Plumbing

Insulation consists of covering pipes and vessels with some porous material to provide a layer of stagnant air around them and so obviate the withdrawal of heat by conduction.

Other Points.

Pipes for conveyance of gas to lighting points, cooking and warming stoves and water heating apparatus are usually of wrought iron or steel with fittings of similar material or malleable iron. Screwed joints being used, the threads are smeared with a lead and oil compound. These pipes must be well fixed to prevent damage. They are usually concealed.

For beer engines, pumps and spirit pipes, block tin pipes are used, joints being of the cupped variety known as blown joints. The solder used contains bismuth to lower its melting point so that a surface alloy is formed at a temperature below the melting point of the pipes. Pewter, an alloy of lead and tin, is used for washing bowls, trays, etc.

Plumbing work in connection with cold storage, etc., consists of bending and fixing wrought iron tubes and connections.

Chemical Plumbing

consists of the erection and jointing of large chambers of heavy sheet or plate lead; the manufacture and fixing of large pipes for conveyance of acids and gases; covering of earthenware cocks; iron fans and lining vessels con structed of other metals with lead. In this work lead is used because of its great immunity from destruction by the action of acids; consequently all joints are made by lead burning or the fusing together of edges with the addition of extra lead to strengthen the seams and joints from a filling rod.

Plumbing work on ships is similar in many respects to that ashore. Fresh water is carried on liners in tanks in the ship's bottom, from which it is pumped to the upper decks for filtration, aeration, and storage for delivery by gravitation to various points about the ship. Waste water, soil, etc., from fittings above the water-line is carried in pipes to openings in the ship's side im mediately above the water-line, and there discharged into the sea through storm valves. Waste matter from decks and fittings below the water-line is carried to bilge tanks in the ship's bottom, from which such is pumped for delivery overboard. Wrought iron pipes are largely used on ships and the process of welding branches to them, as well as flanges for connections by the oxy acetylene flame, is largely followed. Plumbing work on ships is of a heavy character. Special fittings such as water closets ar ranged so that they may be securely bolted to the decks, are used. Materials.—The following is a short description of materials used in plumbing with methods of jointing.

Sheet lead may be either cast or milled. Cast sheet lead is lead poured over a prepared sand-bed and struck off to a required thickness. With milled sheet lead, sheet copper, zinc and iron, the metals are passed backwards and forwards between huge rollers until they assume a required thickness, consequently these latter are more dense.

All sheet metals used for roof coverings are joined by rolls, laps, welts, etc., which, while providing fixings allow for move

ments of the metals under the influence of varying temperatures. Soldering, brazing and rigid fixings are not resorted to unless unavoidable.

For internal work, lead is jointed by soldering With wiped joints. Copper is brazed and iron is welded.

Lead pipes are squirted from a machine under great pressure while the metal is in a plastic condition. These are joined by wiped soldered joints, which process consists of pouring or splashing heated solder on to prepared ends, manipulating them until the pipe is sufficiently heated to permit a surface alloy to form, and then the solder is wiped with a cloth.

Lead burning consists of applying an intense flame, produced by mixing coal-gas and oxygen, oxygen and acetylene or other combinations of gases to prepared edges and fusing them together with local heat; extra lead is added from a filling rod.

Cast iron pipes are made by pouring molten metal into a vertical mould with the socket end downwards, or into a hori zontal water-cooled mould, which revolves rapidly, thereby spin ning the metal to shape with increased density. These pipes are jointed by filling the sockets with yarn and metallic lead tightly staved home with special tools.

Wrought iron and steel pipes are made from strip metal bent to form a tube and welded by either butting or lapping the edges. Lap-welded tubes are the best. These pipes are usually made in three strengths, designated gas, water and steam, and are jointed by threading the ends and screwing together with prepared fittings.

Fittings used with wrought iron and steel tubes are either made from strip metal bent to shape and welded, or of malleable iron, which is cast iron rendered less brittle by extended annealing.

Iron pipes are protected from corrosion by galvanizing, which consists of coating the metal with zinc ; painting; subjecting them to the action of superheated steam which forms a protective coating of magnetic oxide on the surface or by dipping them while hot into a bath containing a mixture of coal tar, pitch, resin and linseed oil, the latter process being known as Dr. Angus Smith's method.

Copper tubes are made by drawing extrusions from cast billets over mandrils, with huge machinery. When of stout substance, these tubes are joined by screwed and socketed joints. Owing to the great strength and excellent physical properties of this metal, it has been found that tubes of thin substance or light gauges are extraordinarily strong, although not of sufficient thickness to cut a thread into their walls. The comparatively recent introduction of compression joints, whereby soundness is assured by simply compressing the ends of tubes in gun-metal joints, has rapidly brought these tubes into prominence for use in connection with hot and cold water supplies and other features of plumbing, thus facilitating installations de luxe at comparative costs.

Welding operations in plumbing are usually carried out by use of the oxy-acetylene flame (q.v.). (W. Sco.)