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91-599: The Folkton Drums are a very rare set of three decorated chalk objects in the shape of drums or solid cylinders dating from the Neolithic period. Found in a child's grave near the village of Folkton in northern England, they are now on loan to Stonehenge Visitor Centre from the British Museum . A similar object, the Burton Agnes drum was found 15 miles away near Burton Agnes in 2015, and another example,

182-402: A square wave pattern instead of the normal sine wave , making rapid zero crossings possible and minimizing the effects of the problem. Resistance welding involves the generation of heat by passing current through the resistance caused by the contact between two or more metal surfaces. Small pools of molten metal are formed at the weld area as high current (1,000–100,000 A ) is passed through

273-552: A 55-gallon drum in the United States and a 44-gallon drum in the United Kingdom and the rest of the world) is a cylindrical container with a nominal capacity of 200 litres (55 US or 44 imp gal). The exact capacity varies by manufacturer, purpose, or other factors. Standard drums have inside dimensions of 572 millimetres (22.5  in ) diameter and 851 millimetres (33.5 in) height. These dimensions yield

364-502: A Russian, Konstantin Khrenov eventually implemented the first underwater electric arc welding. Gas tungsten arc welding , after decades of development, was finally perfected in 1941, and gas metal arc welding followed in 1948, allowing for fast welding of non- ferrous materials but requiring expensive shielding gases. Shielded metal arc welding was developed during the 1950s, using a flux-coated consumable electrode, and it quickly became

455-610: A circular cross section but square drums are also available: these can be packed closer during shipment and storage. Fibre drums are available in a variety of constructions and sizes. They are used for shipping various granular materials, coiled wire and cable, long Fluorescent light bulbs , and (when certified) for dangerous goods. Compatibility with the contents is important; drum liners are commonly used. Steel, fibre, and plastic covers are available with steel lever lock ring closures. Plastic drums are typically made of blow molded high density polyethylene. They are available in

546-742: A common nominal volume of 208 litres (55  US gal ) whereas the barrel volume of crude oil is 42 US gallons (159  L ). In the United States, 25-US-gallon (95-litre) drums are also in common use and have the same height. This allows easy stacking of mixed pallets. Barrels can be constructed of plastic, laminated paperboard or steel. Drums have top and (usually) bottom chimes or rims: sometimes called chines . Most steel drums have reinforcing rolling hoops or rings of thickened metal or plastic. This sufficiently strengthens them so that they can readily be turned on their sides and rolled when filled with heavy materials, like liquids. Over short to medium distances, drums can be tipped and rolled on

637-481: A gas flame (chemical), an electric arc (electrical), a laser , an electron beam , friction , and ultrasound . While often an industrial process, welding may be performed in many different environments, including in open air, under water , and in outer space . Welding is a hazardous undertaking and precautions are required to avoid burns , electric shock , vision damage, inhalation of poisonous gases and fumes, and exposure to intense ultraviolet radiation . Until

728-414: A highly concentrated, limited amount of heat, resulting in a small HAZ. Arc welding falls between these two extremes, with the individual processes varying somewhat in heat input. To calculate the heat input for arc welding procedures, the following formula can be used: where Q = heat input ( kJ /mm), V = voltage ( V ), I = current (A), and S = welding speed (mm/min). The efficiency is dependent on

819-409: A highly focused laser beam, while electron beam welding is done in a vacuum and uses an electron beam. Both have a very high energy density, making deep weld penetration possible and minimizing the size of the weld area. Both processes are extremely fast, and are easily automated, making them highly productive. The primary disadvantages are their very high equipment costs (though these are decreasing) and

910-489: A leaking 55-gallon drum can disperse its contents over a 1,200 square-foot area of level surface. Drums are often cleaned or re-conditioned and then used for storing or shipping various liquids or materials. Although crude oil is sometimes shipped in 55-US-gallon drums, the measurement standard of oil in barrels is based on the whiskey containers of the 1870s that measured 42 US gallons (35 imp gal; 159 L). The measure of 42 US or wine gallons corresponds to

1001-513: A modest amount of training and can achieve mastery with experience. Weld times are rather slow, since the consumable electrodes must be frequently replaced and because slag, the residue from the flux, must be chipped away after welding. Furthermore, the process is generally limited to welding ferrous materials, though special electrodes have made possible the welding of cast iron , stainless steel, aluminum, and other metals. Gas metal arc welding (GMAW), also known as metal inert gas or MIG welding,

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1092-562: A normal three-quarter inch wrench or ratchet wrench. Tops exist with bung holes as above, and these hybrid drums with lid can be used to ship many non-volatile liquids as well as industrial powders. Many drums are used to ship and store powdered products as well as liquids, such as plastic beads for injection moulding, extrusion, and purified industrial grade powders like cleansers (e.g., fertilizers, and powdered aluminum). If used to transport dangerous goods across international boundaries, they may need to have UN certification. In general, drum usage

1183-647: A poem "Folkton Drums" in 2018 in connection with the University of Reading 's Grave Goods project. The three Folkton drums were displayed as part of the 2022 World of Stonehenge exhibition at the British Museum, alongside the Burton Agnes Drum , which was in the public view for the first time. Drum (container) Steel drums are ubiquitous industrial shipping containers. They are manufactured from sheets of cold rolled steel formed into

1274-404: A ribbed outer wall to improve rigidity and for rolling. The lids can be welded or secured with a head gasket and bolt ring. They are commonly used for transporting oils , fuels , chemicals, and dry goods. Drums are frequently transported on pallets for ease of handling by a fork truck and for shipping. The drum's size, shape, and weight distribution lends itself to being moved about readily on

1365-447: A suitable torch was developed. At first, oxyfuel welding was one of the more popular welding methods due to its portability and relatively low cost. As the 20th century progressed, however, it fell out of favor for industrial applications. It was largely replaced with arc welding, as advances in metal coverings (known as flux ) were made. Flux covering the electrode primarily shields the base material from impurities, but also stabilizes

1456-434: A susceptibility to thermal cracking. Developments in this area include laser-hybrid welding , which uses principles from both laser beam welding and arc welding for even better weld properties, laser cladding , and x-ray welding . Like forge welding (the earliest welding process discovered), some modern welding methods do not involve the melting of the materials being joined. One of the most popular, ultrasonic welding ,

1547-576: A tube and welded along the side seam. Stainless steel, nickel, and special alloys are occasionally used. The bottom head is permanently attached by the manufacturer. Two primary options are available for the top head: Henry Wehrhahn, employee of Nellie Bly's Iron Clad Manufacturing Company of New York, received two patents in December 1905 that would lead to the modern 55-gallon steel drum Use of 200-litre drums became widespread in World War II ,

1638-524: A tungsten electrode but uses plasma gas to make the arc. The arc is more concentrated than the GTAW arc, making transverse control more critical and thus generally restricting the technique to a mechanized process. Because of its stable current, the method can be used on a wider range of material thicknesses than can the GTAW process and it is much faster. It can be applied to all of the same materials as GTAW except magnesium, and automated welding of stainless steel

1729-552: A unit of measure thought to have been widely used in Neolithic Britain. The drums could therefore have been used as measuring devices , as a means of achieving standardisation in construction at different locations. The diameters, and hence the circumferences, of the drums also form a mathematical harmonic sequence . According to author Prof. Andrew Chamberlain, "The existence of these measuring devices implies an advanced knowledge in prehistoric Britain of geometry and of

1820-717: A variety of sizes and constructions designed for specific purposes and markets. Plastic drums are used for liquids, granular solids, and inner packages. When designed, tested, and labeled, plastic drums can be used with dangerous goods or hazardous materials. The plastic drum, inner coating, or drum liner should be compatible with the intended contents. Foods and pharmaceuticals can be particularly sensitive. Some liquid chemicals can permeate through plastics or can cause embrittlement. The compression stability of plastic drums can be sensitive to heat. The Plastic Drum Institute does not recommend stacking when temperatures are above about 32 °C (90 °F). Some methods of reinforcing

1911-516: A volume of about 218.7 litres (57.8 US gal; 48.1 imp gal), but they are commonly filled to about 200 litres. The outside dimensions of a 200-litre drum are typically 584 millimetres (23 in) diameter at the top or bottom rim, 597 millimetres (23.5 in) diameter at the chines (ridges around drum), and 876 millimetres (34.5 in) height. Exact dimensions are specified in ANSI MH2. The drums are typically made of steel with

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2002-986: A wine tierce (third-pipe). A wine barrel, or 1 ⁄ 8 tun, measures 31.5 US gallons (26.2 imp gal; 119.2 L). Applicable standards include: Steel drums are commonly reconditioned for further use. Life cycle studies of reconditioning and reuse have been quite favorable. Clean drums go to a qualified reconditioner: hazardous residue can be a concern to regulators. Reconditioning usually consists of inspection, removal of labels, cleaning (mechanical, heat, or caustic cleaner), straightening of dents and chimes, replace gaskets, painting, testing, marking and labeling. Steel drums can often go through many use - reconditioning - reuse cycles before they are recycled or landfilled. Fibre drums (occasionally: fiber drums) are shipping containers with paperboard : laminated paperboard; plastics, foils, and other protective layers. The heads can be of fibreboard, metal, plywood, plastic or other suitable material. Drums typically have

2093-427: Is a highly productive, single-pass welding process for thicker materials between 1 inch (25 mm) and 12 inches (300 mm) in a vertical or close to vertical position. To supply the electrical power necessary for arc welding processes, a variety of different power supplies can be used. The most common welding power supplies are constant current power supplies and constant voltage power supplies. In arc welding,

2184-472: Is a ring surrounding the weld in which the temperature of the welding process, combined with the stresses of uneven heating and cooling, alters the heat-treatment properties of the alloy. The effects of welding on the material surrounding the weld can be detrimental—depending on the materials used and the heat input of the welding process used, the HAZ can be of varying size and strength. The thermal diffusivity of

2275-430: Is a semi-automatic or automatic process that uses a continuous wire feed as an electrode and an inert or semi-inert gas mixture to protect the weld from contamination. Since the electrode is continuous, welding speeds are greater for GMAW than for SMAW. A related process, flux-cored arc welding (FCAW), uses similar equipment but uses wire consisting of a steel electrode surrounding a powder fill material. This cored wire

2366-433: Is allowed to cool, and then another weld is performed on top of it. This allows for the welding of thick sections arranged in a single-V preparation joint, for example. After welding, a number of distinct regions can be identified in the weld area. The weld itself is called the fusion zone—more specifically, it is where the filler metal was laid during the welding process. The properties of the fusion zone depend primarily on

2457-442: Is characterized by a stable arc and high-quality welds, but it requires significant operator skill and can only be accomplished at relatively low speeds. GTAW can be used on nearly all weldable metals, though it is most often applied to stainless steel and light metals. It is often used when quality welds are extremely important, such as in bicycle , aircraft and naval applications. A related process, plasma arc welding, also uses

2548-407: Is commonly used for making electrical connections out of aluminum or copper, and it is also a very common polymer welding process. Another common process, explosion welding , involves the joining of materials by pushing them together under extremely high pressure. The energy from the impact plasticizes the materials, forming a weld, even though only a limited amount of heat is generated. The process

2639-627: Is commonly used for welding dissimilar materials, including bonding aluminum to carbon steel in ship hulls and stainless steel or titanium to carbon steel in petrochemical pressure vessels. Other solid-state welding processes include friction welding (including friction stir welding and friction stir spot welding ), magnetic pulse welding , co-extrusion welding, cold welding , diffusion bonding , exothermic welding , high frequency welding , hot pressure welding, induction welding , and roll bonding . Welds can be geometrically prepared in many different ways. The five basic types of weld joints are

2730-406: Is limited to wholesale distribution of bulk products, which are then further processed or sub-divided in a factory. These metal drums have two openings with flanges, often 51 millimetres (2 in) NPS and 19 millimetres (0.75 in) NPS in diameter. Once the drums are filled, the plugs (bungs) are screwed in the flanges using pneumatic or hand-operated bung tightener (plug wrench). To secure

2821-484: Is made of filler material (typical steel) and is covered with a flux that protects the weld area from oxidation and contamination by producing carbon dioxide (CO 2 ) gas during the welding process. The electrode core itself acts as filler material, making a separate filler unnecessary. The process is versatile and can be performed with relatively inexpensive equipment, making it well suited to shop jobs and field work. An operator can become reasonably proficient with

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2912-433: Is more expensive than the standard solid wire and can generate fumes and/or slag, but it permits even higher welding speed and greater metal penetration. Gas tungsten arc welding (GTAW), or tungsten inert gas (TIG) welding, is a manual welding process that uses a non-consumable tungsten electrode, an inert or semi-inert gas mixture, and a separate filler material. Especially useful for welding thin materials, this method

3003-420: Is obtained by a metallic or chemical bond that is formed between the constituent atoms. Chemical bonds can be grouped into two types consisting of ionic and covalent . To form an ionic bond, either a valence or bonding electron separates from one atom and becomes attached to another atom to form oppositely charged ions . The bonding in the static position is when the ions occupy an equilibrium position where

3094-430: Is one important application of the process. A variation of the process is plasma cutting , an efficient steel cutting process. Submerged arc welding (SAW) is a high-productivity welding method in which the arc is struck beneath a covering layer of flux. This increases arc quality since contaminants in the atmosphere are blocked by the flux. The slag that forms on the weld generally comes off by itself, and combined with

3185-720: Is related to the Old Swedish word valla , meaning 'to boil', which could refer to joining metals, as in valla järn (literally "to boil iron"). Sweden was a large exporter of iron during the Middle Ages , so the word may have entered English from the Swedish iron trade, or may have been imported with the thousands of Viking settlements that arrived in England before and during the Viking Age , as more than half of

3276-400: Is sometimes protected by some type of inert or semi- inert gas , known as a shielding gas, and filler material is sometimes used as well. One of the most common types of arc welding is shielded metal arc welding (SMAW); it is also known as manual metal arc welding (MMAW) or stick welding. Electric current is used to strike an arc between the base material and consumable electrode rod, which

3367-438: Is still widely used for welding pipes and tubes, as well as repair work. The equipment is relatively inexpensive and simple, generally employing the combustion of acetylene in oxygen to produce a welding flame temperature of about 3100 °C (5600 °F). The flame, since it is less concentrated than an electric arc, causes slower weld cooling, which can lead to greater residual stresses and weld distortion, though it eases

3458-470: Is used to connect thin sheets or wires made of metal or thermoplastic by vibrating them at high frequency and under high pressure. The equipment and methods involved are similar to that of resistance welding, but instead of electric current, vibration provides energy input. When welding metals, the vibrations are introduced horizontally, and the materials are not melted; with plastics, which should have similar melting temperatures, vertically. Ultrasonic welding

3549-535: The Lavant drum , was excavated in 1993 in Lavant , West Sussex . Their purpose remains obscure. They were given the name "drum" to describe their shape, rather than from any thought they might be percussion instruments. In 1889, a round prehistoric barrow was opened by the scholar and amateur archaeologist William Greenwell near Folkton in North Yorkshire . Inside, he found a neolithic grave dating to

3640-503: The UN , countries and regional authorities require drum construction and the demonstrated performance of severe testing. The Industrial Steel Drum Institute has also provided guidance for conducting the tests. Drums have embossed symbols to identify certification for shipment of certain types of products. Many drums nominally measure just under 880 millimetres (35 in) tall with a diameter just under 610 millimetres (24 in), and have

3731-461: The 1590 version this was changed to " ...thei shullen welle togidere her swerdes in-to scharris... " (they shall weld together their swords into plowshares), suggesting this particular use of the word probably became popular in English sometime between these periods. The Old English word for welding iron was samod ('to bring together') or samodwellung ('to bring together hot'). The word

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3822-421: The 1930s and then during World War II. In 1930, the first all-welded merchant vessel, M/S Carolinian , was launched. During the middle of the century, many new welding methods were invented. In 1930, Kyle Taylor was responsible for the release of stud welding , which soon became popular in shipbuilding and construction. Submerged arc welding was invented the same year and continues to be popular today. In 1932

3913-564: The Soviet scientist N. F. Kazakov proposed the diffusion bonding method. Other recent developments in welding include the 1958 breakthrough of electron beam welding, making deep and narrow welding possible through the concentrated heat source. Following the invention of the laser in 1960, laser beam welding debuted several decades later, and has proved to be especially useful in high-speed, automated welding. Magnetic pulse welding (MPW) has been industrially used since 1967. Friction stir welding

4004-469: The arc and can add alloying components to the weld metal. World War I caused a major surge in the use of welding, with the various military powers attempting to determine which of the several new welding processes would be best. The British primarily used arc welding, even constructing a ship, the "Fullagar" with an entirely welded hull. Arc welding was first applied to aircraft during the war as well, as some German airplane fuselages were constructed using

4095-437: The atmosphere. Porosity and brittleness were the primary problems, and the solutions that developed included the use of hydrogen , argon , and helium as welding atmospheres. During the following decade, further advances allowed for the welding of reactive metals like aluminum and magnesium . This in conjunction with developments in automatic welding, alternating current, and fluxes fed a major expansion of arc welding during

4186-433: The base material plays a large role—if the diffusivity is high, the material cooling rate is high and the HAZ is relatively small. Conversely, a low diffusivity leads to slower cooling and a larger HAZ. The amount of heat injected by the welding process plays an important role as well, as processes like oxyacetylene welding have an unconcentrated heat input and increase the size of the HAZ. Processes like laser beam welding give

4277-516: The base metal (parent metal) and instead require flowing a filler metal to solidify their bonds. In addition to melting the base metal in welding, a filler material is typically added to the joint to form a pool of molten material (the weld pool ) that cools to form a joint that can be stronger than the base material. Welding also requires a form of shield to protect the filler metals or melted metals from being contaminated or oxidized . Many different energy sources can be used for welding, including

4368-400: The bottom rim while being held at an angle, balanced, and rotated with a two-handed top grip that also supplies the torque (rotational or rolling force). The open-top sub-type is sealed by a mechanical ring clamp (concave inwards) that exerts sufficient pressure to hold many non-volatile liquids and make an airtight seal against a gasket, as it exerts force inward and downward when tightened by

4459-402: The butt joint, lap joint, corner joint, edge joint, and T-joint (a variant of this last is the cruciform joint ). Other variations exist as well—for example, double-V preparation joints are characterized by the two pieces of material each tapering to a single center point at one-half their height. Single-U and double-U preparation joints are also fairly common—instead of having straight edges like

4550-529: The contents of the drums against theft and adulteration during shipment, cap-seals made of metal and other types like metal-plastic laminates are used. These cap-seals sit on top of the flanges and are crimped, using a drum cap-seal crimping tool, also called a drum cap sealer. Once cap-seals are crimped, the plugs can be unscrewed only by breaking these cap-seals. Pneumatic and hand-operated cap-seal crimping tools are available. Pneumatic ones are used in production lines for high production. A 200-litre drum (known as

4641-419: The demand for reliable and inexpensive joining methods. Following the wars, several modern welding techniques were developed, including manual methods like shielded metal arc welding , now one of the most popular welding methods, as well as semi-automatic and automatic processes such as gas metal arc welding , submerged arc welding , flux-cored arc welding and electroslag welding . Developments continued with

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4732-518: The distance between the wire and the base material is quickly rectified by a large change in current. For example, if the wire and the base material get too close, the current will rapidly increase, which in turn causes the heat to increase and the tip of the wire to melt, returning it to its original separation distance. The type of current used plays an important role in arc welding. Consumable electrode processes such as shielded metal arc welding and gas metal arc welding generally use direct current, but

4823-491: The drums were often transported to the island on fast ships, such as destroyers , and shoved over the sides (or, time permitting, lowered in cargo nets). Because gasoline's density is much less than that of water, the drums floated. Navy Seabees in small craft corralled the drums. A wide variety of constructions and sizes are available. When the intended use is for shipment of dangerous goods (hazardous materials), strict regulatory requirements are applicable. Coordinated by

4914-443: The durability of many designs increases significantly. Most solids used are engineering materials consisting of crystalline solids in which the atoms or ions are arranged in a repetitive geometric pattern which is known as a lattice structure . The only exception is material that is made from glass which is a combination of a supercooled liquid and polymers which are aggregates of large organic molecules. Crystalline solids cohesion

5005-600: The electrode can be charged either positively or negatively. In welding, the positively charged anode will have a greater heat concentration, and as a result, changing the polarity of the electrode affects weld properties. If the electrode is positively charged, the base metal will be hotter, increasing weld penetration and welding speed. Alternatively, a negatively charged electrode results in more shallow welds. Non-consumable electrode processes, such as gas tungsten arc welding, can use either type of direct current, as well as alternating current. However, with direct current, because

5096-442: The electrode only creates the arc and does not provide filler material, a positively charged electrode causes shallow welds, while a negatively charged electrode makes deeper welds. Alternating current rapidly moves between these two, resulting in medium-penetration welds. One disadvantage of AC, the fact that the arc must be re-ignited after every zero crossings, has been addressed with the invention of special power units that produce

5187-404: The electrode perfectly steady, and as a result, the arc length and thus voltage tend to fluctuate. Constant voltage power supplies hold the voltage constant and vary the current, and as a result, are most often used for automated welding processes such as gas metal arc welding, flux-cored arc welding, and submerged arc welding. In these processes, arc length is kept constant, since any fluctuation in

5278-408: The end of the 19th century, the only welding process was forge welding , which blacksmiths had used for millennia to join iron and steel by heating and hammering. Arc welding and oxy-fuel welding were among the first processes to develop late in the century, and electric resistance welding followed soon after. Welding technology advanced quickly during the early 20th century, as world wars drove

5369-438: The filler metal used, and its compatibility with the base materials. It is surrounded by the heat-affected zone , the area that had its microstructure and properties altered by the weld. These properties depend on the base material's behavior when subjected to heat. The metal in this area is often weaker than both the base material and the fusion zone, and is also where residual stresses are found. Many distinct factors influence

5460-654: The first war in which trucks , cold rolled steel , stamp or pattern forging machinery and welding were widely available. They were first utilized by the Axis powers (Germany and Italy), but were quickly adopted by Allies . The drums helped win the Guadalcanal Campaign in the first U.S. offensive in the South Pacific Theater . The U.S. Navy could not maintain command of the sea long enough to offload aviation gasoline for aircraft ashore, so

5551-582: The invention of laser beam welding , electron beam welding , magnetic pulse welding , and friction stir welding in the latter half of the century. Today, as the science continues to advance, robot welding is commonplace in industrial settings, and researchers continue to develop new welding methods and gain greater understanding of weld quality. The term weld is derived from the Middle English verb well ( wæll ; plural/present tense: wælle ) or welling ( wællen ), meaning 'to heat' (to

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5642-536: The invention of metal electrodes in the late 1800s by a Russian, Nikolai Slavyanov (1888), and an American, C. L. Coffin (1890). Around 1900, A. P. Strohmenger released a coated metal electrode in Britain , which gave a more stable arc. In 1905, Russian scientist Vladimir Mitkevich proposed using a three-phase electric arc for welding. Alternating current welding was invented by C. J. Holslag in 1919, but did not become popular for another decade. Resistance welding

5733-412: The length of the arc is directly related to the voltage, and the amount of heat input is related to the current. Constant current power supplies are most often used for manual welding processes such as gas tungsten arc welding and shielded metal arc welding, because they maintain a relatively constant current even as the voltage varies. This is important because in manual welding, it can be difficult to hold

5824-574: The loading dock or factory floor with a two-wheeled hand truck . They can be turned on side and rolled. They can also be moved by hand short distances on firm surfaces by tilting and then rolling along the base, or by using a drum handler , which is designed especially for that purpose. Closed-head steel barrels and drums used for shipment of chemicals and petroleum products have a standardised bunghole arrangement, with one 51-millimetre (2 in) (DN50) NPT and one 19-millimetre ( 3 ⁄ 4  in) (DN20) NPT threaded bunghole on opposite sides of

5915-532: The material may not have the ability to withstand the stress and could cause cracking, one method the control these stress would be to control the heating and cooling rate, such as pre-heating and post- heating The durability and life of dynamically loaded, welded steel structures is determined in many cases by the welds, in particular the weld transitions. Through selective treatment of the transitions by grinding (abrasive cutting) , shot peening , High-frequency impact treatment , Ultrasonic impact treatment , etc.

6006-484: The mathematical properties of circles.” The study also proposed that the drums represent ceremonial objects that have uniquely survived due to their unusual material, while most objects of this type may have been made out of wood. The Lavant drum , excavated in 1993, was previously identified as being analogous to the Folkton drums in 2005 by archaeologist Anne Teather. Children's writer and poet Michael Rosen wrote

6097-715: The maximum temperature possible); 'to bring to a boil'. The modern word was probably derived from the past-tense participle welled ( wællende ), with the addition of d for this purpose being common in the Germanic languages of the Angles and Saxons . It was first recorded in English in 1590. A fourteenth century translation of the Christian Bible into English by John Wycliffe translates Isaiah 2:4 as " ...thei shul bete togidere their swerdes into shares... " (they shall beat together their swords into plowshares). In

6188-426: The metal. In general, resistance welding methods are efficient and cause little pollution, but their applications are somewhat limited and the equipment cost can be high. Spot welding is a popular resistance welding method used to join overlapping metal sheets of up to 3 mm thick. Two electrodes are simultaneously used to clamp the metal sheets together and to pass current through the sheets. The advantages of

6279-697: The method include efficient energy use , limited workpiece deformation, high production rates, easy automation, and no required filler materials. Weld strength is significantly lower than with other welding methods, making the process suitable for only certain applications. It is used extensively in the automotive industry—ordinary cars can have several thousand spot welds made by industrial robots . A specialized process called shot welding , can be used to spot weld stainless steel. Like spot welding, seam welding relies on two electrodes to apply pressure and current to join metal sheets. However, instead of pointed electrodes, wheel-shaped electrodes roll along and often feed

6370-650: The most common English words in everyday use are Scandinavian in origin. The history of joining metals goes back several millennia. The earliest examples of this come from the Bronze and Iron Ages in Europe and the Middle East . The ancient Greek historian Herodotus states in The Histories of the 5th century BC that Glaucus of Chios "was the man who single-handedly invented iron welding". Forge welding

6461-415: The most popular metal arc welding process. In 1957, the flux-cored arc welding process debuted, in which the self-shielded wire electrode could be used with automatic equipment, resulting in greatly increased welding speeds, and that same year, plasma arc welding was invented by Robert Gage. Electroslag welding was introduced in 1958, and it was followed by its cousin, electrogas welding , in 1961. In 1953,

6552-440: The parts together and allow them to cool, causing fusion . Common alternative methods include solvent welding (of thermoplastics) using chemicals to melt materials being bonded without heat, and solid-state welding processes which bond without melting, such as pressure, cold welding , and diffusion bonding . Metal welding is distinct from lower temperature bonding techniques such as brazing and soldering , which do not melt

6643-436: The process, and the industry continued to grow during the following centuries. In 1800, Sir Humphry Davy discovered the short-pulse electrical arc and presented his results in 1801. In 1802, Russian scientist Vasily Petrov created the continuous electric arc, and subsequently published "News of Galvanic-Voltaic Experiments" in 1803, in which he described experiments carried out in 1802. Of great importance in this work

6734-553: The process. Also noteworthy is the first welded road bridge in the world, the Maurzyce Bridge in Poland (1928). During the 1920s, significant advances were made in welding technology, including the introduction of automatic welding in 1920, in which electrode wire was fed continuously. Shielding gas became a subject receiving much attention, as scientists attempted to protect welds from the effects of oxygen and nitrogen in

6825-442: The quality of welding procedure specification , how to judge the skill of the person performing the weld, and how to ensure the quality of a welding job. Methods such as visual inspection , radiography , ultrasonic testing , phased-array ultrasonics , dye penetrant inspection , magnetic particle inspection , or industrial computed tomography can help with detection and analysis of certain defects. The heat-affected zone (HAZ)

6916-650: The quality of a weld, either destructive or nondestructive testing methods are commonly used to verify that welds are free of defects, have acceptable levels of residual stresses and distortion, and have acceptable heat-affected zone (HAZ) properties. Types of welding defects include cracks, distortion, gas inclusions (porosity), non-metallic inclusions, lack of fusion, incomplete penetration, lamellar tearing, and undercutting. The metalworking industry has instituted codes and specifications to guide welders , weld inspectors , engineers , managers, and property owners in proper welding technique, design of welds, how to judge

7007-428: The resulting force between them is zero. When the ions are exerted in tension force, the inter-ionic spacing increases creating an electrostatic attractive force, while a repulsing force under compressive force between the atomic nuclei is dominant. Covalent bonding takes place when one of the constituent atoms loses one or more electrons, with the other atom gaining the electrons, resulting in an electron cloud that

7098-414: The sidewalls are available. Plastic drums are used for more than shipping containers . They can be used for water collection and storage. Also, plastic drums are used along highways to mark construction zones. Applicable standards include: Welding Welding is a fabrication process that joins materials, usually metals or thermoplastics , primarily by using high temperature to melt

7189-667: The single-V and double-V preparation joints, they are curved, forming the shape of a U. Lap joints are also commonly more than two pieces thick—depending on the process used and the thickness of the material, many pieces can be welded together in a lap joint geometry. Many welding processes require the use of a particular joint design; for example, resistance spot welding, laser beam welding, and electron beam welding are most frequently performed on lap joints. Other welding methods, like shielded metal arc welding, are extremely versatile and can weld virtually any type of joint. Some processes can also be used to make multipass welds, in which one weld

7280-604: The strength of welds and the material around them, including the welding method, the amount and concentration of energy input, the weldability of the base material, filler material, and flux material, the design of the joint, and the interactions between all these factors. For example, the factor of welding position influences weld quality, that welding codes & specifications may require testing—both welding procedures and welders—using specified welding positions: 1G (flat), 2G (horizontal), 3G (vertical), 4G (overhead), 5G (horizontal fixed pipe), or 6G (inclined fixed pipe). To test

7371-533: The time of Stonehenge , estimated to be between 2600 and 2000 BC. The remains of several bodies were unearthed, one of whom was a child beside which the three drums were found. The rarity of this find suggests that the child came from an elite group in society. Four years after the discovery, the drums were donated by Greenwell, along with other parts of his collection, to the British Museum. The three drum-like forms are made of locally quarried chalk and are decorated with stylized human faces and geometric patterns. On

7462-522: The top head. Drums can also be made of durable plastic or paperboard and this arrangement is echoed in many plastic drums. Various components can be mounted to the drum, such as drum pumps and bung mixers. In the past, hazardous waste was often placed in drums of this size and stored in open fields or buried. Over time, some drums would corrode and leak. As a result, these drums have become iconic of pollution problems, even though they have numerous uses and are ubiquitous in commerce. Tests have shown that

7553-515: The top of the cylinders are a series of concentric circles and two of them have pairs of eyes that schematically denote a human face. The decoration of the drums has similarities to objects made in the Beaker culture and early British Bronze Age , including the use of chevron and lozenge forms. A study published in 2018 noted that the circumferences of the drums form whole-number divisions (ten, nine and eight times, respectively) of ten long feet ,

7644-468: The use of a continuous wire feed, the weld deposition rate is high. Working conditions are much improved over other arc welding processes, since the flux hides the arc and almost no smoke is produced. The process is commonly used in industry, especially for large products and in the manufacture of welded pressure vessels. Other arc welding processes include atomic hydrogen welding , electroslag welding (ESW), electrogas welding , and stud arc welding . ESW

7735-415: The welding of high alloy steels. A similar process, generally called oxyfuel cutting, is used to cut metals. These processes use a welding power supply to create and maintain an electric arc between an electrode and the base material to melt metals at the welding point. They can use either direct current (DC) or alternating current (AC), and consumable or non-consumable electrodes . The welding region

7826-420: The welding process used, with shielded metal arc welding having a value of 0.75, gas metal arc welding and submerged arc welding, 0.9, and gas tungsten arc welding, 0.8. Methods of alleviating the stresses and brittleness created in the HAZ include stress relieving and tempering . One major defect concerning the HAZ would be cracking at the toes , due to the rapid expansion (heating) and contraction (cooling)

7917-585: The workpiece, making it possible to make long continuous welds. In the past, this process was used in the manufacture of beverage cans, but now its uses are more limited. Other resistance welding methods include butt welding , flash welding , projection welding , and upset welding . Energy beam welding methods, namely laser beam welding and electron beam welding , are relatively new processes that have become quite popular in high production applications. The two processes are quite similar, differing most notably in their source of power. Laser beam welding employs

8008-415: Was also developed during the final decades of the 19th century, with the first patents going to Elihu Thomson in 1885, who produced further advances over the next 15 years. Thermite welding was invented in 1893, and around that time another process, oxyfuel welding , became well established. Acetylene was discovered in 1836 by Edmund Davy , but its use was not practical in welding until about 1900, when

8099-519: Was invented in 1991 by Wayne Thomas at The Welding Institute (TWI, UK) and found high-quality applications all over the world. All of these four new processes continue to be quite expensive due to the high cost of the necessary equipment, and this has limited their applications. The most common gas welding process is oxyfuel welding, also known as oxyacetylene welding. It is one of the oldest and most versatile welding processes, but in recent years it has become less popular in industrial applications. It

8190-457: Was the description of a stable arc discharge and the indication of its possible use for many applications, one being melting metals. In 1808, Davy, who was unaware of Petrov's work, rediscovered the continuous electric arc. In 1881–82 inventors Nikolai Benardos (Russian) and Stanisław Olszewski (Polish) created the first electric arc welding method known as carbon arc welding using carbon electrodes. The advances in arc welding continued with

8281-532: Was used in the construction of the Iron pillar of Delhi , erected in Delhi , India about 310 AD and weighing 5.4  metric tons . The Middle Ages brought advances in forge welding , in which blacksmiths pounded heated metal repeatedly until bonding occurred. In 1540, Vannoccio Biringuccio published De la pirotechnia , which includes descriptions of the forging operation. Renaissance craftsmen were skilled in

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