Besides being in this form used for miscellaneous purposes, thousands of tons of wire are annually made into wire nails, staples, wire fence, barbed wire, etc., all of which products are of American derivation, with the possible exception of wire nails. Even this, however, if not originally ours we have made ours through our great production. All are very speedily turned out by automatic machines into which the wire or wires feed. The product drops out into boxes below or is rolled into coils as is the case of the wire fence and barbed wire. The speed of the machines is so great that the eye cannot begin to follow the operation.
Wire being so well known it is not necessary to speak of its uses, but it will be interesting to call attention to the very extensive production of this steel product. Of the 32,000,000 tons of steel produced in 1915, for instance, over 3,000,000 tons were rods and wire, and when we think of the length of small or even average sized wire that it takes to make a pound, a hundred weight, or a ton, some slight conception of the amount of wire produced and used comes to us. As the material for wire gauze and cloth, wire rope, cable, piano strings, springs of all sorts, pins, needles, nails, fence, barbed wire, and the myriad of other things, wire really is one of our great products.
It was mentioned that piano wire had been made which had a tensile strength as high as 400,000 pounds per square inch, which is six or seven times the strength of an equivalent cross-section of steel rail or plate. Wire is undoubtedly the strongest product which is made from steel. This is why wire rope or cable is so strong. It is made by twisting together many small wires.
Though extremely recent from the standpoint of our world’s history, the building of the famous Brooklyn Bridge by the Roeblings was far enough back that we likely have forgotten that each of the four big 15¾–inch cables is made up of 5,296 separate wires tied into a bundle.
Undoubtedly the best preservative against corrosion for iron and steel is what is known as “hot galvanizing.” Much wire is hot galvanized. In this process the wire is “pickled” in weak acid to remove scale, given a soft red coating by dipping in weak muriatic acid and drying. The strands of wire 20 or 30 abreast are run through a kettle of molten zinc. The wires are wiped smooth and free from excess zinc by pulling them through asbestos pads. A continuous coating of zinc is thus permanently left upon the surfaces of the wires which very effectively keeps them from rusting. Wires which have to stand severe weather conditions may not have the excess zinc wiped from them. Telegraph and telephone wires often have the thicker or unwiped coating.
Very naturally the drawing of wire requires use of much greater power than the rolling of rod and the speed of drawing is nowhere near as great. Therefore the cost of wire is comparatively much greater than the cost of rolled products. In the case of watch springs it was once computed that the product had to bring 50,000 times the cost of the steel from which the wire was drawn.
“Continuous” wire drawing has not been so successful nor advantageous as was the continuous rolling of rods. It has been possible in a small way and with certain grades of the product to apply the continuous process, but, mainly on account of mechanical difficulties, continuous drawing of wire seems to be comparatively unimportant.
CHAPTER XX
THE MANUFACTURE OF PIPE AND TUBES
Tubes of some sort have been in use by man since very early times. Nature provided the first ones in the way of hollow stems of shrubs, such as alder and bamboo. Some of these we saw in use by the early smiths conveying the blast of air from their goat-skin bellows into the crude clay furnaces built in the hillside.
Tubes made of clay, stone, lead and bored logs were also used. Much later pipes made of cast iron came into rather extended use for the conveyance of water. The general use of gunpowder greatly accelerated the manufacture of small tubes which the smiths produced for gun barrels by hammering and welding together long, red-hot strips of wrought iron about round rods or “mandrels.” About 1815 illuminating gas came to be used in England for house lighting. This brought a demand for tubes of considerably greater length, which were first made by screwing or otherwise fastening together old gun barrels which were very plentiful at that period.