Ball And Socket Joint

A joint formed by a ball enclosed within and accurately fitting a socket, consisting of about three-fourths of a hollow sphere, the absent portion of which affords space for the tube or rod, attached to the ball, to move freely about in any lateral direction. The socket is made in two pieces, which are either screwed together or else united by flanges and bolts, the plane of junction of the flanges passing through the centre of the ball, so that it can be easily removed when requiring grease. The ball is hollow, and bereft of a portion of its perimeter, as shown in Fig. 162, exactly opposite the corresponding hole in the socket, and in order to obtain free passage for the gas there is a second hole both in the ball and socket opposite those already described, to which the pipes for the exit and entrance of the fluid are respectively attached. Before using for connecting gas pendants the ball and socket must be examined for strength, the ball removed and greased, and the fitting rejected if not air-tight. This elegant form of movable joint is likewise called Ball Joint, and Cup and Ball Joint.

Barrel Union Joint

Barrel Union Joint is one formed between the ends of tubing or barrel pipe by means of a brass connection called a barrel union consisting of three pieces (Fig. 163), two of which are respectively soldered or screwed to the ends of lead or iron pipes. One of these pieces (a), called the lining, is furnished with a flange near its edge, and the other (b) is provided with a socket, having an outside thread, upon which the third piece (c), called the cap, screws. The cap is a sort of hollow nut of octagonal form, which is slipped over the lining previous to attaching it to the pipe, and when screwed up it brings the flange close against the face of the socket, and by means of a leather washer between them (as indicated by the black lines in the figure) a superior air-tight joint is formed, admitting of being easily loosened when desired. In gasfitting all unions require washers, but in other cases the parts screwed up close need only to be truly ground down to a smooth face.

Barrel Union Joint 163

Fig. 162.

Blown Joint

This is another name for a joint made either with the blowpipe or blowing-lamp, as described in the following paragraph.

Blowpipe Joint

Blowpipe Joint is made with an instrument called a blowpipe, which is a tube terminated with a finely pointed nozzle, through which air is forced across a flame to concentrate it upon a particular spot for fusing, etc. The mouth blowpipe usually has a horn, ivory, or wood mouthpiece, and the art of using it consists in blowing and breathing at the same time, or, in other words, in employing only the muscles of the cheeks so as to maintain an even and uninterrupted blast for a moderately long time. Breathing is maintained through the nostrils whilst the mouth is replenished, when necessary, with air without interfering with the blast. Blowpipe joints are chiefly used by gasfitters for joining in., ⅜ in., and in. pipes, or other small jobs. The work being prepared by carefully fitting the parts to be united, as explained under Blown

Blowpipe Joint 164

Fig. 163.

Joint in Section X., they are scraped clean, placed in position, well steadied together, and well sprinkled or dusted with powdered black resin. The workman then puts the blowpipe in his mouth, takes a candle with its wick spread open, or what is not so safe or handy, a bunch of burning rushes covered with tallow, in his left hand, and a strip of fine solder in his right. Holding the flame an inch or so off the work so as not to smoke it, he blows a steady, clear flame on the joint, touching it until sufficiently floated, and moving about or along it with the solder, which must flow evenly, and be worked and sweated together without melting the lead, but at the same time so as to enter into close union with its surface, and without letting the solder come off in bits. The aeolipile or blowing lamp (Fig. 164) is now preferred to the blowpipe, but its flame is not so powerful. It consists of two spirit lamps, one fixed above the other, both being fed with methylated spirits. When the lower one is lighted it almost immediately boils the other, causing the vapour, which is led round to the flame of the lower lamp by a small curved pipe issuing from its top, to ignite and dart out in a horizontal jet of great heat. The joint made either with this instrument or with the blowpipe may be left nearly smooth.