A fitting is a part that serves to connect pipes in a pipeline. They are also installed in the places of branching and bends of the pipeline, in case of transition to a section where the pipeline has a different diameter. Plumbing fittings are used when it is necessary to disassemble and assemble the pipeline. They can hermetically close the line. Fittings that connect pipes with the same diameter are called straight. And those that are used to move to a section with a different diameter - transition joints.
Fittings for steel pipes.
For steel pipes threaded, welded and flanged connectors are available. In order to hermetically connect the pipeline using a threaded connection, it must be sealed with FUM tape, special sealing threads or, in the old fashioned way, with linen.
Steel pipe fittings with threads are made of steel or cast iron (ductile iron). They must be homogeneous, without shells and not contain foreign impurities and inclusions. The end plane must be perpendicular to the axis of the passage. To give greater strength to cast iron fittings, a special ebb is made along the edge. Steel fittings do not have it.
By purpose, threaded parts are divided into the following types:
corner, bend; | tee; | crosspiece; |
coupling (for connecting pipes, with a diameter of the same size, in a straight section); 
adapters (squeegees, nipples, futorki, "American" - for connection in various ways);
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plug (for sealing the ends of the pipe);
fitting (used to connect with flexible hoses); 
Steel Pipe Fittings for welding, are used for installation by welding.
corner;
tee;
crosspiece;
adapter;
stub;
Flanges are used to mount the line with bolts and / or studs. 
Copper pipe fittings .
The connection of copper pipes can be of two types:
non-detachable connection - soldering;
detachable connection:
- using compression mounting parts;
- by means of press fittings;
They are made of copper or brass.
Press fittings:
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Fittings for reinforced plastic pipes.
Plumbing fittings for the installation of a metal-plastic pipeline there are two types:
compression;
press fittings;
Compression fittings can have a collet connection from all sides (tees, crosses, etc.), and can also have a transition from a collet connection to a threaded one. Such fittings for metal-plastic pipes used for joining with metal pipes. Press couplings can also have similar types of assembly.
Fittings for polypropylene pipes.
They are intended for the installation of the pipeline, in short, they have the same purpose as all other connecting parts. Made of the same material as the pipe itself. The pipeline is connected by soldering using a special heating device that heats the connecting parts to the required temperature.
They can be various shapes and have a transition from soldering to a threaded connection, for the possibility of mounting with metal pipes.
Fittings for polypropylene pipes:
Fittings for PVC pipes.
The installation of the PVC pipeline is carried out using accessories by gluing with a special glue. They, like all the previous ones, can be of different shapes and be able to dock with metal pipes through a threaded connection.
Fittings for PVC pipes: 
Fittings for polyethylene pipes.
The assembly of a polyethylene water pipe can be done in two ways:
welded method - using electrofusion couplings;
installation with compression fittings and flanges;
Electrofusion couplings.
Electrofusion couplings are connecting parts in which electric heating coils are mounted. When voltage is applied to them, electrofusion couplings heat up the connecting parts and are fused with them, thereby forming a sealed connection. 
Compression fittings and flanges.
These parts have the same function as the aforementioned cousins. The only difference is in the material from which they are made. Ease of use compression fittings for polyethylene pipes consists in the fact that when using them, the connecting elements do not need preliminary preparation.
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After reading this article, you know what are plumbing fittings... You can start installation of water pipes.
All the best and see you on the pages of the site.
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To provide a detachable method of connecting or changing the direction of a common line during installation and replacement of individual pipeline elements, fittings are used for metal pipes threaded. The catalog of straight and tapered connections is represented by a selection of structures made of homogeneous materials and coated:
- zinc;
- chrome;
- nickel.
Threaded connections are more often used when working with pipes with a cross section of up to 50 mm. For contours from 50 mm, flange mountings are used. In terms of form and functional features, they do not differ in anything, except for the parameters and type of connection, steel and high-strength cast iron (VChShG) are used for manufacturing.
Based on the place of installation and purpose, threaded metal pipe fittings are classified according to their design features:
- Squares - to change the direction of the pipes.
- Tees - for connecting pipes of the same or different diameters.
- Couplings - for joining fixed structures.
- Bends - for deflection of the line (in the vertical or horizontal direction) at an angle of 30-180 degrees.
- Plugs - for sealing the lines.
- Nipples - for pressure change.
- Fittings - for easy cleaning, maintenance or replacement of flow smoothing elements.
Manufacturing of structures is carried out using different materials:
- stainless;
- brass;
- copper
- cast iron;
- bronze.
Types of threaded fasteners
There are pipe and metric threads. The main difference lies in her step. When supplying heating and water mains, an inch (pipe) thread is often used. A pipe thread is also used to connect the pipes of water heating systems, heaters, filtration systems, meters, pumping units.
Pipe threads are used in cylindrical threaded fasteners and in internal cylindrical threads with external tapered threads. The pipe wall thickness is determined by the expected pressure.
Metric threads are used for pressure gauges or gearboxes. It can be internal and external. The first warrant is more commonly referred to as nuts, and the second as union.
Thread parameters
All devices have their own thread diameter. The unit of measurement is inch or mm. It is important to understand that the cross-section of all threaded fasteners made of metal is measured internally.
The cross-section of polypropylene pipes and fittings is measured from the outside. So, if the cross section of PP pipes is 2 cm, then this is an analogue of pipes made of metal with a cross section of 15 mm, a similar situation with fittings.
Direction of the thread
Connecting parts with a right-hand thread are screwed in or screwed in clockwise, left ones - vice versa. In other words, if the threads are raised in the left direction, the threads are left-handed.
When laying the plumbing system, a right-hand thread is usually used. The left one is often found when connecting pipes to batteries. There is a right-hand thread on the right side of the radiators and vice versa. To switch to the right-hand thread and the circuit provided for the connection, you will need a special set of 4 fittings (2 with a left-hand thread, and 2 with a right-hand thread), rubber seals, plugs and air bleed valves.
Brass connections
Brass fittings are well suited for fixing copper pipes. The crimp ring inside the joint provides increased fastening strength. Its placement is done with a wrench. It allows you to tighten the nut by tightening it to the specified level. It is important not to twist the threads, which will lead to leakage.
The disadvantages include the need for timely maintenance, eliminating the loosening of the system and a low limit of allowable pressure.
Copper mounts
Copper fittings are resistant to temperature changes and corrosion. They allow you to combine products from different materials. However, the use of different combinations affects the reduction of the service life. It is not recommended to bond copper to galvanized unalloyed steel. This will cause a rapid onset of corrosive processes leading to rapid destruction of the fitting and the edge of the pipeline.
Cast iron connections
Cast iron fittings are straight threaded connections at the ends. This material is well suited for the creation of couplings, elbows, crosses and tees. For multiple use, placement of waterproof material is required. Low cost and strength of structures is inferior low level anti-corrosion resistance, which forces manufacturers to use more resistant materials.
Steel connections
Steel structures have proven themselves well due to their durable and reliable characteristics, but do not forget about laying fum tape or tow for a better connection. Depending on the materials and design parameters, fittings can have different thread lengths. The main purpose of the fittings is the connection of two or more contours of the same and different sections.
Stainless designs with cylindrical threads with a special seal are in good demand. The main advantage is reusability. For example, if necessary, renovation works, these mounts can be disassembled and reassembled without loss of quality.
Pipe beaters
The elbows are represented by pipe threads at both ends. On the one hand there is a short (5-6 threads) thread, on the other - an elongated thread (20 .... 30 threads). The flanges provide a connection between two fixed pipes. A squeegee is screwed into a reinforcing element or fitting, a nut and a coupling are put on the other side, flax is wound onto the end of a pipe with a short threaded turn and covered with a sealant, then it is combined with the end of the squeeze. The sleeve is screwed onto the end of the pipe and connected to the squeegee. Flax is placed between the coupling and the nut and the nut is pressed against the coupling.
Bends for pipes
Elbows are used to correct changes in direction of the pipeline in vertical and horizontal positions at an angle of 30 °, 45 °, 60 °, 90 ° and 180 °. They feature a smooth inner ball that prevents deposits from forming on the pipes.
According to their design features, the bends are divided into steeply curved and bent, seam and seamless. Bends with a 90 ° swivel angle are especially popular.
For the manufacture of bent bends, a pipe with a diameter that determines the method of manufacturing structures is used:
- cold-formed, from 15m.R;
- hot-bent, with a radius of 1.5-15m.
Serve for transportation of water, gas, non-aggressive liquids at maximum heating up to 175 C.
Steeply curved products are characterized by a small bend angle, which simplifies the line layout. But due to their small parameters, they do not provide compensation thermal expansion pipes, for example in heating system... For the development of bends, a water-gas pipe (GOST 326275) or seamless steel structures with a cross section of 15-50 mm is used. Seamless products with a large diameter are presented in the range.
