Triple Riveted Joint

Triple Riveted Joint is an arrangement of rivets in three rows instead of in two as in double riveting, by which means the rivets can be spaced at greater distances apart to obtain a joint equally strong throughout. Considerable increase of strength amounting to about 20 per cent, results from its adoption, and more still from that of quadruple riveting, but the difficulty of caulking without springing the plates is augmented as the pitch increases, and for structures where this process is imperative it becomes a good argument against adopting this sort of joint. In a grouped riveted joint in girder work this species of multiple riveting, or a modification of it, is frequently met with.

True Joint

This occurs when the surfaces joined are close, smooth, and parallel throughout.

Turned and Bored Joint

Turned and Bored Joint is used in jointing cast iron pipes, and consists of a spigot and socket accurately turned in a lathe, the spigot with a slight taper and the socket a little cone-shaped to exactly fit it. The ends are then smeared with whiting and tallow, or painted with a mixture of red and white lead or other suitable compound, and when put together the joint is perfected by forcing the spigot well home with a mallet or otherwise. This method is only adapted for pipes laid in straight lines or in curves of considerable radius, otherwise the ordinary lead joint or some other admitting of a little cranking must be employed. It has been used, however, with pipes up to 48 in. in diameter, and possesses the advantage of not requiring so wide a trench as when the main layers have to get all round the sockets. A form of turned and bored joint is also found in pinned attachments occurring between the booms and bracing bars of girders where the pins are turned and the holes accurately bored to their exact size.

Union Joint

Union Joint is a mode of uniting the ends of pipes, rods, etc, by means of a coupling, which for pipes will be found in Section XIV. Unions for connecting rods have been explained under Screw Shackle, which embodies the principle of all those most in vogue for tension rods.

Universal Joint

This is the name given to a contrivance for connecting two rods or pipes so that each may have freedom of motion in any direction with certain restrictions as to extent. Fig. 93 is an example admitting great range of motion, the forked ends of two rods being pivoted to the extremities of two crosses which are likewise pivoted to a short intermediate connecting piece.

Vertical Joint occurs between the parts of cast iron rings or cylinders when built up in segments, and likewise at the junctions of iron sheet piling, etc, etc.

Water-Tight Joint

In wrought iron cofferdams the joints between the cylindrical pieces are rendered watertight by driving feather piles of timber into opposite recesses provided in the metal surfaces to receive them. The joints between the segments also of cast iron columns constructed in rings, and used in submerged foundations, and those of other cognate structures, are rendered watertight with red lead, the surfaces being properly faced. Beeswax, asphalte, or other non-porous and adhesive substances are useful in obtaining impermeability between rougher surfaces. Caulking with iron cement is the common method of making the joints of castings water-tight, whilst a liberal application of tar answers the same purpose when wrought iron work is to be insured against percolating jointings. Messrs. Burt and Potts have introduced a patent wrought iron water-tight casement and frame, suitable for very exposed situations.

Water Tight Joint 94

Fig. 93.