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77-415: Beer kegs are made of stainless steel , or less commonly, of aluminium . A keg has a single opening on one end, called a "bung". A tube called a "spear" extends from the opening to the other end. There is a self-closing valve that is opened by the coupling fitting which is attached when the keg is tapped. There is also an opening at the top of the spear that allows gas (usually carbon dioxide ) to drive

154-464: A cardboard outer packaging , which makes them easier to stack and transport, and also protects the plastic container. Some may use either bag in ball or spear technology. Products like the Hybrid keg have a puncture resistant wall and are easy to disassemble after use. Circular by design, the top and bottom chimes can either be re-used or recycled. A quarter barrel , more commonly known as pony keg ,

231-731: A martensitic stainless steel alloy, today known as AISI type 420. The discovery was announced two years later in a January 1915 newspaper article in The New York Times . The metal was later marketed under the "Staybrite" brand by Firth Vickers in England and was used for the new entrance canopy for the Savoy Hotel in London in 1929. Brearley applied for a US patent during 1915 only to find that Haynes had already registered one. Brearley and Haynes pooled their funding and, with

308-449: A beach or campsite. Instead, in the US and Australia, kegs are usually kept in a bucket of ice and/or water to keep the beer cool. Alternately, the keg can be kept at ambient temperature and served using a " jockey box ", consisting of a cooler with beer coils (50–120-foot-long (20–40 m) metal dispensing lines arranged in a coil) and filled with ice, which acts as a heat exchanger to cool

385-575: A body-centered tetragonal crystal structure, and offer a wide range of properties and are used as stainless engineering steels, stainless tool steels, and creep -resistant steels. They are magnetic, and not as corrosion-resistant as ferritic and austenitic stainless steels due to their low chromium content. They fall into four categories (with some overlap): Martensitic stainless steels can be heat treated to provide better mechanical properties. The heat treatment typically involves three steps: Replacing some carbon in martensitic stainless steels by nitrogen

462-478: A company called Bubba Keg is established in the U.S., and appears to not be associated with Molson. Today, mini kegs are widely available in liquor stores worldwide, with Heineken , Grolsch and Bitburger all adopting the design. Recently in Austria, beer is available in mini kegs, either by a one-way type keg made of steel or out of a reinforced thermoplastic for about a 4 € deposit. Another type of mini keg

539-579: A group of investors, formed the American Stainless Steel Corporation, with headquarters in Pittsburgh , Pennsylvania. Brearley initially called his new alloy "rustless steel". The alloy was sold in the US under different brand names like "Allegheny metal" and "Nirosta steel". Even within the metallurgy industry, the name remained unsettled; in 1921, one trade journal called it "unstainable steel". Brearley worked with

616-519: A local cutlery manufacturer, who gave it the name "stainless steel". As late as 1932, Ford Motor Company continued calling the alloy "rustless steel" in automobile promotional materials. In 1929, before the Great Depression, over 25,000 tons of stainless steel were manufactured and sold in the US annually. Major technological advances in the 1950s and 1960s allowed the production of large tonnages at an affordable cost: Stainless steel

693-451: A lower design criteria and corrosion resistance is required, for example in high temperatures and oxidizing environments. Martensitic , duplex and ferritic stainless steels are magnetic , while austenitic stainless steel is usually non-magnetic. Ferritic steel owes its magnetism to its body-centered cubic crystal structure , in which iron atoms are arranged in cubes (with one iron atom at each corner) and an additional iron atom in

770-469: A protective oxide surface film, such as aluminum and titanium, are also susceptible. Under high contact-force sliding, this oxide can be deformed, broken, and removed from parts of the component, exposing the bare reactive metal. When the two surfaces are of the same material, these exposed surfaces can easily fuse. Separation of the two surfaces can result in surface tearing and even complete seizure of metal components or fasteners. Galling can be mitigated by

847-456: A refrigerated room for storage and dispensing, and liquid lines run from this room to all of the faucets in the restaurant. Kegs are too large to fit in a typical home refrigerator. A kegerator (specially designed for kegs, or converted from a suitable small refrigerator) can be used, but as these are somewhat specialized they are cost-prohibitive for the average consumer who has only occasional use for one, and are obviously impractical to bring to

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924-441: A single hole for cleaning, filling, pressurizing, and dispensing. A single bunghole at the top of the keg is used to clean and fill the keg, after which it is sealed with a metal assembly containing a ball bearing which acts as a stopper, held in place by the gas pressure inside the keg. The tap is twisted or slid into place atop the keg, and a lever provides the mechanical force needed to push the ball bearing down, providing access to

1001-489: A standardized bunghole arrangement, with one 2 inch NPT and one 3/4 inch NPT threaded bunghole on opposite sides of the top head. Some steel barrels are also equipped with a 2-inch threaded bunghole on the side. A notable use of the term occurs in Shakespeare's tragedy Hamlet : While holding the skull of the dead court jester , Hamlet wonders: To what base uses we may return Horatio. Why, may not imagination trace

1078-433: A thick frothy head. As with any pressurized container, a keg can cause injury, even at normal operating pressure, whether with compressed air or carbon dioxide: "The tapping system and pressure regulator both should be equipped with a pressure relief (blow off) device. If you are not familiar with tapping equipment, consult your retailer..." (printed on an Anheuser-Busch 's keg cap) Commercially, kegs are usually kept in

1155-406: A useful interchange table. Although stainless steel does rust, this only affects the outer few layers of atoms, its chromium content shielding deeper layers from oxidation. The addition of nitrogen also improves resistance to pitting corrosion and increases mechanical strength. Thus, there are numerous grades of stainless steel with varying chromium and molybdenum contents to suit the environment

1232-475: Is 11 imperial gallons (50 litres/88 imperial pints) and the vast majority of keg beers are supplied in this keg size. There are also smaller 30 litre (≈52.7926 imperial pints) kegs usually reserved for more specialist and premium European beers. A number of manufacturers also produce 18 imperial gallon (81.82 litres/144 imperial pints) and 22 imperial gallon (100 litres/176 imperial pints) kegs, however owing to their size they are not as popular, as manual handling

1309-437: Is 70-75% nitrogen and 25-30% CO 2 , but the ideal ratio depends on the beer being served and the installation; more advanced installations blend the gas on site so it can be adjusted for each beer. A few beers like Guinness are required to be pressurized and dispensed with mixed gas; they usually also require the use of a special faucet that deliberately creates additional friction to force the nitrogen out of solution, creating

1386-549: Is a 5-liter keg produced for retail sales. Some brands come with a spout and pour from the bottom via gravity, while others may use a low cost pressurized tap. Mini kegs are typically not returned to the manufacturer for cleaning and refilling. The disposable kegs, being made of aluminum , may be recycled . In Canada, Molson brewery dubbed the mini keg "Bubba". This name has now been genericized to generally apply to all 5-liter mini kegs in Canada . This might cause confusion, as

1463-461: Is a beer vessel containing approximately 7.75 U.S. gallons (29.33 liters) of fluid. It is half the size of the standard beer keg and equivalent to a quarter of a barrel. The term pony refers to its smaller size – compare pony glass (quarter-pint) and pony bottle . It will serve roughly 82 twelve-ounce cups. The shape of a pony keg resembles that of a full-sized keg while being much easier to move manually. However, it shares many inconveniences with

1540-481: Is a hole bored in a liquid-tight barrel to remove contents. The hole is capped with a cork or cork-like stopper called a bung . Acceptable usage includes other access points that may be capped with alternate materials providing an air- or water-tight access to other vessels. For example, a bunghole on a combustion chamber can be used to remove slag or add coal . Bungholes can also be utilized to insert and remove sensing probes or equipment like mixers to agitate

1617-406: Is a recent development. The limited solubility of nitrogen is increased by the pressure electroslag refining (PESR) process, in which melting is carried out under high nitrogen pressure. Steel containing up to 0.4% nitrogen has been achieved, leading to higher hardness and strength and higher corrosion resistance. As PESR is expensive, lower but significant nitrogen contents have been achieved using

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1694-996: Is an alloy of iron that is resistant to rusting and corrosion . It contains iron with chromium and other elements such as molybdenum , carbon , nickel and nitrogen depending on its specific use and cost. Stainless steel's resistance to corrosion results from the 10.5%, or more, chromium content which forms a passive film that can protect the material and self-heal in the presence of oxygen. The alloy's properties, such as luster and resistance to corrosion, are useful in many applications. Stainless steel can be rolled into sheets , plates, bars, wire, and tubing. These can be used in cookware , cutlery , surgical instruments , major appliances , vehicles, construction material in large buildings, industrial equipment (e.g., in paper mills , chemical plants , water treatment ), and storage tanks and tankers for chemicals and food products. Some grades are also suitable for forging and casting . The biological cleanability of stainless steel

1771-532: Is an extension of the heating- quenching - tempering cycle, where the final temperature of the material before full-load use is taken down to a cryogenic temperature range. This can remove residual stresses and improve wear resistance. Austenitic stainless steel sub-groups, 200 series and 300 series: Ferritic stainless steels possess a ferrite microstructure like carbon steel, which is a body-centered cubic crystal structure, and contain between 10.5% and 27% chromium with very little or no nickel. This microstructure

1848-467: Is becoming the choice for many establishments and breweries that wish to use kegs smaller than a half barrel . The sixth barrel kegs are nominally larger in size and volume compared to the Cornelius keg. They are normally fitted with a standard US Type D Sanke coupler on a single downspout; whereas, Corny kegs are normally fitted with a flip-hatch, and a dual connector pin-lock or ball-lock top. Although

1925-426: Is bent or cut, magnetism occurs along the edge of the stainless steel because the crystal structure rearranges itself. Galling , sometimes called cold welding, is a form of severe adhesive wear, which can occur when two metal surfaces are in relative motion to each other and under heavy pressure. Austenitic stainless steel fasteners are particularly susceptible to thread galling, though other alloys that self-generate

2002-510: Is classified into five main families that are primarily differentiated by their crystalline structure : Austenitic stainless steel is the largest family of stainless steels, making up about two-thirds of all stainless steel production. They possess an austenitic microstructure, which is a face-centered cubic crystal structure. This microstructure is achieved by alloying steel with sufficient nickel, manganese, or nitrogen to maintain an austenitic microstructure at all temperatures, ranging from

2079-409: Is near that of ordinary steel, and much higher than the melting points of aluminium or copper. As with most alloys, the melting point of stainless steel is expressed in the form of a range of temperatures, and not a single temperature. This temperature range goes from 1,400 to 1,530 °C (2,550 to 2,790 °F; 1,670 to 1,800 K; 3,010 to 3,250 °R) depending on the specific consistency of

2156-1421: Is one of the most-produced industrial chemicals. At room temperature, type 304 stainless steel is only resistant to 3% acid, while type 316 is resistant to 3% acid up to 50 °C (120 °F) and 20% acid at room temperature. Thus type 304 SS is rarely used in contact with sulfuric acid. Type 904L and Alloy 20 are resistant to sulfuric acid at even higher concentrations above room temperature. Concentrated sulfuric acid possesses oxidizing characteristics like nitric acid, and thus silicon-bearing stainless steels are also useful. Hydrochloric acid damages any kind of stainless steel and should be avoided. All types of stainless steel resist attack from phosphoric acid and nitric acid at room temperature. At high concentrations and elevated temperatures, attack will occur, and higher-alloy stainless steels are required. In general, organic acids are less corrosive than mineral acids such as hydrochloric and sulfuric acid. Type 304 and type 316 stainless steels are unaffected by weak bases such as ammonium hydroxide , even in high concentrations and at high temperatures. The same grades exposed to stronger bases such as sodium hydroxide at high concentrations and high temperatures will likely experience some etching and cracking. Increasing chromium and nickel contents provide increased resistance. All grades resist damage from aldehydes and amines , though in

2233-402: Is porous and fragile. In addition, as iron oxide occupies a larger volume than the original steel, this layer expands and tends to flake and fall away, exposing the underlying steel to further attack. In comparison, stainless steels contain sufficient chromium to undergo passivation , spontaneously forming a microscopically thin inert surface film of chromium oxide by reaction with the oxygen in

2310-498: Is present at all temperatures due to the chromium addition, so they are not capable of being hardened by heat treatment. They cannot be strengthened by cold work to the same degree as austenitic stainless steels. They are magnetic. Additions of niobium (Nb), titanium (Ti), and zirconium (Zr) to type 430 allow good weldability. Due to the near-absence of nickel, they are less expensive than austenitic steels and are present in many products, which include: Martensitic stainless steels have

2387-718: Is seen by some to be difficult, and as a result they tend to be used only for large-scale events and bars with high output. For bars that sell a large volume of beer, there is the 36 imperial gallon (163.64 litres/288 imperial pints) keg. However, due to its very large size, few people can move it without assistance, making it an impractical choice otherwise. In the U.S. as of 2005, there are 21 states and numerous localities that have keg registration laws. The laws vary widely in terms of whom they target, what their intended purpose is, and how strongly they are enforced. Stainless steel Stainless steel , also known as inox , corrosion-resistant steel ( CRES ), and rustless steel ,

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2464-452: Is superior to both aluminium and copper, and comparable to glass. Its cleanability, strength, and corrosion resistance have prompted the use of stainless steel in pharmaceutical and food processing plants. Different types of stainless steel are labeled with an AISI three-digit number. The ISO 15510 standard lists the chemical compositions of stainless steels of the specifications in existing ISO, ASTM , EN , JIS , and GB standards in

2541-465: Is the "beer ball" or the "party ball", a disposable plastic ball that usually holds around 5.2 US gallons (20 L), roughly the equivalent of 55 twelve- ounce beers, though they can also be found in a smaller 3.8-US-gallon (14 L) size. Like kegs, it is necessary to tap the ball before the beer inside can be served. One-way kegs, also known as disposable kegs or PET kegs, were invented in 1996. They are usually made of plastic. Some types have

2618-571: The Essen firm Friedrich Krupp Germaniawerft built the 366-ton sailing yacht Germania featuring a chrome-nickel steel hull, in Germany. In 1911, Philip Monnartz reported on the relationship between chromium content and corrosion resistance. On 17 October 1912, Krupp engineers Benno Strauss and Eduard Maurer patented as Nirosta the austenitic stainless steel known today as 18/8 or AISI type 304. Similar developments were taking place in

2695-638: The cryogenic region to the melting point. Thus, austenitic stainless steels are not hardenable by heat treatment since they possess the same microstructure at all temperatures. However, "forming temperature is an essential factor for metastable austenitic stainless steel (M-ASS) products to accommodate microstructures and cryogenic mechanical performance. ... Metastable austenitic stainless steels (M-ASSs) are widely used in manufacturing cryogenic pressure vessels (CPVs), owing to their high cryogenic toughness, ductility, strength, corrosion-resistance, and economy." Cryogenic cold-forming of austenitic stainless steel

2772-434: The metric system rather than U.S. gallons. In common parlance, the term keg refers to a half-barrel (15.5 U.S. gallon ) vessel as this is the most common size used in restaurants, bars and limited home use. A quarter-barrel has a volume of 7.75 U.S. gallons. Generally, a keg is a vessel smaller than a barrel; thus, it is 30 gallons or smaller. In the U.S. the terms half-barrel and quarter-barrel are derived from

2849-531: The soft drink industry. It is now commonly used to store and dispense beer , especially homebrewed . Cornelius kegs were originally made by Cornelius, Inc., and were used for premix soft drinks. Since the arrival of newer technology such as bag-in-box packages, Cornelius kegs have become largely obsolete in the soft drink industry, and refurbished ones are readily available to hobbyists. Cornelius kegs use two unique types of tap, both very similar to each other, known as ball locks and pin locks. The mini keg

2926-528: The water industry . Precipitation hardening stainless steels have corrosion resistance comparable to austenitic varieties, but can be precipitation hardened to even higher strengths than other martensitic grades. There are three types of precipitation hardening stainless steels: Solution treatment at about 1,040 °C (1,900 °F) followed by quenching results in a relatively ductile martensitic structure. Subsequent aging treatment at 475 °C (887 °F) precipitates Nb and Cu-rich phases that increase

3003-549: The 1840s, both Britain's Sheffield steelmakers and then Krupp of Germany were producing chromium steel with the latter employing it for cannons in the 1850s. In 1861, Robert Forester Mushet took out a patent on chromium steel in Britain. These events led to the first American production of chromium-containing steel by J. Baur of the Chrome Steel Works of Brooklyn for the construction of bridges. A US patent for

3080-549: The 19th century didn't pay attention to the amount of carbon in the alloyed steels they were testing until in 1898 Adolphe Carnot and E. Goutal noted that chromium steels better resist to oxidation with acids the less carbon they contain. Also in the late 1890s, German chemist Hans Goldschmidt developed an aluminothermic ( thermite ) process for producing carbon-free chromium. Between 1904 and 1911, several researchers, particularly Leon Guillet of France, prepared alloys that would be considered stainless steel today. In 1908,

3157-582: The U.S. beer barrel, legally defined as being equal to 31 U.S. gallons (this is not the same volume as some other units also known as barrels ). A 15.5 U.S. gallon keg is also equal to: However, beer kegs can come in many sizes: Accepted specifications for a standard keg are: In Europe, the most common keg size is 50 liters. This includes the UK, which uses a non-metric standard keg of 11 imperial gallons, which is, by coincidence, equal to 50.007 litres. The German DIN 6647-1 and DIN 6647-2 have also defined kegs in

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3234-667: The United States, where Christian Dantsizen of General Electric and Frederick Becket (1875–1942) at Union Carbide were industrializing ferritic stainless steel. In 1912, Elwood Haynes applied for a US patent on a martensitic stainless steel alloy, which was not granted until 1919. While seeking a corrosion-resistant alloy for gun barrels in 1913, Harry Brearley of the Brown-Firth research laboratory in Sheffield, England, discovered and subsequently industrialized

3311-441: The air and even the small amount of dissolved oxygen in the water. This passive film prevents further corrosion by blocking oxygen diffusion to the steel surface and thus prevents corrosion from spreading into the bulk of the metal. This film is self-repairing, even when scratched or temporarily disturbed by conditions that exceed the inherent corrosion resistance of that grade. The resistance of this film to corrosion depends upon

3388-587: The alloy in question. Like steel , stainless steels are relatively poor conductors of electricity, with significantly lower electrical conductivities than copper. In particular, the non-electrical contact resistance (ECR) of stainless steel arises as a result of the dense protective oxide layer and limits its functionality in applications as electrical connectors. Copper alloys and nickel-coated connectors tend to exhibit lower ECR values and are preferred materials for such applications. Nevertheless, stainless steel connectors are employed in situations where ECR poses

3465-610: The alloy must endure. Corrosion resistance can be increased further by the following means: The most common type of stainless steel, 304, has a tensile yield strength around 210 MPa (30,000 psi) in the annealed condition. It can be strengthened by cold working to a strength of 1,050 MPa (153,000 psi) in the full-hard condition. The strongest commonly available stainless steels are precipitation hardening alloys such as 17-4 PH and Custom 465. These can be heat treated to have tensile yield strengths up to 1,730 MPa (251,000 psi). Melting point of stainless steel

3542-706: The alloy. The invention of stainless steel followed a series of scientific developments, starting in 1798 when chromium was first shown to the French Academy by Louis Vauquelin . In the early 1800s, British scientists James Stoddart, Michael Faraday , and Robert Mallet observed the resistance of chromium-iron alloys ("chromium steels") to oxidizing agents . Robert Bunsen discovered chromium's resistance to strong acids. The corrosion resistance of iron-chromium alloys may have been first recognized in 1821 by Pierre Berthier , who noted their resistance against attack by some acids and suggested their use in cutlery. In

3619-538: The beer but retained a separate bunghole for cleaning and filling the keg which was sealed with a wooden bung. These made it easier to tap the keg, but still had sanitation problems (from the wooden bung and attachments that penetrated the keg, and from ports that were at the bottom of the keg next to the floor) and tended to leave some beer inaccessible at the bottom of the keg. In the 1960s and 70s, several similar styles of tap were created in Europe and America which used

3696-473: The beer must stay cold. Historically a beer barrel was a standard size of 36 US gallons (140 L; 30 imp gal), as opposed to a wine barrel of 32 US gallons (120 L; 27 imp gal), or an oil barrel of 42 US gallons (160 L; 35 imp gal). Over the years barrel sizes have evolved, and breweries throughout the world use different sized containers. Even when the content capacity of two kegs are equal, e.g. metricized to 50 liters,

3773-488: The beer out of the keg. The coupling fitting has one or two valves that control the flow of beer out of and gas into the keg. The keg must be in the upright position, that is, with the opening on top, for the beer to be dispensed. Kegs can be contrasted to casks , which have two or more openings and no spear. Most major breweries now use internally speared kegs. Beer that is sold in kegs is fully conditioned. Beer intended for local use may be kegged without sterilization, however,

3850-413: The beer to go flat. Kegs dispensed with a party pump should be used within 18–24 hours so that the beer does not become unpalatable. Commercial installations, as well as some home users, use pure pressurized gas; these can preserve a keg up to 120 days with proper refrigeration. In simpler installations only CO 2 is used to pressurize and dispense the beer, but in installations with very long lines between

3927-409: The beer to serving temperature by the time it reaches the faucet. European consumers, when not using a party pump, mainly use inline beer chillers, essentially the same concept as a jockey box but using a refrigeration unit instead of ice. Those chillers usually also have their own air compressor for keg pressurization. The Cornelius keg (also known as a "Corny keg" or "soda keg") was originally used by

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4004-499: The bigger kegs, such as: often requiring a deposit when purchased, needing a tap to serve the contents, and posing difficulties in determining the amount of beer remaining (weighing the keg or observing its buoyancy are common techniques). Despite this, a pony keg can be a cheap way to provide beer for a medium-sized party. In some places, such as Cincinnati , the term pony keg can mean a convenience store that sells beer. A sixth barrel keg contains approximately 5.2 gallons, and

4081-405: The carbonation in a beverage by storing it with pressurized carbon dioxide in the headspace above the liquid. The liquid is also dispensed using pressurized gas; the pressure of the gas provides mechanical force to overcome friction and gravity to push the beer to the dispensing location. To serve the beverage, a keg must be tapped to breach the container so that pressurized gas can be added and

4158-580: The center. This central iron atom is responsible for ferritic steel's magnetic properties. This arrangement also limits the amount of carbon the steel can absorb to around 0.025%. Grades with low coercive field have been developed for electro-valves used in household appliances and for injection systems in internal combustion engines. Some applications require non-magnetic materials, such as magnetic resonance imaging . Austenitic stainless steels, which are usually non-magnetic , can be made slightly magnetic through work hardening . Sometimes, if austenitic steel

4235-544: The chemical composition of the stainless steel, chiefly the chromium content. It is customary to distinguish between four forms of corrosion: uniform, localized (pitting), galvanic, and SCC (stress corrosion cracking). Any of these forms of corrosion can occur when the grade of stainless steel is not suited for the working environment. The designation "CRES" refers to corrosion-resistant (stainless) steel. Uniform corrosion takes place in very aggressive environments, typically where chemicals are produced or heavily used, such as in

4312-420: The contents within a vessel. Bungholes were first used on wooden barrels, and were typically bored by the purchaser of the barrel using a brace and bit . Bungholes can be bored in either head (end) of a barrel or in one of the staves (side). With the bung removed, a tapered faucet can be attached to aid with dispensing. When barrels full of a commodity were shipped, the recipient would often bore new bungholes of

4389-457: The keg and dispensing location (bars with customer-operated faucets at each table being an extreme example), the pressure needed to pump the beer for dispensing would over-carbonate the beer. In these situations, "beer gas" or "mixed gas" is used which combines CO 2 with another gas, usually nitrogen . Nitrogen is 80 times less soluble in water than CO 2 , so it can provide additional pressure without noticeably affecting flavor. Typical beer gas

4466-516: The keg shape and tap system may differ greatly. Most U.S. brewers sell beer in 1 ⁄ 2 barrels of 15.5 gallons, 1 ⁄ 4 barrels of 7.75 gallons, and 1 ⁄ 6 barrels of 5.17 gallons. Since keg sizes are not standardized, the keg cannot be used as a standard unit of measure for liquid volumes . Despite this, a number of people still refer to kegs as if they were a unit of measure. This size standard varies from country to country and brewery to brewery with most countries using

4543-422: The keg's contents. These taps, or "couplers", are more sanitary and easy to operate, and were adopted by major U.S. breweries like Anheuser-Busch in the 1970s and quickly displaced other taps to become the industry standard. One such system was referred to as Sankey after its designer ( GKN Sankey Ltd. , named for founder Joseph Sankey). The term Sankey, often misspelled "Sanke", has become a generic name for all of

4620-404: The latter case type 316 is preferable to type 304; cellulose acetate damages type 304 unless the temperature is kept low. Fats and fatty acids only affect type 304 at temperatures above 150 °C (300 °F) and type 316 SS above 260 °C (500 °F), while type 317 SS is unaffected at all temperatures. Type 316L is required for the processing of urea . Bunghole A bunghole

4697-511: The liquid can be dispensed. Originally, this was done by hammering a tapping rod through a cork bung , similar to how a keystone is still used today to tap unpressurized cask ales. Tapping a keg this way would often waste a bit of beer, which would be forced out under pressure until the tap was secured. By the 1950s and 60s when metal kegs had replaced wooden ones, common tap systems included Golden Gate, Hoff–Stevens, and Peerless taps, which all had one or two couplers for pressurizing and dispensing

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4774-423: The most suitable size and placement rather than remove the existing bung. Wooden barrels manufactured by specialty firms today usually are bored by the maker with suitable bungholes, since the hobbyists who purchase them for the making of beer , wine , and fermented foods often do not have a suitable brace and bit. Closed-head steel barrels and drums now used for shipment of chemicals and petroleum products have

4851-506: The most widely used. Many grading systems are in use, including US SAE steel grades . The Unified Numbering System for Metals and Alloys (UNS) was developed by the ASTM in 1970. Europe has adopted EN 10088 . Unlike carbon steel , stainless steels do not suffer uniform corrosion when exposed to wet environments. Unprotected carbon steel rusts readily when exposed to a combination of air and moisture. The resulting iron oxide surface layer

4928-690: The noble dust of Alexander, till he find it stopping a bunghole? … Alexander died, Alexander was buried, Alexander returneth into dust, the dust is earth, of earth we make loam, and why of that loam (whereto he was converted) might they not stop a beer barrel? — Hamlet , act V, scene 1 Usage of the term as a slang word for the anus dates back to at least the 17th century, as shown in Thomas Urquhart 's translation of Gargantua by François Rabelais , first published in 1653. "... I say and maintain, that of all torcheculs, arsewisps, bumfodders, tail-napkins, bunghole cleansers, and wipe-breeches, there

5005-414: The product was issued in 1869. This was followed with recognition of the corrosion resistance of chromium alloys by Englishmen John T. Woods and John Clark, who noted ranges of chromium from 5–30%, with added tungsten and "medium carbon". They pursued the commercial value of the innovation via a British patent for "Weather-Resistant Alloys". Scientists researching steel corrosion in the second half of

5082-429: The pulp and paper industries. The entire surface of the steel is attacked, and the corrosion is expressed as corrosion rate in mm/year (usually less than 0.1 mm/year is acceptable for such cases). Corrosion tables provide guidelines. This is typically the case when stainless steels are exposed to acidic or basic solutions. Whether stainless steel corrodes depends on the kind and concentration of acid or base and

5159-424: The same dimensions as a sixth barrel, but the seven bottom-most inches are hollow. The beer vessel supply structure in the UK and Ireland is quite different, whilst the couplers for kegs have been largely standardised to sankey, grundy and interbrew, a couple of others exist such as UEC and U-Type, however these are much less common. The kegs themselves are made from stainless steel or aluminium. The standard keg size

5236-419: The similar industry standard couplers. Today there are six industry standard couplers: There are two different types of tapping equipment that are available for kegs. A "party tap" or "picnic tap" is a hand-operated pump that utilizes outside air, thus introducing oxygen and bacteria into the keg. This causes the beer to oxidize, affecting the taste; the partial pressure of CO 2 will also decrease, causing

5313-654: The sixth barrel torpedo keg is approximately the same height as the standard half barrel, the smaller foot print of the sixth barrel allows retailers have a greater variety of beer in a small space. This size keg is quickly replacing the quarter barrel size which has the same foot print as a half barrel keg, but is only half as tall. Other than smaller circumference, sixth barrel kegs are very similar to their full-sized counterparts in construction. A stainless Micromatic brand sixth barrel keg weighs approximately 14-15 pounds (6.3–6.8 kg) when empty, and approximately 58-60 pounds (26.3-27.2 kg) when full. An eighth barrel has

5390-454: The sizes of 30 and 20 liters. In some areas it is common to refer to the size not in liters but in beers. In areas such as Germany, where the standard beer size is 0.5 liters, that means a 50-liter keg contains 100 beers. Kegs are sealed to contain the liquid and pressurized gas for storage and transportation. Most beer is served carbonated, and this is most easily accomplished by storing it carbonated as well. Beer kegs are designed to maintain

5467-574: The solution temperature. Uniform corrosion is typically easy to avoid because of extensive published corrosion data or easily performed laboratory corrosion testing. Acidic solutions can be put into two general categories: reducing acids, such as hydrochloric acid and dilute sulfuric acid , and oxidizing acids , such as nitric acid and concentrated sulfuric acid. Increasing chromium and molybdenum content provides increased resistance to reducing acids while increasing chromium and silicon content provides increased resistance to oxidizing acids. Sulfuric acid

5544-949: The standard AOD process. Duplex stainless steels have a mixed microstructure of austenite and ferrite, the ideal ratio being a 50:50 mix, though commercial alloys may have ratios of 40:60. They are characterized by higher chromium (19–32%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. Duplex stainless steels have roughly twice the yield strength of austenitic stainless steel. Their mixed microstructure provides improved resistance to chloride stress corrosion cracking in comparison to austenitic stainless steel types 304 and 316. Duplex grades are usually divided into three sub-groups based on their corrosion resistance: lean duplex, standard duplex, and super duplex. The properties of duplex stainless steels are achieved with an overall lower alloy content than similar-performing super-austenitic grades, making their use cost-effective for many applications. The pulp and paper industry

5621-536: The strength up to above 1,000 MPa (150,000 psi) yield strength. This outstanding strength level is used in high-tech applications such as aerospace (usually after remelting to eliminate non-metallic inclusions, which increases fatigue life). Another major advantage of this steel is that aging, unlike tempering treatments, is carried out at a temperature that can be applied to (nearly) finished parts without distortion and discoloration. Typical heat treatment involves solution treatment and quenching . At this point,

5698-698: The structure remains austenitic. Martensitic transformation is then obtained either by a cryogenic treatment at −75 °C (−103 °F) or by severe cold work (over 70% deformation, usually by cold rolling or wire drawing). Aging at 510 °C (950 °F) — which precipitates the Ni 3 Al intermetallic phase—is carried out as above on nearly finished parts. Yield stress levels above 1400   MPa are then reached. The structure remains austenitic at all temperatures. Typical heat treatment involves solution treatment and quenching, followed by aging at 715 °C (1,319 °F). Aging forms Ni 3 Ti precipitates and increases

5775-487: The use of dissimilar materials (bronze against stainless steel) or using different stainless steels (martensitic against austenitic). Additionally, threaded joints may be lubricated to provide a film between the two parts and prevent galling. Nitronic 60, made by selective alloying with manganese, silicon, and nitrogen, has demonstrated a reduced tendency to gall. The density of stainless steel ranges from 7.5 to 8.0 g/cm (0.27 to 0.29 lb/cu in) depending on

5852-415: The yield strength to about 650 MPa (94,000 psi) at room temperature. Unlike the above grades, the mechanical properties and creep resistance of this steel remain very good at temperatures up to 700 °C (1,300 °F). As a result, A286 is classified as an Fe-based superalloy , used in jet engines, gas turbines, and turbo parts. Over 150 grades of stainless steel are recognized, of which 15 are

5929-476: Was one of the first to extensively use duplex stainless steel. Today, the oil and gas industry is the largest user and has pushed for more corrosion resistant grades, leading to the development of super duplex and hyper duplex grades. More recently, the less expensive (and slightly less corrosion-resistant) lean duplex has been developed, chiefly for structural applications in building and construction (concrete reinforcing bars, plates for bridges, coastal works) and in

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