Flange Joint

This is made by uniting together projecting rims called flanges, as shown in Fig. 83, with rivets or bolts and nuts, the former of which are not used with cast iron. The abutting flanges of cast iron ribsand the external or internal flanges of large columns require to be truly faced before bolting. Iron columns supporting overhead iron or timber girders in warehouses, etc, are provided with large flanges in the form of bearing plates or expanded caps, strengthened with stiffeners, and these require careful facing before attaching the ironwork ; but where flanged cylinders are superimposed upon one another from the foundation upwards, and filled in solid with concrete or a core of masonry, which is carried up an inch or so above the topmost cylinder for bedding the foundation slabs of the superstructure upon, there need be no nice adjustment of the flanges. Not less than four and not more than eight bolts are, as a rule, allowed to each flange. Lengths of cast iron pillars and uprights are generally united with bolts passing through flanged rims. The segments of built columns require bolting together, so that neither bending, nor buckling, nor sliding at the vertical flanges may occur. Cast iron cylinders, bolted together by means of inside horizontal flanges and filled with concrete, have split all round their circumference after severe cold, which has been accounted for from the sections through the flanges contracting more than where the metal is thinner, and the concrete not yielding proportionately to the contraction of the flanges. When necessary in piping and elsewhere, the joint is rendered tight by inserting between the flanges india-rubber washers, rings, or strips, or a composition called red cement, consisting of two parts white lead mixed and one part red lead added dry, the whole being worked up to the consistency of putty. Tar and gasket, with or without iron washers, or iron-wire rings let into opposite annular grooves in the flanges, or rust cement, described under Rust Joint, are likewise used according to circumstances. A ring of metal wrapped round with woollen cloth, then dipped in tar and inserted between the flanges, is well suited for pumps when large. Thin wood fillets or slips are similarly useful and efficacious as packing between the flanges of the elements of cast iron cisterns. In ironwork, angle iron sometimes forms a convenient flange when one has to be attached after rolling or casting. Flanges are generally used for pipes set vertically, and are handy when joints have to be loosened, but they are not adapted for some situations exposed to variable temperature.

Flange Joint 84

Fig. 83.

Folded Angle Joint

One variety is shown in Fig. 84, and is used with solder. Fig. 85 shows another form common in simple kinds of ironwork. The edge of one plate is bent to an angle to fold over the other, and the two are connected with small screw bolts.

Folded Angle Joint 85

Fig. 84.