Modern methods of welding as applied to workshop practice, describing various methods: oxy-acetylene welding, electric seam welding ... eye protection in welding operations [etc.] ...

Front matter

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Preface

We live in a world of wonders. The life of each one of us is, of necessity, so hemmed in by circumstances that none can see much beyond the bounds of his own habitat. We recognise the progress of an industry which comes within our own experience, but we know little of those with which we are not in personal contact.

The pressman who clamps the plates on a modern lightning newspaper press does not see anything very startling or interesting in the work. The man who pulls levers in the pulpit of a great steelworks is not apt to realise that there has been a marvellous advance in the realm of manufacture. The attendant on a bottle-blowing machine has learned to take his work as a matter of course. It is found through the entire list of trades and occupations.

Yet each of these men is at times impressed by the remarkable advances made in some industry other than his own, because such knowledge comes to him, as it were, suddenly, not by the almost imperceptible movement which marks progress in work that is familiar.

The means which have brought about industrial development are worth studying. No armed warrior ever sprang full-grown from his cradle; no giant industry has ever come into being in a year or decade. It takes time to develop the machinery and acquaint the world with the advantages of a new aid to manufacture, to commerce, to civilisation, or to human comfort. He who reads this book can hardly fail to be impressed with the idea that no man can measure the possibilities of industrial growth. Who can say that at the close of the twentieth century " Darkest Africa " may not be under-selling us in our home markets? Who can be sure that with the development of China and the East, there may not come supremacy in industry before which our light shall pale ? To-day the industry is exceptional in which there has not been an entire alteration and renewal in the machinery within the last few years.

The tale of manufacturing progress is one not half told, one which never can be told in full, because it grows faster than the ability vi PREFACE

to record its development. In every vocation, in every city of the globe, are geniuses studying how to advance the lines of work in which they are engaged. Every year the standards that win success are set higher, yet every year witnesses increasing gains and greater triumphs.

Electricity is believed to pervade the universe. Astronomers see evidence of its action in the sun, in the stars, in the comets. Its properties are so varied, it affects substances so differently, that it is safe to say that we have as yet learned but a fraction of what mankind is destined to know about this wonderful thing. Because it so readily lends itself to the transmission of energy, we think of it as a source of power, whereas really it is but a means of transmitting power, like the endless leather belts commonly used for driving machinery.

The man who thinks he will read up a little on electricity is sometimes very much disappointed because he cannot learn at the outset, in a little primer, just what electricity is, and so advance step by step to a full knowledge of the subject. But there is no help for it. The operator of electricity to-day must begin, as did those who came before him, at the other end of the problem, and learn how electricity acts and what it does. After a time he will acquire a notion of things which will satisfy his craving for knowledge, and will cease to bother much about the theory.

Operators and others who follow the instructions in this book will soon be convinced of the great importance of welding processes to the future manufacturing and industrial world. It is the simplest possible axiom, when we stop to think (though few people ever do stop to think), that the only way in the long run for labour as a whole to get more wealth is for it to create more wealth ; the only way to create more wealth is to increase productivity of labour.

The field for the further application of welding is enormous; but this further application is being delayed by lack of complete knowledge of the art, the utterly confusing, and, in many cases, diametrically opposed claims of competing interests. There is needed a cultivation of the co-operation spirit which will permit a frank, open discussion of the merits of the different processes, so that a reasonable agreement as to those merits may be reached. If there are prospective users of welding who are in doubt as to whether they should use gas or electric welding, or neither, can it be supposed that their confidence in any process will be enhanced by hearing its advocates claim that it is the only safe and economical one ? I am not setting forth impracticable ideals, but rather

PREFACE vii

common-sense principles, already found successful in many business fields, the application of which is bound to yield the best results for all concerned.

It would be difficult to suggest a branch of the applied arts which has advanced more rapidly in recent years than that of electric and oxy-acetylene welding. Both processes gained status in the war; and, although some of the more extreme manifestations of their possibilities which the war encouraged are little likely to be paralleled in the early days of peace, the methods have now won for themselves a definite place in the shop routine. They have established their ability to tackle certain classes of work in an economical and satisfactory way. That both methods are destined to advance in usefulness, alike in extension and intension, there is no question; and, although they are in the hands of specialist firms, the general shop manager of the not far distant future is likely to find that he is expected to be able to apply them. Moreover, not only the manager, but others, both the engineers and the " semi-skilled," are likely to find interest and profit in these processes. There is probably no other recent improvement in applied mechanics which has received the scientific study devoted to autogenous welding. The result is that its practice has become an art to which one must give intelligent and well-directed study if one would avail oneself of its uses.

The universal application of this process, in every branch of industry where metals are employed, makes inevitable a great demand for capable operators. It is to the advantage of all concerned that operators should understand their work and their tools, that they should be able to apply intelligently the principles involved.

Introduction

In presenting this book to the welding industry, I may say that I have devoted my whole time to the welding processes and the materials used, and they are all concisely described in their various chapters. If the readers will give attention to the following pages, they will find many points that will help them in their studies and guide them to a knowledge of the processes. In the course of eighteen years' experience of the welding industry I have found that such a book as the present is badly needed. I now make an endeavour to supply the deficiency. It is my desire to do all in my power to raise the status of welders in this country; and this will be best achieved if they can be induced to pursue a course which will make them proficient.

Some time ago an effort was made to establish a system of certificates of proficiency for operators, but unity between the associations interested is not yet sufficient to allow this.

In the comparatively limited space available for my purpose, I have attempted to give a clear and consecutive description of the principles upon which an industry of unsurpassed importance is based. With the object of accomplishing my task, however, in a manner at once agreeable and instructive, I have now and again departed from the general plan to dwell on some particular point.

While sensible of the defects in my book, I venture to hope that to those practically engaged or interested in the conduct of numerous processes covered by its title it may prove to be of service.

I take this opportunity of acknowledging my gratitude for assistance from Messrs. British Oxygen Company, Ltd., Messrs. Charles Bingham and Company, Ltd., Messrs. Leeds and Butterfield, Messrs. British Insulated and Helsby Cables, Ltd., and H. M. Hobart, President of the American Welding Society.

Contents

CHAPTER PAGES

PREFACE ------- V

INTRODUCTION ------ ix

Chapter I Welding In General

It is well known to everyone who takes an interest in welding and welding processes that the existing opinion as to the value of the processes and the practical results obtained is in a state of uncertainty. The chief ground for this uncertainty lies in the fact that these new processes have only been introduced recently into industrial practice, and rest entirely on an empirical basis. Although oxy- acetylene welding is now extensively used, and is of great theoretical and practical interest, it has never been made the object of systematic and exhaustive research.

The author has had eighteen years' experience of welding, and has made exhaustive tests and long studies, not only of what is being done in this country, but also of the progress made in the United States and Germany. The latter country is far more advanced than Great Britain. The Germans have carried out systematic and exhaustive researches. Their operators are scientifically trained, are taught metallurgy and chemistry, including the chemical compositions and melting-points of all metals and oxides, make test-pieces for experimenting with the chemical and mechanical tests, and employ microscopic and macroscopic examinations, both of the melted zone and the neighbouring parts. Their welding, as a rule, is very neat, as they are not allowed to execute commercial work until they have become fully proficient.

The introduction of oxy-acetylene welding has opened up an enormous field, in which any metal can be dealt with, and such an article as a cracked motor frame or cylinder can be rapidly welded. In these directions there seems to be ample scope for the application of engineering skill, and recent developments have shown that it is difficult to put a limit to the purpose to which engineers may yet apply the process.

To-day the business has grown beyond the limits of personal supervision. The necessity for organised instruction of operators is becoming more and more obvious in the interest of both work-

l men and employer. Several welding schools have now been started in various centres about the country, whence a stream of qualified welders is already beginning to flow to the workshops, where most of them are able to turn their training to practical use.

They teach the operator under practical conditions the right flame for different work, the principles on which the blowpipe is constructed, the way to handle it, and a variety of technical and theoretical points, which are always useful to him in his subsequent career. He is also taught thoroughly the construction, working, and maintenance of the plant.

It is the operator of to-day, well instructed in the points, whom we hope to find the professional welder of to-morrow. The time is not far off when employers will refuse to engage a welder unless he can produce the certificate of proficiency. This cannot be obtained unless the operator possesses thorough knowledge and practical experience of the process.

The author has undertaken many investigations in this process. The oxy-acetylene method, when properly worked, possesses numerous marked advantages. In the first place, the operating flame can easily be controlled, and the temperature attained at various zones can be readily regulated. Secondly, the work can be easily accomplished, owing to the high temperatures reached (3,600° C), and the appliances are convenient to handle and reliable in operation.

The most important conditions for securing good results are —

1. The use of the purest acetylene possible.

2. The use of a blowpipe so designed as to ensure accurate adjustment in the proportion of the mixed gases and to secure their exit at a velocity capable of keeping the metal sufficiently fluid without the melting flame being too rigid.

3. The use of an absolutely pure welding-rod.

4. The provision of an absolute neutral zone in the melting flame, neither oxidising nor reducing.

5. The edges must be free from all impurities, and, if over -£$ inch thick, must be bevelled.

6. The use of deoxidising agents eliminating the oxides, in view of unavoidable oxidation of the metal subject to the melting process. It is necessary to bear in mind the relation between the melting-points of the oxides and of the metal itself, which is a most important matter.

7. Rapidity in melting, in order to avoid excessive heating, which not only alters and deteriorates the original structure of

WELDING IN GENERAL , 3

the metal, but would even favour the occlusion of the gases (particularly hydrogen) and so occasion the formation of blowholes in the melted zone.

In addition to these considerations, care should be taken that no sudden cooling occurs. The conditions may have to be modified on account of the conductivity and special dilation of the material, as well as in relation to the thickness, size, and shape of pieces operated upon.

Eor those who are familiar with this process of welding and cutting it is not difficult to appreciate its varied applications. The ease and rapidity with which experienced welders can carry out repairs in situ, and the portability of the plants, make the process valuable, if not indispensable. The service rendered by it in many workshops, where the welding of articles of all kinds is a daily necessity, is calculable.

The oxy-acetylene process occupies a leading place in all aeroplane and airship industries. It is used with advantage in welding sheet steel stampings, cylinders, aluminium crank cases and machinery parts, steel tubes, stamped steel water-jackets for cylinders, broken cast iron. Moreover, for cutting iron and steel this process has no rival whatever. It will cut wrought iron or steel plate 20 inches thick. The flame has been applied to the casehardening of steel, and some firms are using this on a large scale. It is well known that the flame containing an excess of acetylene is a very energetic carboniser.

This process may be employed on any class of work. It will weld 30-gauge steel or lj-inch boiler plates, cut mild steel up to 20 inches thick; weld any commercial metal, such as cast iron, aluminium, copper, bronze, zinc, lead, delta metal. In the repair of broken machinery and parts it is always above its rivals; repairs are executed quickly and can be done without dismantling in many cases. It can be used in the manufacture of safes and tanks, in the jointing of pipes, steam superheaters, casks, artistic ironwork, in adding metal to parts worn by friction, filling up holes or parts of new structure cut away in error, welding of tool steel to wroughtiron bars, and welding of copper or brass tubes. The flame can be used for preheating and for hammering and annealing after welding, thereby ensuring a soft metal, a method not practicable in the electric process.

In the welding of light sheet steels with 24-gauge metal, 45 feet per hour can be welded, with a consumption of only 4 feet of oxygen and 3 feet of acetylene. On the other hand, when the metal reaches

4 MODERN METHODS OP WELDING

| inch thick, electric welding has the advantage both in speed and cost.

When the process of acetylene welding was first introduced, its apparent simplicity led many engineers wrongly to assume that welding appliances might be regarded as general workshop tools, which any inexperienced but handy man could operate with success. Consequently much work was condemned wholesale because of the defects in the weld. The author would emphasise that this is not the fault of the process, but of inefficient workmen.

It is estimated that there were, during the recent war, 33,000 employed in this country in welding processes, of whom 25,000 entered the field during the war. Of the total number, 90 per cent, are not fully skilled — that is, they are incapable of executing satisfactory welds on all metals, being mostly employed on sheet steel. The impetus that has been given under war conditions should stimulate employers to investigate and exploit this revolutionary process, the possibilities of which have no obvious limits.

In the shipbuilding trade this process can be utilised very much more than at present — for instance, in making knee brackets, stays, and frames. These can all be cut and welded by blowpipes, with present costs reduced 50 per cent, and output increased. A blowpipe only requires one man ; but an anglesmith, when welding a knee bracket, requires two or three assistants. Most shipyards have plants, but they are not utilised to advantage.

In all Avelding it is most important that the work should be adequately prepared before commencing to weld, as all time spent in this way is amply repaid afterwards in the easier execution, and also by the homogeneous nature of the weld. It is, however, a subject on which it is impossible to lay down any hard-and-fast rules, the varying nature of the work accomplished making it impossible to do so. The general principles obtained in the best practice point out that the line of weld must be opened out — that is, the two edges must be bevelled to an angle of 45 degrees, to make certain that the weld is well penetrated, not merely sealed over, and to strengthen the weld by increasing the surface of contact.

One of the most important things to do in the preparation is to arrange the pieces to be welded in such a position that there shall be no deformation, breaks, or cracks, or internal strains, and that they may be linable at the conclusion of the operation. This is a point in which the skill and experience of the operator are revealed, as there are no rules to guide him, and upon any work but that of the simplest character failure to grasp and apply the laws of expan-

WELDING IN GENERAL 5

sion and contraction means the partial or total ruin of the work. It is impossible to control expansion and contraction by physical force, so the only way to prevent disastrous results is to foresee the probable direction and extent of the phenomena, and nullify the effects by preheating certain parts of the work, either by the blowpipe or the welder's furnace.

It is good practice to raise the temperature to nearly red heat in the furnace and weld, then allow to cool slowly and uniformly

Fig. 1. — The Radiograph, used for Circular Cutting, Automatically, as shown, is Cutting Annular Rings 31 Inches Diameter by 6 Inches Thick at a Speed of 7 Inches per Minute.

Note the clean cut and accuracy of the rings.

in sand or asbestos; but all cold currents of air must be avoided. All castings should be preheated bodily. This is a great advantage, for not only does it save gases, but it prevents any irregular expansion, and hence no fractures.

The cutting of iron and steel by the oxy-acetylene flame is being very extensively used. This involves the use of a blowpipe of a different design, which provides for the oxy-acetylene flame and an auxiliary jet of pure oxygen to be impinged on the line of cutting. The principle underlying this method consists of taking advantage of the fact that, when heated, iron and steel can be oxidised very quickly by a jet of oxygen, which jet, delivered at high pressure, blows away the oxide that is made, leaving a narrow, clear cut, almost as clean as a saw cut.

Chapter II Lead Burning

This process is one of fusion of lead by oxy hydrogen, air hycrogen, or coal-gas hydrogen. The air-hydrogen process, dating back over one hundred years, for a considerable time was only employed in chemical work on the construction of acid tanks and vessels with their pipe connections. The tanks being built of wood, lined with sheet lead, the junction of the sheet was effected by this method. At a later period this system was employed in large gasworks, more recently for the manufacture of electric batteries and their plate connections. If solder had been used on either class of work, it would have been attacked by the acid. It was restricted on account of its cost.

In the latter part of the year 1888 a series of experiments was carried out by the Brin's (now British) Oxygen Company, with the object of using coal-gas from the ordinary town main and oxygen from a trade cylinder. After due consideration of the matter, it was thought possible to utilise the pressure of the oxygen cylinder to obtain an injection action by which the supply of coal-gas at low or main pressure could be increased and thoroughly mixed with the oxygen in the blowpipe previous to ignition. In order to complete combustion (thus preventing the formation of carbon deposits on the melted lead), after various trials had been made, the injector blowpipe which we illustrate on p. 7 was designed, and was found eminently adapted to the purpose. It fulfilled in other respects all the requirements necessary to ensure good work, and, moreover, as it produced a flame at much higher temperature than could be secured by the old hydrogen-and-air system, it enabled the plumber to execute about double the amount of work, of better quality, and without assistance.

H (Fig. 2) is the inlet for the coal-gas supply ; shows the injector inlet for the oxygen supply, fixed in position with the injector removed, showing the coned end which projects through the chamber into a cone formed in the body. The pipe leading away from the body is screwed at the end to take the nipple, which is of various sizes, to

LEAD BURNING 7

deal with lead from the thinnest section up to J inch thick. The essential features of this type of blowpipe are the shape and design of the injector cones, with their relative position to each other; the reservoir for the coal supply provided between the two gas inlets

Fig. 2. — Injector Blowpipe.

and H; together with the mixing chamber, into which the brass pipe is screwed. The flame also differs somewhat from that of the old hydrogen type of blowpipe, its chief characteristic being a welldefined pale blue cone about a quarter of an inch long. The hottest

Fig. 3. — Shoulder Taps eor Use with Lead-Burning Blowpipe.

part is the point of the cone, which, in use, impinges on the metal operated upon. Melting is clean and bright. This flame is best controlled by the use of what are known as " shoulder taps," illustrated herewith.

These taps in Fig. 3, marked H and respectively, correspond with those on the blowpipe, and are connected by two lengths of rubber tubing, with the twofold object of securing flexibility and lightness, the pressure being previously reduced from the other end of the tap, marked H. A rubber tubing leads to the ordinary coal-gas supply from the main, and the oxygen tap, marked 0, is similarly connected by a rubber tube with the outlet of an endurance regulator, which is illustrated herewith.

This regulator in Fig. 4 is connected by a ring nut, seen at the bottom, to the oxygen cylinder. The knurled nut on the right is screwed into the diaphragm plate, indented on the sleeve, by which means it can be adjusted to maintain any constant outflow of oxygen

Fig. 4. — Oxygen Regulator.

from the cylinder up to 30 pounds pressure per square inch. The projection immediately opposite is a safety valve, the outlet or stop valve being shown on top. These illustrations constitute a complete lead-burning outfit, with the exception of the rubber tubing and the oxygen cylinder. A sample injector blowpipe was submitted to the Gas Light and Coke Company for trial in their chemical works at BeCkton, and gave satisfactory results. A large order was consequently placed. The system has met with universal approval, not only in the trades already mentioned, but also for roof work and general plumbing. If lead burning is required where there is no coal-gas supply, this can be obtained compressed in cylinders similar to those used for oxygen ; but an endurance regulator would have to be used on the coal-gas cylinder. In lead burning, in order to secure sound joints in any class of work, it is necessary that the joints are scraped perfectly clean and bright, and also the strip of lead that is used for filling in the case of a butt joint.

LEAD BURNING

For lap joints no filling strip is necessary. In the latter case, however, it is equally important to scrape clean all surfaces to be welded, including both the overlapping edges, otherwise it is not possible to do sound work. The illustrations represent the best methods of executing the various types of sheet-lead burning. A (Fig. 5) is a butt

Figs. 5 and 6. — Lead-Burned Joints.

A, butt joint; B, vertical joint; C, vertical lap joint; D, lapped joint with metal added.

joint. Where added metal is required, the fine of weld should be about | inch to f inch wide, and thickened up. This is a very strong joint. B is a vertical joint, which is lapped, and no additional metal is needed. This vertical welding is not as easy as the butt. The metal when molten falls very quickly, and unless the welder is sharp the molten metal runs right down instead of in the line of the joint. Much practice is necessary for this type of welding. C (Fig. 6) is a vertical lap joint, too. The same methods have to be adopted as with type B. This weld is not so good as type B, nor so neat. D is a lapped joint with added metal, the weld being about § inch to f inch wide. This is welded horizontally.

In chemical works very often the sheet lead used is 20 to 30 pounds, and when vertical jointing has to be done with this thickness it is usual to employ what is known as a moulding tool, which is held over the lap. The lead is melted and allowed to fall into this moulding tool. As soon as it is cooled, it is pushed up a bit farther, melted, and filled again, the operation being repeated until the joint line is finished. This moulding tool is simply a forged tool shaped half-round on the inside, where it fits against the lead joint; the size is about 1 inch by |- inch semicircular, about | inch thick, with a handle at the other end. Below is an illustration of one.

Fig. 7. — Moulding Tool for Heavy Vertical Welding.

Lead burning, so called, is the autogenous welding of lead with a gas torch. The edges of the lead parts are fused together, using no solder or other metal except pure lead to fill the joint. The term " lead burning " is really a misnomer, as metal is not burnt, but simply fused and flowed together. This process only is employed for applying lead linings of acid tanks used in chemical plants, fertiliser factories, rubber reclaiming works, electroplating shops, nitroglycerine huts, and other industries. The widespread use of storage-battery starting systems on motor-cars has created a demand in garages and battery stations for lead-welding equipment for the welding of lead connectors and terminals.

Lead welding is used to some extent in making up pipe connections; but tank and storage work are the chief applications for which lead-burning equipments are purchased. Considerable skill is required of a lead burner to weld lead sheets together without burning holes through or causing the lead to drop. But the trade is one quickly learned by an intelligent workman. Success depends on clean, thorough preparation, suitable equipment, right material and right working conditions, as well as personal skill. Two forms of joints are used, the butt and the single-lap seams. The latter are

LEAD BURNING 11

used almost exclusively in tank burning. Butt joints are used mostly in lead-pipe jointing.

When making a butt joint, the edges of the sheets or pipes should be trimmed straight. They may be rasped to 75 to 80 degrees in opposite ways, so that when the two sheets are laid together, a V groove of 30 degrees or slightly less angle is formed. If a filler is to be used, the groove is filled with molten lead, flush or slightly above the surface of the sheets or pipes. A preparation of the butt joint by bevelling is practised for sheet burning except on very heavy lead — so thick, that is to say, that it is rarely used. All thicknesses up to, say, 20 pounds to the square foot are butted with square edges and generally burned together without using the filler rod. The use of the latter slows down the work, on account of the necessitj^ of frequently cleaning off the oxide film on the rod. A joint made without the filler rod is slightly thinner than the sheet; but this is rarely objectionable. When burning a butt joint with the filler rod, the flame is played on the sheets until the metal is softened to fusing-point, but is still too stiff to flow freely. The added metal is supplied from the lead filler rod to fill the V, if prepared for a groove. The filling rod is held in the left hand close to the joint, so that the heat of the flame melts it and deposits molten lead into the joint, alternately heating the sheets and the filler rod to the fusing-point, letting a drop fall into place, then whipping the torch off momentarily to allow the fused metal to cool. This practice is slow and seldom necessary.