In plumbing , a trap is a U-shaped portion of pipe designed to trap liquid or gas to prevent unwanted flow; most notably sewer gases from entering buildings while allowing waste materials to pass through. In oil refineries, traps are used to prevent hydrocarbons and other dangerous gases and chemical fumes from escaping through drains. In heating systems, the same feature is used to prevent thermo-siphoning which would allow heat to escape to locations where it is not wanted. Similarly, some pressure gauges are connected to systems using U bends to maintain a local gas while the system uses liquid. For decorative effect, they can be disguised as complete loops of pipe, creating more than one U for added efficacy.
61-566: In domestic applications, traps are typically U, S, Q, or J-shaped pipe located below or within a plumbing fixture . An S-shaped trap is also known as an S-bend . It was invented by Alexander Cumming in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The U-bend could not jam, so, unlike the S-bend, it did not need an overflow. In
122-431: A Mill Test Report (MTR). These tests can be used to prove that the alloy conforms to various specifications (e.g. 316 SS ). The tests are stamped by the mill's QA/QC department and can be used to trace the material back to the mill by future users, such as piping and fitting manufacturers. Maintaining the traceability between the alloy material and associated MTR is an important quality assurance issue. QA often requires
183-429: A bar code and the ends are capped (plastic) for protection. The pipe and pipe spools are delivered to a warehouse on a large commercial/industrial job and they may be held indoors or in a gridded laydown yard. The pipe or pipe spool is retrieved, staged, rigged, and then lifted into place. On large process jobs the lift is made using cranes and hoist and other material lifts. They are typically temporarily supported in
244-501: A cost advantage over LSAW pipes, as the process uses coils rather than steel plates. As such, in applications where spiral-weld is acceptable, SSAW pipes may be preferred over LSAW pipes. Both LSAW pipes and SSAW pipes compete against ERW pipes and seamless pipes in the diameter ranges of 16”-24”. Tubing for flow, either metal or plastic, is generally extruded . Pipe is made out of many types of material including ceramic , glass , fiberglass , many metals , concrete and plastic . In
305-501: A fluidized bed reactor) or from a natural phenomenon such as an earthquake (design basis event or DBE). Pipe hanger assembles are usually attached with pipe clamps. Possible exposure to high temperatures and heavy loads should be included when specifying which clamps are needed. Pipes are commonly joined by welding , using threaded pipe and fittings; sealing the connection with a pipe thread compound, Polytetrafluoroethylene (PTFE) Thread seal tape , oakum , or PTFE string, or by using
366-413: A hollow pipe is far stiffer per unit weight than the solid members. In common usage the words pipe and tube are usually interchangeable, but in industry and engineering, the terms are uniquely defined. Depending on the applicable standard to which it is manufactured, pipe is generally specified by a nominal diameter with a constant outside diameter (OD) and a schedule that defines the thickness. Tube
427-481: A little odd. For example, Sch 20 pipe is even thinner than Sch 40, but same OD. And while these pipes are based on old steel pipe sizes, there is other pipe, like cpvc for heated water, that uses pipe sizes, inside and out, based on old copper pipe size standards instead of steel. Many different standards exist for pipe sizes, and their prevalence varies depending on industry and geographical area. The pipe size designation generally includes two numbers; one that indicates
488-547: A mechanical coupling. Process piping is usually joined by welding using a TIG or MIG process. The most common process pipe joint is the butt weld. The ends of pipe to be welded must have a certain weld preparation called an End Weld Prep (EWP) which is typically at an angle of 37.5 degrees to accommodate the filler weld metal. The most common pipe thread in North America is the National Pipe Thread (NPT) or
549-564: A metric Diameter Nominal (DN) instead of the imperial NPS. For NPS larger than 14, the DN is equal to the NPS multiplied by 25. (Not 25.4) This is documented by EN 10255 (formerly DIN 2448 and BS 1387) and ISO 65:1981, and it is often called DIN or ISO pipe. Japan has its own set of standard pipe sizes, often called JIS pipe. The Iron pipe size (IPS) is an older system still used by some manufacturers and legacy drawings and equipment. The IPS number
610-420: A number of pipes together, and for other purposes. A broad variety of standardized pipe fittings are available; they are generally broken down into either a tee, an elbow, a branch, a reducer/enlarger, or a wye. Valves control fluid flow and regulate pressure. The piping and plumbing fittings and valves articles discuss them further. Cylinder (geometry) Too Many Requests If you report this error to
671-411: A number of processes that may be used to produce ERW pipes. Each of these processes leads to coalescence or merging of steel components into pipes. Electric current is passed through the surfaces that have to be welded together; as the components being welded together resist the electric current, heat is generated which forms the weld. Pools of molten metal are formed where the two surfaces are connected as
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#1732783896324732-619: A number of standards, including API 5L, ANSI / ASME B36.10M (Table 1) in the US, and BS 1600 and BS 1387 in the United Kingdom. Typically the pipe wall thickness is the controlled variable, and the Inside Diameter (I.D.) is allowed to vary. The pipe wall thickness has a variance of approximately 12.5 percent. In the rest of Europe pressure piping uses the same pipe IDs and wall thicknesses as Nominal Pipe Size , but labels them with
793-416: A strong electric current is passed through the metal; these pools of molten metal form the weld that binds the two abutted components. ERW pipes are manufactured from the longitudinal welding of steel. The welding process for ERW pipes is continuous, as opposed to welding of distinct sections at intervals. ERW process uses steel coil as feedstock. The High Frequency Induction Technology (HFI) welding process
854-401: A test of chemical composition and a series of mechanical strength tests for each heat of pipe. A heat of pipe is all forged from the same cast ingot, and therefore had the same chemical composition. Mechanical tests may be associated to a lot of pipe, which would be all from the same heat and have been through the same heat treatment processes. The manufacturer performs these tests and reports
915-423: Is a gasket style where the flanges of the adjoining pipes are bolted together, compressing the gasket into a space between the pipe. Mechanical grooved couplings or Victaulic joints are also frequently used for frequent disassembly and assembly. Developed in the 1920s, these mechanical grooved couplings can operate up to 120 pounds per square inch (830 kPa) working pressures and available in materials to match
976-447: Is for clothes washing machines , which rapidly dispense a large volume of wastewater while draining the wash and rinse cycles. In chemical engineering applications, a trap may be known as a lute. An S-shaped trap is also known as an S-bend . It was invented by Alexander Cumming in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The new U-bend could not jam, so, unlike
1037-418: Is formed by rolling plate and welding the seam (usually by Electric resistance welding ("ERW"), or Electric Fusion Welding ("EFW")). The weld flash can be removed from both inner and outer surfaces using a scarfing blade. The weld zone can also be heat-treated to make the seam less visible. Welded pipe often has tighter dimensional tolerances than the seamless type, and can be cheaper to manufacture. There are
1098-516: Is generally available in diameters of 6, 8, 10, 12, 15, 18, 21, and 24 inches (15, 20, 25, 30, 38, 46, 53, and 61 cm). The manufacture and installation of pressure piping is tightly regulated by the ASME "B31" code series such as B31.1 or B31.3 which have their basis in the ASME Boiler and Pressure Vessel Code (BPVC) . This code has
1159-490: Is incompatible with the service fluid or where weight is a concern; aluminum is also used for heat transfer tubing such as in refrigerant systems. Copper tubing is popular for domestic water (potable) plumbing systems; copper may be used where heat transfer is desirable (i.e. radiators or heat exchangers). Inconel , chrome moly , and titanium steel alloys are used in high temperature and pressure piping in process and power facilities. When specifying alloys for new processes,
1220-488: Is most often specified by the OD and wall thickness, but may be specified by any two of OD, inside diameter (ID), and wall thickness. Pipe is generally manufactured to one of several international and national industrial standards. While similar standards exist for specific industry application tubing, tube is often made to custom sizes and a broader range of diameters and tolerances. Many industrial and government standards exist for
1281-414: Is neither the inside nor outside diameter. Plastic tubing, such as PVC and CPVC, for plumbing applications also has different sizing standards . Agricultural applications use PIP sizes, which stands for Plastic Irrigation Pipe . PIP comes in pressure ratings of 22 psi (150 kPa), 50 psi (340 kPa), 80 psi (550 kPa), 100 psi (690 kPa), and 125 psi (860 kPa) and
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#17327838963241342-577: Is never the same as SCH 160. XXS is in fact thicker than SCH 160 for NPS 1/8" to 6" inclusive, whereas SCH 160 is thicker than XXS for NPS 8" and larger. Another old system is the Ductile Iron Pipe Size (DIPS), which generally has larger ODs than IPS. Copper plumbing tube for residential plumbing follows an entirely different size system in America, often called Copper Tube Size (CTS); see domestic water system . Its nominal size
1403-413: Is often used in the gravity-flow transport of storm water. Usually such pipe will have a receiving bell or a stepped fitting, with various sealing methods applied at installation. When the alloys for piping are forged, metallurgical tests are performed to determine material composition by % of each chemical element in the piping, and the results are recorded in a material test report, also known as
1464-414: Is spectrographically analyzed. Pipe sizes can be confusing because the terminology may relate to historical dimensions. For example, a half-inch iron pipe does not have any dimension that is a half inch. Initially, a half inch pipe did have an inner diameter of 1 ⁄ 2 inch (13 mm)—but it also had thick walls. As technology improved, thinner walls became possible, but the outside diameter stayed
1525-418: Is the same as the NPS number, but the schedules were limited to Standard Wall (STD), Extra Strong (XS), and Double Extra Strong (XXS). STD is identical to SCH 40 for NPS 1/8 to NPS 10, inclusive, and indicates .375" wall thickness for NPS 12 and larger. XS is identical to SCH 80 for NPS 1/8 to NPS 8, inclusive, and indicates .500" wall thickness for NPS 8 and larger. Different definitions exist for XXS, however it
1586-606: Is used for manufacturing ERW pipes. In this process, the current to weld the pipe is applied by means of an induction coil around the tube. HFI is generally considered to be technically superior to "ordinary" ERW when manufacturing pipes for critical applications, such as for usage in the energy sector, in addition to other uses in line pipe applications, as well as for casing and tubing. Large-diameter pipe (25 centimetres (10 in) or greater) may be ERW, EFW, or Submerged Arc Welded ("SAW") pipe. There are two technologies that can be used to manufacture steel pipes of sizes larger than
1647-507: Is usually delivered to a customer or jobsite as either "sticks" or lengths of pipe (typically 20 feet (6.1 m), called single random length) or they are prefabricated with elbows, tees and valves into a prefabricated pipe spool [A pipe spool is a piece of pre-assembled pipe and fittings, usually prepared in a shop so that installation on the construction site can be more efficient.]. Typically, pipe smaller than 2 inches (5.1 cm) are not pre-fabricated. The pipe spools are usually tagged with
1708-686: The Dryseal (NPTF) version. Other pipe threads include the British Standard Pipe Thread (BSPT), the garden hose thread (GHT), and the fire hose coupling (NST). Copper pipes are typically joined by soldering , brazing , compression fittings , flaring , or crimping . Plastic pipes may be joined by solvent welding , heat fusion , or elastomeric sealing. If frequent disconnection will be required, gasketed pipe flanges or union fittings provide better reliability than threads. Some thin-walled pipes of ductile material, such as
1769-410: The heat number to be written on the pipe. Precautions must also be taken to prevent the introduction of counterfeit materials. As a backup to etching/labeling of the material identification on the pipe, positive material identification (PMI) is performed using a handheld device; the device scans the pipe material using an emitted electromagnetic wave ( x-ray fluorescence/XRF ) and receives a reply that
1830-416: The 1870s ), until by the early 1930s these methods were replaced by welding , which is still widely used today. There are three processes for metallic pipe manufacture. Centrifugal casting of hot alloyed metal is one of the most prominent process. Ductile iron pipes are generally manufactured in such a fashion. Seamless pipe (SMLS) is formed by drawing a solid billet over a piercing rod to create
1891-574: The S-bend, it did not need an overflow. Once invented, despite being simple and reasonably reliable, widespread use was slow coming. In Britain, the requirement to use traps was introduced only after the Great Stink in London, in the summer of 1858, when the objectionable smell of the River Thames , which was effectively an open sewer, affected the nearby Houses of Parliament . That motivated
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1952-402: The US, BS 1600 and BS EN 10255 in the United Kingdom and Europe. There are two common methods for designating pipe outside diameter (OD). The North American method is called NPS (" Nominal Pipe Size ") and is based on inches (also frequently referred to as NB ("Nominal Bore")). The European version is called DN ("Diametre Nominal" / "Nominal Diameter") and is based on millimetres. Designating
2013-666: The US, "S" traps are no longer accepted by the building codes as unvented S-traps tend to siphon dry. It may be possible to determine whether a household uses an S- or U-bend by the presence of an overflow pipe outlet. What is required instead is a P-trap with proper venting. Certain drum-styled traps are also discouraged or banned. Pipe (material) A pipe is a tubular section or hollow cylinder , usually but not necessarily of circular cross-section , used mainly to convey substances which can flow — liquids and gases ( fluids ), slurries , powders and masses of small solids. It can also be used for structural applications;
2074-485: The United States, traps are commonly referred to as P-traps. It is the addition of a 90 degree fitting on the outlet side of a U-bend, thereby creating a P-like shape (oriented horizontally). It is also referred to as a sink trap because it is installed under most sinks. Because of its shape, the trap retains some water after the fixture's use. This water creates an air seal that prevents sewer gas from passing from
2135-500: The composition in a mill traceability report and the mechanical tests in a material test report , both of which are referred to by the acronym MTR. Material with these associated test reports is called traceable . For critical applications, third party verification of these tests may be required; in this case an independent lab will produce a certified material test report (CMTR), and the material will be called certified . Some widely used pipe standards or piping classes are: API 5L
2196-440: The drain pipe by venting room air into the drain pipe (behind the trap). A " Chicago Loop " is another alternative. When a trap is installed on a fixture that is not routinely used—such as a floor drain—the eventual evaporation of the water in the trap must be considered. In these cases, a trap primer may be installed; these are devices that automatically recharge traps with water to maintain their water seals. In some regions of
2257-480: The drain pipes back into the building. Essentially all plumbing fixtures including sinks , bathtubs , and showers must be equipped with either an internal or external trap. Toilets almost always have an internal trap. Because it is a localized low-point in the plumbing, sink traps also tend to capture small and heavy objects (such as jewellery or coins) accidentally dropped down the sink. Traps also tend to collect hair, sand, food waste and other debris and limit
2318-481: The force of law in Canada and the US. Europe and the rest of the world has an equivalent system of codes. Pressure piping is generally pipe that must carry pressures greater than 10 to 25 atmospheres, although definitions vary. To ensure safe operation of the system, the manufacture, storage, welding, testing, etc. of pressure piping must meet stringent quality standards. Manufacturing standards for pipes commonly require
2379-497: The hollow shell in a process called rotary piercing . As the manufacturing process does not include any welding, seamless pipes are perceived to be stronger and more reliable. Historically, seamless pipe was regarded as withstanding pressure better than other types, and was often more available than welded pipe. Advances since the 1970s, in materials, process control, and non-destructive testing, allow correctly specified welded pipe to replace seamless in many applications. Welded pipe
2440-399: The known issues of creep and sensitization effect must be taken into account. Lead piping is still found in old domestic and other water distribution systems , but is no longer permitted for new potable water piping installations due to its toxicity . Many building codes now require that lead piping in residential or institutional installations be replaced with non-toxic piping or that
2501-469: The legislators to authorise the construction of a modern sewerage system in the city, of which the S-bend was an essential component. As of 2017, only about two-thirds of the world population have access to traps, in spite of the evidence that good sewage systems significantly improve economic productivity in places that employ them. Maintaining the water seal is critical to trap operation; traps might dry out, and poor venting can suction or blow water out of
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2562-410: The outage. After the pipe is installed it will be tested for leaks. Before testing it may need to be cleaned by blowing air or steam or flushing with a liquid. Pipes are usually either supported from below or hung from above (but may also be supported from the side), using devices called pipe supports. Supports may be as simple as a pipe "shoe" which is akin to a half of an I-beam welded to the bottom of
2623-540: The outside (OD) or nominal diameter, and the other that indicates the wall thickness. In the early twentieth century, American pipe was sized by inside diameter. This practice was abandoned to improve compatibility with pipe fittings that must usually fit the OD of the pipe, but it has had a lasting impact on modern standards around the world. In North America and the UK, pressure piping is usually specified by Nominal Pipe Size (NPS) and schedule (SCH). Pipe sizes are documented by
2684-640: The outside diameter allows pipes of the same size to be fit together no matter what the wall thickness. Since the outside diameter is fixed for a given pipe size, the inside diameter will vary depending on the wall thickness of the pipe. For example, 2" Schedule 80 pipe has thicker walls and therefore a smaller inside diameter than 2" Schedule 40 pipe. Steel pipe has been produced for about 150 years. The pipe sizes that are in use today in PVC and galvanized were originally designed years ago for steel pipe. The number system, like Sch 40, 80, 160, were set long ago and seem
2745-431: The past, wood and lead ( Latin plumbum , from which comes the word ' plumbing ') were commonly used. Typically metallic piping is made of steel or iron, such as unfinished, black (lacquer) steel, carbon steel , stainless steel , galvanized steel , brass , and ductile iron . Iron based piping is subject to corrosion if used within a highly oxygenated water stream. Aluminum pipe or tubing may be utilized where iron
2806-491: The pipe grade. Another type of mechanical coupling is a flareless tube fitting (Major brands include Swagelok, Ham-Let, Parker); this type of compression fitting is typically used on small tubing under 2 inches (51 mm) in diameter. When pipes join in chambers where other components are needed for the management of the network (such as valves or gauges), dismantling joints are generally used, in order to make mounting/dismounting easier. Fittings are also used to split or join
2867-400: The pipe. Under buried conditions, gasket-joint pipes allow for lateral movement due to soil shifting as well as expansion/contraction due to temperature differentials. Plastic MDPE and HDPE gas and water pipes are also often joined with Electrofusion fittings. Large above ground pipe typically uses a flanged joint, which is generally available in ductile iron pipe and some others. It
2928-641: The pipe; they may be "hung" using a clevis , or with trapeze type of devices called pipe hangers. Pipe supports of any kind may incorporate springs, snubbers, dampers, or combinations of these devices to compensate for thermal expansion , or to provide vibration isolation, shock control, or reduced vibration excitation of the pipe due to earthquake motion. Some dampers are simply fluid dashpots, but other dampers may be active hydraulic devices that have sophisticated systems that act to dampen peak displacements due to externally imposed vibrations or mechanical shocks. The undesired motions may be process derived (such as in
2989-448: The production of pipe and tubing. The term "tube" is also commonly applied to non-cylindrical sections, i.e., square or rectangular tubing. In general, "pipe" is the more common term in most of the world, whereas "tube" is more widely used in the United States. Both "pipe" and "tube" imply a level of rigidity and permanence, whereas a hose (or hosepipe) is usually portable and flexible. Pipe assemblies are almost always constructed with
3050-399: The same so it could mate with existing older pipe, increasing the inner diameter beyond half an inch. The history of copper pipe is similar. In the 1930s, the pipe was designated by its internal diameter and a 1 ⁄ 16 -inch (1.6 mm) wall thickness. Consequently, a 1-inch (25 mm) copper pipe had a 1 + 1 ⁄ 8 -inch (28.58 mm) outside diameter. The outside diameter
3111-435: The size of objects that enter the plumbing system, thereby catching oversized objects. For all of these reasons, most traps may be disassembled for cleaning or provide a cleanout feature. Where a volume of water may be rapidly discharged through the trap, a vertical vented pipe called a standpipe may be attached to the trap to prevent the disruption of the seal in other nearby traps. The most common use of standpipes in houses
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#17327838963243172-413: The smaller copper or flexible plastic water pipes found in homes for ice makers and humidifiers, for example, may be joined with compression fittings . Underground pipe typically uses a "push-on" gasket style of pipe that compresses a gasket into a space formed between the two adjoining pieces. Push-on joints are available on most types of pipe. A pipe joint lubricant must be used in the assembly of
3233-526: The steel pipes that can be produced by seamless and ERW processes. The two types of pipes produced through these technologies are longitudinal-submerged arc-welded (LSAW) and spiral-submerged arc-welded (SSAW) pipes. LSAW are made by bending and welding wide steel plates and most commonly used in oil and gas industry applications. Due to their high cost, LSAW pipes are seldom used in lower value non-energy applications such as water pipelines. SSAW pipes are produced by spiral (helicoidal) welding of steel coil and have
3294-462: The steel structure using beam clamps, straps, and small hoists until the pipe supports are attached or otherwise secured. An example of a tool used for installation for a small plumbing pipe (threaded ends) is the pipe wrench . Small pipe is typically not heavy and can be lifted into place by the installation craft laborer. However, during a plant outage or shutdown, the small (small bore) pipe may also be pre-fabricated to expedite installation during
3355-493: The traps. This is usually avoided by venting the drain pipes downstream of the trap; by being vented to the atmosphere outside the building, the drain lines never operate at a pressure much higher or lower than atmospheric pressure. In the United States, plumbing codes usually provide strict limitations on how far a trap may be located from the nearest vent stack . When a vent cannot be provided, an air admittance valve may be used instead. These devices avoid negative pressure in
3416-643: The tubes' interiors be treated with phosphoric acid . According to a senior researcher and lead expert with the Canadian Environmental Law Association , "[...] there is no safe level of lead [for human exposure]". In 1991 the US EPA issued the Lead and Copper Rule , a federal regulation which limits the concentration of lead and copper allowed in public drinking water, as well as the permissible amount of pipe corrosion occurring due to
3477-545: The use of fittings such as elbows, tees, and so on, while tube may be formed or bent into custom configurations. For materials that are inflexible, cannot be formed, or where construction is governed by codes or standards, tube assemblies are also constructed with the use of tube fittings. Additionally, pipes are used for many purposes that do not involve conveying fluid. Handrails , scaffolding, and support structures are often constructed from structural pipes, especially in an industrial environment. The first known use of pipes
3538-1139: The water itself. In the US it is estimated that 6.5 million lead service lines (pipes that connect water mains to home plumbing) installed before the 1930s are still in use. Plastic tubing is widely used for its light weight, chemical resistance, non-corrosive properties, and ease of making connections. Plastic materials include polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), fibre reinforced plastic (FRP), reinforced polymer mortar (RPMP), polypropylene (PP), polyethylene (PE), cross-linked high-density polyethylene (PEX), polybutylene (PB), and acrylonitrile butadiene styrene (ABS), for example. In many countries, PVC pipes account for most pipe materials used in buried municipal applications for drinking water distribution and wastewater mains. Pipe may be made from concrete or ceramic , usually for low-pressure applications such as gravity flow or drainage. Pipes for sewage are still predominantly made from concrete or vitrified clay . Reinforced concrete can be used for large-diameter concrete pipes. This pipe material can be used in many types of construction, and
3599-462: Was changed in the second half of 2008 to edition 44 from edition 43 to make it identical to ISO 3183. It is important to note that the change has created the requirement that sour service, ERW pipe, pass a hydrogen induced cracking (HIC) test per NACE TM0284 in order to be used for sour service. Pipe installation is often more expensive than the material and a variety of specialized tools, techniques, and parts have been developed to assist this. Pipe
3660-839: Was in Ancient Egypt . The Pyramid of Sahure , completed around the 25th century BC, included a temple with an elaborate drainage system including more than 380 m (1,247 ft) of copper piping. During the Napoleonic Wars Birmingham gunmakers tried to use rolling mills to make iron musket barrels. One of them, Henry Osborne, developed a relatively effective process in 1817 with which he started to make iron gas tubes ca. 1820, selling some to gas lighting pioneer Samuel Clegg . When steel pipes were introduced in 19th century, they initially were riveted, and later clamped with H-shaped bars (even though methods for making weldless steel tubes were known already in
3721-545: Was the important dimension for mating with fittings. The wall thickness on modern copper is usually thinner than 1 ⁄ 16 -inch (1.6 mm), so the internal diameter is only "nominal" rather than a controlling dimension. Newer pipe technologies sometimes adopted a sizing system as its own. PVC pipe uses the Nominal Pipe Size . Pipe sizes are specified by a number of national and international standards, including API 5L, ANSI / ASME B36.10M and B36.19M in
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