T-Joint is formed by uniting pipes or plates by means of a T-piece shaped like the letter T. A gas main must be bladdered, and a bye pipe inserted before a portion of the main can be cut out to introduce a T for a large service, since the supply of gas cannot be even momentarily cut off with, the same impunity as water for a much longer interval. By cutting out round the main a deep groove with a round-nosed cutting punch at the two ends of the length to be removed, it will easily part with a few blows of the hammer, and after the piece is taken out a collar is slipped over the main to cover the butt between the plain ends of the main and T, whilst the joint at the other end of the T-piece is made in the usual way by inserting the spigot into the socket.

Thimble Joint

Thimble Joint is a form of expansion joint between lengths of pipe with butt ends which, being turned true, are encompassed by a narrow strip of tin, and this again is enclosed by a metal collar or thimble. Between this thimble and the tin strip, packing is stuffed to insure a tight joint, whilst permitting the ends to separate and approach during changes of temperature.

Through And Through Joint

A variety of butt otherwise called a full butt.

Tie Joint

Tie Joint is made when the end of any part or piece in tension is secured to its support. Tie-bolts which are usually made out of 1 in. round iron securing concrete floors, etc, either pass through the wall and are held by anchor plates or cast iron discs, to which they are screwed, or else their ends are flattened and turned down and rest against a wrought bar 3 in. or 4 in. wide by in. thick, built purposely into the wall to receive them. The bar, however, is often dispensed with. In timber partitions the end of the rod is usually retained in place by a nut and large washer. Tie-bars are riveted or bolted, as preferred, to the joint plates, etc, of girders. Horizontal bracing between girders, tension rods, diagonal ties, etc, are bolted or riveted at one extremity, and adjusted with cottered or screw shackle joints at the other. The chairs at the feet of rafters and the heads at their apices form convenient holds for the ties of a truss. The tie bolts of cofferdams require to be very stout, and are secured with nuts and large washers. Girders may be tied to walls with horizontal straps bolted to the former, and built into the latter, or else vertical bolts may be built up with the masonry, or lewis bolts, or dowels even, may be leaded to the stone templates. Provision for expansion is not necessary when the span is less than 60 feet.

Tight Joint, in piping or allied work, is one that is impervious to air or fluid under any pressure likely to be applied to it, and the method of obtaining it has been described under previous headings. In the construction of cofferdams, which have been aptly defined as water-tight walls, the joints of iron piling are usually made impenetrable to any abnormal ingress of water by careful fitting and fixing and a backing of concrete. The subject is further noticed under Water-tight Joint.