Pipe fitting is the occupation of installing or repairing piping or tubing systems that convey liquid, gas, and occasionally solid materials. This work involves selecting and preparing pipe or tubing, joining it together by various means, and the location and repair of leaks.
Pipe fitting work is done in many different trades:
PlumbingPlumbing is the skilled trade of working with pipes, tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters...
,
HVACHVAC is an acronym that stands for the closely related functions of "Heating, Ventilating, and Air Conditioning"-the technology of indoor environmental comfort...
,
manufacturingManufacturing is the use of machines, tools and labor to make things for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale...
, fire prevention, and many others. Pipe fitters (sometimes called simply "fitters") are represented in the USA by the United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry of the United States and Canada.
Fitters work with a variety of pipe and tubing materials including several types of plastic, copper, steel, iron, aluminium, clay, and lead.
Steel pipe
Steel pipe (or black iron pipe) was once the most popular choice for supply of water and flammable gases, but fell from favor as water pipe in the mid 20th century due to its tendency to rust. Steel pipe is still used in many homes and businesses to convey
natural gasNatural gas is a gas consisting primarily of methane. It is found associated with fossil fuels, in coal beds, as methane clathrates, and is created by methanogenic organisms in marshes, bogs, and landfills...
or propane, and is a popular choice in fire sprinkler systems due to its high heat resistance.
Steel pipe is joined using thread connections, where tapered threads (See
National Pipe ThreadNational Pipe Thread Tapered Thread is a U.S. standard for tapered threads used to join pipes and fittings. ANSI/ASME standard B1.20.1 covers threads of 60-degree form with flat crests and roots in sizes from 1/16 inch to 24 inch Nominal Pipe Size [NPS]...
) are cut into the tubing section end, sealant is applied in the form of thread compound or PTFE tape (similar to teflon tape) and it is then threaded into a corresponding threaded fitting using a
pipe wrenchThe pipe wrench, or Stillson wrench is an adjustable wrench used for turning soft iron pipes and fittings with a rounded surface. The design of the adjustable jaw allows it to rock in the frame, such that any forward pressure on the handle tends to pull the jaws tighter together. Teeth angled in...
.
Usages vary from country to country as different nations have different standards to install pipe.
In Canada, in respect to natural gas (NG) and propane (LP gas), black iron pipe (BIP) is used to connect an appliance to the supply, it must however be marked (either painted yellow or yellow banding attached at certain intervals) and certain restrictions apply to which nominal pipe size (NPS) can be put through walls and buildings. With propane in particular BIP can be run from an exterior tank (or cylinder) provided it is well protected from the elements and an anode-type of protection is in place for when the pipe is to be installed underground.
Copper tubing
Copper tubing is most often used for supply of hot and cold water, and as refrigerant line in HVAC systems. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, or sweat (solder). Copper offers a high level of resistance to corrosion, but is becoming very costly.
Soft copper
Soft (or ductile) copper tubing can be bent easily to travel around obstacles in the path of the tubing. While the work hardening of the drawing process used to size the tubing makes the copper hard/rigid, it is carefully annealed to make it soft again; it is therefor more expensive to produce than non-annealed, rigid copper tubing. It can be joined by any of the three methods, and it is the only type of copper tubing suitable for flare connections. Soft copper is the most popular choice for refrigerant lines in
split-system air conditioners and heat pumps.
Flare connections
Flare connectionsFlare fittings are a type of compression fitting used with metal tubing, usually soft steel and ductile copper, though other materials are also used. Tube flaring is considered to be a type a forging operation, and is usually a cold working procedure. During assembly, a flare nut is...
require that the end of a tubing section be spread outward in a bell shape using a
flare tool. A
flare nut then compresses this bell-shaped end onto a male fitting. Flare connections are the most labor intensive of the three options, but are quite reliable over the course of many years.
Rigid copper
Rigid copper is a popular choice for water lines. It is joined using a sweat, compression or crimped/pressed connection. Rigid copper, rigid due to the work hardening of the drawing process, cannot be bent and must use
elbow fittings to go around corners or around obstacles. If heated and allowed to slowly cool, called
annealingAnnealing may refer to:*Annealing , a heat treatment that alters the microstructure of a material causing changes in properties such as strength and hardness*Annealing , heating a piece of glass to remove stress...
, then rigid copper will become soft and can be bent/formed without cracking.
Sweat connections
Sweat fittingSweat fitting is a means of joining copper tubing, using solder as a filler metal. Sweat connections are rapid to create, and offer a high degree of reliability. Until the mid 20th century, solder contained lead...
. These are smooth, and easily slip onto the end of a tubing section. The joint is then heated using a
torchTorch can mean:*In Britain, very often, the type of portable electric light which in the USA is called a "flashlight"*In industry and construction, a small hand-held gas burner which makes a hot flame, usually fueled by oxygen and either acetylene or propane:**Blowtorch**Cutting torch**Welding...
, and solder is melted into the connection. When the solder cools, it forms a very strong bond which can last for decades. Sweat connected rigid copper is the most popular choice for water supply lines in modern buildings. In situations where many connections must be made at once, (such as plumbing of a new building) sweat offers much quicker joinery than compression or flare.
Compression connections
Compression fittings use a soft metal ring (the compression ring) which is squeezed onto the pipe and into the fitting by a compression nut. The soft metal conforms to the surface of the tubing and the fitting, and creates a seal. Compression connections do not typically have the long life that sweat connections offer, but are advantageous in many cases because they are easy to make using basic tools. A disadvantage in compression connections is that they take longer to make than sweat, and sometimes require retightening over time to stop leaks.
Crimped or pressed connections
Crimped or pressed connections use special copper fittings which are permanently attached to rigid copper tubing with a powered crimper. The special fittings, manufactured with sealant already inside, slide over the tubing to be connected. Thousands of pounds-force per square inch of pressure are used to deform the fitting and compress the sealant against the inner copper tubing, creating a water tight seal. The advantages of this method are that it should last as long as the tubing, it takes less time to complete than other methods, it is cleaner in both appearance and the materials used to make the connection and no open flame is used during the connection process. The disadvantages are that the fittings used are harder to find and cost significantly more than sweat type fittings.
Plastic pipe
Plastic pipe is becoming a very popular choice for water supply and drain lines. It offers good durability, is low in cost, and easy to install.
PVC and CPVC
PVCPolyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter - a small, flexible tube placed into a peripheral vein in order to administer medication or fluids...
or
polyvinyl chloridePolyvinyl chloride, commonly abbreviated PVC, is the third most widely used thermoplastic polymer after polyethylene and polypropylene. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Around the world, over 50% of PVC manufactured is used in...
, is the most popular choice in plastic pipe. It is rigid, and uses
thread or
solvent weld (glue) connections, it also can be heat fused. It is available in various pressure ratings, with the most common choice being
Schedule 40 for pressurized uses, it is available for waste water lines. Standard PVC can only be used for cold water supply, and is a very popular choice for drain line.
CPVC is a different type of plastic, which has an extra chlorine atom in the compound. It can be used for the hot water supply, and in industry.
Polyethylene
PolyethylenePolyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons. Its primary use is within packaging .- Description :Polyethylene is a thermoplastic polymer consisting of long chains of the monomer ethylene...
or PE pipe is often used for the supply of hot and cold water. It can be joined using barb-fittings with clamp rings, or it can be heat-fused (sections can be melted together) using an appropriate tool. Because PE pipe is flexible, it can be curved through a radius to make turns, and thus avoid the complexity and expense of fittings required to make turns with other types of piping.
Undyed PE is colorless, and uncolored PE tubing has a frosted, translucent appearance. Colored varieties include red, blue, black, gray and white.
PEXCross-linked polyethylene, commonly abbreviated PEX or XLPE, is a form of polyethylene with cross-links. It is formed into tubing, and is used predominantly in hydronic radiant heating systems, domestic water piping and insulation for high tension electrical cables...
(cross linked polyethelyne) is a popular choice for underground loops in
geothermal heatingGeothermal heating is the direct use of geothermal power for heating applications. Humans have taken advantage of geothermal heat this way since the paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of geothermal heating in 2004...
, as supply line for lawn sprinkler systems and in water supply applications.
Rigid Polypropylene
Sections and fittings can be heat fused or threaded together. Heat fusing is a two-person job requiring specialized equipment and therefore is not commonly done. Comes in black or opaque white. Has the advantage of higher temperatures than PVC.
ABS
ABS or
acrylonitrile butadiene styreneAcrylonitrile butadiene styrene is a common thermoplastic used to make light, rigid, molded products such as piping , musical instruments , golf...
is recognizable by its rigidity and black color. It is used only for drainage lines and is lower in cost than PVC.
Nylon
NylonNylon is a generic designation for a family of synthetic polymers known generically as polyamides and first produced on February 28, 1935 by Wallace Carothers at DuPont...
tubing is often used for water lines inside appliances, and to convey various flammable fluids and solvents. It offers high resistance to chemical reaction.
Aluminium tubing
AluminiumAluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13. It is not soluble in water under normal circumstances....
is sometimes used due to its low cost, resistance to corrosion and solvents, and for its ductility. Aluminium tube is more desirable than steel for the conveyance of flammable solvents, since it cannot create sparks when manipulated. Aluminium tubing can be connected by flare or compression fittings, or it can be welded by the
TIGTig may refer to:*TIG Welding, a metal welding process.*Tig Notaro, an American stand-up comic** TIG, abbreviation of Triennial Inter-varsity Games, held by the University of Hong Kong, the National University of Singapore, the University of Malaya and the University of Indonesia every three years...
or heliarc processes.
Occupational hazards
Pipe fitters are often exposed to hazardous or dangerous materials, such as
asbestosAsbestos is a naturally occurring silicate mineral with long, thin fibrous crystals. The word asbestos is a borrowed Greek adjective meaning inextinguishable. The Greeks termed asbestos the miracle mineral because of its soft and pliant properties, as well as its ability to withstand...
,
leadLead is a main-group element with symbol Pb and atomic number 82. Lead is a soft, malleable poor metal, also considered to be one of the heavy metals. Lead has a bluish-white color when freshly cut, but tarnishes to a dull grayish color when exposed to air...
,
ammoniaAmmonia is a compound of nitrogen and hydrogen with the formula NH
3. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to foodstuffs and fertilizers...
,
steamSteam is vaporized water. It is a transparent gas . At standard temperature and pressure, pure steam occupies about 1,600 times the volume of an equal mass of liquid water...
, flammable gases, various resins and solvents including
benzeneBenzene, or benzol, is an organic chemical compound with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point...
, and various refrigerants. Much progress was made in the 20th century toward eliminating hazardous materials. Many aspects of this are now regulated by law in most countries, including asbestos usage and removal, and refrigerant selection and handling; these being the result of many scientific discoveries in regard to the damage certain materials can cause to humans, animals, and the earth's ecological system.
See also
- Compression fittings
- Coupling (piping)
A Coupling is a very short length of pipe or tube, with a socket at one or both ends that allows two pipes or tubes to be welded , brazed or soldered together....
- Nipple (plumbing)
In plumbing and piping, a nipple is a fitting, consisting of a short piece ofpipe, usually provided with a male pipe thread at each end, for connecting two other fittings....
- Pipe
A pipe is round tubular section or hollow cylinder used mainly to convey media. It can also be used for structural applications. In layman's terms the appelations pipe and tube are almost interchangeable, but in industry and engineering discipline the terms are uniquely defined...
- Piping and plumbing fittings
Fittings are used in pipe and plumbing systems to connect straight pipe or tubing sections, to adapt to different sizes or shapes, and to regulate fluid flow, for example. Fittings, especially noncommon types, can be expensive, and require time, materials, and tools to install, so they are a...
- Plumbing
Plumbing is the skilled trade of working with pipes, tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters...
- Street elbow
A street elbow is a type of plumbing or piping fitting intended to join a piece of pipe and another fitting at an angle. The difference between a "street" elbow and a regular elbow is the nature of the fittings on either end....
- Sweat fitting
Sweat fitting is a means of joining copper tubing, using solder as a filler metal. Sweat connections are rapid to create, and offer a high degree of reliability. Until the mid 20th century, solder contained lead...
- Water pipe
Water pipes are pipes or tubes, frequently made of polyvinyl chloride , ductile iron, polyethylene, or copper, that carry pressurized and treated fresh water to buildings , as well as inside the building....
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