Steel pipe fittings. Threaded fittings for steel pipes: types and scope of application. Features of using metal pipes in heating systems

The main purpose of fittings is to connect pipes into a single continuous system that supplies the working medium in the required direction. Fittings include adapters, elbows, tees, plugs and other products. For steel pipes, parts made of identical material are used. For example, connecting elements made of steel grades AISI 304, 316 or 12Х18Н10Т are installed on food-grade stainless steel pipelines.

Fittings for metal pipes not only connect sections of pipelines, but also change direction, divide the flow into several parts, help reduce or increase the volume of transported liquid, or stop its movement.

Metal fittings are made by stamping from rolled sheets or finished pipes with mandatory machining of the pipes on a lathe. Parts are often subjected to subsequent galvanizing to extend service life and enhance anti-corrosion resistance.

There are several types of products based on the type of connection:

• Threaded steel fittings are attached to pipes using threads. This connection is removable, which increases its maintainability. The thread on the part can be cylindrical or conical (for imported products). The main application is water supply and consumer gas pipelines;
• another collapsible connection - a flange element used for attaching shut-off valves, radiators and convectors, and measuring instruments to the main line;
• One-piece crimp fitting is installed on high-pressure pipelines;
• The steel weld fitting is tightly welded to the pipe, which complicates the repair of this section, but ensures a reliable and durable connection.

Commercial offer from Trubmarket

Our company offers interested organizations and individuals to buy a wide range of steel fittings at the best price in the region. We sell certified domestic and imported goods that meet established standards.

Our consultants will help you select parts according to specifications. Orders are shipped on the day payment is received, regardless of the calendar day or time of day. Delivery is carried out by transport companies. The type of transport is chosen by the customer.

Today, the market for plumbing materials is incredibly abundant. Despite the emergence of a mass of modern materials that meet all requirements, most owners still use metal pipes. The connection of these pipes is carried out using special devices - fittings. This article will discuss which fittings to choose for metal pipes.

The classification of fittings is as follows:

• Threaded;
• Crimping;
• Flanged;
• Welded (with smooth edges suitable for welding).

They differ in purpose, installation technology, dimensions and shapes, so it is impossible to say unequivocally which fittings are better. To understand how to choose steel pipe fittings for a specific situation, you need to look at each type in more detail.

Threaded fittings for metal pipes

High-strength metal is used to manufacture threaded fittings necessary for the installation of steel pipes for main water supply. A cylindrical thread is initially cut on the workpieces. To achieve tightness, the thread is sealed with a linen gasket treated with drying oil-based impregnation. Also, FUM tape or other materials that can now be purchased at any plumbing store can be used as a sealant.

The material for the manufacture of connecting fittings can be steel or cast iron. In accordance with the requirements, ready-made threaded fittings for metal pipes do not have inclusions of other substances or visually noticeable holes that arise due to improper technology for the production of metal products. This requirement is relevant for both external and internal surfaces of fittings. The standards also indicate that the ends of the shut-off valves must be located at a 90-degree angle relative to the axes of each passage.

Sometimes during production, the edges of fittings are equipped with thick sides, which do not carry a functional load, but serve only as a decorative element. Steel shut-off valves do not have such an addition.

The nominal diameter of threaded fittings can vary from 8 to 100 mm. As a rule, this type of fitting is installed on water mains in which the operating temperature does not exceed 175 degrees and the upper pressure limit is 1.6 MPa.

The main advantage of a threaded connection, which distinguishes such fittings from other types, is the possibility of their disassembly: if necessary, you can easily dismantle the pipes without the cost of cutting equipment or hiring specialists (more details: ""). Most often, threaded fittings for steel pipes are installed in apartments, private houses and summer cottages, since it is in these cases that these devices fully justify their purpose.

Pipe Compression Fittings

Crimping fittings for steel pipes have many positive qualities, which is why they are used quite often. They are well suited for installing various communications in different conditions and do not lose their effectiveness depending on them. Compression fittings are installed mainly on indirect connections - and these are various angles, pipeline turns, connections of pipes of different diameters, branches and even direct connections of metals.

Due to this category of fittings, the disassembly of individual parts of the line is greatly simplified. Also, these devices are successfully used to achieve tightness and smooth installation of pipeline connections and pipe sections. Thanks to compression fittings, liquid leakage from the pipeline and various debris from entering it from the outside are prevented.

Steel compression fittings should not be used in all situations - but knowing their specifics, you can significantly increase the reliability of the pipeline and ensure its normal functioning. The operating conditions for this type of fitting are the same as the previous one - the temperature of the liquid in the pipeline should not exceed 175 degrees, and the operating pressure cannot be more than 1.6 MPa. Through pipes connected by compression fittings, gaseous substances, various solvents, water, oils and others can be transported.

Types of crimp fittings

For metal pipes, press fittings with one or two rings can be used. Press fittings are quite convenient, but they are pressed tightly against the pipes, so it will not be possible to disassemble them in the future, and the pipes will have to be cut out if replacement or repair is necessary. For this reason, compression fittings for metal pipes are used only in hard-to-reach places or for other specific reasons.

Compression fittings are designed with one or two ferrules that secure the device to the pipe without the need for a threaded or welded connection. The materials and characteristics of crimp rings may be different, but the requirements for them are the same - the ability to withstand a certain pressure and hold the pipes in a connected state for a long time.

Metal crimp fittings for steel pipes have many advantages in their arsenal:

• Complete sealing of the pipeline without the use of welding or other methods of connecting pipes;
• Possibility of repeated installation and dismantling;
• Reliable fixation of pipes throughout the entire period of operation;
• Ability to withstand vibration for a long time;
• Compression fittings are successfully used in high pressure equipment.

Types of fittings

Fittings can differ not only in design, but also in their purpose, depending on which the following types of devices can be distinguished:

1. Angle fittings. Such elements are used if it is necessary to rotate the pipeline to a certain angle. The use of corner fittings has significantly simplified the installation of pipes, because previously for these purposes it was necessary to use welding, which took much more time.
2. Straight couplings. These parts are used to connect two straight pipes. Direct couplings are characterized by their simple design and limited scope of application - in practice, such elements are only suitable if you need to change a section of pipe or establish a connection between two parts of the pipeline. Very often these couplings are the connecting element of a pipe and, for example, measuring equipment. Couplings are also needed for mounting products that have different diameters or different materials.
3. Tee fittings. The purpose of such fittings is encrypted in their name - tees have three branches for connecting three pipes. A standard metal pipe tee has a right angle or a 45-degree angle, allowing you to separate the pipes in the most convenient way. Tee fittings can be used to connect pipes of both the same and different diameters.
4. Cross fittings. These fittings are a logical continuation of the theme of tees - the cross has four inlet holes and allows you to connect four metal pipes. All crosspiece outputs are located at an angle of 90 degrees relative to each other.

The use of different fittings can significantly simplify pipeline installation work without using welding or other special equipment for these purposes.

Conclusion

The choice of suitable fittings for specific conditions must be extremely competent and conscious. It would not be superfluous to consult with a specialist or seller. You also need to connect and understand your own experience - for example, high-quality fittings for metal pipes always have a smooth surface without defects, scratches or sagging. The correct choice of connecting devices will allow you to create a reliable pipeline that does not have flaws in the form of leaks.

The growing popularity of metal-plastic gave reason to believe that metal communications will gradually be replaced by more modern material. Practice has shown that it is difficult to argue with the strength and durability of steel heating and water supply systems, and fittings for steel pipes have solved many problems in the assembly, dismantling and repair of such communications.

Relevance of steel communications

Over the past few decades, heating and water supply systems have been actively replaced from metal ones to more flexible and lightweight metal-plastic ones. The advantages of the latter are difficult to overestimate: they are easy to cut and install both among themselves and with measuring instruments and valve elements without welding. Until recently, installation of steel pipelines was impossible without the use of welding equipment. Metal fittings for steel pipes make this possible without difficulty, forming a strong, hermetically sealed connection between pipeline sections even under high internal pressure.

There are a number of arguments in favor of choosing a steel pipeline:

• water hammer and pressure surges inside the system are more easily tolerated by steel pipes;
• the service life laid down by rolled metal manufacturers is higher than that of alternative options;
• the thermal coefficient of expansion of metals is lower, which reduces the risk of pipe deformation when the coolant temperature increases;
• inertness to ultraviolet radiation;
• high stable thermal conductivity, easily calculated when laying pipes in ceilings and walls;
• low price.

Among the disadvantages, most sources of information note electrical conductivity, instability to corrosion and difficulty of installation. It is worth clarifying that two of these points have lost their relevance: chrome coating minimizes corrosion, and steel, brass and cast iron fittings for threaded steel pipes make the process of laying communications simplified.

Types of fittings for steel pipes

Types of fittings for steel communications

Fittings are called connecting fittings used in the installation of heating plants, water and gas supply systems. According to their shape and purpose, fittings made from both metals and plastics are usually divided into several types:

• corner and branch, that is, changing the direction of the pipeline;
• crosspieces dividing one stream into several;
• bends, collectors and multi-pass elements serving as splitters;
• adapters connecting pipes of different types and/or diameters;
• fittings that allow you to connect a rigid pipeline with a flexible one;
• plugs and caps that serve as hermetic sealing elements.

For steel pipelines, appropriate fittings are used: the priority is affordable steel, durable and wear-resistant cast iron, corrosion-resistant and long-term use brass.

Welded

Welded or segment fittings for metal pipes are non-dismountable systems, that is, they cannot be dismantled and then reused. The welded seam is sealed and does not stand out much on the surface of the pipe. The principle of choosing welded fittings is based not only on the identical diameters of the connecting element and the pipe itself, but also on the similarity of characteristics. Fittings for steel pipes must comply with the permissible internal pressure of the medium, which are provided for by a specific GOST. Fittings for steel pipes for welding are used, as a rule, in communications placed inside structures and do not require replacement for a long time.

Flanged

The design of the flange fitting, which is more durable than other types of fastenings, is rarely used in household communications. The increased thickness due to the diameter of the flange makes them unaesthetic and inconvenient for use in home heating systems and private water supply systems. The scope of their use is large highways connected in series. The advantage of flange fittings is reliability, however, not exceeding the performance of welded systems.

Crimping

Compression fittings for steel pipes consist of several basic elements:

• housings;
• clamping and pressure rings;
• seal that ensures tightness.

Although the compression fitting is considered a dismountable system, all elements except the body will have to be replaced during repair or reinstallation with new ones.

After fixing all elements selected according to the diameter of the pipe on the connected sections, the crimp ring is tightened using an automatic or manual press. The edges of the connected pipeline sectors do not require any other processing other than calibration and stripping: threads are not required for this type of connection. A slight deviation from the axis when connecting pipes is not critical; curvature of up to 3° is acceptable, which is unacceptable when installing using threads.

Disadvantages of compression fittings:

1. Limitation of the temperature regime by the resistance of the gaskets, for example, silicone and plastic ones can withstand heating of no more than 100°C.
2. Low resistance to mechanical damage; significant pressure on the connection point can tear the fitting.

Threaded

The most popular and universal way of connecting metal pipes is threaded fittings for steel pipes and their variety, called “American”. The sealing of the connection, consisting of a body and a union nut, is ensured by a sealant, while experienced craftsmen often lean towards the time-tested piece of flax fiber. The service life of this detachable connection is up to 50 years, and when dismantling, only the seal will have to be replaced. American steel pipe fittings, named after the country in which this convenient method was patented, are in demand by non-professional plumbers precisely for their ease of use. After checking the pressure characteristics, permissible media and pipe diameter indicated on the packaging, you can apply threads to the ends of the pipes and begin installation.

Video: assembly of threaded connections

Experts warn that any interference in the communications of apartment buildings shifts responsibility for possible accidents to the foreman or organization who carried out the work. If you don’t have the skills to do the work, it’s better to entrust them to specialists and keep the documents in case of litigation.

The pipeline is an integral part of most engineering structures, be it a heating system, sewerage or water supply. Not so long ago, steel pipe was actively used to arrange all these communications. However, with the advent of plastic parts, characterized by their resistance to corrosion and ease of installation, it began to be used much less frequently. New technologies make it possible to produce modernized steel products that are less susceptible to corrosion. The presence of special fittings allows you to install pipelines of various configurations without the use of welding. All this has significantly increased the demand for steel parts, the variety of which we will examine.

Range of steel products

Steel pipes are a general term that unites a wide group of products. There are several classifications of parts.

The cross-section of steel pipes can be of very different shapes. In addition to traditional round products, you can find rectangular, hexagonal, octagonal, oval, square and other elements on sale.

Types of pipes by linear dimensions

Based on this feature, several types of elements are distinguished:

• According to the outer diameter, all pipes are divided into products of medium diameter (102-426 mm), small diameter (5-102 mm) and capillary (0.3-4.8 mm).
• According to the cross-section geometry, square, oval, round, segment, ribbed, octagonal, hexagonal, rectangular parts, etc. are distinguished.
• Based on the ratio of the outer diameter to the wall width, especially thin-walled, thin-walled, normal, thick-walled and extra thick-walled products are produced.
• By processing class. The first class involves trimming the edges of the pipe and removing burrs. The second class is only cutting parts.
• Elements vary in length, which can be short, measured or unmeasured.

Types of products by production method

All steel products can be produced in one of two ways: with or without welding. Accordingly, parts can be either with or without a weld. In the first case, the steel sheet is rolled in various ways, after which it is welded in an inert gas with tungsten electrodes. This is the so-called TIG welding. Or the high frequency current welding method or HF welding is used.

The steel strip can either be rolled into a tube using rollers, which produces a straight seam, or wound in a spiral, resulting in spiral-seam products. Water and gas pressure and profile pipes are produced only by welding.

Steel pipes can be manufactured using welding or without it. Profile and water-gas pressure pipes always have a seam

Seamless parts are made from steel rods by drilling, cold or hot deformation and casting. In the first case, a steel cylinder is drilled, in the latter, molten metal is poured into the mold, inside which the rod is installed. However, deformation methods are most often used for production. With the hot method, the rod is heated in a furnace to a plastic state and sent to rollers, where it is brought to the required length and diameter.

Cold forming assumes that the workpiece is cooled before processing in rollers, but is annealed before the final sizing begins. Thick-walled pipes are produced in this way. Based on the production method, the range of steel pipes is as follows. Electric welded ones are divided into:

• spiral seam;
• straight-seam;
• profile;
• water and gas pressure.

Accordingly, seamless ones are divided into cold-deformed and hot-deformed.

Classification by type of anti-corrosion coating

Corrosion protection can be achieved in various ways. For these purposes, various coatings are used: extruded polyethylene, cement-sand mixture, polyethylene laid in one, two or three layers, epoxy-bitumen mixture or zinc. In the latter case, cold or hot galvanizing is used.

Advantages and disadvantages of steel parts

Steel pipes have many advantages:

• Wide range of operating temperatures. The metal loses its strength characteristics at temperatures above 500°, so the pipe can withstand temperatures of 100° and even 200° without problems. Moreover, in this mode the pipeline can be operated for years.
• Availability of material. Standard products made of structural steel, as well as pipes made of stainless steel, can be purchased almost everywhere.
• High strength and resistance to longitudinal and lateral loads. The maximum pressure for steel lines can be measured in tens of atmospheres. In addition, fittings and pipes are extremely difficult to damage.

A steel pipeline is very strong and reliable, but it is not without its drawbacks. So steel parts heat up very quickly. This is very good for heating systems and bad for transporting liquid and gaseous media, which must be carried out in a stabilized temperature mode. In the latter case, the carrier cools down quite quickly, and the pipe cools down even faster. At subzero temperatures, the part may burst, unable to cope with the expansion of the cooling liquid. To prevent this phenomenon, steel pipes are usually protected using heating systems or.

Also, without protection, steel becomes covered with a thin layer of rust after just a few hours of use. This is not terrible for its strength, but the quality of the transported water deteriorates. It cannot be used as drinking water; in addition, the risk of the formation of silt deposits increases, which can easily be applied to loose rust. The performance characteristics of the product are irreversibly deteriorated. To prevent these unpleasant phenomena, special protection is required.

Steel pipes have insufficient corrosion resistance. After just a few hours of use, the inner walls of the product are covered with a layer of rust.

Initially, steel pipes were connected only by welding. This is the most complex and time-consuming installation option. Today he has alternatives: or a collet. These are simpler methods, but even they require the performers to have at least minimal knowledge and skills in plumbing. In addition, the products are massive, which complicates the already difficult installation.

Types and classification of fittings

Fittings are used to assemble pipelines of various configurations. They are reliable, structurally simple and do not create additional problems in operation. On sale you can find parts that allow you to work with pipes of various diameters: from 16 to 110 mm. You need to remember that:

• Elements with a diameter of 16 and up to 63 mm can only be used for systems in which the maximum pressure is 16 atm.
• Parts ranging in size from 75 to 110 mm are intended for structures in which the maximum pressure does not exceed 10 atm.

Fittings, if necessary, allow you to connect parts made of different materials, but with similar threads, as well as structures with different diameters.

Several types of fittings for steel pipes are available. Among them are crosses, tees, couplings and other parts

The purpose of connecting elements for steel pipes is indicated in the marking of the parts. There are several types of fittings:

• Crosses. Designed for branching four pipes. They are distinguished by the presence of four outlets located at an angle to each other. Most often they are located at right angles to each other.
• Squares. They are used to change the direction of the highway in the horizontal or vertical plane. The slope angle varies from 45° to 90°.
• Tees. The part is similar to the crosspiece, but has only three outlets. Models are produced for parts with equivalent, as well as for products with different diameters.
• Couplings. Connecting elements intended for installation of straight sections of highways. Products are produced with equivalent outlets, as well as with pipes of different diameters.

There are two classifications of parts. One of them is based on the dimensions of the pipes and involves dividing the range of products into many standard sizes. The second involves the identification of several types according to the method of installation of connecting elements.

Fittings for welding installation

A distinctive feature of such elements is the presence of at least one “clean” end, on which there are no threads or any other fasteners. It is designed for applying a weld seam. To secure an element, the following operations are performed:

• The parts are placed on the welding table and aligned precisely. After which they are “grabbed” with two spot seams.
• The fitting is aligned with the central axis of the pipe. For this, a special device is used - a caliber.
• The groove between the pipe and the fitting is filled with a weld seam, which is performed by moving the electrode along the joint line.

Read more about welding in other articles on our website.

Fittings intended for welding installation have at least one smooth end that will be secured to the pipe by welding

Threaded elements

Such fittings are distinguished by the presence of an internal thread, the diameter and standard pitch of which are determined according to a special GOST. Installation of parts is carried out in stages:

• The end part of the pipe is equipped with a thread. The procedure can be performed in two ways: either weld the threaded bend, or simply cut the required number of turns.
• Then you should select a lock nut of the required size and screw the element onto the pipe bend.
• The squeegee is wrapped with FUM polymer sealing tape, after which the fitting is screwed onto it.
• The joint is tightened with a lock nut.

The use of threaded elements is the optimal way to arrange a detachable connection. If you intend to transport aggressive liquids, it is better to choose fittings made of stainless steel.

Using threaded fittings is the best way to create a detachable connection on a section of steel pipeline

Compression fittings

These are products similar to crimping elements for plastic pipelines. The parts are used to arrange a collapsible connection of sections of the highway with an outer diameter of less than 60 mm. Installation of the product is carried out as follows:

• Installation begins with disassembling the fitting. The clamping nut is unscrewed and the clamping ring, seal and washer are removed from the body.
• The pipe is measured and then cut at an angle of 90°. The end must be chamfered.
• The seal is installed in the product body. A clamping nut, ring and washer are put on the pipe.
• With a precise movement, the pipe is pressed into the fitting. At the same time, it passes through the seal, which is tightened with a nut.
• The collet ring is moved to the fixation area, and the entire system is firmly fixed with a clamping nut. It presses on the ring, ensuring the tightness of the connection.

Installing a pipeline using compression fittings can be considered the simplest and fastest option. However, the high strength of such a connection cannot be guaranteed.

Crimping fittings for steel pipes are similar in design to elements used for plastic products. You need to understand that the connection made with their help is not very strong.

Steel pipes are an excellent solution for arranging communications. Not so long ago they were considered unpopular. However, today some of their inherent shortcomings are being successfully leveled out. Modern products are protected from corrosion. In addition, they can be connected using a variety of fittings, which greatly simplifies and speeds up the installation process. Thus, using steel products, you can quite easily build a reliable and durable pipeline that will function smoothly for many years.

Seamless and electric-welded pipes made of galvanized and non-galvanized steel of various thicknesses and diameters, stainless steel pipes, steel, cast iron and brass fittings of various types (welded, threaded, collet) are distinguished by an affordable price and durability and satisfy any construction needs - from industrial to residential spheres. Transportation of coolant and heat supply distribution in residential buildings, municipal institutions, and office centers are traditionally carried out using metal pipelines. The flexibility of corrugated steel pipes and the tightness of welded fittings ensures the safety of communications.

Features of using metal pipes in heating systems

Agree, there is nothing better when a comfortable microclimate is maintained in a house or apartment if the temperature outside is sub-zero. It all depends on the heating system. In particular, great attention should be paid to the autonomous heat source and the most important parts associated with it (heating boiler, radiators, pipes for transporting coolant). Also in this matter, shut-off and control valves for pipelines play an important role. But we will dwell in more detail on the pipes themselves.

So, the coolant is delivered to the radiators and circulates through the pipes. The most familiar option to many is a round metal pipe. It is durable and has a long service life. Galvanized pipes are less susceptible to rust, the inner walls are resistant to corrosion, they do not so often collect various impurities, causing the circulation pump to become clogged with dirt. Ordinary black steel pipes are very vulnerable to rust. But today it is not at all difficult to buy a galvanized, rust-resistant metal pipe. For large-scale work, it is convenient to immediately buy everything you need in bulk, having previously selected a reliable, honest supplier of high-quality parts. Without a doubt, the Santekhvoz company meets these requirements. We offer to buy in Moscow with delivery not only metal pipes for heating, but also steel and cast iron fittings.

Buy metal pipes for heating - Santekhvoz company

It is convenient to buy steel and metal pipes and fittings in bulk, so to speak, in one set. When you don’t have to worry that any part does not fit the thread or is completely incompatible with the pipe or radiator. Thus, the Santezvoz company offers to purchase in bulk all the necessary components strictly according to the specified characteristics; steel and cast iron fittings are certainly durable, capable of withstanding large pressure drops and high temperatures. There are no less reliable heating pipes available, which can be used in open spaces, are suitable for transporting coolants of different densities, and are used in both central heating systems and autonomous ones. Pipes and fittings for metal pipes are delivered throughout Russia. You can submit an application directly on the website by filling out the form in the “Contacts” section, or call us by phone (the number is listed in the same section).