Blown Joint

Blown Joint is a soldered joint made with a blowpipe (under which name in Section XIV. it is more fully described) or aeolipile, otherwise blowing apparatus or blowing lamp. "When this joint occurs in plumbing it is not wiped, though, on the other hand, a wiped joint maybe made with the above instruments and strip wiping solder. In forming the joint between two pieces of lead pipe, the end of one piece is rasped off at the edge and inserted into the end of the other previously tafted with the turnpin, tanpin, or tompion, as the tool is indifferently called, and the cup is filled with fine solder, described under Soldered Joint, and in the manner explained under Blowpipe Joint. In any case, whenever the elements to be joined are lead ones, whatever may be the form of the edges, the parts where the solder is to stick, and of course unite, must be brightened with the shavehook, well dusted with resin - or covered with whatever flux may be used - and floated with solder so as to get the work into combination with it, and not merely in superficial contact, the strip solder being dipped by some artificers into powdered resin, and held to the flame, whilst the excess is removed, if necessary, after becoming hard by filing, etc. Brass and iron fittings must be previously tinned, as noticed under Copper-bit Joint, and smudge or soil, described under Wiped Joint, may be used if desired to prevent the solder from sticking beyond the confines of the joint.

Bottle Nose Drip Joint occurs occasionally, and is, as its name implies, a variety of drip possessing somewhat more character than the common sort. The rough boarding terminating the drip step is finished off with a nosing, either square or round, called in this instance a bottle nose, and the lower sheet of lead is dressed down so that its upstand stops against it, as in Fig. 137. The upper sheet is then dressed round and over the nosing and upstand, but not quite reaching, for the reasons given under Drip Joint, the nearly horizontal surface of the lower level of the drip.

Blown Joint 138

Fig. 137.

Branch Joint

Branch Joint is one occurring between a main and branch. Sometimes the latter starts from the main at right angles and at others obliquely, but in both cases its end is first prepared by rasping, and the size of the necessary incision struck off from it. The hole is then made with a gimlet or red-hot iron, and enlarged with a bolt or other tool so as to leave the edge slightly upraised. The two pipes are then fitted without allowing any burr to remain in the bore, and after being prepared and put together in the usual way for soldering, are ultimately dexterously united by wiping.

Burnt-In Joint

The lead of gutters is secured to grooves in stone cornices, and that of flats to sills, by turning down the edges of the metal into the grooves and pouring nearly red-hot lead upon them until the whole become blended into one mass. Should moisture be present, a little resin spread along the groove before pouring will prevent the molten metal flying out in spray. The joint is finally caulked when cold. Similarly a lead pipe is joined to another by pouring lead round the junction instead of solder. The lower of the two pipes is first opened out and then stopped up with sand nearly to the throat of the opening, a wad being placed on the top of the sand. A funnel is then attached outside, and the tafted edge of the pipe surrounded with a small upstand of sheet lead, the funnel being fitted with sand up to the level of its top. As soon as the upper length is inserted, having been previously rasped and fitted, and both pipes being independently secured, the red-hot metal is poured into the cup so as to fill it without leaving vacuities or air holes. In other cases the edges of halves of pipes, traps, etc, are united by melting off lead from a stick with a red-hot iron.