{
    "system": "GoGuides Verified Text",
    "api_version": "verified-text-v1",
    "status": "ok",
    "response_type": "verified_text_record",
    "source_key": "britannica_1926",
    "source_title": "Encyclopaedia Britannica (1926)",
    "license_code": "public_domain",
    "attribution": null,
    "license_url": null,
    "chunk_id": "1926:welding:a7113f32b9ae",
    "title": "WELDING",
    "section": null,
    "hash_alg": "sha256",
    "hash_sha256": "7b0514404f238a9afcd3f82c6bf7e3a6a74d1944558f25e18462f4d22c60c71b",
    "normalizer": {
        "name": "ggnorm",
        "version": "1.0"
    },
    "verified_text": "this article discusses electric weld- ing and gas-torch welding. a third form of welding, thermit welding, is discussed in the article thermit. i. electric welding spot welding—the important development known.as spot welding is a modification of the thomson process, peculiarly appli- cable to uniting overlapped sheets of metal by welded “‘ spots ”’ or localised areas of union of the sheets in place of riveting them. it leaves little or no projection or deformation on the outer sur- faces of the shects so united. fig, 2. fic. 1.—spot welder with electrodes (e). ‘ 3 the machine for such work is called a ‘‘ spot welder,” and usually has two electrodes arranged in a vertical line, one above the other. the electrodes consist of short, heavy, blunt copper bars, e e (fig. 1) (watercooled in the larger machines); the upper electrode e is made movable up and down under control of a manually operated pressure lever, l, or by a piston actuated by air or water pressure controlled by a valve. the opposed ends of the electrodes, which bear upon and form contact with the sheets to be united, are usually chamfered or given the form of frustums of shallow cones. this reduces resistance loss in the electrodes and adds to their rigidity and durability. the elec- trodes, as in other resistance welders, are made the terminals of welding the heavy secondary circuit of a welding transformer, t, the usual single turn of large section. the current is large, but is delivered to the work at low voltage. the weld which unites the sheets is a spot, usually round in form, confined in extent to the area covered by the ends of the electrodes. the opposed faces of the sheets are thus locally and quickly heated to welding temperature, and the pressure of the electrodes causes complete union; such welded spots are suc- cessively made at intervals over any extent of surface of the sheets as in riveting (see figs. 2 and 3). while spot welding has been yuu rk <€ fic. 3.—t wo welded sheets found to be best adapted to the union of overlapped sheets or edges of comparatively thin metal, plates of 4 in. or more in thickness may be spot-welded by heavy welders constructed for the purpose. in some of these, for mechanical and electrical rea- sons, two spot welds are made simultaneously by the same cur- rent passed in series through two spots covered by two pairs of opposed electrodes connected in series in the welding circuit. projection welding—another form of welding, known as “ projection ” welding, resembles spot welding, differing there- from, however, in the use of electrode faces which do not in themselves determine the welded area or spot, and in permitting the instantaneous union of plates or pieces at many parts of their surfaces. raised spots or projections are formed on one or both pieces, which when brought together form the paths for current and consequent development of welding heat irrespective both of the other parts of the plates and of the electrode contact with the sheets. the contact covers a wide extent of the pieces to be welded, and serves to press them together 4s the pro- jections between them become heated and softened. roller welding.—in roller or line welding, for forming con- tinuous lapped seams in sheet metal work, the overlapped edges of the sheets to be united are passed steadily between an upper copper roll with an edge of the width of seam weld desired, and a conducting mandrel, plate or similar copper roll forming the under electrode. the weld so formed is a line or strip of a width determined by the width of the contact surface of the welding roll. thin steel tubes with lap welds are made by this method, and it has also found application in the construction of thin metal containers such as steel thermos bottles, the parts of which are united without solder. flash welding.—by the thomson resistance process welds are made by light contact of the pieces during heating, followed by quick application of heavy pressure to force the heated sur- faces together. with iron and steel the method secures a very strong weld, and the heating is confined closely to the weld itself. moreover, there is a saving of time and often of energy. the speed of output in resistance welding was at first limited by the comparatively restricted energy supply and the capacity of the electric welding machine to deliver it to the work. this was especially true of operations such as the longitudinal welding of a seam in making steel pipe. with the modern extension in electric supply from large stations and enlargement of the capacity of welding transformers, etc., rates of production several times that of early practice have been achieved, with a possibility of future increase. in one enterprise alone, making electrically welded steel tubing, a production of over 100,000,000 ft. a year, or about 20,000 m., has been reached. percussion welding.—h an electric condenser of large capacity be discharged by wire terminals of relatively small section mace to approach each other in line, the discharge occurs with a flash of light at or before actual contact, depending on their potential difference. with sufficient capacity of condenser the restricted areas of the opposed ends of the discharge wires are brought superficially for an instant to a high temperature, and if immedi- ately pressed into firm contact will weld or unite. modifications of this process tending to increase the range and scale of its application have been brought out. ioot electric arc welding.—this process of fusion and union of metals in which an electric arc is the source of heat has now a wide extension. many forms of arc-welded joint in steel struc- tures have already been to a degree standardised. the arc term- inal applied to the work (usually the negative electrode when direct current is used) is a wire or rod of mild steel, mounted in a suitable holder manipulated by the operator, upon whose skill the perfection of the work largely depends. these electrode wires ordinarily vary in diameter according to the scale of the work or current strength used, and range from 3; in. to 7; in. or more. as the welding wire is rapidly consumed in the operation of fusing a joint, etc., it is constantly fed forward. automatic arc welders have been devised in which the arc separation is controlled automatically and the wire fed automatically from a reel. in operation the arc voltage may be from 10 to 20 volts and the current traversing the arc 80 to 200 amperes or more. the welding is attended by much sputtering and projection of fused and superheated globules of iron from the end of the wire electrode toward the cooler and heavier masses of the work- pieces. in fact, the deposition of metal on the work is possibly due to a jet of iron vapour from the electrode wire, carrying fused iron globules as a result of explosive boiling of the iron. this action would be a natural consequence of the central area of the end of the electrode wire being at the highest temperature, as it loses heat by radiation less readily than the outer surface of the wire at the arc. this central area reaches a temperature of about the boiling point of iron. the temperature of the arc is so high that the surface of the work-pieces, however massive such pieces may be, is penetrated and fused so that the metal of the work is incorporated with that from the welding electrode wire. the welding may be regarded as a progressive filling or plastering action by condensed iron vapour and fused iron. the operation is facilitated by coating the electrode wire lightly with mineral films, such as lime, which probably act by furnishing volatile material which adds to the stability of the arc. de- pending on the strength of current in the arc and the skill of the operator, from ¢ lb. to 2 ib. of metal per hour may be deposited in effecting the welds. when plates of over 3 in. in thickness are to be butt welded they should be bevelled before abutting them, so that a groove of not less than 60° flare shall be pro- vided, to be filled with the fused metal (see fig. 4). where the plates meet at an angle, as in fig. 5, the fused metal is deposited either at a or 8, or both. figs, 4 and 5.—welding operations arc welding can be carried on even upon the under side of the work (such as a boiler or tank in situ). the actual rate at which seams can be made in arc welding naturally depends upon the thickness of the plates to be united, the kind of joint to be made and other conditions. with automatic machines on small work it may rise to about 2 ft. per min., while in heavy work by hand operation it may not exceed 2 in. per minute. ordinary arc welds on steel may possess a tensile strength of as high as 50,000 lb. per sq. in., but arc welds under tension showed little elonga- tion before fracture, and were consequently brittle on bending. this defect of arc welds in steel or iron has, however, been re- moved by recent inventions preventing absorption of deleterious substances and oxidation of the metal of the weld, which instead of being brittle becomes highly ductile as well as strong. such improvements are the result of laboratory research work by one of our large industrial organisations. cast iron is amenable to arc welding when proper precautions are taken. likewise bronze or copper and its alloys may be welded, a favourable con- dition for which is preheating of the workpieces. in these welds 1002 the carbon arc is employed, as it is found to favour the proper union of the weld metal with the other picces. arc welding has usually been done by the use of direct current, and special dynamo generators are constructed for supplying the current, with regulating characteristics suitable to welding. the alternating-current arc 1s, however, adaptable to welding, provided the frequency is not too low. arc welding 1s employed in the construction of tanks, and in caulking the seams of tanks which must retain oil or thin liquids without leak. it is much used for repair work. it is readily applicable to joining broken pieces and to replacing metal worn away in use, e.g., the restora- tion of rail surfaces of tramways in sifu. it is generally less costly in application than the other forms of fusion welding, such as that by the use of oxvgen blowpipe or thermit welding. the improve- ments which have been made point to a greatly extended applica- tion of’arc work in the future; as in the construction of steel ships, pressure tanks and steam boilers without riveting. (e. t.) ii. gas-torch welding gas-torch welding is variously known as “ autogenous ”’ welding, “‘ oxy-acetylene blowpipe ” welding, ‘‘ hot gas flame ” welding, “‘ fusion ” welding, and other terms which are more or less accurate, general and confusing. the gas combinations more commonly used for torch or blowpipe welding are either oxygen-acetylene or oxygen-hydrogen. of these two, oxy- acetylene is in more general use for welding, while oxy-hydrogen, on account of its longer flame, is generally used to supply heat for steel-cutting torches. the oxy-acetylene flame has a maxi- mum heat, under ideal conditions, of about 3,400° c., and oxy- hydrogen about 2,000° c. sss assesses as oe bs z = ss fic, 6.—principle of the low-pressure or injector type of gas torch. the use of a blowpipe or torch in some form was known to the ancients, but the high-temperature gas flame is principally a de- velopment since 1910. the application of the oxy-acetylene torch to metallic welding dates experimentally from 1901 and com- mercially from 1903; edmond fouche, paris, who did consider- able experimenting in conjunction with picard, is generally credited with making the first really practical torch. the early torches used both oxygen and acetylene under high pressure, but this proved too dangerous, and a low-pressure or injector type was next used. following this was the gauthier-ely posi- tive- or medium-pressure torch, which used both gases under moderate and independent pressure. the injector and the positive-pressure types are the ones now in commercial use. the development of the latter is largely due to augustine davis and eugene bournonville. . fic. 7.—-principle of the medium or positive-pressure type of gas torch. the fundamental principle of the low-pressure or injector type of torch is shown in fig. 6. the acetylene enters at a and the wielding oxygen at b. the acetylene, at less than 1 ib. pressure, goes to chamber c, from which it is sucked by the oxygen, under 5 to 30 lb. pressure, pouring out of nozzle d, and is carried along with the oxygen into the mixing chamber i. ‘the thoroughly mixed gases issue from the nozzle of the torch, where they are burned. carbureting device which positively and { intimately mixes the two gases in proper proportion oxygen needle valve 2 \\ acetylene «.the two gases strike together at right angtes creating 2 vortex which insures intimate mixture the diameters of the parts in the carbureting device are proportioned to each size of tip, to deliver proper volumes of gas for each size of flame produced a luminous cone of flame secondary reaction. hydrogen and carbon i] monoxide burn, taking the necessary oxygen efi: from the air and produce water vapor an i fl carbon dioxide. 8, fi \\ th’ ip acetylene need! valve y fic. 8.—a typical positive pressure torch. 4 positive-pressure torch.—the positive-pressure torchjprinciple is illustrated in fig. 7. here the oxygen, at from 1 to 14 lb. pressure, enters at a, and the acetylene, at from 1 to 24 |b. pressure, enters at b. the oxygen enters the small chamber c and thence out through the centre hole. the acetylene goes to chamber d and also out through the centre hole. the two gases start to mix at e andare thoroughly mixed in the channel f in the torch nozzle g. a typical positive-pressure torch is shown in fig. 8. torches are made with tips set at various angles from go° to straight, the latter being principally used in welding and cutting machines. where the work is heavy the tips are water-cooled. in welding very thin metal the edges are often turned up or “ flanged ” and the torch used to fuse them together without using any additional metal. on heavier work the edges to be welded are v'd out at an angle of from 60° to 90°, and this channel is filled in by using a welding rod or wire, care being taken to obtain perfect fusion between the old metal and new. welding of this kind is progressive, as the welder gradually oxygen regulator oa tank or high- a _ pressure gage oxygen tank valve ----> 3 paye--low- pressure connection nut-” eev: bs lane safety vatve ---- (2e aie 4 —= -—outlet connection i) ult se ° we acetylene regulator =\\j |) sag} cutting tank or high- (9 handl =4 nozzle pressure gage “q_/% dust ,---2 *-<torch ' connecting nut---\" 4 (©). plug = ¥ head adapter--- - (f e galt oo = « safety valve --- {gul s 2 = a i eee = = 5 torch sane tone or = cutting valve acetylene? = we a « “lever tank valve ==\" = fl d e=5 \\¥ 2s 1 ust plug’ = j\\ts £3 .--handle outlet------\" = oxygen z st connection tank = hart) opyeen ae valve = s \"oxygen hose : 23 connection acetylene= 2s tank = se = meen lfife hf ayu acetylene hose. .-’ fic. 9.—typical oxy-acet ylene cutting unit. works along the channel, filling as he goes. the torch is given a weaving motion from side to side in order to fuse the sides of the welfare work—wells v and to puddle in the added metal from the rod. on all torch welding work allowance must be made for expansion and con- traction, and on repair work of complicated design, like an auto- mobile cylinder, preheating with charcoal, gas-and-air torches or other means is usually necessary. preheating is also sometimes resorted to in order to save the more expensive gases. nearly all of the common metals may be welded with the gas torch, though some are more difficult than others. steel ship or boiler plate is about the easiest, though aluminium, cast iron, copper and many alloys present no serious difficulties. cutting torches.—the set-up for a welding outfit is practically the same as that of the one for cutting shown in fig. 9. a cutting torch, however, differs from a welding torch in that it has a separate high-pressure oxygen vent. the cutting of stcel and wrought iron is based on the fact that a jet of oxygen directed on to a previously heated spot of steel causes it to ignite and burn away rapidly in the form of iron oxide. the oxide runs or is blown out of the cut or “ kerf ” in a stream, provided the torch is fed along properly. the tips used for cutting may have one or several heating jets preceding or surrounding the cutting oxygen jet. only steel or wrought iron can be successfully cut on a commercial scale, though channels or slots may be melted in any metal. a typical job of steel plate cutting is shown in fig. to, and a typical cutting torch’in fig. 11. cast iron is cut with difficulty, and only by using a special tip and highly preheating the oxygen in a positive-pressure torch or by using an excess of acetylene and an unusually large tip on the low-pressure types. fic. 10.—cutting through a steel! plate. ground ake a as ae acetylene acetylene } \\[- oxygen cutting preheating oxygen set trigger valve oxygen cutting valve acetylene valve rtyea packing es ee eld 8 packing nut cutting si, ne ee jet of is oxygen shy od a vy “4 -removable plug spring - trigger {remains in open position) fig. 11.—a typical cutting torch. gas supply.—the same sources of gas supply are used in cut- ting asin welding. these are, commonly, cylinders or drums con- taining the gases under pressure up to 225 tb. per sq. in. and from 50 to roo cu. ft. capacity for acetylene, and 1,800 ib. per sq. in. and from too to 200 cu. it. capacity for oxygen or hydrogen. acety- lene, however, may be generated on the premises, in which case the pressure must not exceed r5 lb. per sq. inch. obviously, pressure as great as that mentioned for cylinders must be reduced for use in the torch, and for this purpose regulators are used which automatically keep the gases supplied to the torch close to the pressure for which they are set. in many large plants prac- tically automatic gas-torch welding machines are used for straight or circular seam welding of drums, cylinders, tubes, kettles and the like. 1003 cutting machines —cutting machines are much more com- monly used than welding machines. the cutting machines range from the simple, hand-fed, straight-line cutters to complicated motor-driven automatic machines that will cut rounds, squares, ovals or other patterns. one type of cutting machine is made on the pantograph principle, and by following a template or pattern the operator can use two torches and cut two separate steel plates at once. a cutting machine will, as a rule, cut a narrower and more even kerf than can be done by hand. under favourable conditions a machine can be made to cut a kerf not over #3 in. wide, while a careless or inexperienced operator with a hand torch may cut a kerf !}¢ in. or more in width. torches are also now made so that divers can cut stcel ship plates while completely submerged under water. (e. v1.) welfare work: see industrial welfare. wellhausen, julius (1844-1918), german biblical scholar and orientalist (sce 28.507), died at gettingen jan. 7 1918. wellington, new zealand (see 28.513), has recently in- creased largely. onslow, karori and miramar have been incor- porated in the city area, which has now an acreage of 15,951, with 1,613 ac. of reserves. the population of the city proper was 94,340 in 1923, and that of the whole area was 114,510 in 1924. there is a town belt of 970 ac., which is leased for graz- ing but is open to public access. robertson park, (3 ac.) was given to the city in ro19, and keith izard park (11 ac.) in 1921. the municipality owns a seaside resort outside its boun- dairies at days bay, which has been renamed williams park in memory of the donor of a large sum of money towards its pur- chase. the municipality has also controlled the sale and supply of milk since 1919, and has a butter and cheese factory 47 m. from the city. in 1924 a water supply scheme was finished, in- volving a pipe-line from the orongorongo river to karori reser- voir and a tunnel two miles long under the mountains. a power station at evans bay was finished in 1925, and water and drain- age schemes are being carried out at onslow and karori. an automatic telephone exchange was built in 1925. wells, herbert george (1866- ), british man of letters (see 28.514), continued between 1910 and the outbreak of the world war to publish novels of which the plots are sub- ordinated to sociological speculation. the most famous of these, the new machiavelli (1911) describes an ambitious reformer who begins his political career as a liberal member of parlia- ment, and then, disgusted by party politics, advocates a demo- cratic, an almost socialistic imperialism, but is ruincd by the publicity given to his private amours. in afarriage (1912) are described a husband and wife who, despite the romance attending their first mecting, bore each other until they leave civilisation and rediscover themselves in icy and dangerous labrador. men- tion should also be made of the passionate friends (1913), the wife of sir isaac harman (1914) and the research magnificent (1915) which, despite the date of its publication, is essentially a pre-war novel. boon (1915) was not immediately acknowledged by mr. wells. this work, nevertheless, displays wells at his best. that impartial artist henry james is fiercely mocked, more fiercely perhaps than he deserved; and a flood of mr. wells’ excellent scorn is directed against such journalists as mr. fe. b. osborn of the aforning post. the wild asses of the devil have been released, and until they could be gathered again, civilisation was in jeopardy. war broke out; and eagerly, per- haps too eagerly, mr. wells tried to corral those errant asses. during the war mr. wells’ liberal imagination was freely given to the support of the allied cause. a host of pamphlets, written at red heat, championed western europe against the brutal stupidity which mr. wells thought to discover both in the german enemy, and the cruder english propaganda. afr. britling sees it through (1916) is the best known of his war time publications. this novel explains the mentality of a british publicist, whose eldest son is at the front, and finally displays mr. britling, half maddened by the outrages of war, and wholly broken hearted because his best beloved son is dead, poring over an atlas, and tracing new fronticrs. subsequently mr. wells failed to resurrect his novelistic talents. the undying 1004 fire (1919) more nearly resembles a philosophic dialogue than a story, and has been awarded less praise than it deserves. ifex like gods (1923) was a bold and brilliant experiment in utopi- anism, but too often crude satire took the place of intelligent criticism. in the dream (1924) mr. wells mingled prophecy and humour, and found that his public was tired of the future. therefore in christina alberta’s father (1925) he magnificently returned to his earlier manner, and again succeeded in impressing upon the general imagination the delightful creatures of his fancy. meanwhile, in his outline of history (1919-20), mr. wells gave his most powerful and his most delightful criticisms of modernity. many have found fault with the book. scholars have been shocked by the author’s contempt for cacsar and napoleon, or have denounced in the prehistoric chapters a too ready acceptance of fragile hypothesis as solid fact; and parti- sans have declared that mr. wells, despite the expert advice given to him, remains a slave of the late victorian materialism. no one else, however, has written a history of the world, and mr. wells, in the interim, holds the ground. morcover, it sup- plies as no other history has done, a fairly complete conspectus of the past. no one has done, or can do, more than mr. wells to suggest an alternative to our present civilisation. mr. wells is radically minded, and would like to replace what is by what might be. he is also so susceptible to fashion, that he is unable to break away from the apparatus of ordinary civilisation. he has, how- ever, ideas of his own. in the clash of these three things, mr. wells is in danger of losing direction. apart from his literary talents, mr. wells seems, by the influence exercised on his jun- iors, to belong to the tradition of carlyle and ruskin. he has supplied rebellious youth with a formula whereby existing in- stitutions are challenged and condemned, and he has offered to conformists a prospect of a civilisation steadily increasing in strength. in his style he avoids both carlyle’s obscurity and ruskin’s affectations, and his pure bright english will survive the themes on which it is expended. bisliography.—john d. beresford, 7. g. wells (1915); edward guyot, iz. g. wells (1920); ivor j. c. brown, i7. g. wells (1923). (h. c. ha.)",
    "source_url": "https://archive.org/details/encyclopaedia-britannica-encyclopaedia-britannica.-3-encyclopaedia-britannica-inc.-1926",
    "observed_at": "2026-05-17 12:14:22",
    "integrity": {
        "hash_check": "match",
        "hash_scope": "full_normalized_text",
        "computed_sha256": "7b0514404f238a9afcd3f82c6bf7e3a6a74d1944558f25e18462f4d22c60c71b"
    },
    "machine_use": {
        "read": true,
        "cite": true,
        "decision": "verified_public_domain_text"
    },
    "goguides_data_license": "https://www.goguides.com/data-license",
    "goguides_data_license_version": "2.0",
    "documentation": {
        "white_paper_url": "https://www.goguides.com/white-paper.php",
        "pdf_url": "https://www.goguides.com/whitepapers/goguides-ai-source-clearance-white-paper.pdf"
    }
}