Branch for plastic pipes of water supply. Steel outlets. Materials and manufacturing methods

If you need to make the pipe change its direction, pipeline parts are used, which are called "branches". They provide indispensable assistance when there are obstacles on the way of the laid pipe that need to be bypassed.

Description

An elbow is a section of pipe that has been given a certain angle. Depending on the task, you can choose the appropriate outlet. There are many varieties, and this article is about them.

The bends are closely connected to the pipes with the help. According to GOST, such products are produced on special ones.

Application

The scope of the bends is very extensive: from the installation of an oil pipeline to the installation of a boiler house in a residential building. Water pipelines, gas pipelines, oil pipelines - wherever pipes are used, bends are used.

Branch classification

Branches differ, first of all, in the materials from which they are made. In addition, they can have different diameters, bending angles. Each branch corresponds to a brand defined by GOST, by which you can find out all the necessary information about the product.

Kinds

There are three types of steel bends, differing in the type of steel from which they are made. They can be made from stainless, alloy or carbon steel. Different types of taps are used for different purposes. The material from which it is made depends on the environmental conditions in which it will be operated.

The size

If the diameter of the pipes used in the pipeline is less than 50 mm, steel bends are used for their branches. Such products can be welded or seamless. It depends on how the product is made. Better and more expensive are seamless fittings.

Production

Production of curved bends from steel and stainless pipes

It also depends on the production method whether the bends will be stamped, cold-formed, or otherwise.

Which outlet to choose?

It depends on the purpose for which it is purchased. If these are pipes of large diameter, then it is better to use sectional bends.

As mentioned above, steel bends are used in a huge number of areas. These are household and industrial sectors.

Characteristics

Peculiarities

Advantages

Another undoubted advantage of such parts is the ease of their installation. In order to assemble a pipeline from this material, it is not necessary to use welding, and this saves on electricity or gas, depending on what type of welding could be used if the pipes were made of metal.

Similar in positive qualities, the material from which pipes and bends can be made is PVC. The following is a list of these benefits.

1. Relatively small specific gravity.
2. Durability with proper use.
3. Ease of installation.
4. Acceptable price.

Mounting

It is possible to mount such pipes and bends without any additional tools. Parts are simply inserted into each other, forming a firmly connected inseparable system. Installation of parts under the force of novice builders.

Elbows can also be divided into welded and cold-formed. Weld fittings can be made from different types of metal. This includes carbon steel, stainless steel, and low alloy steel. Like other taps, they can be used in almost all areas of human activity.

In order to make segmented bends, separate ones are welded together, made like a wedge. Such parts are used for gas pipelines and water pipelines, the pressure in which does not exceed low limits.

These bends are useful when you need to connect sections of pipes with large diameters.

Existing sizes and diameters of branches

There are several possible angles that a pipe bend can deviate. These are 15, 30, 45 90 and 180 degrees.

To know what size branch to purchase, you need to know the diameter of the pipes that it will connect. The diameter can vary from 426 mm to 2000. Manufacturers can also produce non-standard bends in terms of diameter and deviation angle.

For transportation of various working environment pipelines are used. Pipelines are necessary to supply heat and water to homes, as well as to enterprises in various sectors of the economy. An important element of the pipeline are steel bends that allow you to change the direction of movement of the working medium.

Types of steel bends

A steel bend is a piece of pipe bent at the required angle. Steel bends are divided into types depending on the material, diameter, bending angle, as well as the production method.

Steel of various types can serve as a material for bends:

• carbonaceous;
• stainless (alloyed);

According to the method of manufacture, the bends are divided into the following types:

• steeply curved seamless;
• stamp-welded;
• welded sector;
• bent.

Bent bends are cold-bent and hot-bent.

Steel bends for pipes

Branch material

For right choice the material from which the outlet will be made, it is necessary to take into account the conditions of its operation, the necessary reliability of this element, as well as the aggressiveness of the working environment in which it operates.

For example, in general-purpose pipelines, bends made of carbon steel are used.

In the presence of an aggressive environment that can cause corrosion of the material, alloyed and stainless steels are used. Elbows made of such steels are used in pipelines for the oil and gas, chemical, food or pharmaceutical industries.

For example, 12X18H10T stainless steel bends can be used in pipelines transporting steam, hot water, alkaline, acidic and other working media prone to metal corrosion. Elbows made of 3XFA alloy steel can operate at ambient temperatures from -60 ºС to + 40 ºС, working medium temperature up to +40 ºС and pressure up to 7.4 MPa. Such bends have increased resistance to corrosion in the cold and are used in oil and gas systems in the conditions of the North.

According to SmartInox specialists, in order to correctly select the material from which the branch will be made, it is necessary to take into account the conditions of its operation, the necessary reliability of this element, as well as the aggressiveness of the working environment in which it operates.

Design features

Angled Elbows

The main characteristics of curved bends are given in GOST 17235-2001, GOST 17235-83 and other documents, including various departmental specifications.

Steeply curved seamless elbows are made by pulling a piece of pipe through a special mold. This method allows you to get a high quality output. Elbows of this type are produced both from carbon steel (type steel 20) and stainless steel (type 10X18H10T). In this case, the bends can have a bending radius from one Du to one and a half Du (Du is the nominal diameter of the pipe), with angles of 30º, 45º, 60º and 90º. The diameter of such a branch can be from 18 to 426 mm and it must withstand pressure up to 16 MPa.

Twisted Elbows

Stamp-welded bends

Stamp-welded bends are made from stamped steel sheets by welding. This method allows you to create a branch with a thick wall and a diameter of up to 1420 mm. These bends are used in the main pipelines of the oil and gas industry. The material for such taps is structural, stainless or alloy steel. Regulatory document in this case, they are departmental specifications (for example, TU 102-988-95).

Stamp-welded bends

Sectional bends

Welded sectional bends consist of individual sectors of pipes that are welded together. This design is cheaper, but it is less reliable. Typically, bends of this type are used in pipelines operating at low (up to 2.5 MPa) pressure and temperature not higher than +425 degrees. The permissible diameter ranges from 108 to 1620 mm. Branches of this type are made of carbon or low alloy steel and are used in thermal power plants.

Sectional bends

Bent bends

Bent bends are usually used when it is not possible to use sharp bends. The difference between the former and the latter is that the latter have a much larger bending radius and a straight section. Bent bends can have a bending radius from 2 to 20 Du, and a bending angle of 2º - 90º. Such bends are made in accordance with GOST 24950-81 and TU and can be used in pipelines with pressure up to 100 MPa and temperatures from -50 to +510 ºС.

Bent bends can be cold or hot bent on special pipe bending machines. The presence of a straight section in such bends increases their weight, which is a disadvantage.

Bent bends

Branch welding

Welding bends with pipes is a rather responsible operation. It must be done by welders. highly qualified.

In this case, various types of welding can be used - gas welding, manual arc welding (RDS), automatic submerged arc welding, in shielding gases, and the like.

When welding pipes and bends, a number of requirements must be met, which are set out in the relevant instructions, for example, VSN-006-89.

Before welding, it is necessary to check the welded surfaces of the branch and pipe. All detected external and internal defects must be eliminated.

It is necessary to control the displacement of the inner edges. For example, when connecting elements with equal diameters, such an offset should not be more than 2 mm.

Centering of welded products is carried out using centralizers or rotators.

With RDS, welding of the first root weld is carried out with direct current. In this case, in the event of a break in welding, it is necessary to maintain the preheating temperature in this place.

After welding and grinding of the root weld, a second pass is made, which must be carried out along the hot root weld. The time between these two processes should not exceed 5 minutes.

Next, filling joints and a facing joint are performed. In this case, it is necessary to ensure the temperature of the seam is not lower than +5 ºС. The facing seam should overlap the main layer of the pipe by 2.5-5 mm and have a height of 1-3 mm more than the level of the pipe wall or bend.

For welding bends in production conditions, various devices and entire complexes are used.

The most common are pipe rotators. The principle of operation of such a rotator is that the elements of the pipeline are clamped in special clamps and rotate around its axis. This makes it easier and better manual welding or automatic welding.

A feature of welding a pipe with a branch is that the system must work taking into account the uneven distribution of masses. To solve this problem, the rotator uses servo drives and special supporting racks with rollers.

The advantages of using such a rotator are as follows:

• work with pipes of large diameters;
• thanks to an autonomous drive, the ability to change the speed of rotation of the pipe;
• precise centering of the parts to be welded. In this case, the clamping rollers themselves act as a centralizer;
• the ability to work with both straight pipes and complex pipe parts (bends, tees, flanges).

Welding of steel bends

Pipe rotator

On sale there are a large number of models of pipe rotators made in China, Germany, Russia.

For example, the middle pipe rotator from the U500 series (Germany) is designed to rotate welded pipe parts by 360º. It also allows the workpiece to be tilted, which is useful when welding complex parts such as bends.

This unit has the following features:

• adjustable workpiece rotation speed - 0-130 cm / min;
• diameter of clamped pipes - 20-400 mm;
• tilt moment - up to 7500 kg-cm;
• vertical load capacity - up to 500 kg;
• torque of rollers -2000 kg-cm;
• power consumption from the network - 750 VA.

The U500 pipe rotator can be equipped with a semi-automatic welding control unit. In this case, the burner is mounted on a support that allows you to move the burner to the desired location.

Thanks to the control unit, the operation of the rotator and the welding unit is synchronized:

• arc ignition;
• workpiece rotation;
• seam overlap.

Pipe rotator

1. To change the direction of transportation of the working medium in the pipeline, steel bends are used.
2. Depending on the working conditions and technical requirements of the pipeline, bends of various designs made of different steel grades can be used in it.
3. Welding of bends with pipes under production conditions is carried out using pipe rotators from different manufacturers.

Steel bends are special products used when it is necessary to change the direction of the working flow in various piping systems. The bends are in the form of a round tube bent at the required angle. Steel bends are divided into types depending on the size (diameter, weight), bending angle, manufacturing method and material. Installation of steel bends directly on the pipeline is carried out by welding.

Areas of use of steel bends

The scope of use of bends made of various steel grades is quite extensive. They are most widely used in industrial pipelines (gas, oil, chemical), as well as in domestic pipeline systems (water, gas) and pumping stations. The type and materials of the branches mounted in the main network are selected based on the conditions of their further operation (temperature, pressure of the working medium), the degree of aggressiveness of the working medium, the given reliability and the geometry of the connected pipes.

For example, pipelines operating with an aggressive working medium at high pressures should be equipped with seamless, welded, bent bends made of alloyed or stainless steel, including those with zinc coating. Bent or round bends made of steel with a high carbon content are suitable for household communications. The diameter of the cross section of steel bends can vary in the range of 15-2000 mm.

Materials and manufacturing methods

The domestic metallurgical industry manufactures bends from steel of various grades: alloyed (st. 3HFA), carbon, corrosion-resistant stainless (st. 12X18H10T), galvanized, chrome-plated and nickel-plated with improved anti-corrosion characteristics, etc. Methods for manufacturing bends are based on plastic and casting properties this material. Can be distinguished the following types bends according to the method of their manufacture:

• stamp-welded;
• welded sectional (sector);
• bent;
• steeply curved seamless;
• turned.

Stamp-welded

They are obtained by welding blanks from stamped steel sheets of the required thickness. This technology makes it possible to manufacture products with increased strength characteristics, with a sufficiently large wall thickness and a diameter of up to 1420 mm. The bends obtained by this method are intended for operation in pipelines of oil and gas production. The main materials used for the manufacture of bends by stamping are stainless, structural and alloy steels. The technical characteristics of these taps must comply with departmental specifications(for example, TU 102-988-95).

Welded sectional

Obtained by welding individual sectors (sections) of pipes. This type of bend is less expensive, but it is inferior in reliability. Sectional products are used mainly in main pipelines operating at sufficiently high pressures of the working medium (maximum 2.5 MPa) and temperature (up to 425 ° C), for example, in pipelines of thermal power plants. Diameter finished product can be from 108 to 1620 mm. Sectional bends are made of low-alloy and carbon steel grades.

bent

Made by bending metal pipe, both hot and cold on specialized pipe bending machines. Such bends are a straight section of pipe with an end bent at the desired angle. A straight section in terms of mass can significantly increase the weight of the entire structure, which negatively affects the overall cost, the need to use special reinforcements, etc.

Bent products are obtained with a bending radius of 20 D y (D y is the nominal diameter of the pipe), the bending angle can vary from 2º to 90º. The main document in accordance with which they are made this species bends, is GOST 24950-81. Suitable operating conditions: the pressure of the working medium in the pipeline can reach 100 MPa, the temperature is in the range from minus 50 to plus 510ºС.

steeply curved

Bent bends are often used when it is not possible to mount steep bends. The difference of the latter type is the larger bending radius of the pipe. By technical specifications this type of bend must comply with GOST 17235-83 and GOST 17235-2001. The production of steeply curved bends is carried out by drawing a straight pipe through a special template with a given bending angle (30º, 45º, 60º and 90º). This technology allows to produce high quality products. The materials from which these bends are made are steel grades: carbon (st. 20) and stainless (st. 10X18H10T). Note that, if necessary, it is possible to manufacture a branch of this type with a non-standard bending angle according to an individual drawing or order.

Turned

They are made on a lathe from cast metal blanks. This is the most expensive type of products under consideration, due to the complexity of the technology for their production. The main advantage of turned parts in comparison with the previous types is the possibility of manufacturing parts of any thickness and their high resistance to high pressures, up to 100 MPa.

Methods for centering steel bends during welding

Features of welding in relation to installation different types bends are to constantly monitor how cleanly the inner surfaces and edges of the parts to be welded are combined. The indicator of the displacement of pipe sections relative to each other should usually not exceed 2 mm. In order to control the displacement of the edges of the parts to be joined during welding, they are centered. When welding parts with a small diameter, as a rule, you can use a special vice for welding pipes. They come in various designs.

For large pipe diameters, rotators are used - special technical devices for welding. Parts are firmly fixed in this device and rotate around its axis with adjustable rotation speed. In the process of welding, a high quality of the weld is achieved. This technological technique allows you to firmly fasten pipes and bends of large diameter, as well as work not only with straight products, but also with parts that have a more complex design, such as tees.

Rules for the installation of steel bends

Installation of bent parts on the pipeline with provision high level tightness is a complex process that requires highly qualified specially trained personnel. Steel bends are mounted into the pipe mainly by welding, the safety rules and standards of this process must be prescribed in separate instructions. The welding process itself can be carried out in different ways, but some general rules should be followed.

The process of manual electric arc welding of a pipe section and a branch proceeds at a constant current in two stages with the application of the first and second welds while maintaining a constant temperature of the process. After the first seam is completed, it is polished. After the second seam, filling furrows are carried out and facing seams are applied.

Obviously, steel bends are used in almost any pipeline. To create a tight connection between the main pipe and this element, and to ensure the reliability of the pipeline as a whole, it is especially important to choose the right outlet for the material, design and carry out its high-quality installation.

When laying pipelines, there are often obstacles of various types that need to be bypassed. To do this, they decide to buy steel bends that allow you to smoothly turn the pipeline and give it a new direction. The integrity of the structure, the stability of the entire system directly depends on the products.

Types of steel bends

The performance characteristics of parts directly depend on the materials used in the production process. Buy steel bends will best solution because they are of high quality, long service life. There are other types of products:

• Bent bends - for their production, cold or high-temperature bending of pipes is used. To create products, water and gas pipes made of carbon, low-alloy steels are used.
• Stamped pipes are made from seamless pipes. The absence of seams gives the product high quality, increased performance.

The choice of material, type of product should be made according to the field of application. So, steel parts are in demand in pipelines that work with non-aggressive media. You can buy steel bends in Moscow in our company. We offer convenient terms of purchase, reasonable prices.

Installation of branched and complex pipelines is not a problem when you have special steel bends of the required dimensions. To supply water and gas to a holiday village, or to remote corners of our Motherland, pipes of different diameters are laid every day. A branch installed in the right place allows you to go around any obstacle, or change direction altogether.

Used for gas pipelines, metal bends are installed using a high-precision welding method. The tightness of the connections must be 100%, since gas leaks can lead to disasters on a national scale. Without loss, water must also be pumped through pipes, for the safety of which a well-established water outlet is not least responsible.

According to legislative framework, branches are produced in accordance with GOST 17380-2001. The standard establishes general technical requirements, on bends made of low-alloy carbon steel. Also blanks are produced in accordance with GOST 17375-2001 for steel seamless welded elbows of the 3D type, and in accordance with GOST 30753-2001 for steeply curved elbows of the 2D type.

Buy bends in Moscow

On our website and in stores represented by Metall-DK on large construction markets, you can buy steel bends of any brands. Products differ in diameter and angle of rotation. Steeply curved bends allow you to change the direction of the pipeline in the range from 45 to 360 degrees. If you were looking for bends in Moscow, then we are pleased to offer you our range. If you cannot find the right outlet on your own, contact our managers for help. Steel bends are most often used, however, sometimes it becomes necessary to purchase galvanized steel bends for certain tasks. The price presented for our bends will be of interest to individuals and representatives of large construction corporations. For steel bends, the price is indicated in rubles, since we work for the domestic market.