Pipelines ensure the fulfillment of domestic and industrial needs of the population. However, to create them, you will need to use only proven and high-quality fasteners. In order not to lose in the choice, most experts try to study the full range of fittings.

Fig 1. Fittings

Technical specifications

Fittings are classified based on technical criteria:

  • To perform what technical role is required to install fasteners — fittings;
  • What material is the structure made of?
  • How will the mount be fixed;
  • Distinctive design features and size.

The size range starts from 4 — 600 mm and depends on the direct purpose (connection of brake-type hoses or in the preparation of the main pipeline). It is customary to distinguish several standard sizes of fittings: 20, 25, 50, 110 and 32mm. As a rule, due to the great popularity, such models will not be difficult to find.


For competent and high-quality installation of plumbing, it is impossible to do without connecting elements. The basis is often durable metal — steel, cast iron, metal, brass. No less common are constructions made of plastic and synthetic materials: polyvinyl chloride, polypropylene, polyethylene.

Considering the diverse device of the fitting system for heated towel rails, several options can be distinguished:

  1. Threaded connection

    Fig 2. Threaded

  2. Compression.
  3. With capillary soldering.
  4. Press.
  5. Self-locking.

To build a reliable water supply, several types are used at once:

  • If the section is straight, the clutch is relevant;
  • If the system is branched — a tee or a cross;
  • To change the direction of flow — branch.

What are the connections

The choice of design depends primarily on the material of the water pipes, the diameter. Among the most popular are threaded, welded, compression, collet. In order to connect a pipe corrugated from stainless steel with high quality and without leaks, the brass look is best suited, where there are additional silicone sealing elements.

To connect the pipe to the element, a fitting must be present at one end, and a coupling must be screwed into the other. This is necessary to achieve maximum fixation in the structure. In practice, «mother» is called the type of connecting element, made as a coupling, and «dad» — in the form of a fitting.

It is important to take into account that designs using these types of connections are relevant with a small and medium cross-sectional diameter, where the diameter is more than 50mm. Welding or connection by means of flanges is used.

Fig 3. Steel structures


If you need to connect radiators, it is recommended to use a straight or angled American. When the pipeline is planned to be laid for outbuildings or household buildings, when organizing heating or a sewer system, it is recommended to use systems with adhesive, welding or threaded types of connections.

To create a ventilation system, additional seals are not required. Ideal for sealants. To connect the hoses, it is most relevant to use threaded fittings.

As a rule, when an artificial irrigation system is created, pipes made of plastic or other synthetic material are used. Professionals use shutoff valves (faucets, valves, gate valves) or tees, couplings. It is actual to choose a diameter in the range of 20-25mm.

When creating a pneumatic system, it is important to pay attention to the conditions in which operation is planned. As a rule, connecting elements made of polymeric material, stainless steel, copper alloys are suitable.

For radiators, a 90, 45 degree elbow and fittings are used. Most often they are equipped with stainless steel threads. Brake hoses are also not complete without models that ensure the tightness of the structure. They are presented in various diameters: 4-18mm. The design retains strength -50 to +100 degrees. The optimum pressure is 12 bar.


Types of fittings are determined depending on the parameter in question, so familiarize yourself with several classifications at once. Depending on the material used, there are:

  1. Stainless. When creating, stainless steel is used. Among the main figurations, it is worth highlighting tees, crosses, bends, transitions. The most common type is threaded.
  2. Bronze. Differs in big service life. They are versatile and can be used in conjunction with pipes made of steel, plastic or copper.
  3. Metal. In production, only ferrous metals (steel, cast iron) or non-ferrous metals (bronze, brass or copper) are used.
  4. Cast iron. Belongs to the threaded category. Optimal for creating sealed structures using seals.
  5. Chrome plating is often used to improve the performance of fasteners. They can be used with pipes of various materials.

The second type of classification involves the division of fisting according to the design features:

  1. DKO with metric straight thread. In the subcategory, it is customary to single out straight, angular structures of 45 or 90 degrees.
  2. For straight sections, a straight construction is used.
  3. To create a sealed structure, the connecting fittings are crimped using two special rings. The design avoids leaks over time.
  4. Push fitting. Visually it consists of a seal in the form of a ring, a coupling and a ferrule. No additional press tools are used for creation. Relevant for the creation of heating systems or water supply.
    Fig 4. Push

    Fig 5. PUSH device

  5. Baggio. Visually, the design does not imply any difficulties. There is a body, rings with seals and threaded bolts. You can also find straight or at angles of 45 and 90 degrees. Suitable for creating a control system for machines 6-25mm

    Fig 6. Baggio

  6. A container connection will be required to install containers of various orientations.

The third classification system is built according to the type of connection:

  1. collet. Belong to the category of crimp. Experts do not advise using them to connect pipes made of PVC material, since there is a high probability of causing serious mechanical damage.
  2. With the inclusion of a union nut, it presents a split view. Actual to carry out the dismantling of pipes without the need to additionally create rotation.
  3. Air is referred to as a quick-release type. Ideal for creating pneumatic systems. Used in the manufacture of plastic or metal.
  4. Hydraulic — the main representative of threaded or crimped connections.
  5. American is made from various types of materials.
  6. To work with polymer pipes, electric welded structures are the most relevant. Overlapping or end-to-end installation is allowed.


The last classification implies the type of pipe connection:

  1. Polypropylene. Relevant when creating hot or cold water supply. They can create a combined version using brass inserts.

    Figure 7. Polypropylene structures

  2. Pneumatics with steel, copper fittings, bronze or brass polymers. Suitable for pipes made of polypropylene.
  3. Polyethylene with laying of electric heating elements. As a rule, a heating wire is used. With its help, reliable welding of the connecting element and the pipe is carried out.

    Figure 8. Polyethylene

  4. With high pressure relevant for hydraulics. The system transports fluid.

Scope of various connections for polyethylene pipes

The underlying material is polyethylene with different densities or brass. The diameters of the fittings used are used in variations of 20-1200mm. To get acquainted with all types and characteristics, you can refer to the following table:

View Characteristics and scope
compression It is used in the creation of a drinking water supply system. Resistantly tolerates temperature conditions in the range of 0 + 45 degrees, pressure 10-16 bar. Welding is used during installation
Electrowelded Using the heating element as a wire. Finds application in the manufacture of gasification systems
Metal Suitable if there are additional elements from other materials
cast The manufacturing system is identical to the HDPE system, the temperature is 0-40 degrees
Segment (welded) It is made from separate segments that are connected into a single system. The part for the connection must allow the organization of branching when creating a water supply system
Brass Differs in reliability and tightness. Actual use in conjunction with bushings, reduces the risk of deformations, when using a compression fitting, it allows to narrow the pipe diameter
75mm HDPE pipe Relevant for creating a non-pressure sewer system
Fig 9. Electric welded

How to choose the best PP option


In order not to make a mistake and choose the best fittings, it is recommended to take into account the material from which the connection is made and its diameter for:

  1. organization of solid structures made of copper or steel — flanges. They are suitable if it is impossible to avoid welding or the components are threaded. When ordering a batch, you need to consider how flat they are, whether the ends are perpendicular. From these indicators depends on how tight the connection will be. To achieve tightness, it is better to use a special FUM tape. The locknut will help to achieve optimal fixation of the seal made of various metals (cast iron, steel or bronze).
  2. solving plumbing problems, it is better to select connecting elements from the same material as pipes. As a rule, it is PVC. Soldering is carried out with special tools. It is important to take into account that such models are characterized by high cost.
  3. systems with metal-plastic present, it is better to use several fasteners, on average 3-4. When ordering them, it is important to consider the weight. As a rule, the better the design, the more it weighs.

It is not recommended to save on the purchase of connecting elements, since the likelihood of serious leaks and pipe deformations depends on them. This is especially true for systems that must withstand high pressure.

The popularity of polymer models, which differ from the above categories in ease (you can install it yourself without the help of a team of professionals), the duration of operation (an average of 30-40 years without replacement), it is allowed to create water supply systems of various levels of complexity. However, it is also necessary to take into account the specifics of the planned work and the material from which the pipes are made and their diameter in order to ensure tightness and maximum tightness of the joints.


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