When wiring pipelines, there is often a need to connect the parts to each other at an angle, to create branches, bends or transitions to another pipe diameter. For these purposes use special auxiliary parts - fittings. They are copper, steel, bronze or cast iron, but brass fittings are most popular. Bronze analogues are similar in properties, but less durable due to the lack of zinc in the composition. Of course, stainless steel products are stronger than brass and less susceptible to corrosion and deformation, but they are much more expensive to manufacture and require significant installation effort.
Material properties
Brass is an alloy of copper and zinc in varying proportions using additives. It was first obtained in 1781 in England, although the combination of copper and zinc ore has been used since ancient Rome.
Not only prosaic things like fittings are made from brass. For example, a monument to Minin and Pozharsky on Red Square was made from it, although for a long time it was believed that the statue was made of bronze. For a long time in Russia and Europe, brass was also used as a fake for gold.
The material has high ductility and low thermal conductivity, which determines the high popularity of brass fittings.
Depending on the proportions of the alloy, the melting temperature of the material is from 880 ° C to 950 ° C, and the density is from 8300 to 8700 kg / m 3 . Brass tolerates welding with other metals - both arc and gas.
What supplements are used?
The following substances are used as alloying additives that increase the beneficial properties of the metal:
- Iron - reduces the graininess of the material and adds hardness.
- Tin, nickel, aluminum and silicon are used to increase resistance to corrosion and abrasion, as well as the effects of salts. Silicon also additionally gives hardness.
- Manganese - increases resistance to high temperatures.
- Arsenic prevents water from leaching zinc from the alloy.
- Lead is used as a “lubricating” component - it facilitates the processing of brass and reduces tool wear during the cutting process, and also makes the metal surface smooth. Lead also reduces brass expansion when heated.
Brass with a zinc content of more than 15% when stored in a damp room is prone to spontaneous cracking. To avoid this, it is fired at a temperature of about 300 ° C, which allows to reduce the residual stress without loss in strength.
The addition of 0.5% aluminum gives brass a golden color and high resistance to corrosion in the open air, so the composition is used as a substitute for gold in artwork.
Brass, containing 1.5% tin, is used in marine shipbuilding, as it resists sea water very well.
High lead alloys are used in watchmaking and in the automotive industry. Adding only 3% lead allows you to get a very clean surface during processing.
Anticorrosion coating
Compared to copper, brass fittings are less resistant to corrosion, which is offset by a special protective coating. Basically, galvanic deposition of nickel and chromium is used for this.
Chrome plating is of two types: glossy or matte. The first type is characterized by durability and lack of pores, the second is better processed. The chromium thickness is 0.33-1.5 microns.
Nickel coating is also well polished and protects brass from corrosion, has low porosity. It is applied with a layer of 12.5-15.5 microns.
If the coating is thicker than the recommended values, it threatens with cracking and loss of product quality.
Chrome and nickel-plated brass fittings look very beautiful. They will not spoil their home or apartment interiors.
Varieties of Brass Fittings
These piping components can be classified according to two main characteristics - the application and method of fastening. In application, the assortment of brass fittings is great - elbows, bends, tees, crosses and so on.
According to the method of fastening, fittings are detachable and one-piece. The former are used in pipelines involving periodic repairs, maintenance, or structural changes. Detachable fittings are easy to install, but they require additional sealing. One-piece connections are used where access to the pipeline will be blocked - for example, when installing underfloor heating.
Bends
They are used in cases where you need to change the direction of the pipe by a certain angle (usually from 45 to 120 degrees). Other names for this part are brass elbow fitting or elbow.
Driving
These are small pieces of pipe with an external thread, designed to extend the pipe to the required length. The standard sizes are 10, 15 and 20 centimeters, but there are also very short ones - “barrels”.
Bends are also used to connect two fixed pipelines. In this case, the thread is made from one end long, from the other - short. The bend is screwed at one end into the fitting of the first pipe, then connected to the second using a sleeve that is tightened with a nut.
Tees
These brass fittings are designed to branch off from the main pipeline. Depending on the angle at which it is necessary to derive the branch, they are straight (at 90 degrees) and oblique.
By bandwidth, they are divided into equidistant and transitional. For the former, all three outputs are made identical and divide the stream into equal parts, and the latter are designed to create branches of a smaller diameter.
Spider
This brass fitting is similar in design to the previous one. The difference is that the crosspiece provides a branch from the main pipeline in two directions. As a rule, brass crosses are made only straight, that is, bends are made at an angle of 90 degrees. Crosses and tees are used most often when installing heating pipes from low pressure polyethylene (HDPE).
Futorka
It is mainly used for installing measuring instruments on a pipe - most often water or heating meters. It is a short length of pipe with an internal thread at one end and an external thread at the other. It is installed through a tee. The foot is also used when you need to reduce the diameter of the internal thread of the pipeline. It is screwed into the end of the pipe with an internal thread, and a segment of a smaller diameter is already screwed into it.
Other varieties
- Plug - used to seal one end of the pipe.
- The fitting at one end has an external thread, at the other - a special "brush" for connection to a brass hose fitting.
- Nipple is a short fitting with two external threads. Designed to connect the two ends of the pipes.
- Nut - designed for the same purpose as the fitting, but the thread has not external but internal.
Threaded Brass Fittings
This is the simplest type of detachable fitting. She is the most simple and popular. Installation does not require special skills or special tools - just a wrench or a maximum of two.
A significant minus of threaded fittings is that most often it is necessary to seal the connection with the help of various additional materials - plumbing thread, tow, fum tape and paste. Sealing materials have a certain service life, therefore, such connections must be periodically monitored, tightened, or even reassembled if a leak is detected.
A threaded brass fitting may have an internal or external thread, as well as both at the same time. With its help, only metal pipes can be connected, since a thread is required for joining.
Brass compression fittings are another type of detachable connection. When using them, there is no need to use additional sealing materials, since the sealing parts are already part of the product. One of the important advantages of compression fittings is that they can connect any pipes, without taking into account the material and diameter - the joints are made in the range of 16-110 mm. Other advantages of these compounds:
- they do not require constant monitoring of leaks and periodic pull-ups;
- design is able to withstand high pressure;
- long service life;
- ease of installation;
- mounted pipes can be from any material: steel, metal-plastic, HDPE, copper and so on.
Compression brass pipe fitting consists of the following parts:
- case with rubber gaskets at the ends;
- nut;
- crimp ring, which, when tightening the nut, is compressed and provides sealing of the connection.
Compression fitting is a fairly universal connection, it allows you to mount pipelines underground and even under water. The only limitation is that the temperature of the substance flowing in the pipes should not be higher than + 40 .
Since the material of the pipes is not fundamental, compression brass fittings for HDPE 32 mm pipes, as well as metal-plastic pipes, are very popular in the installation of household, commercial and industrial pipelines.
Press fittings
This is the newest type of fittings, which has become a real salvation for professional plumbers and plumbers. For an ordinary person, when installing the pipeline independently (for example, in the country), it does not make sense to use press fittings. Firstly, for their installation you need a special tool - crimping pliers, which are not profitable to purchase for a single operation. Secondly, the press fitting is an integral connection, therefore, in case of any error, the part will have to be thrown out and a new one purchased.
On the contrary, professional plumbing brass press fittings greatly facilitate the work, since their installation is much simpler and faster than conventional compression. The connection is extremely reliable. It is well suited for installation of concealed pipelines, which are often required in everyday life - for example, when installing a washing machine or underfloor heating.
The press fitting consists of the following main parts:
- brass body - its shape depends on the purpose of the fitting (tee, coupling, fitting and so on);
- the sleeve is the main component of the press fitting, made of stainless steel, it is crimped during installation of the fitting, maintaining its shape and ensuring the tightness of the connection;
- clip - a plastic part, plays the role of a dielectric;
Crimp brass fittings have significant advantages:
- these compounds are very durable - withstand pressure up to 10 atmospheres;
- manufacturers declare a service life of connections of about 50 years with proper installation;
- with proper installation, press fittings do not require periodic checks;
- They are ideal for heating systems and hot water supply, as they are resistant to temperature deformations.
The disadvantages of press fittings include the fact that they can only be dismantled together with a piece of pipe - they cannot be unclenched. Reuse is also excluded.
In addition, the installation of a press fitting requires some skills - if you squeeze the connection hard, it can leak and cause an accident.
Push fittings
This type of connection has appeared relatively recently, but it is very promising due to the extreme ease of installation. These brass fittings are designed for HDPE or metal-plastic pipes. No special tools are required, and the connection is almost instant. The end of the pipe is simply inserted into the fitting - fixing takes place automatically. The connection is extremely reliable, it can be concreted and buried in the ground. At the same time, push fittings are detachable joints - after dismantling, they can be reused.
The push fitting device is as follows:
- brass case of one form or another, depending on the purpose of the connection;
- at the ends of the body are fittings with o-rings that provide protection against leaks;
- inside the case there is a collet that carries out the capture and retention of the end of the pipe; special inspection openings are located on the body to control the pipe entry into the capture.
All elements of push-fittings are completely made of brass, without the use of plastic, which increases the reliability of the design. The compound withstands temperatures up to 95 ° C and a pressure of 10 bar. Service life - more than 50 years.
Installation of push fittings is extremely simple. This is an ideal solution for laying the pipeline with your own hands, especially taking into account the fact that the connection is tight, reliable and does not require constant monitoring of leaks. The only subtlety during installation is that the pipe end must be perfectly calibrated. You need a cut that is even and clearly perpendicular to the longitudinal surface of the pipe, otherwise the connection will be loose. Professionals use a special tool for this - the butt calibrator. Manual alignment of the cut will require a bit more time, but this is more than compensated by the speed and reliability of installation.
Welded joints
This type of fittings is used infrequently, since it requires special equipment and highly qualified personnel. In this way, only metal pipes can be connected, for HDPE brass fittings for welding will not work. In addition, the connections are non-separable - it will not work to change the configuration of the pipeline if necessary. Have to completely dismantle the structure.
The most popular type of welding using brass fittings is capillary brazing. It is produced using a burner and an additive. A gap of about 0.5 mm is left between the parts. The molten additive, under the influence of capillary forces, is “absorbed” into the gap and fills it, creating a sealed monolithic compound.
For the installation of pipelines in the premises, butt welding is most often used. For this purpose, a special welding machine is used, which melts the end of the pipe and firmly presses it to the fitting, forming a monolithic seam. A very important point is the exact coincidence of the diameters of the pipe and fitting - then the seam will turn out to be of high quality.
You can press the parts with the help of hand tools, but this method is less reliable: if the force is insufficient or at some point weaken, the seam will come out of poor quality. This can lead to an accident in the future, the elimination of which in a welded pipeline requires much more time than in the case of threaded or crimping structures.
There are two more ways of welding brass pipe fittings - socket and electrofusion. In the first case, the process is similar to butt welding, but a different type of welding machine is used for it, since welding occurs when the ends of the pipes come into each other. If, at a butt joint, the pipe diameters should be identical, then here the outer dimension of the first part should be equal to the inner dimension of the other.
When electrofusion welding between the ends of the pipes to be connected, there is a special coupling that directly connects due to the heating element located in it. Power is supplied to the coupling by a transformer, the ends of the parts to be welded are melted, and in the process of cooling, the connection acquires additional strength.
Buying Tips
When purchasing fittings, you should pay attention to some points that may indicate a low quality of the products offered:
- Weight - A quality brass fitting cannot weigh like a feather. Low weight means that the product is made of thin metal and will be short-lived.
- Price - a very low cost indicates that the product is made in China, such fittings can be made of low-grade alloy or may be of poor quality.
- Marking - for a quality product, all marking symbols should be well read, there should be no missing letters or numbers.
- The quality of the coating - if the fitting is chrome or nickel-plated, you need to carefully inspect the surface - it should not be scratched, chipped or scuffed, which can eventually lead to corrosion.
Fittings are specific products; they cannot be bought anywhere. You need to purchase them in specialized stores and do not hesitate to ask sellers for quality certificates.