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Use of Handbooks on Steel

web, sizes, rolls, shapes, thickness and called

USE OF HANDBOOKS ON STEEL.

The steel used in a building is in the form of single pieces., or combinations of one or more pieces, to which the general term "shapes" is applied. All shapes are made by rolling out the rectangular prisms or ingots that come from the blast furnace. The following comprise nearly all the shapes rolled : Bars or Flats, Rounds, Half Rounds, Ovals, Flat Ovals, Plates, Angles, Tees, Zees, I Beams, Deck Beams, Channels, Trough Plates, Corrugated Plates, Buckled Plates. Il lustrations of some of these are given in Figs. 25 to 35.

flethod of Rolling. The processes of manufacture are prac tically identical in all mills; and the sizes of the different shapes are identical in all mills for nearly all sizes. Certain sizes are known as "standard," because they are rolled constantly by all mills. Certain other sizes not so commonly used are known as " special," and vary some what in the different mills. These distinctions will be explained in greater detail later on.

The process of rolling an I beam is in general as follows: The ingots are put into what are called "soaking pits" below ground, which are heated by natural gas. When white hot or at just the right temperature, they are taken out and passed several times through the first set of shaping rolls. These rolls are at first spread nearly the depth of the ingot. They are cally lowered, however, as the ingot is passed through, and so reduce the thickness sufficiently to enable the piece to pass through the next set of rolls, which give it the general shape of the letter I, though it still retains much thickness, and is only partly formed. After being shaped sufficiently by these rolls, the piece is passed to the third or finishing set of rolls, where the final shaping takes place. The piece, still very hot, is then passed on by movable tables to circular saws, where it is cut into certain lengths. Each size and weight of beam or other shape requires a distinct set of rolls in order that the pieces may be given exactly the required thickness and dimensions. Therefore, only one size

and weight is rolled at a time, and all orders that have accumu lated since the last rolling of this size are then rolled at once.

The intervals of time that elapse between rollings of a given size vary considerably, being in some cases perhaps six weeks, and in other cases several months. Generally the larger sizes are rolled at one mill and the smaller sizes at another.

Characteristics of Shapes. Having seen in general how shapes are formed, the student should now become thoroughly familiar with the features of each. Beams and channels consist of a thin plate-like portion, called the " web," and, outstanding at each end of the web and at right angles to it, what are called ,‘ flanges." A beam has the shape of a letter I and is therefore called an I beam. A channel is like a letter I with the flanges on one side of the web omitted. The connec tion of flange to web is curved, and this curve is called the " fillet "; also, the inner side of a flange is beveled, and this bevel is in all sizes the same, viz., 161 per cent with the outer side of the flange. A curve of varying radius connects the outer edge with the inner side of a flange. The distribution of metal in the heavier sections of a given shape is shown by the portion not cross hatched in Figs. 25 to 29. It will be seen therefore that for a given depth, the only difference in the different weights is in the thickness of webs and width of flanges.

The accompanying cuts, Fig.

36, shows the relations, radii of curvature, and other data which are standard for all beams.

c..60 minimum web C= minimum web + inch s = thickness of web = t minimum