PIPE. 47 PIPE. pipe to a larger diameter than the other, and turning down tlie other end to a like exterior dian-.eter, then inserting the small end of one pipe in the large 'end of the next; or both ends of the pipe may be bored, as described, and the space thus formed may be filled by inserting a short length of pipe just thick enough so its inner side will be flush with the inside of the main pipe. To avoid the limitations in size incident to bored logs, and to secure still greater facility in transportation and construction, particularlj' in rough country, pipes built up in place from wood staves are now used. In its present form wood stave pipe is composed of staves cut internally and on the edges (or radially) to form a conduit of the desired diameter. By breaking joints a continuous pipe is .secured. The staves are held together and strength to resist any desired moderate pressure is secured by the use of steel bands or rods, provided with screw ends and nuts for tightening. Since about 1895 smaller sizes of stave pipe, for which the construction just described is not suitable, have been made by winding them spirally with steel rods under tension by means of a machine; a little later small, wire-wound stave pipe was put on the market. WooD-FiBBE Pipes, in sizes from 11^ to 8 inches, in lengths of 5 feet, with screw coupling joints, are made and used for conveying gas, acids, and water, under a pressure of not more than 50 pounds. They are made from wood pulp. (See Papeb. ) A thin sheet of pulp is wound around a core until the requisite thick- ness is obtained. The pipe thus formed is dried, impregnated with a wood preservative, and then has its ends turned in a lathe to form joints. Wrought-Iron Pipes. The earliest wrought- iron pipes appear to have been made from an over-stock of gun barrels, early in the nine- teenth century. The small end of one tube was screwed into the large end of the other. The pipes thus made were used to convey illuminat- ing gas. The longitudinal joints were lap-welded. The increasing demand for ^vrought-iron gas pipe led to the adoption of butt-welded pipes of uniform size and thickness, united by sockets or couplings into which the ends of the pipe were screwed. Like the gun barrels, these pipes were welded by hand, a few inches at a time. In 1825 Cornelius Whitehouse invented a process of butt-welding which was, in its essentials, con- tinued in use through the remainder of the cen- tury. He first rounded up the iron plate, or skelp, then heated half the length of the pipe and drew it through two dies by means of a chain. The dies pressed the heated metal to- gether. Til is patent was bought by .Tames and .Tohn Russell, pipe manufacturers, one of whom had just patented a process of butt-welding by pressing the edges together, but in which only a few inches could be welded at a time. With the development of steam engineering larger and stronger pipes were demanded. The Russells bent their energies to meeting this demand by improving on the old lap-welding process already described. This appears to have been about 1S.S.5, but whatever the date, their process for lap-welding, like theirs for butt- welding, involved the main principles still fol- lowed. In the recent process of lap-welding pipe and tubes the strips or plates of metal are heat- ed, have their edges beveled or scarfed by pass- ing through rolls, and then drawn through a die and formed with edges overlapping, ready to be welded. The partly made pipe, or skelp, is now licated a second time' and welded by passing it through two rolls, the inner lap resting on a stationarj- mandrel, which corresponds to a blacksmith's anvil. Finally, the pipe thus made is straightened, threaded, screwed into a coup- ling, and tested by means of water pressure. Butt-welded pipes are now made by drawing a. heated plate, by means of tongs, through a conical-shaped die, thus pressing the edges so firmly together that they unite. The further steps in the process are the same as for lap- welded pipe. Butt-welded wrought-iron pipe is made in small sizes, from % to about 1 inch in diameter, and is tested at an internal pressure of 300 pounds per square inch. Lap- welded pipe is made in sizes from 1% or 1% to 30 inches in diameter, and is often subjected to very high pressures. Pipes are also drawn from hollow or cylin- drical ingots formed by passing a heated round billet through diagonal rolls and over a mandrel. By reheating and rolling under pressure the ingot is finally brought down to the desired diameter and thicloiess. It is then annealed, pickled, and cold-drawn, to give it the desired finish. In the Mannesman process, invented in Europe, and patented in America in 1887, pipe is rolled from a solid, but heated, bar or rod by means of two tapering rolls and a mandrel. Steel Pipes are made in the same general way as has been described for wrought iron. In addition, they are sometimes cast and are frequently riveted for large sizes, as described below. In 1901 patents were granted for the Bartlett- Kent process of rolling large sizes of seamless steel pipe from hollow cast ingots or cylinders. The range of sizes proposed by the manufac- turers is 12 to 30 inches in diameter, with shells from % to 11/4 inches thick. The essential parts of the machine are two sets of internal and two sets of external rolls, all placed at right angles to the axis of the pipe being rolled and all hav- ing curved surfaces corresponding to the inner and outer circumferences, respectively, of the ingot which is being rolled. There are three rolls in each set. making altogether contact with about one-half the respective surfaces of the ingot. The second set of rolls in each case is so placed as to come in contact with those por- tions of the ingot which are not touched by the first set. In addition, the ingots can be rotated through a part of their circumference. The machine is fully described in the Iron Age (New York) for April, 1901. Riveted Wrought Iron .xd Steel Pipes have their longitudinal and frequently their circular joints riveted, instead of welded. Wrought-iron sheets, rounded and riveted, have long been used for stovepipes, and in 1853 a California miner laid a 5 or fi inch length of ordinary stovepipe for hydraulic mining. In a few years this sort of pipe, only heavier and better made, was in general use. Both spirally riveted and spirally icelded steel pipe have been used, and the former Is still on the market. In each case plates of steel are
