Piping And Plumbing Fittings
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A fitting or adapter is used in pipe systems to connect straight sections of
pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circular ...
or
tube Tube or tubes may refer to: * ''Tube'' (2003 film), a 2003 Korean film * ''The Tube'' (TV series), a music related TV series by Channel 4 in the United Kingdom * "Tubes" (Peter Dale), performer on the Soccer AM television show * Tube (band), a ...
, adapt to different sizes or shapes, and for other purposes such as regulating (or measuring)
fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...
flow. These fittings are used in
plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delivery ...
to manipulate the conveyance of water, gas, or liquid waste in domestic or commercial environments, within a system of pipes or tubes. Fittings (especially uncommon types) require money, time, materials, and tools to install and are an important part of
piping Within industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid. Industrial process piping (and accompan ...
and
plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delivery ...
systems.
Valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...
s are technically fittings, but are usually discussed separately.


Standards

Standard codes are followed when designing (or manufacturing) a piping system. Organizations which promulgate piping standards include: *
ASME The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing ...
: American Society of Mechanical Engineers ** A112.19.1 Enameled cast-iron and steel plumbing fixtures standards ** A112.19.2 Ceramic plumbing fixtures standard *
ASTM International ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, ...
: American Society for Testing and Materials * API:
American Petroleum Institute The American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industry. It claims to represent nearly 600 corporations involved in production, refinement, distribution, and many other aspects of the pet ...
* AWS:
American Welding Society The American Welding Society (AWS) was founded in 1919 as a non-profit organization to advance the science, technology and application of welding and allied joining and cutting processes, including brazing, soldering and thermal spraying. Headq ...
* AWWA:
American Water Works Association American Water Works Association (AWWA) is an international non-profit, scientific and educational association founded to improve water quality and supply. Established in 1881, it is a lobbying organization representing a membership (as of 2012) o ...
* MSS: Manufacturers Standardization Society * ANSI:
American National Standards Institute The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...
* NFPA:
National Fire Protection Association The National Fire Protection Association (NFPA) is an international nonprofit organization devoted to eliminating death, injury, property and economic loss due to fire, electrical and related hazards. As of 2018, the NFPA claims to have 50,000 mem ...
* EJMA:
Expansion Joint Manufacturers Association The Expansion Joint Manufacturers Association is an organization of a metal bellows expansion joint manufacturers. It was founded in 1955 to create and maintain a set of standards for quality expansion joint design and manufacturing. The EJMA stand ...
* CGA:
Compressed Gas Association The Compressed Gas Association (CGA) is an American trade association for the industrial and medical gas supply industries. The CGA publishes standards and practices that codify industry practices. In cases where government regulation is inspec ...
*PCA
Plumbing Code of Australia
Pipes must conform to the dimensional requirements of: * ASME B36.10M: Welded and seamless wrought-steel pipe * ASME B36.19M: Stainless-steel pipe * ASME B31.3 2008: Process piping * ASME B31.4 XXXX: Power piping


Materials

The material with which a pipe is manufactured is often the basis for choosing a pipe. Materials used for manufacturing pipes include: *
Carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
(CS) and
galvanized Galvanization or galvanizing ( also spelled galvanisation or galvanising) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are submerged ...
steel * Impact-tested carbon steel (ITCS) * Low-temperature carbon steel (LTCS) *
Stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...
(SS) * Malleable iron * Chrome-molybdenum (alloy) steel (generally used for high-temperature service) * Non-ferrous metals (includes
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
,
inconel Inconel is a registered trademark of Special Metals Corporation for a family of austenitic nickel-chromium-based superalloys. Inconel alloys are oxidation-corrosion-resistant materials well suited for service in extreme environments subjected t ...
,
incoloy Incoloy refers to a range of superalloys now produced by the Special Metals Corporation (SMC) group of companies and created with a trademark by the Inco company in 1952. Originally Inco protected these alloys by patent. In 2000, the SMC published ...
, and
cupronickel Cupronickel or copper-nickel (CuNi) is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. The copper content typically varies from 60 to 90 percent. (Monel is a nickel-copper alloy that contains a minimu ...
) * Non-metallic (includes
acrylonitrile butadiene styrene Acrylonitrile butadiene styrene (ABS) (chemical formula (C8H8)''x''·(C4H6)''y''·(C3H3N)''z'' is a common thermoplastic polymer. Its glass transition temperature is approximately . ABS is amorphous and therefore has no true melting point. A ...
(ABS), fibre-reinforced plastic (FRP), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC),
high-density polyethylene High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...
(HDPE), and
toughened glass Tempered or toughened glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering puts the outer surfaces into compression and the interior into tens ...
;
polybutylene Polybutylene (polybutene-1, poly(1-butene), PB-1) is a polyolefin or saturated polymer with the chemical formula (CH2CH(Et))n. Not be confused with polybutene, PB-1 is mainly used in piping. Production Polybutylene is produced by polymerisatio ...
has also been used, but is now banned in North America because of poor reliability) The bodies of fittings for pipe and tubing are often the same base material as the pipe or tubing connected: copper, steel, PVC, CPVC, or ABS. Any material permitted by the plumbing, health, or building
code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communication ...
(as applicable) may be used, but it must be compatible with the other materials in the system, the fluids being transported, and the temperature and pressure inside (and outside) the system.
Brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...
or
bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids such ...
fittings are common in copper piping and plumbing systems. Fire resistance,
earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
resistance, mechanical ruggedness, theft resistance, and other factors also influence the choice of pipe and fitting materials.


Gaskets

Gasket Some seals and gaskets A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to c ...
s are mechanical seals, usually ring-shaped, which seal flange joints. Gaskets vary by construction, materials and features. Commonly used gaskets are non-metallic (ASME B 16.21), spiral-wound (ASME B 16.20) and ring-joint (ASME B 16.20). Non-metallic gaskets are used with flat- or raised-face flanges. Spiral-wound gaskets are used with raised-face flanges, and ring-joint gaskets are used with ring-type joint (RTJ) flanges. Stress develops between an RTJ gasket and the flange groove when the gasket is bolted to a flange, leading to plastic deformation of the gasket.


Gender

Piping or tubing is usually inserted into fittings to make connections. Connectors are assigned a gender, abbreviated M or F. An example of this is a "-inch female adapter NPT", which would have a corresponding male connection of the same size and thread standard (in this case also NPT).


Common piping and plumbing fittings

This section discusses fittings primarily used in pressurized piping systems, though there is some overlap with fittings for low-pressure or non-pressurized systems. Specialized fittings for the latter setups are discussed in the next major subsection.


Adapter

In plumbing, an ''adapter'' is generally a fitting that interfaces two different parts. The term commonly refers to: *any fitting that connects pipes of different materials, including: **expansion adapters which have a flexible section to absorb expansion or contraction from two dissimilar pipe materials **mechanical joint (MJ) adapters for joining polyethylene pipe to another material **bell adapters which are like mechanical joint adapters but contain a stainless steel backup ring to maintain a positive seal against the mating flange **flange adapters which attach to a polyethylene pipe with butt fusion to stiffen a junction and allow another flanged pipe or fitting to be bolted on *a fitting that connects pipes of different diameters, genders, or threads **adapter spools (also called crossover spools), used on oilfields and pressure control, have different diameters, pressure ratings or designs at each end **adapters to convert NPT to BSP pipe threads are available *a fitting that connects threaded and non-threaded pipe


Elbow

An elbow is installed between two lengths of pipe (or tubing) to allow a change of direction, usually a 90° or 45°
angle In Euclidean geometry, an angle is the figure formed by two Ray (geometry), rays, called the ''Side (plane geometry), sides'' of the angle, sharing a common endpoint, called the ''vertex (geometry), vertex'' of the angle. Angles formed by two ...
; 22.5° elbows are also available. The ends may be machined for
butt welding Butt welding is when two pieces of metal are placed end-to-end without overlap and then welded along the joint (as opposed to lap joint weld, where one piece of metal is laid on top of the other, or plug welding, where one piece of metal is ins ...
, threaded (usually
female Female (Venus symbol, symbol: ♀) is the sex of an organism that produces the large non-motile ovum, ova (egg cells), the type of gamete (sex cell) that fuses with the Sperm, male gamete during sexual reproduction. A female has larger gamet ...
), or socketed. When the ends differ in size, it is known as a reducing (or reducer) elbow. Elbows are also categorized by length. The
radius of curvature In differential geometry, the radius of curvature, , is the reciprocal of the curvature. For a curve, it equals the radius of the circular arc which best approximates the curve at that point. For surfaces, the radius of curvature is the radius o ...
of a long-radius (LR) elbow is 1.5 times the pipe diameter, but a short-radius (SR) elbow has a radius equal to the pipe diameter. Wide available short elbows are typically used in pressurized systems and physically tight locations. Long elbows are used in low-pressure gravity-fed systems and other applications where low turbulence and minimum deposition of entrained solids are of concern. They are available in
acrylonitrile butadiene styrene Acrylonitrile butadiene styrene (ABS) (chemical formula (C8H8)''x''·(C4H6)''y''·(C3H3N)''z'' is a common thermoplastic polymer. Its glass transition temperature is approximately . ABS is amorphous and therefore has no true melting point. A ...
(ABS plastic), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and copper, and are used in DWV systems, sewage, and
central vacuum A central vacuum cleaner (also known as built-in or ducted) is a type of vacuum cleaner appliance, installed into a building as a semi-permanent fixture. Central vacuum systems are designed to remove dirt and debris from homes and buildings, sen ...
systems.


Coupling

A
coupling A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end mov ...
connects two pipes. The fitting is known as a reducing coupling, reducer, or adapter if their sizes differ. There are two types of collars: "regular" and "slip." A regular coupling has a small ridge or stops internally to prevent the over-insertion of a pipe and, thus, under-insertion of the other pipe segment (which would result in an unreliable connection). A slip coupling (sometimes also called a repair coupling) is deliberately made without this internal stop to allow it to be slipped into place in tight locations, such as the repair of a pipe that has a small leak due to
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
or freeze bursting, or which had to be cut temporarily for some reason. Since the alignment stop is missing, it is up to the installer to carefully measure the final location of the slip coupling to ensure that it is located correctly.


Union

A union also connects two pipes but is quite different from a coupling, as it allows future disconnection of the pipes for maintenance. In contrast to a coupling requiring
solvent welding Plastic welding is welding for semi-finished plastic materials, and is described in ISO 472 as a process of uniting softened surfaces of materials, generally with the aid of heat (except solvent welding). Welding of thermoplastics is accomplishe ...
,
soldering Soldering (; ) is a process in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involv ...
, or rotation (for threaded couplings), a union allows easy connection and disconnection multiple times if needed. It consists of three parts: a nut, a female, and a male end. When the female and male ends are joined, the nut seals the joint by pressing the two ends tightly together. Unions are a type of very compact flange connector. Dielectric unions, with
dielectric In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mate ...
insulation, separate dissimilar metals (such as copper and galvanized steel) to prevent
galvanic corrosion Galvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte. A sim ...
. When two dissimilar metals are in contact with an electrically conductive solution (ordinary tap water is conductive), they form an electrochemical couple which generates a voltage by
electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...
. When the metals are in direct contact with each other, the
electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
from one to the other also moves metallic
ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
s from one to the other; this dissolves one metal, depositing it on the other. A dielectric union breaks the electrical path with a plastic liner between its halves, limiting galvanic corrosion.
Rotary union A rotary union is a union that allows for rotation of the united parts. It is thus a device that provides a seal between a stationary supply passage (such as pipe or tubing) and a rotating part (such as a drum, cylinder, or spindle) to permit the ...
s allow mechanical
rotation Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...
of one of the joined parts while resisting leakage.


Nipple

A nipple is a short stub of pipe, usually male-threaded
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
, brass, chlorinated polyvinyl chloride (CPVC), or copper (occasionally unthreaded copper), which connects two other fittings. A nipple with continuous uninterrupted threading is known as a close nipple. Nipples are commonly used with plumbing and hoses.


Reducer

A reducer reduces the
pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circular ...
size from a larger to a smaller bore (inner
diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...
). Alternatively, ''reducer'' may refer to any fitting which causes a change in pipe diameter. This change may be intended to meet
hydraulic Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...
flow requirements of the system or adapt to existing piping of a different size. The reduction length is usually equal to the average of the larger and smaller pipe diameters. Although reducers are usually
concentric In geometry, two or more objects are said to be concentric, coaxal, or coaxial when they share the same center or axis. Circles, regular polygons and regular polyhedra, and spheres may be concentric to one another (sharing the same center point ...
,
eccentric reducer An eccentric reducer is a fitting used in piping systems between two pipes of different diameters. The same fitting can be used in reverse as an eccentric increaser or expander. They are used where the diameter of the pipe on the upstream side of t ...
s are used as needed to maintain the top- or bottom-of-pipe level. A reducer can also be used either as a nozzle or diffuser, depending on the
mach number Mach number (M or Ma) (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after the Moravian physicist and philosopher Ernst Mach. : \mathrm = \frac ...
of the flow.


Bushing

A double-tapped bushing, commonly shortened to bushing, is a fitting which serves as a
reducer A fitting or adapter is used in pipe systems to connect straight sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating (or measuring) fluid flow. These fittings are used in plumbing to manipulat ...
. It is a sleeve similar to a close nipple, but is threaded on both its inner and outer circumferences. Like a reducer, a double-tapped bushing has two threads of different sizes. A common type of this style fitting is a "hex bushing" with a hex head for installation with a pipe wrench. A double-tapped bushing is more compact than a reducer but not as flexible. While a double-tapped bushing has a more minor female thread concentric to a larger male thread (and thus couples a smaller male end to a larger female), a reducer may have large and small ends of either gender. If both ends are the same gender, it is a ''gender-changing reducer''. There are similar fittings for both sweat and solvent joinery. Since they are not "tapped" (threaded), they are simply called reducing bushings''.


Tee

A tee, the most common pipe fitting, combines or divides fluid flow. Tees can connect pipes of different diameters, change the direction of a pipe run, or both. Available in various materials, sizes and finishes, they may also be used to transport two-fluid mixtures. Tees may be equal or unequal in size of their three connections, with equal tees the most common.


Diverter tee

This specialized type of tee fitting is used primarily in pressurized
hydronic heating Hydronics () is the use of liquid water or gaseous water (steam) or a water solution (usually glycol with water) as heat-transfer medium in heating and cooling systems. The name differentiates such systems from oil and refrigerant systems. ...
systems to divert a portion of the flow from the main line into a side branch connected to a radiator or heat exchanger. The diverter tee allows the flow in the main line, even when the side branch is shut down and not calling for heat. Diverter tees must be heeded with directional markings; a tee installed backwards will function very poorly.


Cross

Crosses, also known as four-way fittings or cross branch lines, have one inlet and three outlets (or vice versa), and often have a solvent-welded sockets or female-threaded ends. Cross fittings may stress pipes as temperatures change because they are at the center of four connection points. A tee is steadier than a cross; it behaves like a three-legged stool, and a cross behaves like a four-legged stool. Geometrically, any three non-
collinear In geometry, collinearity of a set of points is the property of their lying on a single line. A set of points with this property is said to be collinear (sometimes spelled as colinear). In greater generality, the term has been used for aligned ...
points can self-consistently define a plane; three legs are inherently stable, whereas four points overdetermine a plane and can be inconsistent, resulting in physical stress on a fitting. Crosses are common in
fire sprinkler A fire sprinkler or sprinkler head is the component of a fire sprinkler system that discharges water when the effects of a fire have been detected, such as when a predetermined temperature has been exceeded. Fire sprinklers are extensively use ...
systems (where stress caused by thermal expansion is not generally an issue), but are not common in plumbing. One cross fitting is more expensive than two tees.


Cap

Caps, usually liquid- or gas-tight, cover the otherwise open end of a pipe. The exterior of an industrial cap may be round, square, rectangular, U- or I-shaped, or may have a handgrip.


Plug

A plug is a short barbed fitting with a blank end that can only be used with PEX piping to end the continuation of a water line that is no longer in use due to tying in elsewhere within the system or to seal the end of a water line which may be used for future use in the case of additional facilities. All plugs are sealed watertight with a PEX crimp.


Barb

A barb (or
hose barb Hose barbs are cylindrical pieces or parts for attaching and securing of hoses (tubing). The barb-like rings on the cylindrical piece allow for an easy push-connection of flexible-plastic or rubber tubing that is not so easily disconnected. Hose ...
), which connects flexible hose or tubing to pipes, typically has a male-threaded end which mates with female threads. The other end of the fitting has a single- or multi-barbed tube—a long tapered cone with ridges, which is inserted into a flexible hose.


Valve

Valves stop (or regulate) the flow of liquids or gases. They are categorized by application, such as isolation, throttling, and non-return. Isolation valves temporarily disconnect part of a piping system to allow maintenance or repair, for example. Isolation valves are typically left in either a fully open or closed position. A given isolation valve may be in place for many years without being operated but must be designed to be readily operable whenever needed, including for emergency use. Throttling valves control the amount or pressure of a fluid allowed to pass through and are designed to withstand the stress and wear caused by this operation. Because they may wear out in this usage, they are often installed alongside isolation valves which can temporarily disconnect a failing throttling valve from the rest of the system, so it can be refurbished or replaced. Non-return or check valves allow the free flow of a fluid in one direction but prevent its flow in a reverse direction. They are often seen in drainage or sewage systems but may also be used in pressurized systems. Valves are available in several types, based on design and purpose: *Gate, plug, or ball valves – Isolation *Globe valve – Throttling *Needle valve – Throttling, usually with high precision but low flow *Butterfly or diaphragm valves – Isolation and throttling *Check valve – Preventing reverse flow (non-return)


Drain-waste-vent (DWV) and related fittings

Because they operate at low
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
and rely on
gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
to move fluids (and entrained solids),
drain-waste-vent system In modern plumbing, a drain-waste-vent (or DWV) is a system that allows air to enter the plumbing system to maintain proper air pressure to enable the removal of sewage and greywater from a dwelling. Drain refers to water produced at fixtures s ...
s use fittings whose interior surfaces are as smooth as possible. The fittings may be "belled" (expanded slightly in diameter) or otherwise shaped to accommodate the insertion of pipe or tubing without forming a sharp interior ridge that might catch debris or accumulate material, and cause a clog or blockage. Freshly cut ends of pipe segments are carefully deburred to remove projecting slivers of material which may snag debris (such as hair or fibers) which can build up to cause blockages. This internal smoothness also makes it easier to "snake out" or "rod out" a clogged pipe with a
plumber's snake A plumber's snake or drain snake is a slender, flexible auger used to dislodge clogs in plumbing. The plumber's snake is often reserved for difficult clogs that cannot be loosened with a plunger. It is also sometimes called a toilet jack. A plumb ...
. Underground piping systems for
landscaping Landscaping refers to any activity that modifies the visible features of an area of land, including the following: # Living elements, such as flora or fauna; or what is commonly called gardening, the art and craft of growing plants with a goal o ...
drainage Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging (anaerobic conditio ...
or the disposal of
stormwater Stormwater, also spelled storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil ( infiltrate) and become groundwater, be stored on depressed la ...
or
groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
also use low-pressure gravity flow, so fittings for these systems resemble larger-scale DWV fittings. With high peak-flow volumes, the design and construction of these systems may resemble those of storm sewers. Fittings for central vacuum systems are similar to DWV fittings but usually have thinner and lighter construction because the weight of the materials conveyed is less. Vacuum-system designs share with DWV designs the need to eliminate internal ridges, burrs, sharp turns, or other obstructions which might create clogs.


Slip-joint fitting

Slip-joint fittings are frequently used in kitchen, bathroom and tub drainage systems. They include a detached (movable) slip nut and slip-joint washer; the washer is made of rubber or nylon. An advantage of this type of fitting is that the pipe it is connecting to does not need to be cut to a precise length; the slip joint can attach within a range of the end of the inserting pipe. Many slip fittings may be tightened or loosened by hand for easier access to residential drainpipe systems (for example, to clean out a trap or access a drain line past a trap).


Sweep elbow

DWV elbows are usually long-radius ("sweep") types. To reduce flow resistance and solid deposits when the direction of flow is changed, they use a shallow curve with a large
radius of curvature In differential geometry, the radius of curvature, , is the reciprocal of the curvature. For a curve, it equals the radius of the circular arc which best approximates the curve at that point. For surfaces, the radius of curvature is the radius o ...
. In addition, a well-designed system will often use two 45° elbows instead of one 90° elbow (even a sweep 90° elbow) to reduce flow disruption as much as possible. Central vacuum system inlet fittings are intentionally designed with a tighter curvature radius than other bends in the system. If vacuumed debris becomes stuck, it will jam at the inlet, where it is easy to find and remove.


Closet flange

A
closet flange {{Unreferenced section, date=May 2021 In plumbing, a closet flange (also known as a toilet flange) is a pipe fitting (specifically, a type of flange) that both mounts a toilet to the floor and connects the closet bend to a drain pipe. The name ...
(the drainpipe
flange A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...
to which a
flush toilet A flush toilet (also known as a flushing toilet, water closet (WC) – see also toilet names) is a toilet that disposes of human waste (principally urine and feces) by using the force of water to ''flush'' it through a drainpipe to another lo ...
is attached) is a specialized flange designed to be flush with the floor, allowing a toilet to be installed above it. The flange must be mechanically strong to accommodate slight misalignments or movements and resist corrosion.


Clean-out

Clean-outs are fittings with removable elements, allowing access to drains without removing plumbing fixtures. They are used to allow an auger (or
plumber's snake A plumber's snake or drain snake is a slender, flexible auger used to dislodge clogs in plumbing. The plumber's snake is often reserved for difficult clogs that cannot be loosened with a plunger. It is also sometimes called a toilet jack. A plumb ...
) to clean out a plugged drain. Since clean-out augers are limited in length, clean-outs should be placed in accessible locations at regular intervals throughout a drainage system (including outside the building). Minimum requirements are typically at the end of each branch in piping, just ahead of each water closet, at the base of each vertical stack and inside and outside the building in the main drain or sewer. Clean-outs usually have screw-on caps or screw-in plugs. They are also known as "rodding eyes", because of the eye-shaped cover plates often used on external versions.


Trap primer

A
trap primer A trap primer (or trap seal primer) is a plumbing device or valve that adds water to traps. The water seals in traps are needed to prevent sewer gases from entering buildings, but because this water is exposed to the air, it is subject to evapor ...
automatically injects water into a
trap A trap is a mechanical device used to capture or restrain an animal for purposes such as hunting, pest control, or ecological research. Trap or TRAP may also refer to: Art and entertainment Films and television * ''Trap'' (2015 film), Fil ...
, maintaining a water seal to keep
sewer gas Sewer gas is a complex, generally obnoxious smelling mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage. Sewer gases may inc ...
out of buildings. It must be installed in an easily accessible place for adjustment, replacement, and repair. A trap primer, a specialized
valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...
, is usually connected to a clean-water supply in addition to a DWV system. Because of the dual connection, it must be designed to resist the accidental
backflow Backflow is a term in plumbing for an unwanted flow of water in the reverse direction. It can be a serious health risk for the contamination of potable water supplies with foul water. In the most obvious case, a toilet flush cistern and its wat ...
of contaminated water.


Combo tee

A combination tee (combo tee, combo wye, tee-wye, long-sweep wye, or combi) is a tee with a gradually curving central connecting joint: a wye plus an additional 1/8 bend (45°), combined in one 90° unit. It is used in drains for a smooth, gradually curving path to reduce the likelihood of clogs, to ease the pushing of a
plumber's snake A plumber's snake or drain snake is a slender, flexible auger used to dislodge clogs in plumbing. The plumber's snake is often reserved for difficult clogs that cannot be loosened with a plunger. It is also sometimes called a toilet jack. A plumb ...
through a drain system and to encourage water flow in the direction of the drain.


Sanitary tee

A sanitary tee has a curved center section. In drainage systems, it is primarily used to connect horizontal drains (including fixture trap arms) to vertical drains. The center connection is generally to the pipe leading to a trap (the trap arm). It must not connect a vertical drain to a horizontal drain because of the likelihood that solids will accumulate at the bottom of the junction and cause a blockage.


Baffle tee

Also called a tee with a diverter baffle, a waste tee or an end-outlet tee, it typically connects waste lines before they enter the trap and has a baffle to keep water from one waste pipe from entering the other at the connection.


Double sanitary tee (sanitary cross)

This fitting differs from a standard cross in that two ports have curved inlets. Although it has been used in the past for connecting the drains of back-to-back fixtures (such as back-to-back sinks), some current codes—including the 2006
Uniform Plumbing Code Designated as an American National Standard, the Uniform Plumbing Code (UPC) is a model code developed by the International Association of Plumbing and Mechanical Officials ( IAPMO) to govern the installation and inspection of plumbing systems a ...
in the United States—prohibit the use of this fitting for that purpose and require a double-fixture fitting (double combination wye) to minimize wastewater from one side flowing into the other.


Wye (Y) or tee-wye (TY)

Tee-wyes are similar to tees, except for angling the branch line to reduce friction and turbulence. They are commonly used to attach a vertical drainpipe to a horizontal one, reducing the deposition of entrained solids at the junction. Wyes and combo wyes follow a long-sweep pattern relative to sanitary tees and other short-sweep bends, which have a smaller radius and require less space. Wyes also have industrial applications. Although low-priced wyes are often spot-welded, industrial-strength wyes are flash-welded at each seam. In long-distance pipeline applications, a specialized wye is used to allow insertion of
pigging In pipeline transportation, pigging is the practice of using pipeline inspection gauges or gadgets, devices generally referred to as pigs or scrapers, to perform various maintenance operations. This is done without stopping the flow of the pr ...
to keep pipes clear and flowing.


Side inlet tee-wye (TY)

This fitting (also known as a "bungalow fitting" or a "cottage fitting") is a sanitary tee that allows two trap arms to be connected at the same level. A toilet is the main connection, with the option of a right or left-hand outlet to the 3" inlet with a choice of 1-1/2" or 2" in size. It is used to keep stack-vented fixtures high to the joist space and thus conserves the headroom in a basement. As the water closet must be the lowest fixture, the smaller side outlet (usually used to connect the bathtub trap arm) enters slightly above the larger connection.


Hydraulic fittings

Hydraulic systems use high fluid pressure, such as the
hydraulic actuators A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment ( engineering vehicle ...
for
bulldozer A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous track ...
s and backhoes. Their hydraulic fittings are designed and rated for much greater pressure than that experienced in general piping systems, and they are generally not compatible with those used in plumbing. Hydraulic fittings are designed and constructed to resist high-pressure leakage and sudden failure.


Connection methods

Much of the work of installing a piping or plumbing system involves making leakproof, reliable connections, and most piping requires mechanical support against
gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
and other forces (such as
wind load Wind engineering is a subset of mechanical engineering, structural engineering, meteorology, and applied physics that analyzes the effects of wind in the natural and the built environment and studies the possible damage, inconvenience or benefits w ...
s and
earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
s) which might disrupt an installation. Depending on the connection technology and application, basic skills may be sufficient, or specialized skills and professional licensure may be legally required.


Fasteners and supports

Fasteners join, or affix, two or more objects. Although they are usually used to attach pipe and fittings to mechanical supports in buildings, they do not connect the pipes. Fasteners commonly used with piping are a stud bolt with nuts (usually fully threaded, with two heavy, hexagonal nuts); a machine bolt and nut; or a
powder-actuated tool A powder-actuated tool (PAT, often generically called a Hilti gun or a Ramset gun after their manufacturing companies) is a type of nail gun used in construction and manufacturing to join materials to hard substrates such as steel and concrete ...
(PAT) fastener (usually a
nail Nail or Nails may refer to: In biology * Nail (anatomy), toughened protective protein-keratin (known as alpha-keratin, also found in hair) at the end of an animal digit, such as fingernail * Nail (beak), a plate of hard horny tissue at the tip ...
or threaded stud, driven into concrete or masonry).


Threaded pipe

A
threaded pipe A threaded pipe is a pipe with screw-threaded ends for assembly. Tapered threads The threaded pipes used in some plumbing installations for the delivery of gases or liquids under pressure have a tapered thread that is slightly conical (in co ...
has a screw thread at one or both ends for assembly. Steel pipe is often joined with threaded connections; tapered threads are cut into the end of the pipe, and sealant is applied in the form of thread-sealing compound or
thread seal tape Thread seal tape (also known as PTFE tape, Teflon tape, or plumber's tape) is a polytetrafluoroethylene (PTFE) film tape commonly used in plumbing for sealing pipe threads. The tape is sold cut to specific widths and wound on a spool, making it ...
(also known as
PTFE Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemour ...
or Teflon tape) and the pipe is screwed into a threaded fitting with a
pipe wrench A pipe wrench is any of several types of wrench that are designed to turn threaded pipe and pipe fittings for assembly (tightening) or disassembly (loosening). The Stillson wrench, or Stillson-pattern wrench, is the usual form of pipe wrench, e ...
. Threaded steel pipe is widely used in buildings to convey
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
or
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
fuel and is also a popular choice in
fire sprinkler A fire sprinkler or sprinkler head is the component of a fire sprinkler system that discharges water when the effects of a fire have been detected, such as when a predetermined temperature has been exceeded. Fire sprinklers are extensively use ...
systems due to its resistance to mechanical damage and high heat (including the threaded joints). Threaded steel pipe may still be used in high-security or exposed locations because it is more resistant to vandalism, more difficult to remove, and its scrap value is much lower than copper or brass. A
galvanized Galvanization or galvanizing ( also spelled galvanisation or galvanising) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are submerged ...
coating of metallic
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
was often used to protect steel water pipes from
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
, but this protective coating eventually would dissolve away, exposing the iron to deterioration. Pipes used to convey fuel gas are often made of "black iron", which has been chemically treated to reduce corrosion, but this treatment does not resist erosion from flowing water. Despite its ruggedness, steel pipe is no longer preferred for conveying drinking water because corrosion can eventually cause leakage (especially at threaded joints), deposits on internal surfaces will eventually restrict flow, and corrosion will shed black or
rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH ...
y residues into the flowing water. These disadvantages are less problematic for fire sprinkler installations because standing water in the steel pipes does not flow, except during occasional tests or activation by a fire. Introducing oxygen dissolved in freshwater supplies will cause some corrosion, but this soon stops without any source of additional water-borne oxygen. In older installations, the threaded
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...
pipe was similarly used and was considered superior to steel for drinking water because it was more resistant to
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
and shed much fewer residues into the flowing water. Assembling threaded pipe is labor-intensive, and requires skill and planning to allow lengths of pipe to be screwed together in sequence. Most threaded-pipe systems require strategically located pipe-union fittings in final assembly. The threaded pipe is heavy and requires adequate attachment to support its weight.


Solvent welding

A solvent is applied to PVC,
CPVC Chlorinated polyvinyl chloride (CPVC) is a thermoplastic produced by chlorination of polyvinyl chloride (PVC) resin. CPVC is significantly more flexible than PVC, and can also withstand higher temperatures. Uses include hot and cold water deli ...
, ABS or other plastic piping to partially dissolve and fuse the adjacent surfaces of piping and fitting. Solvent welding is usually used with a sleeve-type joint to connect pipe and fittings made of the same (or compatible) material. Unlike metal welding, solvent welding is relatively easy to perform (although care is needed to make reliable joints). Solvents typically used for plastics are usually
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
and may be
carcinogenic A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...
and
flammable A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
, requiring adequate ventilation.


Soldering

To make a
solder Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable ...
connection, a chemical
flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport ph ...
is applied to the inner sleeve of a joint and the pipe is inserted. The joint is then heated, typically by using a
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
or
MAPP gas MAPP gas was a trademarked name, belonging to The Linde Group, a division of the former global chemical giant Union Carbide, for a fuel gas based on a stabilized mixture of methylacetylene (propyne), propadiene and propane. The name comes from ...
torch, although electrically heated soldering tools are sometimes used. Once the fitting and pipe have reached sufficient temperature, solder is applied to the heated joint, and the molten solder is drawn into the joint by
capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces li ...
as the flux vaporizes. "Sweating" is a term sometimes used to describe the soldering of pipe joints. Where many connections must be made in a short period (such as plumbing of a new building), soldering is quicker and less expensive joinery than compression or flare fittings. A degree of skill is needed to make several reliable soldered joints quickly. If flux residue is thoroughly cleaned, soldering can produce a long-lasting connection at a low cost. However, using an open flame for heating joints can present fire and health hazards to building occupants and requires adequate ventilation.


Brazing


Welding

The
welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing Fusion welding, fusion. Welding is distinct from lower ...
of metals differs from soldering and brazing in that the joint is made without adding a lower-melting-point material (e.g. solder); instead, the pipe or tubing material is partially melted, and the fitting and piping are directly fused. This generally requires piping and fitting to be the same (or compatible) material. Skill is required to melt the joint sufficiently to ensure good fusion while not deforming or damaging the joined pieces. Properly welded joints are considered reliable and durable. Pipe welding is often performed by specially licensed workers whose skills are retested periodically. For critical applications, every joint is tested with nondestructive methods. Because of the skills required, welded pipe joints are usually restricted to high-performance applications such as
shipbuilding Shipbuilding is the construction of ships and other floating vessels. It normally takes place in a specialized facility known as a shipyard. Shipbuilders, also called shipwrights, follow a specialized occupation that traces its roots to befor ...
, and in
chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...
and
nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat fr ...
s. Adequate
ventilation Ventilation may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Ventilator, a m ...
is essential to remove metal fumes from welding operations, and
personal protective equipment Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, elec ...
must be worn. Because the high temperatures during welding can often generate intense
ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
, dark goggles or full face shields must be used to protect the eyes. Precautions must also be taken to avoid fires caused by stray sparks and hot welding debris.


Compression fittings

Compression fittings (sometimes called "lock-bush fittings") consist of a tapered, concave conical seat; a hollow, barrel-shaped compression ring (sometimes called a ferrule); and a compression nut which is threaded onto the body of the fitting and tightened to make a leakproof connection. They are typically brass or plastic, but stainless steel or other materials may be used. Although compression connections are less durable than soldered (aka sweated) connections, they are easy to install with simple tools. However, they take longer to install than soldered joints and sometimes require re-tightening to stop slow leaks which may develop over time. Because of this possible leakage, they are generally restricted to accessible locations (such as under a kitchen or bathroom sink) and are prohibited in concealed locations such as the interiors of walls.


Push-to-pull compression fittings

Push-to-pull fittings are easily removed compression fitting that allows pipes to be connected with minimal tools. These fittings are similar to regular compression fittings but use an
O-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...
for sealing and a grip ring to hold the pipe. The main advantage is that it can easily be removed and re-used, it is easy to assemble, and the joints are still rotatable even after assembly. The pipe end should be square, so it sits against the stop in the fittings and does not create turbulence, and needs to be a clean cut to avoid damaging the O-ring during insertion.


Flare fittings

Flared connectors should not be confused with compression connectors, which are generally not interchangeable. Lacking a compression ring, they use a tapered conical shaped connection instead. A specialized flaring tool is used to enlarge tubing into a 45º tapered bell shape matching the projecting shape of the flare fitting. The flare nut, which had previously been installed over the tubing, is then tightened over the fitting to force the tapered surfaces tightly together. Flare connectors are typically brass or plastic, but stainless steel or other materials may be used. Although flare connections are labor-intensive, they are durable and reliable. Considered more secure against leaks and sudden failure, they are used in hydraulic brake systems and in other high-pressure, high-reliability applications.


Flange fittings

Flange fittings are generally used to connect valves, inline instruments or equipment nozzles. Two surfaces are joined tightly together with threaded bolts, wedges, clamps, or other means of applying high
compressive In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elon ...
force. Although a
gasket Some seals and gaskets A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to c ...
, packing, or
O-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...
may be installed between the flanges to prevent leakage, it is sometimes possible to use only a special grease or nothing at all (if the mating surfaces are sufficiently precisely formed). Although flange fittings are bulky, they perform well in demanding applications such as large
water supply network A water supply network or water supply system is a system of engineered hydrologic and hydraulic components that provide water supply. A water supply system typically includes the following: # A drainage basin (see water purification – source ...
s and
hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...
systems. Flanges are rated at 150, 300, 400, 600, 900, 1500, and 2500 
psi Psi, PSI or Ψ may refer to: Alphabetic letters * Psi (Greek) (Ψ, ψ), the 23rd letter of the Greek alphabet * Psi (Cyrillic) (Ѱ, ѱ), letter of the early Cyrillic alphabet, adopted from Greek Arts and entertainment * "Psi" as an abbreviatio ...
; or 10, 15, 25, 40, 64, 100, and 150 bars of pressure. Various types of flanges are available, depending on construction. Flanges used in piping (orifice, threaded, slip-on, blind, weld neck, socket weld, lap-joint, and reducing) are available with a variety of facings, such as raised, flat, and ring-joint. Flange connections tend to be expensive because they require the precision forming of metal. Factory-installed flanges must meet carefully measured dimensional specifications, and pipe segments cut to length on-site require skilled precision welding to attach flanges under more-difficult field conditions.


Mechanical fittings

Manufacturers such as
Victaulic Victaulic is a developer and manufacturer of mechanical pipe joining systems, and the originator of the grooved pipe couplings joining system. The firm is a global company with 15 major manufacturing facilities, 28 branches, and over 3600 emplo ...
and Grinnell produce sleeve-clamp fittings, which replace many flange connections. They attach to the end of a pipe segment via circumferential grooves pressed (or cut) around the end of the pipe to be joined. They are widely used on larger steel pipes and can also be used with other materials. The chief advantage of these connectors is that they can be installed after cutting the pipe to length in the field. This can save time and considerable expense compared to flange connections, which must be factory- or field-welded to pipe segments. However, mechanically fastened joints are sensitive to residual and thickness stresses caused by dissimilar metals and temperature changes. A grooved fitting, also known as a grooved coupling, has four elements: grooved pipe, gasket, coupling housing, and nuts and bolts. The groove is made by cold-forming (or machining) a groove at the end of a pipe. A gasket encompassed by coupling housing is wrapped around the two pipe ends, with the coupling engaging the groove; the bolts and nuts are tightened with a
socket Socket may refer to: Mechanics * Socket wrench, a type of wrench that uses separate, removable sockets to fit different sizes of nuts and bolts * Socket head screw, a screw (or bolt) with a cylindrical head containing a socket into which the hexag ...
or
impact wrench An impact wrench (also known as an impactor, impact gun, air wrench, air gun, rattle gun, torque gun, windy gun) is a socket wrench power tool designed to deliver high torque output with minimal exertion by the user, by storing energy in a rota ...
. The installed coupling housing encases the gasket and engages the grooves around the pipe to create a leakproof seal in a self-restrained pipe joint. There are two types of grooved coupling; a flexible coupling allows a limited amount of angular movement, and a rigid coupling does not allow movement and may be used where joint immobility is required (similar to a flange or welded joint).


Crimped or pressed fittings

Crimped or pressed connections to use special fittings permanently attached to tubing with a powered crimper. The fittings, manufactured with a pre-installed sealant or
O-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...
, slide over the tubing to be connected. High pressure is used to deform the fitting and compress the sealant against the inner tubing, creating a leakproof seal. The advantages of this method are durability, speed, neatness, and safety. Some crimped fittings are designed to be used with copper tubing without requiring flux or filler metal. The connection can be made even when the tubing is wet. Although crimped fittings are suitable for drinking water pipes and other hot-and-cold systems (including central heating), they are substantially more expensive than sweated fittings. Press fittings with either V and M profile (or contour) in stainless steel, carbon steel, and copper are trendy in Europe, and several manufacturers such as Viega, Geberit, Swiss Fittings, and ISOTUBI, distribute proprietary systems of press fittings. Compared to other connection types, press fittings have the advantages of installation speed and safety. Pressing a stainless steel fitting can be completed within 5 seconds with the correct equipment. Primary pressing of fittings to pipes or other fittings is performed using electrically powered press equipment, but mechanically driven press equipment is also available. Most of the significant brands further have a plastic slip on the end of the press fittings allowing a simple identification if a press fitting has securely been installed. Further, the installation does not use welding; press fittings with appropriate and region-specific certification may be installed for gas lines. Stainless steel and carbon steel press fittings can hold up to 16 bars of pressure.


Leaded hub fittings

Cast iron piping was traditionally made with one "spigot" end (plain, which was cut to length as needed) and one "socket" or "hub" end (cup-shaped). The larger-diameter hub was also called a "bell" because of its shape. In use, the spigot of one segment was placed into the socket of the preceding one, and a ring of
oakum Oakum is a preparation of tarred fibre used to seal gaps. Its main traditional applications were in shipbuilding, for caulking or packing the joints of timbers in wooden vessels and the deck planking of iron and steel ships; in plumbing, for ...
was forced down into the joint with a caulking iron. Then the remainder of the space in the hub was filled up. Ideally, this would be done by pouring molten
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
, allowing it to set, and hammering it tightly with a caulking tool. If this was not possible due to position or some other constraint, the joint could be filled with
lead wool Lead wool consists of thin strands of Lead, lead metal that can be used to cold-caulk cast iron and steel pipes. It was manufactured by the New York Lead Wool Company in the United States and by Lead Wool Company, The Lead Wool Company, Limited ...
or rope, which was forcibly compacted one layer at a time.Damm, John A. and Waugaman, Charles H. (1948) ''The Practical and Technical Encyclopedia'' Wm. H. Wise & Co., Inc. New York. pg. 94,395,396 This labor-intensive technique was durable if appropriately done but required time, skill, and patience for each joint to be made up. Quicker and lower-cost methods, such as rubber sleeve joints, have replaced mainly leaded hub connections of cast-iron piping in most new installations, but the older technology may still be used for some repairs. In addition, some conservative plumbing codes still require leaded hub joints for final connections where the sewer main leaves a building.


Rubber sleeve fittings

Cast iron DWV pipe and fittings are still used in premium construction because they muffle the sound of wastewater rushing through them, but today they are rarely joined with traditional lead joints. Instead, pipe and fittings with plain (non-belled) connections are butted against each other, and clamped with special rubber sleeve (or "no-hub") fittings. The rubber sleeves are typically secured with stainless steel worm drive clamping bands, which compress the rubber to make a tight seal around the pipes and fittings. These pipe clamps are similar to
hose clamp A hose clamp (hose clip, hose lock or Jubilee clip (UK)) is a device used to attach and seal a hose onto a fitting such as a barb or nipple. Types Many types are available, including : Screw/band (worm gear) clamps Screw clamps consist of a ...
s, but are heavier-duty and ideally are made completely of stainless steel (including the screw) to provide maximum service life. Optionally, the entire rubber sleeve may be jacketed with thin sheet metal, to provide extra stiffness, durability, and resistance to accidental penetration by a misplaced nail or screw. Although the fittings are not cheap, they are reasonably durable (the rubber is typically
neoprene Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene.Werner Obrecht, Jean-Pierre Lambert, Michael Happ, Christiane Oppenheimer-Stix, John Dunn and Ralf Krüger "Rubber, 4. Emulsion R ...
or flexible PVC). An alternative design also allows the selective use of belled fittings made entirely of flexible rubber, including more-complex shapes such as wyes or tee-wyes. They are secured to cast iron pipe segments by use of stainless steel worm drive clamps. Because these fittings are not as stiff as traditional cast-iron fittings, the heavy pipe segments may need better anchoring and support to prevent unwanted movement. The lighter rubber fittings may not muffle sound as well as the heavy cast-iron fittings. An advantage of flexible rubber fittings is that they can accommodate small misalignments and can be flexed slightly for installation in tight locations. A flexible fitting may be preferred to connect a shower or heavy tub to the drainage system without transmitting slight movements or stresses, which could eventually cause cracking. Flexible fittings may also be used to reduce the transmission of vibration into the DWV system. If necessary, clamped joints can be disassembled later, and the fittings and pipe may be reconfigured. However, it is often not customary to re-use the clamps and rubber sleeves, which their previous installation may deform and may not seal well after rearranging. Clamped fittings may occasionally need to be disassembled to provide access for "
snaking Snaking may refer to: *Use of plumber's snake * Snaking (logging), a way of moving timber in logging * Undulating motion * A technique used in Mario Kart DS ''Mario Kart DS'' is a 2005 kart racing video game developed by Nintendo EAD Group N ...
" or "rodding-out" with a unique tool to clear blockage or clogs. This is also an indication that a clean-out fitting could be installed to provide easier future access.


See also

*
Cutting ring fitting Cutting ring fittings are flareless fittings used for connections in fluid applications. They are widely used worldwide in hydraulic systems. The cutting ring fitting consists of the body, the cutting ring and the nut. On assembly, the two cuttin ...
*
Drain (plumbing) A drain is the primary vessel or conduit for unwanted water or waste liquids to be flumed away, either to a more useful area, funnelled into a receptacle, or run into sewers or stormwater mains as waste discharge to be released or processed. ...
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Flange A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...
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Gladhand connector A gladhand connector or gladhand coupler is an interlocking hose coupling fitted to hoses supplying pressurized air from a tractor unit to air brakes on a semi-trailer, or from a locomotive to railway air brakes on railroad cars. Gladhand conn ...
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Pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circular ...
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Pipefitter A pipefitter or steamfitter is a tradesman who installs, assembles, fabricates, maintains, and repairs mechanical piping systems. Pipefitters usually begin as helpers or apprentices. Journeyman pipefitters deal with industrial/commercial/marine ...
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Pipe support A pipe support or pipe hanger is a designed element that transfer the load from a pipe to the supporting structures. The load includes the weight of the pipe proper, the content that the pipe carries, all the pipe fittings attached to pipe, and t ...
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Plumber A plumber is a tradesperson who specializes in installing and maintaining systems used for potable (drinking) water, and for sewage and drainage in plumbing systems.
* Rainwater, surface, and subsurface water drainage *
Septic system Onsite sewage facilities (OSSF), also called septic systems, are wastewater systems designed to treat and dispose of effluent on the same property that produces the wastewater, in areas not served by public sewage infrastructure. A septic tank a ...
s * Traps, Drains, and Vents *
Victaulic Victaulic is a developer and manufacturer of mechanical pipe joining systems, and the originator of the grooved pipe couplings joining system. The firm is a global company with 15 major manufacturing facilities, 28 branches, and over 3600 emplo ...
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Water cooling Cooling tower and water discharge of a nuclear power plant Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non ...
* Water supply systems


References


External links


International Association of Plumbing and Mechanical Officials

International Code Council

the American Society for Testing and Materials
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