Part Four.—STEEL WELDING
(104) When steel is in a melted condition, it seems to be in a very susceptible state. It appears to absorb gases, and with constant working an oxidation is in evidence which materially effects the strength of the metal. When working on vanadium and other alloyed steels, if kept in a molten condition too long, many of their principal characteristics are destroyed. For this reason it is advisable to execute steel welds just as rapidly as possible. While this is true of most work, it is especially to be emphasized on steel. To assist the welder in executing welds on large steel castings, the pieces are generally preheated, so that the work will take less time, be more successful, and save both oxygen and acetylene. When working on preheated jobs, in order to get the desired angle on the filler-rod so the welder may use it without discomfort, a light heat is played on the filler-rod, a matter of six or eight inches from the end being fused and then bent to an angle of 90 degrees, so that the operator may hold the rod at some distance from his work and still introduce it in the manner he desires. Some operators weld their cast-iron filler-rods together, to get the desired angle as shown in [Fig. 69], but this is not as common as the steel method, probably because cast iron will not bend and it requires some time to weld the rods together in this manner.
Fig. 69.—Kinks for Handling “Filler-rod” on Large Work to Remove Welder’s Hand away from Heat of Flame.
(a) shows how the steel “Filler-rod” is heated by the torch flame about 6 inches from the end and bent to the angle desired.
(b) illustrates how cast “Filler-rods” are handled. Since they will not bend, they are welded in the T shape shown. First one side is used in fusing, and then the other.
(105) In some parts of the country boiler flues are acted upon and eaten away by the impure water used, and when high prices prevail, retipping is generally resorted to. A simple method in which they can be satisfactorily and cheaply done is as follows: Cut off the poor end until solid metal is reached, with a pipe cutter, which will tend to “V” the work as it cuts and at the same time will squeeze the edge of the pipe in. After cutting, this end of the flue is placed on the horn of an anvil and the burr on the inside, which has been made by the cutter, is flattened out. It is very important that the flue be of the same size throughout in order to permit its being cleaned. It is then placed in “V” blocks or a trough, made of angle iron, such as shown in [Fig. 70], and the new end which has been prepared in much the same way is placed in the position shown in A in the same figure. The piece is tacked on at two or more spots and then laid aside until the whole set of flues has been prepared in this manner. Then they are replaced in the trough and welded, one after another, being turned at one end by a helper, thus allowing the welder to do continuous work. Care must be taken at all times that perfect fusion takes place between the flue proper and the piece being added, yet at no time should the metal be allowed to run on the inside of the pipe. More metal can be added than is really necessary and can later be dressed down on a grinding wheel to the desired size, which must be such that replacement of the flue can be made. Various-sized pipes can be welded in much the same way where no reducers are obtainable, the only change being that there must be a step made in the trough which will permit the various-sized pipes being lined up correctly. Jigs for the speeding up of manufactured articles which are to be welded are always being brought out by the ingenious workman and are to be encouraged whenever possible.
Fig. 70.—Showing a Simple Way to “Line-up” Flues when Retipping. B Represents the old Flue, and A the New Piece to be Added.
