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Steel and tin cans

A steel can, tin can, tin (especially in British English, Australian English, Canadian English and South African English), steel packaging, or can is a container for the distribution or storage of goods, made of thin metal. Many cans require opening by cutting the "end" open; others have removable covers. They can store a broad variety of contents: food, beverages, oil, chemicals, etc. Steel cans are made of tinplate (tin-coated steel) or of tin-free steel. In some dialects, even aluminium cans are called "tin cans".[1]

An empty tin can

Steel cans are highly recyclable, unlike materials like plastic, with around 65% of steel cans being recycled.[2]

History

The tin canning process was conceived by the Frenchman Philippe de Girard, who got a British merchant Peter Durand to patent the idea in 1810.[3][4] The canning concept was based on experimental food preservation work in glass containers the year before by the French inventor Nicholas Appert. Durand did not pursue food canning, but, in 1812, sold his patent to two Englishmen, Bryan Donkin and John Hall, who refined the process and product, and set up the world's first commercial canning factory on Southwark Park Road, London. By 1813 they were producing their first tin canned goods for the Royal Navy. By 1820, tin canisters or cans were being used for gunpowder, seeds, and turpentine.

Early tin cans were sealed by soldering with a tin–lead alloy, which could lead to lead poisoning.

In 1901 in the United States, the American Can Company was founded, at the time producing 90% of United States tin cans.[5]

Canned food in tin cans was already quite popular in various countries when technological advancements in the 1920s lowered the cost of the cans even further.[6]: 155–170, 265–280  In 1935, the first beer in metal cans was sold; it was an instant sales success.[6]: 155–170, 265–280 

Description

Most cans are right circular cylinders with identical and parallel round tops and bottoms with vertical sides. However, cans for small volumes or particularly-shaped contents, the top and bottom may be rounded-corner rectangles or ovals. Other contents may suit a can that is somewhat conical in shape.

Fabrication of most cans results in at least one rim—a narrow ring slightly larger than the outside diameter of the rest of the can. The flat surfaces of rimmed cans are recessed from the edge of any rim (toward the middle of the can) by about the width of the rim; the inside diameter of a rim, adjacent to this recessed surface, is slightly smaller than the inside diameter of the rest of the can.

Three-piece can construction results in top and bottom rims. In two-piece construction, one piece is a flat top and the other a deep-drawn cup-shaped piece that combines the (at least roughly) cylindrical wall and the round base. Transition between wall and base is usually gradual. Such cans have a single rim at the top. Some cans have a separate cover that slides onto the top or is hinged.

Two piece steel cans can be made by "drawing" to form the bottom and sides and adding an "end" at the top: these do not have side seams. Cans can be fabricated with separate slip-on, or friction fit covers and with covers attached by hinges. Various easy opening methods are available.[7]

In the mid-20th century, a few milk products were packaged in nearly rimless cans, reflecting different construction; in this case, one flat surface had a hole (for filling the nearly complete can) that was sealed after filling with a quickly solidifying drop of molten solder. Concern arose that the milk contained unsafe levels of lead leached from this solder plug.

Advantages of steel cans

A number of factors make steel cans ideal containers for beverages. Steel cans are stronger than cartons or plastic, and less fragile than glass, protecting the product in transit and preventing leakage or spillage, while also reducing the need for secondary packaging.[8][9]

Steel and aluminium packaging offer 100% barrier protection against light, water and air, and metal cans without resealable closures are among the most tamper-evident of all packaging materials.[10] Steel cans preserve and protect the product from damage by light, oxidation, extremes of temperature and contamination, safeguarding flavour, appearance and quality from factory to final consumer. Food and drink packed in steel cans has equivalent vitamin content to freshly prepared, without needing preserving agents.[10] Steel cans also extend the product's shelf-life, allowing longer sell-by and use-by dates and reducing waste.[8]

As an ambient packaging medium, steel cans do not require cooling in the supply chain, simplifying logistics and storage, and saving energy and cost.[8] At the same time, steel's relatively high thermal conductivity means canned drinks chill much more rapidly and easily than those in glass or plastic bottles.[11]

A World Steel Association initiative, Choose Steel, is encouraging the use of steel for beverage cans.[12]

Materials

No cans currently in wide use are composed primarily or wholly of tin;[14] that term rather reflects the nearly exclusive use in cans[clarification needed], until the second half of the 20th century, of tinplate steel, which combined the physical strength and relatively low price of steel with the corrosion resistance of tin. Depending on contents and available coatings, some canneries still use tin-free steel.

In some local dialects, any metal can, even aluminium, might be called a "tin can". Use of aluminium in cans began in 1957.[15] Aluminium is less costly than tin-plated steel but offers the same resistance to corrosion in addition to greater malleability, resulting in ease of manufacture; this gave rise to the two-piece can, where all but the top of the can is simply stamped out of a single piece of aluminium, rather than laboriously constructed from three pieces of steel.

A can traditionally has a printed paper or plastic label glued to the outside of the curved surface, indicating its contents. Some labels contain additional information, such as recipes, on the reverse side. More recently labels are sometimes printed directly onto the metal before or after the metal sheet is formed into the individual cans.

In November 1991, US can manufacturers voluntarily eliminated lead seams in food cans. However, imported food cans continued to include lead soldered seams.[16] In 1995, the US FDA issued a rule prohibiting lead soldered food cans, including both domestic and imported food cans.[17]

In modern times, the majority of food cans in the UK[18] have been lined with a plastic coating containing bisphenol A (BPA). The coating prevents acids and other substances from corroding the tin or aluminium of the can, but leaching of BPA into the can's contents was investigated as a potential health hazard.[19]

Standard sizes

Cans come in a variety of shapes: two common ones are the "soup tin" and the "tuna tin". Walls are often stiffened with rib bulges, especially on larger cans, to help the can resist dents that can cause seams to split.

Can sizes in the United States have an assortment of designations and sizes. For example, size 7/8 contains one serving of half a cup with an estimated weight of 4 ounces; size 1 "picnic" has two or three servings totalling one and a quarter cups with an estimated weight of 1012 ounces; size 303 has four servings totalling 2 cups weighing 1512 ounces; and size 10 cans, most widely used by food services selling to cafeterias and restaurants, have twenty-five servings totalling 13 cups with an estimated weight of 10312 ounces (size of a roughly 3 pound coffee can). These are U.S. customary cups, not British Imperial standard.

In the United States, cook books sometimes reference cans by size. The Can Manufacturers Institute defines these sizes, expressing them in three-digit numbers, as measured in whole and sixteenths of an inch for the container's nominal outside dimensions: a 307 × 512 would thus measure 3 and 7/16" in diameter by 5 and 3/4" (12/16") in height. Older can numbers are often expressed as single digits, their contents being calculated for room-temperature water as approximately eleven ounces (#1 "picnic" can), twenty ounces (#2), thirty-two ounces (#3) fifty-eight ounces (#5) and one-hundred-ten ounces (#10 "coffee" can).[20]

Can Name Dimensions (inches) Capacity (U.S. fluid ounces) No. 2 can equivalent Typical products
6Z 2216 × 312 6.08 0.295
8Z Short 21116 × 3 7.93 0.386
8Z Tall 21116 × 328 8.68 0.422
No. I (Picnic) 21116 × 4 10.94 0.532
No. 211 Cylinder 21116 × 41416 13.56 0.660
No. 300 3 × 4716 15.22 0.741 Cranberry Sauce, Pork & Beans
No. 300 Cylinder 3 × 5916 19.40 0.945
No. I Tall 3116 × 41116 16.70 0.813
No. 303 3316 × 438 16.88 0.821 Fruits, Vegetables, Soups
No. 303 Cylinder 3316 × 5916 21.86 1.060
No. 2 Vacuum 3716 × 338 14.71 0.716
No. 2 3716 × 4916 20.55 1.000 Juices, Soups, Vegetables
Jumbo 3716 × 558 25.80 1.2537
No. 2 Cylinder 3716 × 568 26.40 1.284
No. 1.25 4116 × 238 13.81 0.672
No. 2.5 4116 × 41116 29.79 1.450 Fruits, Vegetables
No. 3 Vacuum 414 × 3716 23.90 1.162
No. 3 Cylinder 414 × 7 51.70 2.515
No. 5 518 × 558 59.10 2.8744 Fruit Juice, Soups
No. 10 6316 × 7 109.43 5.325 Fruits, Vegetables

In parts of the world using the metric system, tins are made in 250, 500, 750 ml (millilitre) and 1 L (litre) sizes (250 ml is approximately 1 cup or 8 ounces). Cans imported from the USA often have odd sizes such as 3.8 L (1 US gallon), 1.9 L (1/2 US gallon), and 946 ml (2 US pints / 1 quart).

In the UK and Australia, cans are usually measured by net weight. A standard size tin can holds roughly 400 g; though the weight can vary between 385 g and 425 g depending on the density of the contents. The smaller half sized can holds roughly 200 g, typically varying between 170 g and 225 g.

Fabrication of cans

Rimmed three-piece can construction involves several stages;

  • Forming a tube and welding or soldering the seam of the sides
  • Joining the bottom end to the tube
  • Printing or attaching labels to the can
  • Filling the can with content; sterilization or retorting is required for many food products
  • Joining the wall and top "end".

Double seam rims are crucial to the joining of the wall to a top or bottom surface. An extremely tight fit between the pieces must be accomplished to prevent leakage; the process of accomplishing this radically deforms the rims of the parts. Part of the tube that forms the wall is bent, almost at its end, turning outward through 90 degrees, and then bent further, toward the middle of the tube, until it is parallel to the rest of the tube, a total bend of 180 degrees.

The outer edge of the flat piece is bent against this toward the middle of the tubular wall, until parallel with the wall, turning inward through 90 degrees. The edge of bent portion is bent further through another 90 degrees, inward now toward the axis of the tube and parallel to the main portion of the flat piece, making a total bend of 180 degrees. It is bent far enough inward that its circular edge is now slightly smaller in diameter than the edge of the tube. Bending it yet further, until it is parallel with the tube's axis, gives it a total bend of 270 degrees. It now envelops the outward rim of the tube.

Looking outward from the axis of the tube, the first surface is the unbent portion of the tube. Slightly further out is a narrow portion of the top, including its edge. The outward-bent portion of the tube, including its edge, is still slightly further out. Furthest out is the 90-degree-bent portion of the flat surface.

The combined interacting forces, as the portion of the flat surface adjacent to the interior of the tube is indented toward the middle of the tube and then outward forward the axis of the tube, and the other bent portions of the flat piece and the tube are all forced toward the axis of the tube, drives these five thicknesses of metal against each other from inside and out, forming a "dry" joint so tight that welding or solder is not needed to strengthen or seal it. Illustrations of this process can be found on pages 20–22 of the FAO Fisheries Technical Paper 285 "Manual on fish canning" located here.

Design and manufacture

Steel for can making

The majority of steel used in packaging is tinplate, which is steel that has been coated with a thin layer of tin, whose functionality is required for the production process.[21] The tin layer is usually applied by electroplating.[22]

Two-piece steel can design

Most steel beverage cans are two-piece designs, made from 1) a disc re-formed into a cylinder with an integral end, double-seamed after filling and 2) a loose end to close it.[9] Steel cans are made in many different diameters and volumes, with opening mechanisms that vary from ring pulls and tab openers, to wide open mouths.[23] Modern can making lines may produce up to 1000 cans per minute.[21]

Drawn-and-ironed (DWI) steel cans

The process of re-forming sheet metal without changing its thickness is known as 'drawing'. Thinning the walls of a two-piece can by passing it through circular dies is called 'ironing'. Steel beverage cans are therefore generally referred to as drawn-and-ironed, or DWI, cans (sometimes D&I). The DWI process is used for making cans where the height is greater than the diameter, and is particularly suited to making large volumes of cans of the same basic specification.[9]

Steel can wall thicknesses are now 30% thinner and weigh 40% less than 30 years ago, reducing the amounts of raw materials and energy required to make them. They are also up to 40% thinner than aluminium.[24]

Magnetic properties

Steel is a ferrous metal and is therefore magnetic. For beverage packaging this is unique. This allows the use of magnetic conveyor systems[25] to transfer empty cans through the filling and packing processes, increasing accuracy and reducing potential spillage and waste.[26] In recycling facilities, steel cans may be readily separated from other waste using magnetic equipment including cross-belt separators, also known as overband magnets, and drum magnets.[27]

Opening cans

The first cans were heavy-weight containers that required ingenuity to open, with implements such as knives. Not until several years later, after can manufacturers started using thinner metal sheets, were any dedicated can openers developed.

While beverage cans or cans of fluid such as broth can merely be punctured to remove the product, solid or semisolid contents require removing one end of the can. This can be accomplished with a heavy knife or other sharp tool—but can openers are much more convenient.

Some cans, such as those used for sardines, have a specially scored lid so that the user can break out the metal by the leverage of winding it around a slotted church key. Until the mid-20th century, some sardine tins had solder-attached lids, and the winding key worked by forcing the solder joint apart.

The advent of pull tabs in beverage cans spread to the canning of various food products, such as pet food or nuts (and non-food products such as motor oil and tennis balls). The ends are known as easy open lids because they open without any tools or implements.[28] An additional innovation developed for specifically for food cans uses a tab that is bent slightly upwards, creating a larger surface area for easier finger access.[29]

Cans can be made with easy open features. Some cans have screw caps for pouring liquids and resealing. Some have hinged covers or slip-on covers for easy access. Paint cans often have a removable plug on the top for access and for reclosing.

Recycling and re-use

Steel from cans and other sources is the most recycled packaging material.[8] Around 65% of steel cans are recycled.[2] In the United States, 63% of steel cans are recycled, compared to 52% of aluminium cans.[30] In Europe, the recycling rate in 2016 is 79.5%.[8] Most can recycling occurs at the smelters, but individual consumers also directly reuse cans in various ways. For instance some people use two tin cans to form a camp or survival stove to cook small meals.[citation needed]

 
Food tin cans reused for art and storage

Sustainability and recycling of steel beverage cans

Steel recycling

From an ecological perspective, steel may be regarded as a closed-loop material: post-consumer waste can be collected, recycled and used to make new cans or other products.[31] Each tonne of scrap steel recycled saves 1.5 tonnes of CO2, 1.4 tonnes of iron ore and 740 kg of coal. Steel is the world's most recycled material, with more than 85% of all the world's steel products being recycled at the end of their life: an estimated 630 million tonnes of steel scrap were recycled in 2017, saving 945 million tonnes of CO2.[32]

Steel can recycling

A steel can can be recycled again and again without loss of quality,[33] however for the food grade steel it's required to remove tin from the scrap metal, which is done by way of electrochemistry: the tin is leached from a high pH solution at low negative voltage.[34]

Recycling a single can saves the equivalent power for one laundry load, 1 hour of TV or 24 hours of lighting (10W LED bulb).[35]

Steel beverage cans are recycled by being melted down in an electric arc furnace or basic oxygen furnace.[citation needed]

Most steel cans also carry some form of recycling identification such as the Metal Recycles Forever Mark [36] Recyclable Steel [37] and the Choose Steel campaign logo.[12] There is also a campaign in Europe called Every Can Counts, encouraging can recycling in the workplace [38]

Smaller carbon footprint

All beverage packaging creates CO2 emissions at every stage in the production process, from raw material extraction, processing and manufacture through to recycling. However, steel cans are an ecological top performer, as cans can always be recycled. The steel industry needs the used cans and will use them in the production of new steel product. By recycling the cans and closing the loop, CO2 emissions are dramatically reduced. There is also the potential for higher global steel recycling rates as consumers become more aware of the benefits.[citation needed]

Health issues

Dissolution of tin into the food

Tin is corrosion resistant, but acidic food like fruits and vegetables can corrode the tin layer. Nausea, vomiting, and diarrhea have been reported after ingesting canned food containing 200 mg/kg of tin.[39] A 2002 study showed that 99.5% of 1200 tested cans contained below the UK regulatory limit of 200 mg/kg of tin, an improvement over most previous studies largely attributed to the increased use of fully lacquered cans for acidic foods, and concluded that the results do not raise any long term food safety concerns for consumers. The two non-compliant products were voluntarily recalled.[40]

Evidence of tin impurities can be indicated by color, as in the case of pears, but lack of color change does not guarantee that a food is not tainted with tin.[41]

Bisphenol-A

 
The chemical compound Bisphenol A found in can linings "...is associated with organizational changes in the prostate, breast, testis, mammary glands, body size, brain structure and chemistry, and behavior of laboratory animals",[42] unborn children and adults.

Bisphenol-A (BPA) is a controversial chemical compound present in commercially available tin can plastic linings[43] and transferred to canned food. The inside of the can is coated with an epoxy coating, in an attempt to prevent food or beverage from coming into contact with the metal. The longer food is in a can, and the warmer and more acidic it is, the more BPA leaches into it. In September 2010, Canada became the first country to declare BPA a toxic substance.[44][45] In the European Union and Canada, BPA use is banned in baby bottles. The FDA does not regulate BPA (see BPA controversy#Public health regulatory history in the United States). Several companies, like Campbell's Soup, announced plans to eliminate BPA from the linings of their cans,[43] but have not said which chemical they plan to replace it with. (See BPA controversy#Chemical manufacturers reactions to bans.)[citation needed]

See also

References

  1. ^ Kraus, F J (2009). "Steel Cans". In Yam, K L (ed.). Encyclopedia of Packaging Technology. Wiley. pp. 205–216. ISBN 978-0-470-08704-6.
  2. ^ a b "64.9% of steel cans are recycled". worldsteel.org. 10 January 2007. from the original on 18 July 2011. Retrieved 24 November 2010.
  3. ^ Robertson, Gordon L (2016). Food packaging (3rd ed.). CRC Press. p. 123.
  4. ^ Geoghegan, Tom (2013-04-21). "BBC News – The story of how the tin can nearly wasn't". Bbc.co.uk. from the original on 2013-06-06. Retrieved 2013-06-04.
  5. ^ American Can Company: Revolution in Containers 2009-07-15 at the Wayback Machine, Excerpts of William C. Stolk; Address of The Newcomen Society of North America, April 21, 1960 – Printed July 1960, from oilcans.net, retrieved 16 July 2010
  6. ^ a b Reutter, Mark (1988). Sparrows Point: Making Steel—the Rise and Ruin of American Industrial Might. University of Illinois Press. ISBN 9780671553357.
  7. ^ Soroka (2002) Fundamentals of Packaging Technology, Institute of Packaging Professionals ISBN 1-930268-25-4
  8. ^ a b c d e . apeal.org. Archived from the original on 2013-08-08.
  9. ^ a b c "Beverage | Tata Steel in Europe". www.tatasteeleurope.com. Retrieved 2018-07-09.
  10. ^ a b "Steel For Packaging – Home". www.steelforpackaging.org. Retrieved 2018-07-09.
  11. ^ "Does a Drink Stay Colder in a Metal Can or a Plastic Bottle?". Sciencing. Retrieved 2018-07-09.
  12. ^ a b "Home". Retrieved 2018-07-09.
  13. ^ a b Soroka, W. Illustrated Glossary of Packaging Terminology (Second ed.). Institute of Packaging Professionals. from the original on 2011-01-29.
  14. ^ Hertzberg, Ruth; Greene, Janet; Vaughan, Beatrice (2010-05-25). Putting Food By: Fifth Edition. Penguin. ISBN 9781101539903. from the original on 2018-02-06.
  15. ^ Petroleum week 2018-02-06 at the Wayback Machine, Volume 9, 1959, p. 82 (Google Books)
  16. ^ PUZO, DANIEL P. (29 April 1993). . Los Angeles Times. Archived from the original on 1 July 2018. Retrieved 29 August 2018.
  17. ^ Code of Federal Regulations. United States of America. April 1, 2017. pp. 21CFR189.240. from the original on 8 March 2021. Retrieved 29 August 2018.
  18. ^ Hickman, Martin (2010-04-01). "Revealed: the nasty secret in your kitchen cupboard". The Independent. London. from the original on 2010-04-02. Retrieved 2010-04-01.
  19. ^ "Are Cans BPA-Free in the UK?". Food Standards Agency. 2018-10-26. from the original on 2021-09-17. Retrieved 2020-11-17.
  20. ^ "Can standards". cancentral.com. from the original on 20 November 2010. Retrieved 24 November 2010.
  21. ^ a b "Steel packaging". Retrieved 2018-07-09.[permanent dead link]
  22. ^ "Tinning", Wikipedia, 2018-03-03, retrieved 2018-07-09
  23. ^ "Beverage can", Wikipedia, 2018-07-01, retrieved 2018-07-09
  24. ^ "Steel Cans – Developments in Design and Materials". AZoM.com. 2002-10-11. Retrieved 2018-07-09.
  25. ^ "Magnets for transport of aerosol cans and tins". www.goudsmitmagnets.com. Goudsmit Magnetics. Retrieved 2018-07-09.
  26. ^ . www.canmakers.co.uk. The Can Makers. Archived from the original on 2012-07-14. Retrieved 2018-07-09.
  27. ^ "Recycling". www.buntingeurope.com. 15 March 2018. Retrieved 2018-07-09.
  28. ^ "The Canmaker". canmaker.com. from the original on 2013-12-03.
  29. ^ Jing Han (1 August 2005). "Ergonomics designs of aluminum beverage cans & bottles". ResearchGate. from the original on 24 September 2015.
  30. ^ . cancentral.com. Archived from the original on 5 December 2010. Retrieved 24 November 2010.
  31. ^ "The sustainable material | Tata Steel in Europe". www.tatasteeleurope.com. Retrieved 2018-07-09.
  32. ^ . Archived from the original on 2019-04-20. Retrieved 2018-07-09.
  33. ^ . Archived from the original on 2019-02-26. Retrieved 2018-07-09.
  34. ^ . United Kingdom: Cambridge University. 2008. Archived from the original on January 15, 2008.
  35. ^ "Circular Economy". circulareconomy-worldsteel.org. Retrieved 2018-07-09.
  36. ^ "Recycles Mark | Metal Packaging Europe". www.metalpackagingeurope.org. Retrieved 2018-07-09.
  37. ^ (PDF). Archived from the original (PDF) on 2018-02-22. Retrieved 2019-02-26.{{cite web}}: CS1 maint: archived copy as title (link)
  38. ^ . Every Can Counts. Archived from the original on 2017-12-14. Retrieved 2018-07-09.
  39. ^ Blunden, Steve; Wallace, Tony (2003). "Tin in canned food: a review and understanding of occurrence and effect". Food and Chemical Toxicology. 41 (12): 1651–1662. doi:10.1016/S0278-6915(03)00217-5. PMID 14563390.
  40. ^ "Tin in canned fruit and vegetables (Number 29/02)" (PDF). Food Standards Agency. 2002-08-22. (PDF) from the original on 2010-10-19. Retrieved 2009-04-16.
  41. ^ Chandler, BV; Clegg, K Marry (1970). "Pink discoloration in canned pears I.—Role of tin in pigment formation". Journal of the Science of Food and Agriculture. 21 (6): 315. doi:10.1002/jsfa.2740210612.
  42. ^ Vogel, S. (2009). "The Politics of Plastics: The Making and Unmaking of Bisphenol A 'Safety'" 2017-05-30 at the Wayback Machine. American Journal of Public Health 99 (S3): 559–566.
  43. ^ a b "Campbells Eliminating BPA in Soup Cans". www.torontosun.com. from the original on 2014-03-23. Retrieved 2013-06-04.
  44. ^ Canada Gazette Part II (PDF). 144 (21): 1806–18. 13 October 2010 http://www.gazette.gc.ca/rp-pr/p2/2010/2010-10-13/pdf/g2-14421.pdf. (PDF) from the original on 18 March 2012. {{cite journal}}: Missing or empty |title= (help)
  45. ^ Martin Mittelstaedt (13 October 2010). "Canada first to declare bisphenol A toxic". Globe and Mail. Canada. from the original on 2 January 2012.

General references, further reading

External links

  • Steeluniversity Packaging Module
  • Standard U.S. can sizes at GourmetSleuth

steel, cans, historic, north, carolina, basketball, arena, basketball, arena, canadian, film, film, american, naval, slang, term, destroyer, steel, especially, british, english, australian, english, canadian, english, south, african, english, steel, packaging,. For the historic North Carolina basketball arena see Tin Can basketball arena For the Canadian film see Tin Can film For the American naval slang term see destroyer A steel can tin can tin especially in British English Australian English Canadian English and South African English steel packaging or can is a container for the distribution or storage of goods made of thin metal Many cans require opening by cutting the end open others have removable covers They can store a broad variety of contents food beverages oil chemicals etc Steel cans are made of tinplate tin coated steel or of tin free steel In some dialects even aluminium cans are called tin cans 1 An empty tin can Steel cans are highly recyclable unlike materials like plastic with around 65 of steel cans being recycled 2 Contents 1 History 2 Description 3 Advantages of steel cans 4 Materials 5 Standard sizes 6 Fabrication of cans 7 Design and manufacture 7 1 Steel for can making 7 2 Two piece steel can design 7 3 Drawn and ironed DWI steel cans 7 4 Magnetic properties 8 Opening cans 9 Recycling and re use 9 1 Sustainability and recycling of steel beverage cans 9 1 1 Steel recycling 9 1 2 Steel can recycling 9 1 3 Smaller carbon footprint 10 Health issues 10 1 Dissolution of tin into the food 10 2 Bisphenol A 11 See also 12 References 12 1 General references further reading 13 External linksHistory EditThe tin canning process was conceived by the Frenchman Philippe de Girard who got a British merchant Peter Durand to patent the idea in 1810 3 4 The canning concept was based on experimental food preservation work in glass containers the year before by the French inventor Nicholas Appert Durand did not pursue food canning but in 1812 sold his patent to two Englishmen Bryan Donkin and John Hall who refined the process and product and set up the world s first commercial canning factory on Southwark Park Road London By 1813 they were producing their first tin canned goods for the Royal Navy By 1820 tin canisters or cans were being used for gunpowder seeds and turpentine Early tin cans were sealed by soldering with a tin lead alloy which could lead to lead poisoning In 1901 in the United States the American Can Company was founded at the time producing 90 of United States tin cans 5 Canned food in tin cans was already quite popular in various countries when technological advancements in the 1920s lowered the cost of the cans even further 6 155 170 265 280 In 1935 the first beer in metal cans was sold it was an instant sales success 6 155 170 265 280 Further information Canning History and developmentDescription EditMost cans are right circular cylinders with identical and parallel round tops and bottoms with vertical sides However cans for small volumes or particularly shaped contents the top and bottom may be rounded corner rectangles or ovals Other contents may suit a can that is somewhat conical in shape Fabrication of most cans results in at least one rim a narrow ring slightly larger than the outside diameter of the rest of the can The flat surfaces of rimmed cans are recessed from the edge of any rim toward the middle of the can by about the width of the rim the inside diameter of a rim adjacent to this recessed surface is slightly smaller than the inside diameter of the rest of the can Three piece can construction results in top and bottom rims In two piece construction one piece is a flat top and the other a deep drawn cup shaped piece that combines the at least roughly cylindrical wall and the round base Transition between wall and base is usually gradual Such cans have a single rim at the top Some cans have a separate cover that slides onto the top or is hinged Two piece steel cans can be made by drawing to form the bottom and sides and adding an end at the top these do not have side seams Cans can be fabricated with separate slip on or friction fit covers and with covers attached by hinges Various easy opening methods are available 7 In the mid 20th century a few milk products were packaged in nearly rimless cans reflecting different construction in this case one flat surface had a hole for filling the nearly complete can that was sealed after filling with a quickly solidifying drop of molten solder Concern arose that the milk contained unsafe levels of lead leached from this solder plug Advantages of steel cans EditA number of factors make steel cans ideal containers for beverages Steel cans are stronger than cartons or plastic and less fragile than glass protecting the product in transit and preventing leakage or spillage while also reducing the need for secondary packaging 8 9 Steel and aluminium packaging offer 100 barrier protection against light water and air and metal cans without resealable closures are among the most tamper evident of all packaging materials 10 Steel cans preserve and protect the product from damage by light oxidation extremes of temperature and contamination safeguarding flavour appearance and quality from factory to final consumer Food and drink packed in steel cans has equivalent vitamin content to freshly prepared without needing preserving agents 10 Steel cans also extend the product s shelf life allowing longer sell by and use by dates and reducing waste 8 As an ambient packaging medium steel cans do not require cooling in the supply chain simplifying logistics and storage and saving energy and cost 8 At the same time steel s relatively high thermal conductivity means canned drinks chill much more rapidly and easily than those in glass or plastic bottles 11 A World Steel Association initiative Choose Steel is encouraging the use of steel for beverage cans 12 A can of French linseed oil Compressed gas with dispensing valve Flip top can 13 with hinged cover Can of lighter fluid Special can for dispensing oil Camp stove fuel in F Style can 13 Paint can with double friction cover plug Can with slip on cover Can of shoe polish Tea tinMaterials EditNo cans currently in wide use are composed primarily or wholly of tin 14 that term rather reflects the nearly exclusive use in cans clarification needed until the second half of the 20th century of tinplate steel which combined the physical strength and relatively low price of steel with the corrosion resistance of tin Depending on contents and available coatings some canneries still use tin free steel In some local dialects any metal can even aluminium might be called a tin can Use of aluminium in cans began in 1957 15 Aluminium is less costly than tin plated steel but offers the same resistance to corrosion in addition to greater malleability resulting in ease of manufacture this gave rise to the two piece can where all but the top of the can is simply stamped out of a single piece of aluminium rather than laboriously constructed from three pieces of steel A can traditionally has a printed paper or plastic label glued to the outside of the curved surface indicating its contents Some labels contain additional information such as recipes on the reverse side More recently labels are sometimes printed directly onto the metal before or after the metal sheet is formed into the individual cans In November 1991 US can manufacturers voluntarily eliminated lead seams in food cans However imported food cans continued to include lead soldered seams 16 In 1995 the US FDA issued a rule prohibiting lead soldered food cans including both domestic and imported food cans 17 In modern times the majority of food cans in the UK 18 have been lined with a plastic coating containing bisphenol A BPA The coating prevents acids and other substances from corroding the tin or aluminium of the can but leaching of BPA into the can s contents was investigated as a potential health hazard 19 Standard sizes EditCans come in a variety of shapes two common ones are the soup tin and the tuna tin Walls are often stiffened with rib bulges especially on larger cans to help the can resist dents that can cause seams to split Can sizes in the United States have an assortment of designations and sizes For example size 7 8 contains one serving of half a cup with an estimated weight of 4 ounces size 1 picnic has two or three servings totalling one and a quarter cups with an estimated weight of 101 2 ounces size 303 has four servings totalling 2 cups weighing 151 2 ounces and size 10 cans most widely used by food services selling to cafeterias and restaurants have twenty five servings totalling 13 cups with an estimated weight of 1031 2 ounces size of a roughly 3 pound coffee can These are U S customary cups not British Imperial standard In the United States cook books sometimes reference cans by size The Can Manufacturers Institute defines these sizes expressing them in three digit numbers as measured in whole and sixteenths of an inch for the container s nominal outside dimensions a 307 512 would thus measure 3 and 7 16 in diameter by 5 and 3 4 12 16 in height Older can numbers are often expressed as single digits their contents being calculated for room temperature water as approximately eleven ounces 1 picnic can twenty ounces 2 thirty two ounces 3 fifty eight ounces 5 and one hundred ten ounces 10 coffee can 20 Can Name Dimensions inches Capacity U S fluid ounces No 2 can equivalent Typical products6Z 22 16 31 2 6 08 0 2958Z Short 211 16 3 7 93 0 3868Z Tall 211 16 32 8 8 68 0 422No I Picnic 211 16 4 10 94 0 532No 211 Cylinder 211 16 414 16 13 56 0 660No 300 3 47 16 15 22 0 741 Cranberry Sauce Pork amp BeansNo 300 Cylinder 3 59 16 19 40 0 945No I Tall 31 16 411 16 16 70 0 813No 303 33 16 43 8 16 88 0 821 Fruits Vegetables SoupsNo 303 Cylinder 33 16 59 16 21 86 1 060No 2 Vacuum 37 16 33 8 14 71 0 716No 2 37 16 49 16 20 55 1 000 Juices Soups VegetablesJumbo 37 16 55 8 25 80 1 2537No 2 Cylinder 37 16 56 8 26 40 1 284No 1 25 41 16 23 8 13 81 0 672No 2 5 41 16 411 16 29 79 1 450 Fruits VegetablesNo 3 Vacuum 41 4 37 16 23 90 1 162No 3 Cylinder 41 4 7 51 70 2 515No 5 51 8 55 8 59 10 2 8744 Fruit Juice SoupsNo 10 63 16 7 109 43 5 325 Fruits VegetablesIn parts of the world using the metric system tins are made in 250 500 750 ml millilitre and 1 L litre sizes 250 ml is approximately 1 cup or 8 ounces Cans imported from the USA often have odd sizes such as 3 8 L 1 US gallon 1 9 L 1 2 US gallon and 946 ml 2 US pints 1 quart In the UK and Australia cans are usually measured by net weight A standard size tin can holds roughly 400 g though the weight can vary between 385 g and 425 g depending on the density of the contents The smaller half sized can holds roughly 200 g typically varying between 170 g and 225 g Fabrication of cans EditRimmed three piece can construction involves several stages Forming a tube and welding or soldering the seam of the sides Joining the bottom end to the tube Printing or attaching labels to the can Filling the can with content sterilization or retorting is required for many food products Joining the wall and top end Double seam rims are crucial to the joining of the wall to a top or bottom surface An extremely tight fit between the pieces must be accomplished to prevent leakage the process of accomplishing this radically deforms the rims of the parts Part of the tube that forms the wall is bent almost at its end turning outward through 90 degrees and then bent further toward the middle of the tube until it is parallel to the rest of the tube a total bend of 180 degrees The outer edge of the flat piece is bent against this toward the middle of the tubular wall until parallel with the wall turning inward through 90 degrees The edge of bent portion is bent further through another 90 degrees inward now toward the axis of the tube and parallel to the main portion of the flat piece making a total bend of 180 degrees It is bent far enough inward that its circular edge is now slightly smaller in diameter than the edge of the tube Bending it yet further until it is parallel with the tube s axis gives it a total bend of 270 degrees It now envelops the outward rim of the tube Looking outward from the axis of the tube the first surface is the unbent portion of the tube Slightly further out is a narrow portion of the top including its edge The outward bent portion of the tube including its edge is still slightly further out Furthest out is the 90 degree bent portion of the flat surface The combined interacting forces as the portion of the flat surface adjacent to the interior of the tube is indented toward the middle of the tube and then outward forward the axis of the tube and the other bent portions of the flat piece and the tube are all forced toward the axis of the tube drives these five thicknesses of metal against each other from inside and out forming a dry joint so tight that welding or solder is not needed to strengthen or seal it Illustrations of this process can be found on pages 20 22 of the FAO Fisheries Technical Paper 285 Manual on fish canning located here Inside of a tin can Design and manufacture EditSteel for can making Edit The majority of steel used in packaging is tinplate which is steel that has been coated with a thin layer of tin whose functionality is required for the production process 21 The tin layer is usually applied by electroplating 22 Two piece steel can design Edit Most steel beverage cans are two piece designs made from 1 a disc re formed into a cylinder with an integral end double seamed after filling and 2 a loose end to close it 9 Steel cans are made in many different diameters and volumes with opening mechanisms that vary from ring pulls and tab openers to wide open mouths 23 Modern can making lines may produce up to 1000 cans per minute 21 Drawn and ironed DWI steel cans Edit The process of re forming sheet metal without changing its thickness is known as drawing Thinning the walls of a two piece can by passing it through circular dies is called ironing Steel beverage cans are therefore generally referred to as drawn and ironed or DWI cans sometimes D amp I The DWI process is used for making cans where the height is greater than the diameter and is particularly suited to making large volumes of cans of the same basic specification 9 Steel can wall thicknesses are now 30 thinner and weigh 40 less than 30 years ago reducing the amounts of raw materials and energy required to make them They are also up to 40 thinner than aluminium 24 Magnetic properties Edit Steel is a ferrous metal and is therefore magnetic For beverage packaging this is unique This allows the use of magnetic conveyor systems 25 to transfer empty cans through the filling and packing processes increasing accuracy and reducing potential spillage and waste 26 In recycling facilities steel cans may be readily separated from other waste using magnetic equipment including cross belt separators also known as overband magnets and drum magnets 27 Opening cans EditThe first cans were heavy weight containers that required ingenuity to open with implements such as knives Not until several years later after can manufacturers started using thinner metal sheets were any dedicated can openers developed While beverage cans or cans of fluid such as broth can merely be punctured to remove the product solid or semisolid contents require removing one end of the can This can be accomplished with a heavy knife or other sharp tool but can openers are much more convenient Some cans such as those used for sardines have a specially scored lid so that the user can break out the metal by the leverage of winding it around a slotted church key Until the mid 20th century some sardine tins had solder attached lids and the winding key worked by forcing the solder joint apart The advent of pull tabs in beverage cans spread to the canning of various food products such as pet food or nuts and non food products such as motor oil and tennis balls The ends are known as easy open lids because they open without any tools or implements 28 An additional innovation developed for specifically for food cans uses a tab that is bent slightly upwards creating a larger surface area for easier finger access 29 Cans can be made with easy open features Some cans have screw caps for pouring liquids and resealing Some have hinged covers or slip on covers for easy access Paint cans often have a removable plug on the top for access and for reclosing Mechanism of a can opener Can that requires a can opener Soup can with a ring pull tab Opened can with a ring pull tab Keyed side opening Easy open sardine can Stay on tabRecycling and re use EditSteel from cans and other sources is the most recycled packaging material 8 Around 65 of steel cans are recycled 2 In the United States 63 of steel cans are recycled compared to 52 of aluminium cans 30 In Europe the recycling rate in 2016 is 79 5 8 Most can recycling occurs at the smelters but individual consumers also directly reuse cans in various ways For instance some people use two tin cans to form a camp or survival stove to cook small meals citation needed Food tin cans reused for art and storage Sustainability and recycling of steel beverage cans Edit Steel recycling Edit From an ecological perspective steel may be regarded as a closed loop material post consumer waste can be collected recycled and used to make new cans or other products 31 Each tonne of scrap steel recycled saves 1 5 tonnes of CO2 1 4 tonnes of iron ore and 740 kg of coal Steel is the world s most recycled material with more than 85 of all the world s steel products being recycled at the end of their life an estimated 630 million tonnes of steel scrap were recycled in 2017 saving 945 million tonnes of CO2 32 Steel can recycling Edit A steel can can be recycled again and again without loss of quality 33 however for the food grade steel it s required to remove tin from the scrap metal which is done by way of electrochemistry the tin is leached from a high pH solution at low negative voltage 34 Recycling a single can saves the equivalent power for one laundry load 1 hour of TV or 24 hours of lighting 10W LED bulb 35 Steel beverage cans are recycled by being melted down in an electric arc furnace or basic oxygen furnace citation needed Most steel cans also carry some form of recycling identification such as the Metal Recycles Forever Mark 36 Recyclable Steel 37 and the Choose Steel campaign logo 12 There is also a campaign in Europe called Every Can Counts encouraging can recycling in the workplace 38 Smaller carbon footprint Edit All beverage packaging creates CO2 emissions at every stage in the production process from raw material extraction processing and manufacture through to recycling However steel cans are an ecological top performer as cans can always be recycled The steel industry needs the used cans and will use them in the production of new steel product By recycling the cans and closing the loop CO2 emissions are dramatically reduced There is also the potential for higher global steel recycling rates as consumers become more aware of the benefits citation needed Health issues EditDissolution of tin into the food Edit Tin is corrosion resistant but acidic food like fruits and vegetables can corrode the tin layer Nausea vomiting and diarrhea have been reported after ingesting canned food containing 200 mg kg of tin 39 A 2002 study showed that 99 5 of 1200 tested cans contained below the UK regulatory limit of 200 mg kg of tin an improvement over most previous studies largely attributed to the increased use of fully lacquered cans for acidic foods and concluded that the results do not raise any long term food safety concerns for consumers The two non compliant products were voluntarily recalled 40 Evidence of tin impurities can be indicated by color as in the case of pears but lack of color change does not guarantee that a food is not tainted with tin 41 Bisphenol A Edit Main article Bisphenol A The chemical compound Bisphenol A found in can linings is associated with organizational changes in the prostate breast testis mammary glands body size brain structure and chemistry and behavior of laboratory animals 42 unborn children and adults Bisphenol A BPA is a controversial chemical compound present in commercially available tin can plastic linings 43 and transferred to canned food The inside of the can is coated with an epoxy coating in an attempt to prevent food or beverage from coming into contact with the metal The longer food is in a can and the warmer and more acidic it is the more BPA leaches into it In September 2010 Canada became the first country to declare BPA a toxic substance 44 45 In the European Union and Canada BPA use is banned in baby bottles The FDA does not regulate BPA see BPA controversy Public health regulatory history in the United States Several companies like Campbell s Soup announced plans to eliminate BPA from the linings of their cans 43 but have not said which chemical they plan to replace it with See BPA controversy Chemical manufacturers reactions to bans citation needed See also EditAlbion metal Drink can Oil can Tin box Tin can wallReferences Edit Kraus F J 2009 Steel Cans In Yam K L ed Encyclopedia of Packaging Technology Wiley pp 205 216 ISBN 978 0 470 08704 6 a b 64 9 of steel cans are recycled worldsteel org 10 January 2007 Archived from the original on 18 July 2011 Retrieved 24 November 2010 Robertson Gordon L 2016 Food packaging 3rd ed CRC Press p 123 Geoghegan Tom 2013 04 21 BBC News The story of how the tin can nearly wasn t Bbc co uk Archived from the original on 2013 06 06 Retrieved 2013 06 04 American Can Company Revolution in Containers Archived 2009 07 15 at the Wayback Machine Excerpts of William C Stolk Address of The Newcomen Society of North America April 21 1960 Printed July 1960 from oilcans net retrieved 16 July 2010 a b Reutter Mark 1988 Sparrows Point Making Steel the Rise and Ruin of American Industrial Might University of Illinois Press ISBN 9780671553357 Soroka 2002 Fundamentals of Packaging Technology Institute of Packaging Professionals ISBN 1 930268 25 4 a b c d e APEAL Steel for packaging cans Home Food Beverage Aerosol Paint and Specialty cans apeal org Archived from the original on 2013 08 08 a b c Beverage Tata Steel in Europe www tatasteeleurope com Retrieved 2018 07 09 a b Steel For Packaging Home www steelforpackaging org Retrieved 2018 07 09 Does a Drink Stay Colder in a Metal Can or a Plastic Bottle Sciencing Retrieved 2018 07 09 a b Home Retrieved 2018 07 09 a b Soroka W Illustrated Glossary of Packaging Terminology Second ed Institute of Packaging Professionals Archived from the original on 2011 01 29 Hertzberg Ruth Greene Janet Vaughan Beatrice 2010 05 25 Putting Food By Fifth Edition Penguin ISBN 9781101539903 Archived from the original on 2018 02 06 Petroleum week Archived 2018 02 06 at the Wayback Machine Volume 9 1959 p 82 Google Books PUZO DANIEL P 29 April 1993 Lead in Cans Still a Problem Still Preventable Los Angeles Times Archived from the original on 1 July 2018 Retrieved 29 August 2018 Code of Federal Regulations United States of America April 1 2017 pp 21CFR189 240 Archived from the original on 8 March 2021 Retrieved 29 August 2018 Hickman Martin 2010 04 01 Revealed the nasty secret in your kitchen cupboard The Independent London Archived from the original on 2010 04 02 Retrieved 2010 04 01 Are Cans BPA Free in the UK Food Standards Agency 2018 10 26 Archived from the original on 2021 09 17 Retrieved 2020 11 17 Can standards cancentral com Archived from the original on 20 November 2010 Retrieved 24 November 2010 a b Steel packaging Retrieved 2018 07 09 permanent dead link Tinning Wikipedia 2018 03 03 retrieved 2018 07 09 Beverage can Wikipedia 2018 07 01 retrieved 2018 07 09 Steel Cans Developments in Design and Materials AZoM com 2002 10 11 Retrieved 2018 07 09 Magnets for transport of aerosol cans and tins www goudsmitmagnets com Goudsmit Magnetics Retrieved 2018 07 09 How cans are filled www canmakers co uk The Can Makers Archived from the original on 2012 07 14 Retrieved 2018 07 09 Recycling www buntingeurope com 15 March 2018 Retrieved 2018 07 09 The Canmaker canmaker com Archived from the original on 2013 12 03 Jing Han 1 August 2005 Ergonomics designs of aluminum beverage cans amp bottles ResearchGate Archived from the original on 24 September 2015 Recyclings FAQ cancentral com Archived from the original on 5 December 2010 Retrieved 24 November 2010 The sustainable material Tata Steel in Europe www tatasteeleurope com Retrieved 2018 07 09 Blog steel the surprising recycling champion Archived from the original on 2019 04 20 Retrieved 2018 07 09 Steel the Permanent Material in the Circular Economy Archived from the original on 2019 02 26 Retrieved 2018 07 09 Tin can processing Leaching and electrolysis of tin from steel cans United Kingdom Cambridge University 2008 Archived from the original on January 15 2008 Circular Economy circulareconomy worldsteel org Retrieved 2018 07 09 Recycles Mark Metal Packaging Europe www metalpackagingeurope org Retrieved 2018 07 09 Archived copy PDF Archived from the original PDF on 2018 02 22 Retrieved 2019 02 26 a href Template Cite web html title Template Cite web cite web a CS1 maint archived copy as title link Every Can Counts Who we are Every Can Counts Archived from the original on 2017 12 14 Retrieved 2018 07 09 Blunden Steve Wallace Tony 2003 Tin in canned food a review and understanding of occurrence and effect Food and Chemical Toxicology 41 12 1651 1662 doi 10 1016 S0278 6915 03 00217 5 PMID 14563390 Tin in canned fruit and vegetables Number 29 02 PDF Food Standards Agency 2002 08 22 Archived PDF from the original on 2010 10 19 Retrieved 2009 04 16 Chandler BV Clegg K Marry 1970 Pink discoloration in canned pears I Role of tin in pigment formation Journal of the Science of Food and Agriculture 21 6 315 doi 10 1002 jsfa 2740210612 Vogel S 2009 The Politics of Plastics The Making and Unmaking of Bisphenol A Safety Archived 2017 05 30 at the Wayback Machine American Journal of Public Health 99 S3 559 566 a b Campbells Eliminating BPA in Soup Cans www torontosun com Archived from the original on 2014 03 23 Retrieved 2013 06 04 Canada Gazette Part II PDF 144 21 1806 18 13 October 2010 http www gazette gc ca rp pr p2 2010 2010 10 13 pdf g2 14421 pdf Archived PDF from the original on 18 March 2012 a href Template Cite journal html title Template Cite journal cite journal a Missing or empty title help Martin Mittelstaedt 13 October 2010 Canada first to declare bisphenol A toxic Globe and Mail Canada Archived from the original on 2 January 2012 General references further reading Edit Nicolas Appert Guide to Tinplate History of the Tin Can permanent dead link on About com Yam K L Encyclopedia of Packaging Technology John Wiley amp Sons 2009 ISBN 978 0 470 08704 6 Soroka W Fundamentals of Packaging Technology Institute of Packaging Professionals IoPP 2002 ISBN 1 930268 25 4External links Edit Wikimedia Commons has media related to Cans Steeluniversity Packaging Module Steel industry fact sheet on food cans Standard U S can sizes at GourmetSleuth Retrieved from https en wikipedia org w index php title Steel and tin cans amp oldid 1146005697, wikipedia, wiki, book, books, library,

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