for pressures from 118 to 294 lb. The (British) Engineering Standards Committee have recommended that flanges should be standardised in four classes :

1. Low-Pressure Standard, for steam pressures up to 55 lb., and water pressures up to 200 lb. per sq. in.

2. Intermediate-Pressure Standard, for steam pressures over 55 lb., but not exceeding 125 lb. per sq. in.

3. High-Pressure Standard, for steam pressures over 125 lb., but not exceeding 225 lb. per sq. in.

4. Extra High-Pressure Standard, for steam pressures over 225 lb., but not exceeding 325 lb. per sq. in.

The numbers of bolts are multiples of four; as four, eight, twelve, sixteen; without which interchangeability is impossible, when attaching fittings at different angles.

Uniformity in the diameter of bolt circle, and in the number of bolt holes for a given size of flange, with uniform dimensions of flanges for varying conditions, entail compromises, and dimensions not strictly in harmony with stresses, but that is unavoidable in any attempts at standardisation.

The term flange has a wider significance, being applied to numerous objects in which ribs or members stand at right or other angles to another, irrespective of whether they are employed as a means of bolt attachment or not. Thus a common joist is a flanged beam. A flanged seam denotes a joint made by flanging tubes for the purpose of union, as in some furnace flues, and in the shells of some vertical boilers. A flanged wheel is a railway or trolley wheel having either one or two flanges; a flange rail is a flat-bottomed rail.

Flanging. Turning over the edge of a plate or sheet, or the ends of a tube, in order to provide a means of union to another portion. Flanging in modern boiler practice takes the place of many angle joints formerly employed. It is safer, being less liable to groove, because more elastic. Fig. 11, A, shows a flanged crown of suitable proportions. Its elastic capacity and superiority to an angle are at once apparent. Flanging is done by hand hammering, or by hydraulic power pressure.

Bending blocks are employed in hand flanging to serve as guides by which to curve the edges. Round-faced wooden mallets are used in order not to bruise the metal, but final corrections are made with sledges. The work is held down with a clip cottered across, or by other convenient methods, similar to those illustrated under Angle Iron Work, while a portion of the edge is being turned over. Then the piece is removed to the hollow fire of bricks, covered with a plate, and another heat taken, and returned to the bending block, and re-cottered for bending the next section, and so on until the job is completed.

A

Cross tubes are flanged while held horizontally on a block supported on a stand. They are manipulated with a cross handle, against which the helper throws his weight in opposition to the blows of the smith. Fig. 11, B, C, shows how flanging of cross and furnace flues is effected when done by hand, B and c illustrating successive stages of the work. These are done by machine in large shops. Furnace flues were formerly flanged by hand, but now by machine. See Boiler Flue Flanging Machine. The same remark applies to steel mouthpieces, and all work of that class.

Fig. 11.-Flanging.

The flanging of tube plates, smoke box sheets, and throat plates was formerly done by hand, but now in dies. If done by hand, flanging blocks are necessary, and the edges are turned in successive heats and stages, occupying several hours for each plate. Flanging between dies is done at a single heat, and occupies less than two minutes in the actual pressing, exclusive of heating and corrections. But the apparatus used is costly, and separate dies are required for every size and type of boiler. See Flanging Press.

Hand flanging stresses and injures the metal, which is a consideration quite apart from the tedious nature of the process. There are certain temperatures suitable for doing work upon

of iron there is less risk of injuring the fibre by successive heating and flanging than there is with steel.

The most injurious heat at which steel can be worked is that at which the red fades away and blackness begins to supervene. It will stand bending and hammering cold with far less injurious effects than it will while at the temperature say of melted lead, tin, or tallow. The ductility of steel is also impaired when work is done upon it at locally varying temperatures. When a plate or flue, therefore, has been flanged at successive heats by hand, subsequent annealing is necessary if evil effects are to be avoided. This is not cssential when flanging is done by machine, the red heat remaining after the work is completed.

Flanging Press. A hydraulic press which is designed for turning over flanges between

Fig. 12.-Hydraulic Flanging Press. (Fielding & Platt, Ltd.)

dies; in some cases complete at one heat, in others in successive heats. Though termed flanging presses from their main function, they are used for many other purposes; as, pressing frames of railway wagons, bending cranks, and other forgings, and for stamping, and punching;

all of which can be done by the substitution of different dies.

The regular press, used largely for turning over the flanges of locomotive fire-box sheets, is shown in Fig. 12. The press cylinder is in the foundations, the ram A rising when pressing. This lifts the plate carrying stools, to which the power flanging die is attached. Between this and the upper die, which is attached by stools The to the crosshead, the work is flanged. height of the crosshead is adjustable to suit different dies and pieces of work. Precise adjustments of the work to be flanged are made through a plate (not shown) which is elevated by the four small press rams. The piece of work is thus held against the upper die, while the lower one is brought into action.

The dies required for large plates, as those of locomotive fire-boxes, are expensive items, but the expense is generally well covered by the large numbers of similar plates required. But for odd jobs such expense is not warranted. The plates for marine boilers are too large to be flanged at one heat. Some kinds of smaller work also cannot be flanged by a single squeeze. To cover all these cases the machine shown by Fig. 13 is made by Messrs Fielding & Platt, Ltd., to accomplish the flanging in detail (they term it a progress or step-by-step system). There are three rams, two vertical, and one horizontal. A length of several feet to be flanged, is heated, and laid on a segmental block, cast to suit the job, and held thereon by the outer vertical ram. The inner vertical ram then turns down the flange. The work is shifted until several feet are thus bent, and then the horizontal ram is brought into action, squaring up the flange neatly. The two vertical rams can also be coupled to operate with their united power on dome ends, furnace mouths, &c. Some of these utilities are shown in Figs. 14 and 15.

Fig. 16, Plate I., shows a large hydraulic flanging press, with one main, and two side rams, the arrangement of piping and the working valves being clearly seen. Ample tee-slot provision is made, on faces and sides, to attach various styles of dies. Fig. 17, Plate I., gives a view of the lay-out of a flanging plant, with press, crane, and furnace.

Flap Valve.-A leather valve stiffened with

plates of iron or brass, and hinged at one side; used in lift pumps, and lifting vertically.

A plain form of flap valve is also employed for sewage outfall works, an example being shown in Fig. 18 (Glenfield & Kennedy, Ltd.). The flap cover is hinged with short links, and falls by gravity. The shackle at the bottom forms an anchorage for a chain which goes up into a brick-lined chamber, and is pulled up or lowered by a barrel and worm gear. Some valves are closed with a balance weight. Twoway valves are hinged at the junction of two pipes, and the flap has double faces, to close the mouth of either pipe.

the pressure finds an outlet it ceases to exist. The writer has had the experience of being on an automobile fitted with a flash boiler, when owing to the relief valve having been tampered with, one of the tubes burst. The steam pressure at the time was well over 1,200 lb. per sq. in., but beyond some of the burners being extinguished by the sudden puff of steam, no damage was done to either the car or the occupants.

Rapidity of steaming is a characteristic which this type of boiler possesses in a marked degree. It is possible, and even usual, to raise the pressure from zero to over 800 lb. in less than a minute. Moreover, provided there is a good fire the pressure is maintained so long as water is supplied to the boiler. The degree of superheat of the steam depends entirely on the design of the boiler and the connections of the various coils. For automobile work the coils of tube are usually so connected that the superheat is very high. What it is in degrees Fahr. is not easy to say exactly, but probably it ranges. as high as 1,700° or even more. At such temperatures all ordinary rules for the flow of steam through pipes become useless. The steam behaves more as a perfect gas in its mobility. For instance, for supplying an engine with two double-acting cylinders of 6-in. bore by 6-in. stroke, a steam pipe with a 3-in. bore was found more than ample in size. The throttle was never more than half open, whereas with saturated steam such a pipe would have been far too small. Cylinder condensation is quite unknown after the first few moments of running, whence it has been found that there is little or no economy in the use of compound engines. All the expansion necessary can be carried out in one cylinder with very little loss. On small engines, as used for motor car propulsion, the cut-off is frequently as early as

of the stroke. It is far from uncommon to find

the steam pipe at a bright red heat, and that this is not due to heat conducted along the metal from the boiler is proved by the fact that the fire can be full on for a considerable time without the pipe being more than comfortably hot to the touch. Within a few seconds of the opening of the throttle valve the pipe rapidly becomes bright red, thus showing that it is the steam which heats the pipe. With such a superheat it is possible to get as great economy with small engines as is to be had with large Corliss mill engines.

Owing to the scouring action of the highly superheated steam through the tubes these are very seldom troubled with scale. The writer has tested the point by operating a flash boiler with strong brine as feed water, but no scale was formed in the tubes. A separating drum was required to allow the powdered salt to drop out of suspension before admitting the steam to an engine, but otherwise no difficulties were apparent. From this it would appear that the flash boiler would be of great utility for marine work, especially where space is limited (as in torpedo boats), as all need for fresh water is done away with. Oil does not appear to have the slightest influence, good or bad, on the action of these boilers. It is only necessary to keep the feed water free from grease for the sake of the feed pump valves.

As an example of the small space occupied by flash boilers there may be instanced the following:

The outside dimensions of a boiler casing were 3 ft. 4 in. wide, 1 ft. 9 in. deep, and 3 ft. 1 in. high. The tube coils contained in this case were as follows:

A feed-heating coil around the inner surface. of the fire-box, made up of 30 ft. of 18-in. bore tube. Three lowest coils each of 33 ft. of 5 1-in. bore; the centre three coils each 33 ft. of-in. bore, and the top four coils each 33 ft. of -in. bore; the total heating surface being 85 sq. ft. Water is fed to the feed heating coil which surrounds the inside of the fire-box, thence it goes to the top in. coil, and descends through these three coils to the lowest. From the outlet of this the wet steam is led to the top coil of all (in. bore), and descends through all the remaining coils in regular succession, till it

issues from the lowest of the three-in. bore coils as highly superheated steam. To prevent any possibility of wet steam being delivered to the engines, a steam trap is fitted between the last of the in. coils, and the first of the-in. bore coils, by means of which all water is separated from the steam. The weight of the boiler in working order is 73 cwt. and it is easily able to steam an engine of 60 I.H.P.

The following figures are the result of a long test of the boiler while steaming a pair of 6-in. by 6-in. double-acting engines. As the engines were not designed for use with highly superheated steam, the superheat had to be reduced by employing a live steam feed water heater through which all the steam supplied by the generator was passed on its way to the engine. The estimated superheat of the steam as it left the boiler was 1,270° Fahr., and the feed water was raised to over 400° Fahr. by the live steam heater before entering the boiler coils.

The boiler evaporates 1,309 lb. of water at a superheat of 800° Fahr. per hour. Evaporation per square foot of heating surface was 15.4 lb. per hour. Evaporation per pound of Russian oil, in the second hour of test was 14.2 lb. per hour. Working pressure during test, 550 lb. per sq. in. The hydraulic test (cold) was 4,000 lb. per sq. in., there being an ample factor of safety for the working pressure.

A second test was then made of the same boiler, but with an additional feed water heater using the exhaust steam from the engines. The evaporation per square foot of heating surface was increased to 20-3 lb. of water per hour, and the evaporation per pound of Russian fuel oil rose to 18.5 lb. of water per hour.

The oil burner used was of the "Hecla" or multiple jet type, and the oil was under an air pressure of from 45 to 55 lb. per sq. in.

All the joints between the various coils are outside the boiler casing, and they can all be inspected or tightened up while under steam. No joints of any description are out of sight or exposed to the action of the fire. The fittings are few, there being no water gauge or gauge cocks, no safety valve in the ordinary sense is fitted, but its place is taken by a steamactuated relief valve in the feed water pipe line, close up to the boiler. The steam pressure