ground, so long, at least, as it is kept filled with water, or, in other words, in a state of constant saturation. This is especially true of Mexico, on account of the soil being so impregnated with alkalies and other chemicals, which rapidly corrode iron or steel, whereas wood pipe is benefited by these same chemicals, which harden it and make it more lasting. Mexico, therefore, naturally prefers to make use of redwood pipe. It is easily carried—sometimes the staves are lashed to the backs of burros and transported without difficulty to otherwise inaccessible places. The specific gravity of the wood of the sequoia is lighter than that of any other known timber—it weighs only two and one-half pounds to the hoard foot—and, as it is free from pitch, knots and seams, has a great power of resistance. On the Pacific slope, where irrigation is in such vogue, hydraulic engineers make great use of these stave pipes, which are rapidly superseding the oldfashioned trestle flume across deep canons and gulches. This style of pipe is then generally used as an inverted syphon. The staves, three or more in number, with diameter ranging from three inches upwards, are banded spirally with heavily galvanised, stout, steel rods, passed through a bath of hot asphaltum, as it is wound on the pipe. This pipe is handed for four different pressures—namely, twenty, fifty, too, and 150 feet. The bands are spaced from two and a half to four and a half inches apart, according to the pressure which the pipe has to stand, and the bands never supply less than six times the strength necessary to retain the pressure. In most sizes of pipe the bands are from ten to thirty times as strong as indicated by pressure tables. By this peculiar method of banding, the pipe, which before banding is a little larger to allow for compression, is firmly compressed in a machine to the point of a slight reduction in diameter. This is effected by subjecting it to a pressure applied spirally along the pipe and continuously increasing from the point at which the pressure is first applied to the point at which the band is wound on under a tension sufficient to retain the compression previously gained. This seats the band so deeply in the wood that no future expansion is possible. The process is continuous, and the tension never varies after being set at the required point. An indicator shows the slightest variation. The staves are thus drawn firmly together and compressed to the point that secures a uniform density of wood, so that a perfect joint is made before the bands are applied. The bands are required simply to hold the members firmly in place, and to resist internal pressure. The pipe is banded in lengths of ten to twenty feet, the ends being sawed off square and turned down to a slight taper. The joints are connected by cast iron collars the thickness of cast iron pipe. These collars taper from both ends to the centre, to correspond to the taper of the pipe, but are made one-eighth of an inch smaller to allow for compression in driving, which is done with a heavy maul or sledge hammer, and driving block. A joint can thus be made that will stand 100 pounds pressure per square inch, even before swelling, and will never give future trouble. Like the couplings, the fittings used for this pipe, such as tees, elbows, bends, branches, Y’s, etc., are made of cast iron, with taper socket to fit the taper ends of the pipes. The stave-pipes can be made with an internal diameter of nine, possibly ten feet—one, which is to furnish a domestic supply for Lynchburg, Va., which, as already stated, started with wooden pipe for its water supply, includes twenty miles of pipe of thirty-inch diameter, while a section of waterpower pipe of the same redwood at Cornell University has an internal diameter of sixty inches. A two-foot domestic water service redwood stave pipe, showing a two-foot gate, and a pipe of the same material with steel and iron elbows illustrate this article by courtesy of the Scientific American. These staves are likewise used for water tanks; they may also be made to hold wine, oil, sewage or chemicals, and the pipes may be employed for the same purposes. The tank is built in the shape of a perfect cylinder. The larger-sized redwood staves are made in short sections. In the completed pipe lines the radii of the curves are of necessity long; in a ten-inch the radius of the ordinary curve is about 125 feet; in a nine-foot, about 800. Where sharp Curves are met. riveted steel elbows must be introduced, instead of cast iron. While the compression process is being undergone, in order to close the butt-joints, the staves are driven endwise, and jack-screws are generally used to bring the larger sized pipe into proper curve. In previous numbers of this journal have appeared articles on wooden stave pipes, one of which described that in use at Atlantic City, N. J.
The plant for Osceola, Neb., may be installed before spring. Bonds for $20,000 have been issued for the system.