What is coupling fittings?

Pin and shut-off valves: structure and scope of application / MK NHTS LLC

Pin and shut-off valves: structure and scope of application

Fittings are a set of additional parts or devices that ensure the operation of machines, equipment or structures. Separately, we can distinguish pipeline fittings and reinforced concrete reinforcement, thanks to which the concrete structure of buildings is strengthened. The main types of valves that are used in the construction of pipelines are pin and shut-off valves.  

Pin fittings

Pin fittings for pipelines are distinguished externally by the presence of connecting pipes with external threads and the presence of a collar. 

Pin-type fittings are used for work in high-pressure areas. Parts of the pipeline with pin fittings are sealed.  

Thanks to the threads at the points where the reinforcement is connected to other parts, pin fittings have a small number of connecting elements. Therefore, the pin fittings are light in weight. Another feature is the reduction in the thickness of the pipe wall at the threaded connection. This type of connection is unsuitable for pipes with thin walls.  

In addition to pipelines, pin fittings are used for special equipment and devices.

The use of such fittings is recommended in work with process pipelines. For example, to transport materials of a neutral and non-flammable nature, cast iron fittings with a diameter of up to 50 mm are used. To transport any media, steel reinforcement with a diameter of up to 40 mm can be used.   

The pin-type connection is used in fittings with low pressure values ​​and small dimensions. It is this type of connection that is more preferable when screwing into the bodies of devices, vessels, and various types of installations.

A common example of a pin-type connection is the system for connecting a fire hose to a fire hydrant.

Features of the structure of pin fittings 

In pin-type fittings, the thread is located on the outside at the connecting ends. Fittings with this type of connection are intended for use in systems with pressure within 10 MPa and Dy values ​​up to 200 mm.

Pin fittings are produced with union nuts or nipples for flanging pipes, as well as for welding to them. Pin-type fittings can have a coupling connecting end and a pin-type end.

Tightness of pin connection

Tightness in pin-type connections is ensured through the additional use of special gaskets and lubricants. When tightened, the gasket compresses at the joint and seals the joint. Additionally, special lubricants can be used.

All types of threaded connections have such advantages as the use of a minimum of connecting elements, low metal consumption, high manufacturability, and low weight.

High-quality installation work requires complete matching of threads (both internal and external), as well as the use of special sealing materials. 

Source: https://mk-nhts.ru/news/czapkovaya-i-zapornaya-armatura-stroenie-i-sferyi-primeneniya.html

How to choose coupling fittings for water supply

One of the most popular methods of connecting water pipes is threaded, which uses coupling fittings. Docking using couplings has a number of advantages and disadvantages that should be taken into account when laying the main line.

Coupling fittings

What it is?

Pipeline connecting fittings come in several types, some of them are mounted by welding, others are fixed with a fitting, plastic products are soldered. But the threaded design has remained the most common for many decades. Such a coupling, angle, tee or shut-off valve is equipped with female threaded fittings that simply screw onto the end of the pipe.

The coupling connection of the reinforcement is reliable. Its tightness is achieved by winding flax tow, fluoroplastic sealing material or a special viscous lubricant onto the thread turns.

There are PVC couplings, the connection of which is carried out not only by threading, but also by pressing.

Features and purpose

Coupling fittings are designed to connect parts of pipes made of different materials in the event of replacing a section of the main line, installing an additional fitting, branching the system or turning it, in some cases for installing a blind end with the possibility of extending the pipeline in the future.

The peculiarity of this element is its versatility. The product can be used in systems made of metal, metal-plastic and plastic pipes. Regardless of the material, maximum tightness and durability of the joint is ensured.

Couplings are available in various configurations and sizes, which allows you to choose the most suitable option in each individual case. In this case, installation is carried out quickly and without the use of special tools (except for cases when it is necessary to cut threads on the pipe).

Coupling fittings are used in everyday life, in the gas and oil industries, when laying cold and hot water supply lines, and for installing heating mains.

Operating principle and design

Coupling fittings are a piece of pipe with connecting pipes on both sides, equipped with internal threads (in the case of metal products) or a rubber sealing gasket (in plastic parts).

Inch threads on couplings are formed by rolling, cutting or stamping. Moreover, due to the fine pitch, the height of the teeth does not affect the diameter of the pipeline in any way. To ensure quick screwing of the product from the outside, the ends form a hexagon for keys. Apart from this tool, you won't need anything else.

The design of the American coupling eliminates the need to rotate the entire part. The pipes in it are replaced with union nuts. For tightness, the product is equipped with a firmly fixed gasket in the form of a ring on the outer surface of the housing.

PVC couplings are used when laying sewers, water pipes, organizing irrigation, etc. They can be either threaded or equipped with a rubber seal for a tight connection with the outer surface of the pipe.

Types of coupling fastenings

Coupling fastenings are simple. They do not require additional fasteners, as is the case with the installation of flanges, for which you need to use bolts and nuts.

The coupling connection of pipeline fittings is carried out by:

• inserting the ends of the pipe into the socket;
• gluing adjacent surfaces;
• by screwing a thread;
• using diffusion welding.

The first type of connection implies the absence of pressure in the system. It is used to connect sewer and drainage sections. Tightness is ensured by a dense rubber ring with an edge protruding towards the center. Additionally, you can treat the edge with silicone or glue the surface with construction tape.

Adhesive or welded joints are used when laying plumbing and heating systems. The process is carried out in this way: an adhesive is applied to the surface of the pipe and fitting, then they are combined and the time required for the substance to set and harden is maintained.

The majority of threaded connections are used not for connecting work, but when installing shut-off and control valves with manual drive or automatic control.

The latest method is made possible thanks to an electrode installed inside the coupling and a material that easily melts under the influence of current. It is enough to connect 2 elements of the main line and connect the wires, and melting occurs. After this, the transmission of electricity is stopped and they wait for the material to harden, simultaneously soldering the surfaces and ensuring complete tightness.

Advantages and disadvantages

The most important advantage of coupling fittings is ease of use without the need for complex tools. Everything you need is included in the product body. It is also important that the connections are made tightly and firmly. The joint is able to withstand mechanical loads and high temperatures.

Threaded fittings do not require twisting of the pipes, since the turns are arranged in such a way that screwing occurs simultaneously on both sides. This is important when the highway is modified.

Any type of coupling has high performance characteristics that allow them to be used for several decades.

The disadvantages include the fact that when screwing the nut, physical effort has to be applied, so such fittings do not have large diameters. When laying large pipelines, it is better to use the flange method. In addition, it is not recommended to use threads on thin-walled pipes, as this significantly reduces their strength.

Features of application

The most widespread use of coupling fittings is when modifying already installed pipeline systems. This includes creating branches, turns, installing functional elements in the form of a tap, valve or stopper.

There is a demand for equipping such a collapsible joint in places where the main line and the units and devices installed on it are constantly being replaced or reconstructed. This allows you to shut down at any time without dismantling the pipes.

The most recommended pipeline diameter is no more than 40 mm in areas with open access. When laying underground pipelines, it is better to use fittings that are welded or fixed with flanges.

Installation technology

The installation of couplings of various types during pipeline installation has several similar features:

1. The edges of the pipe to which the fitting will be joined must be cut strictly perpendicular to the axis to ensure a tight fit of the surfaces to each other.
2. For installation, you only need an adjustable wrench, additional sealing means and components suitable for the diameter.

The threaded method of connecting fittings implies the presence of a counter thread on the pipe. If there is none, you will have to use a tap and a die. Then the entire structure is joined and the coupling is screwed onto both pipes at the same time.

The American is installed in the following sequence: a crimp nut and an O-ring are put on the pipe, then its edge is inserted into the fitting and the structure is tightened with a wrench. At the end, both hexagons are turned simultaneously to ensure a strong connection.

Press couplings are installed differently: a pipe cut perpendicularly is inserted into a sleeve and pressed into place.

Source: https://trubyda.ru/armatura/muftovaya

Types of connection of pipeline fittings. What are they?

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One of the main issues when choosing pipeline fittings is the type of connection to the system. Usually the existing pipeline system itself dictates to us which type of connection to choose.

But if you are faced with the task of designing such a system, then it is important to know all the possible types of connecting pipeline fittings to the system in order to choose the ideal option for your conditions.

From our article you will learn about all types, their pros and cons, and you will better understand the types of connections. We'll start with the most popular ones.

Flange connection

This is a connection using two metal plates adjacent to each other. The plates have holes through which bolts or studs pass and are tightened with nuts on the other side, thus pressing the flanges together. For greater reliability and tightness of the connection, protrusions, grooves, etc. are made on the plates.

, and gaskets are installed between the metal plates. Most often the plates have a rounded shape, but this is not necessary. Occasionally you can find square flanges, rectangular or with three corners, but their production is more expensive. Such forms of flanges are used only when strictly necessary, for example, if space limitations require it.

Used on industrial pipelines with a diameter of DN 50 mm.

The word “flange” comes from the German flansch, which means the same thing as in Russian – a flat metal plate with holes.

Flange connection is one of the most popular connections in pipeline fittings. For the manufacture of flanges, cast iron is most often used - gray or malleable, as well as steel of various grades. Gray cast iron is the most inexpensive solution, but ductile iron can generally withstand a greater range of pressures and temperatures. An even more expensive and durable solution is cast steel flanges. But at the same time, steel is more susceptible to plastic deformation than cast iron, which is brittle but holds its shape well.

Advantages of flange connection of pipeline fittings

• Strong, reliable connection.
• Withstands high pressure.
• High tightness. But it depends on the seals used.
• Can be mounted and dismantled many times.

Flaws

• Large overall dimensions of the flange connection. Large mass.
• High metal consumption and labor-intensive production, and therefore the price.
• The bolts holding the flanges together must be tightened periodically to ensure proper tightness. This is especially important in systems where the pipe is subject to vibration (solved by installing a vibration compensator in front of the flange connection) or temperature changes.

Threaded, coupling connection

Also one of the most popular types of connections, but for pipeline systems of small diameter (usually up to DN 50) and low pressures (up to 1.6 MPa). Very often found in household pipeline fittings, for example for ball valves. Its essence is simple: the pipe has a thread and the fittings have a thread, the latter is screwed onto the former.

You can cut a thread on a pipe using special tools if it does not exist and the equipment has not been installed before. Threaded pipeline fittings at one end are made in the form of a hexagon for gripping with an adjustable wrench and screwing the fittings onto the pipe thread.

how to cut threads on a metal pipe and install a threaded ball valve

There are various options for making threaded connections: internal or external thread. The fittings may have an internal thread on one side and an external thread on the other, or the same type on both sides. There are also different thread standards, for example ISO 228/1 or DIN 2999. You need to take this into account when choosing.

The word “muff” comes from the Dutch word mouw, meaning “sleeve”.

To ensure the tightness of threaded types of connections, additional sealants are used in them - special FUM tapes, flax thread, as well as especially thick lubricants on top of them. All this is applied to the external thread.

Union connection

This is a subtype of threaded connection, which is used on taps of tiny sizes - up to DN 5. When connecting, the threaded fittings are tightened to the threads on the pipe with a union nut. Used for pipes for narrow purposes, such as laboratory pipes. Also used for implanting various measuring devices into pipelines.

Advantages of threaded connections for pipeline fittings

• Low price.
• They do not require additional parts for installation, such as the flange type.
• Easy to install, even easier to replace.

Welded connection

If the ends of the pipeline fittings look simply like pipes without any additions, then they are connected to the system by welding. This is the most reliable and hermetically sealed connection, and if done correctly, you can obtain absolute structural compliance of the materials. By welding a valve or tap to a pipe, you will not have to tighten the bolts, as with a flange connection, and the cost and weight of such fittings will be significantly less.

This type of connection can often be found on pipeline systems transporting liquids and gases hazardous to health, where the slightest leaks cannot be allowed and absolute tightness is required. For a welded joint, the saying “set it and forget it” is typical. The main thing is to properly connect the pipe to the fittings so that the welding point is not weaker than the pipe wall.

The ends of the pipes must be prepared before welding, and each metal is prepared differently. We offer you a video with the simplest welding method.

Advantages of a welded connection

• Absolute tightness when the welding procedure is performed correctly.
• Low cost of fittings.
• Light weight.
• Small size, the connection does not take up much space.

Clamp quick release connection (Tri-Clamp)

A modern quick-release connection for pipeline fittings, used mainly in the food industry, pharmacology and other industries where sterility and cleanliness are important. After all, this type of connection allows you to regularly remove, clean, and disinfect the equipment installed with this mount.

The clamp connection consists of two fittings, a seal and a clamp. The clamp presses the two fittings against the seal and against each other, resulting in a tight connection. We suggest you study what such a clamp is in the video.

The fittings are welded to the section of pipes where it is necessary to install pipeline fittings. Then just tighten the clamp and the equipment is secured. However, installing pipeline fittings with this type of connection is impractical if there is no need to regularly remove and reinstall taps or valves.

Other methods of installing pipeline fittings

Pin connection. Fastening using two pipes with external threads and a collar at the ends. The two collars are pressed against each other with a union nut, or the fittings are screwed directly into the body of the device. High tightness is ensured by sealing gaskets and lubricants. Used for small diameter pipelines under high pressure, including for measuring instruments.

Durite compound. Multilayer cylindrical couplings made of rubberized fabric (like those on a hose) are put on the protrusions on the nozzles and held in place by metal clamps (clamps). It is used for connecting pipes with inevitable vibration in water supply, oil and fuel pipelines.

Soldering. Used for pipes with a low melting point, such as copper. The pipe with solder is inserted into the machined pipe.

You can purchase pipeline fittings for connection to any system from the RU100 company!

In our catalog we always have pipeline equipment from leading manufacturers in the industry. We will select the appropriate equipment specifically for your system. We work directly with suppliers, we have our own warehouse, so prices remain low. We are a reliable supplier of pipeline fittings!

• Our engineers have been working in the industry since 2008. We know what we sell and will be happy to help you choose the right model.
• We will deliver your order throughout Russia! Or pickup from our warehouse in Moscow is possible.
• Placing an order is very simple.
• We work with both individuals and legal entities.
• We provide a complete set of documents.
• We accept payment in cash, non-cash, bank cards (for pickup)

Still have questions? The answer may already be in the FAQ section. And if not, then ask us:

Enjoy the convenience of working with RU100!

Source: https://py100.ru/tipy-prisoedineniya-truboprovodnoj-armatury-kakie-byvayut/

What are couplings for fittings?

Couplings for reinforcement are an assembly element that replaces welding or fastening of rods with binding wire. By type they are divided into two main groups: threaded and crimped. This connection method is innovative. It simplifies the assembly process, allows you to eliminate defects and build up additional areas. With strict adherence to technology, it ensures the reliability of the finished structure.

The coupling connection of the reinforcement does not require the additional use of fasteners and reduces the installation time of the reinforcement cage. The affordable price allows them to be used even for low-rise construction.

Couplings for reinforcement - an assembly element that replaces welding or fastening of rods with binding wire

Coupling design

Mechanical couplings have the following design features:

• couplings with conical threads are manufactured on mobile threading machines;
• couplings with parallel threads have smaller dimensions compared to other varieties;
• The crimp coupling does not require special equipment to form threads.

Crimp couplings require subsequent mechanical pressing of each joint. Couplings are made from small-diameter pipes, due to which the finished joint is slightly thickened.

Crimp couplings require subsequent mechanical pressing of each joint

Features of the application of innovative technology

The innovation of using a coupling connection is that it provides better quality compared to a welded connection.

Advantages of using couplings:

• does not require complex welding equipment;
• material costs for the construction of joints are reduced;
• the speed of connecting reinforcing bars increases up to 10 times.

An equal-strength connection of rods increases the nominal strength of the reinforcement. This joining method does not affect the strength of the reinforcing bar.

Results

Joining reinforcing bars with special couplings is an optimal alternative to assembly using the overlap method or welding. This technology simplifies the frame installation process and ensures durability.

Mechanical elements are divided into two main groups: threaded and crimped. Each of them has several subspecies, which have their own manufacturing and installation features.

When using connecting elements, you need to know how corner reinforcement and reinforcement of a pile-strip foundation are carried out. You already know the answer to the question whether it is possible to weld reinforcement for the foundation, as well as the nuances of manufacturing reinforcement cages.

Assembling a metal frame reduces the labor intensity of the process and is used to build up or correct structural elements in the future. There is also an alternative option - plastic reinforcement: the pros and cons of using this material will be interesting to know for those who start construction on their own.

Source: https://pobetony.expert/armirovanie/mufty-dlya-armatury

Coupling connection of pipeline fittings

Couplings for reinforcement are an assembly element that replaces welding or fastening of rods with binding wire. By type they are divided into two main groups: threaded and crimped. This connection method is innovative. It simplifies the assembly process, allows you to eliminate defects and build up additional areas. With strict adherence to technology, it ensures the reliability of the finished structure.

The coupling connection of the reinforcement does not require the additional use of fasteners and reduces the installation time of the reinforcement cage. The affordable price allows them to be used even for low-rise construction.

Couplings for reinforcement - an assembly element that replaces welding or fastening of rods with binding wire

What is coupling fittings?

In connection with the intensive development of monolithic frame construction of high-rise buildings, hydroelectric power stations, bridges, nuclear power plants, the problem of joining reinforcing bars during construction work has become more acute.

Multi-storey buildings and complex reinforced concrete structures, especially those located in areas with high seismic hazard, are currently being built from monolithic reinforced concrete, which requires correct and high-quality reinforcement binding.

It is the reinforcement of ordinary concrete that provides the structural strength of reinforced concrete buildings.

More recently, reinforcement was joined by welding or overlapping tying wire. Today, in our country, the main inexpensive and proven method for joining reinforcement bars is coupling. The use of the coupling system consists of replacing fragmentary joints of pins with coupling connections of reinforcement. This technique eliminates any damage from mechanical influences and is actively used in all areas of construction.

Application

A strong metal skeleton of a concrete building is necessary for stable resistance of the structure to bending loads. The commonly used methods of tying reinforcement with wire or by welding are labor-intensive, complex, ineffective and expensive.

The use of mechanical joining makes it possible to quickly fix the connection of reinforcing bars. In about 7-10 minutes, threads are cut at the ends of the pins, the coupling is centered and screwed on with a torque wrench. It also simplifies quality control of joints.

Couplings connecting reinforcement are classified according to different criteria.

• Couplings with conical internal threads allow connecting reinforcement bars with a diameter from 12 to 50 mm.
• If it is necessary to fix the reinforcement already built into the structure, crimp (threadless) connections are used. They fix the rods by the action of special friction linings inside a solid pipe element.
• The screw-shaped pins are secured with two locking nuts. This compact connection is used when connecting pins that carry a high load.

• Rods with the appropriate diameter are connected with a standard fastening.
• Rods with different cross-sectional sizes are fixed with transition connections.
• In some cases, combined fastening of reinforcement is used.

Sequence of actions for a crimp connection

1. Crimping elements are installed on the reinforcing bars at the junction.
2. The coupling is pressed using a hydraulic device.
3. The build quality is visually checked.
4. Comprehensive inspection of the entire assembled structure.

Connecting couplings are made from pipes with a small diameter corresponding to the size of the reinforcing bars. For tightening with a wrench, the upper surface has the shape of a hexagon. An inch thread is cut inside with a minimum pitch.

The use of pipes with thick walls allows you to cut turns to the required depth and ensure the strength of the connection. Experts consider coupling fittings an ideal solution for overlapping pins.

Stages of assembling longitudinal reinforcing pins with threaded couplings

• Couplings of appropriate sizes are purchased and equipment is prepared.
• Threads are cut at the ends of the rods.
• The fittings are installed in the working position.
• The coupling is screwed on at one end.
• The second end is screwed on.
• The knot is tightened to its extreme positions.
• The build quality is checked.

In order to prevent problems with the condition of the frame in the future, it is necessary to tighten the reinforcement units efficiently and with special keys.

Reinforcement connected by the coupling method forms a very strong connection. For such an assembly there is no need to hire expensive specialists. It is enough to simply connect the prepared ends of the pins and secure them with the appropriate metal cylinders.

Advantages

• Ability to connect rods at any angle.
• Special connecting devices increase the intensity of assembly work.
• Identical connectors guarantee a high-quality joining process.
• Economical use of reinforcing pins.
• Connecting blocks are used without restrictions.
• A simplified visual method for monitoring the quality of joints.
• Regardless of the concrete mass, the reinforcement frame maintains its integrity.
• Eliminating the need to hire qualified welders saves financial resources.
• Strength is distributed evenly along the entire length of the pin.
• The features of the equipment used reduce construction time.
• Thread cutting is carried out with universal devices by rolling or stamping.

Installation of coupling fittings significantly simplifies and speeds up the process of constructing monolithic buildings.

Practice proves that a rod tens of meters long, assembled with coupling fastenings, is not inferior in reliability and strength to a solid rod (not divided into segments).

Coupled pipeline fittings

Today, the building materials market offers a wide selection of pipeline fittings from different materials: time-tested, strong and durable cast iron, steel and brass, which are less resistant to mechanical damage.

Pipeline fittings made of aluminum, nickel and titanium alloys are less popular. Polymer reinforcement is distinguished by its lightness, plasticity, and low price.

Taps and valves made of porcelain, ceramics and glass can boast resistance to any chemicals.

When choosing shut-off elements of coupling fittings for a pipeline, it is recommended to focus on the material the pipes are made of. With similar material, many indicators coincide:

• Chemical composition of the liquid.
• Galvanic neutrality of all pipeline elements.
• Resistance to mechanical damage.
• Thermal identity.

Manual coupling fittings

A manual drive is usually called a flywheel or handle mounted on the valve spindle bushing, on the valve spindle, on the drive head roller or the built-in electric drive roller.

The valve valve is moved by a manual drive. Such systems are installed in places convenient for maintenance.

More often, remote manual drives are used, which make it possible to control valves of any diameter installed in inaccessible places.

Source: https://vseogaze.ru/gazovye-kotly-i-armatura/armatura-muftovaja-chto-jeto-takoe.html

Coupling fittings: description, types, installation principles

In connection with the intensive development of monolithic frame construction of high-rise buildings, hydroelectric power stations, bridges, nuclear power plants, the problem of joining reinforcing bars during construction work has become more acute.

Multi-storey buildings and complex reinforced concrete structures, especially those located in areas with high seismic hazard, are currently being built from monolithic reinforced concrete, which requires correct and high-quality reinforcement binding.

It is the reinforcement of ordinary concrete that provides the structural strength of reinforced concrete buildings.

More recently, reinforcement was joined by welding or overlapping tying wire. Today, in our country, the main inexpensive and proven method for joining reinforcement bars is coupling. The use of the coupling system consists of replacing fragmentary joints of pins with coupling connections of reinforcement. This technique eliminates any damage from mechanical influences and is actively used in all areas of construction.

Application

A strong metal skeleton of a concrete building is necessary for stable resistance of the structure to bending loads. The commonly used methods of tying reinforcement with wire or by welding are labor-intensive, complex, ineffective and expensive.

Connecting reinforcement with a coupling is a more durable fixation of the two ends of the rods in a hollow metal cylinder in a certain way. The diameter of the reinforcing coupling is identical to the size of the incoming rod, the wall thickness is 2–5 mm, and its length varies from 7 to 20 cm.

The main task of the coupling element is to be securely fixed inside and not to become loose during operation.

Today, manufacturers of metal products offer a huge selection of coupling connections for fittings of any type, made of high-quality, high-grade carbon steel.

This connection of reinforcement allows you to easily and simply join two pins of the structure located in the same direction. That is, make their end-to-end connection. This type of assembly is not efficient using wire binding and was previously accomplished by a combination of welding and wire binding. The use of coupling reinforcement significantly reduces labor costs, costs for building materials and increases the speed of construction of a strong and reliable reinforced concrete structure.

The use of mechanical joining makes it possible to quickly fix the connection of reinforcing bars. In about 7-10 minutes, threads are cut at the ends of the pins, the coupling is centered and screwed on with a torque wrench. It also simplifies quality control of joints.

Kinds

Couplings connecting reinforcement are classified according to different criteria.

• Couplings with conical internal threads allow connecting reinforcement bars with a diameter from 12 to 50 mm.
• If it is necessary to fix the reinforcement already built into the structure, crimp (threadless) connections are used. They fix the rods by the action of special friction linings inside a solid pipe element.
• The screw-shaped pins are secured with two locking nuts. This compact connection is used when connecting pins that carry a high load.

Coupling connections are divided depending on the diameter of the pins:

• Rods with the appropriate diameter are connected with a standard fastening.
• Rods with different cross-sectional sizes are fixed with transition connections.
• In some cases, combined fastening of reinforcement is used.

1. Crimping elements are installed on the reinforcing bars at the junction.
2. The coupling is pressed using a hydraulic device.
3. The build quality is visually checked.
4. Comprehensive inspection of the entire assembled structure.

If you use special crimping devices for mechanized joining, strong fixation of the joints of the coupling fittings is guaranteed for a long time.

Connecting couplings are made from pipes with a small diameter corresponding to the size of the reinforcing bars. For tightening with a wrench, the upper surface has the shape of a hexagon. An inch thread is cut inside with a minimum pitch. The use of pipes with thick walls allows you to cut turns to the required depth and ensure the strength of the connection. Experts consider coupling fittings an ideal solution for overlapping pins.

Pipeline coupling fittings and features of the use of threaded connections

The simplest coupling fittings are a hollow cylinder with a thread on the inner wall. A threaded coupling is used to connect two pipes or metal rods to each other.

The part is widely used in modern construction technologies, as well as when laying gas and water communications. Connection using coupling fittings does not require special equipment or special skills.

This is a simple, convenient and reliable way to connect segments of pipes or metal rods.

Purpose of coupling fittings

A threaded coupling is a connecting fitting that is actively used in the laying and distribution of pipelines, as well as in construction. The main purpose of coupling fittings is to connect elements end to end, without changing direction. Manufacturers produce couplings from various alloys and polymers.

Note! Threaded coupling fittings are used to connect not only metal but also polymer pipes.

Coupling fittings allow you to connect metal structures without the use of welding, glue or additional fasteners. The connection is removable. To ensure the tightness of threaded connections on pipelines, a special winding, linen or polymer, is used.

Construction technologies using threaded coupling fittings allow the construction of high-rise buildings at lower costs. The coupling allows you to connect metal rods quickly, without additional material costs for a welder and materials.

Coupling reinforcement used in construction is designed to connect and hold the ends of a reinforcing rod motionless. It has a longer body than piping parts.

Design features of the coupling

The coupling is a hollow metal cylinder, inside of which there is an inch (pipe) thread with a fine pitch. The tube body is equipped with special turnkey hooks or made in the shape of a hexagon. The term "muff" comes from the German "mouw", which means sleeve. The connection does not require additional fasteners - the ends of the pipes are inserted into the coupling, as if into a sleeve, and twisted.

The thread is applied in such a way that when the coupling is tightened, both ends to be connected are simultaneously pulled into it. It is important that the thread at the end of the pipe or rod is half a thread smaller than the thread inside the coupling. When tightened, this prevents the pipe from resting against the coupling body.

There are right-hand threads on both sides of the coupling, as well as on the ends of the parts being connected. The method of applying threads can be any: stamping, rolling or cutting. When screwing the coupling, it is forbidden to increase the arm of the wrench with additional attachments, since excessive force will strip the thread.

Note! The connection using threaded coupling fittings is performed manually. The required physical force is directly proportional to the diameter of the pipeline, therefore, for communications with a nominal diameter of more than 50 mm, threaded couplings are not used.

Large diameter connections are made using flange or crimp couplings.

Threaded couplings for building reinforcement have a wall thickness of 2 to 5 mm, part length from 7 to 20 cm. They connect rods from 12 to 50 mm in diameter.

Threaded pipeline couplings are sized according to the diameter of the pipes. Produced from cast iron, steel, stainless steel, brass, galvanized.

Application of coupling connection

There are two directions where coupling fittings on threads are used:

1. Laying pipelines with a diameter of up to 50 mm - coupling fittings are designed for connecting pipes.
2. Construction of monolithic reinforced concrete structures - couplings are used to build up a metal rod in the frame.

The construction of monolithic structures made of concrete requires the creation of a strong, solid frame made of metal rods. Until recently, the frame was knitted by hand, using special wire and welding. The use of coupling reinforcement on a thread allows you to create a strong metal frame that prevents concrete from collapsing. Research shows that a coupling joint is not inferior in strength to a solid product.

Construction coupling fittings

Mechanical joining using coupling fittings simplifies quality control of frame extensions.

The work is carried out according to the following scheme:

1. Couplings of the appropriate size are purchased in the required quantity (the inner diameter coincides with the outer diameter of the rod).
2. Threads are cut at the ends of the rod (slightly shorter than in the coupling).
3. Install the initial reinforcement.
4. Screw on the coupling.
5. Attach the next metal rod.
6. The connection is tightened to the extreme position.
7. Work on standard parts is carried out using a torque wrench, which eliminates the need to control every tightening.

Assembling the frame of a monolithic structure using coupling fittings does not require the involvement of qualified workers. When using standard rods and a torque wrench, visual quality control is sufficient. Extended coupling reinforcement distributes the load evenly across the entire pin, strengthening the joint. The same type of parts guarantees uniform strength of the entire frame.

Note! Transition couplings allow you to connect pins of different diameters.

Pipeline coupling fittings

Traditionally, cast iron couplings with a diameter of up to 50 mm are popular when installing pipelines. Steel and brass parts are slightly inferior to them. They are used in systems designed for operation under a pressure of 10 atm. Aluminum and duralumin couplings are used less frequently. Products made of porcelain, ceramics and glass have a special purpose - they connect pipelines for chemically aggressive liquids.

Pipeline couplings are used in the distribution of local pipelines, usually inside buildings. A special feature of coupling connections in pipeline installation is their versatility.

Pipeline coupling fittings allow:

• make the transition from metal to plastic;
• connect metal-plastic pipes with plastic or metal;
• change from one pipe diameter to another.

Using coupling fittings, measuring equipment and instruments are built into the pipeline in production or in boiler rooms. In this case, a detachable threaded connection is optimal for servicing pipelines and built-in equipment.

Source: https://InfoTruby.ru/armatura/muftovaya

Connecting couplings for fittings

One of the important tasks of modern monolithic construction is the reliable joining of load-bearing metal reinforcement. If previously welding assembly and overlapping strapping were used for connections, now mechanical coupling fastening is being introduced everywhere. Construction technology using reinforcing couplings is in demand for the construction of buildings with increased load-bearing loads: multi-storey buildings, hydroelectric power plants, bridges, as well as in seismically unstable areas.

What are couplings?

In the production of parts, small diameter pipes are used - smooth or with microthreads. The material for production is high-quality steel of different grades, depending on the type of fittings. The finished hollow parts have a cylindrical shape. The length of the cylinder ranges from 7-20 cm, and the diameter depends on the thickness of the rod. The walls of the part have a thickness of 2-5 mm. Reinforcement couplings are similar in shape to similar elements used when laying pipelines.

To ensure a strong connection, the shape and source material of the coupling and rod reinforcement must comply with GOST 10922-2012. Regarding the connection of reinforced concrete monolithic structures, they are guided by GOST 34278-2017.

Purpose and features

With the development of monolithic frame construction technology, couplings have become more in demand. They facilitate reliable fastening of reinforcement directly in the work area.

Installation of the coupling unit takes up to 10 minutes. Does not require specialized equipment or training. The ends of the reinforcement are fixed inside the coupling and then screwed onto the thread or the following fasteners are used:

• valves;
• valves;
• limiters.

If you need to connect reinforcement of different thicknesses, positional couplings are used. They are also suitable for cross and straight fastening of curved rods. The cost of assembling the structure is calculated when planning the overall estimate.

Connecting reinforcement with couplings: pros and cons

The socket connection technology has 5 main advantages over welding and lap joints:

1. Speeds up construction speed. Provides up to 500 joints per 1 construction team per shift.
2. Allows you to reduce the number of workers due to high productivity.
3. Eliminates the need for highly qualified welders, as a mechanical joining method is used.
4. Guarantees material savings. The joining of reinforcement and the absence of overlaps eliminates overexpenditure.
5. Allows you to increase the height due to the strength and lower weight of the reinforcement in the frame.

Using a mechanical connection, it becomes possible to carry out knurling and installation simultaneously. No additional hardware is required for vertical installation. This significantly reduces the operating time of the cranes.

The disadvantages of mechanical fastening include:

• reduction in metal thickness as a result of cutting, and, as a result, decrease in strength;
• the need for physical effort when tightening the coupling;
• the use of expensive hydraulic presses for crimping;
• high cost of cylinders.

It is worth noting that the costs in this case quickly pay off.

To fix the rods and prevent loosening of the structure, threads are made inside the couplings or crimp rings are installed. According to the type of fastening on the rod, couplings are divided into 2 types:

• threaded, with a thread applied inside;
• crimp, implying the additional use of tightening elements (rings or nuts).

For each method, appropriate preparation and processing of materials is provided.

Threaded couplings

If threaded installation technology is used, couplings with applied threads are used. At the end of the reinforcement there is a thread with an appropriate pitch. Thus, correct fixation is ensured, and the connected rods are no worse in strength than solid ones.

Threaded technology is optimal for reinforcement with a thickness of over 16 mm.

The thread type can be conical or straight. With straight threads, the cylinder size is minimal. The type is determined during the preliminary preparation of the reinforcement. The rod ends are threaded, which must match the thread of the coupling.

During professional threaded installation, rods up to 20-30 meters in length are assembled without segmentation. In this case, no additional elements or wire are used. To fix it, you just need to prepare the joints of the reinforcement and screw it into the coupling. Threaded fastening is a low-cost and easy-to-use method.

Bolted reinforcement couplings

For equal-strength installation of reinforcement without preliminary preparation of the ends, bolted couplings are used. The design includes the following elements:

• cylindrical metal tube with holes for bolts;
• shear bolts;
• screwing tool.

The bolt system is universal. It is applicable to reinforcement of any thickness and shape, smooth and profile. This type of fastening is used for the reconstruction of monolithic buildings.

Crimp fittings

Hydraulic equipment is required for operation. The coupling rods may have an internal partition. They thicken the joints somewhat, but at the same time, ensure quick installation.

Types of connection equipment

The equipment for joining depends on the type of coupling used and the location of work. There are 2 types of machines available: for crimping and threaded fastening.

For crimping under construction conditions, mobile hydraulic presses are used, consisting of: a press, an oil station and high-pressure hoses. The press operates in semi-automatic mode. Control is carried out from a remote control built into the handle or manually.

Using a portable press, mechanical crimp fasteners form a reinforcement joint with high tensile strength. At the same time, the actual force to the temporary resistance of the compressed rolled product increases significantly and unlimited endurance is guaranteed.

Machine for thread cutting on fittings

The machines are designed to prepare joints for subsequent coupling fastening. They are applicable to rods with a diameter of 16 to 40 mm. Provide a maximum thread length at the outlet of up to 80 mm.

Depending on the cutting, there are 2 types of machines:

• For conical cutting. Mechanism of action: removing excess body from the reinforcement with cutters, followed by giving it a cone shape and cutting. Productivity - up to 1000 notches per shift.
• For cylindrical knurling. The reinforcement ribs are cut with cutters, and the notches are rolled with rollers. Can be used directly on a construction site with a productivity of 400 threads per shift.

Crimping machine

The machines provide a complete set of crimping technology. The system connects reinforcement in the range of 16-55 mm. The kit includes replacement dies for different rod diameters. The standard machine consists of the following components:

1. Reinforcement press (stationary or portable).
2. Pumping station.
3. Winch for moving the press relative to the coupling.
4. High pressure hose.

The machine creates a fastening that is identical in strength to a reinforcing bar. Managed by one operator. Can be used in any position in space.

Coupling principle

The technological sequence of crimping depends on the location of the work. To connect reinforcing steel at a construction site, the following sequence of actions is followed:

• the coupling is placed at the joint;
• pressure testing is performed;
• visual inspection is carried out;
• a comprehensive check is carried out.

For mechanical threaded connections, small diameter pipes are used. Microthreads of the required diameter are drawn inside the structures, and the connecting ends are formed “turnkey” in the form of a polyhedron. Inch microthreads are applied with the smallest pitch to avoid the teeth from overlapping the pipe walls. In this case, the standard assembly of longitudinal reinforcement consists of 7 stages:

1. Preparation of equipment and purchase of couplings of appropriate sizes.
2. Cutting threads at the ends of rods.
3. Fixation of reinforcement.
4. Screwing to one end of the cylinder.
5. Twisting on the other side.
6. Tightening the knot to the maximum.
7. Checking the build result.

This method does not require a large number of fasteners. Since threading thins the material, thick-walled pipes are used.

Regardless of the type of mechanical coupling fastening and fixation technology, this method is advanced. Thus, the production of one mechanical joint takes 20 times less time compared to welding. The work time of welders is reduced by 90%, thereby eliminating downtime due to lack of personnel. Costs for joining reinforcement are reduced by up to 25%. Connection without welding is a pressing problem in construction.

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Source: https://dvabrevna.ru/stroitelstvo/soedinitelnyie-muftyi-dlya-armaturyi.html

Types of pipeline fittings connections

All types of reinforcement connections can be divided into two large groups: detachable and permanent. A permanent connection (in most cases welding, sometimes soldering) is used where the tightness or other characteristics of other types of connections are not suitable for one reason or another.

The most common types of detachable connections of pipeline fittings include:

• Flanged;
• Coupling;
• Fitting.

Flange connection

Flanged pipeline fittings have become widespread and are used on pipelines for a wide variety of purposes. The main advantage of a flange connection is the ability to absorb axial forces, as well as the ability to quickly install/dismantle fittings. To ensure the tightness of flange connections, gaskets made of rubber or other materials are used.

The word "flange" is derived from the German Flansch, and means a flat metal plate with holes for fasteners located at the end of a pipe. Most often this plate is round; flanges of other shapes are used less frequently.

Pipeline flange fittings have many advantages. A reliable flange connection is able to maintain tightness even at high operating pressures. It can be installed and dismantled an unlimited number of times. On many process pipelines, the installation of flanged shut-off valves is mandatory, since only such valves can provide periodic access for cleaning and maintenance of the pipeline.

Depending on the type and technical characteristics of the shut-off flange valve, the flange can be made of one material or another. As a rule, these are various types of steel, gray or ductile iron.

Flanges made from ductile iron can operate over a wider range of temperatures and pressures than gray cast iron valves. Steel flanges can withstand high temperatures.

The disadvantages of a flange connection arise from its advantages. The downside of high reliability and strength is the considerable weight and size of the valves with a flange connection.

As a rule, flanged shut-off valves are installed on pipelines with a diameter of 50 mm. Our catalog presents a wide selection of flanged pipeline fittings at affordable prices. These are flanged wedge and flanged gate valves, flanged butterfly valves, gate valves, taps.

Coupling connection

To connect small and medium diameter fittings installed on medium and low pressure pipelines, a coupling connection is used. A threaded coupling connection of pipeline fittings can provide the necessary strength and tightness, subject to the use of various seals.

The connecting pipes of the fittings with a coupling connection are made in the form of a hexagon for ease of installation. The thread is usually pipe thread. An inch thread with a fine pitch in connection with a sealing material (linen thread, FUM tape, or sealing gels) creates the proper tightness of the connection.

The detachable coupling connection does not require the use of additional fasteners. Coupled pipeline fittings can have external or internal threads, or both at once. When choosing pipeline fittings with a coupling connection, it is important to select a product with the correct type of thread.

In our catalog, pipeline coupling fittings are presented in a wide range: coupling wedge gate valves, coupling ball valves, coupling shut-off valves, and other products.

Coupling connection of fittings

Buildings consisting of several floors, located in seismically dangerous zones and withstanding heavy loads are now being built using a huge number of reinforced concrete structures. And first of all, it is necessary to observe the correctness of the work when knitting reinforcement for the foundation.

Reinforced concrete in them performs the main job of maintaining structural strength. And the main component of reinforced concrete, which transforms ordinary concrete into a much more durable and practical material, is reinforcement.

Reinforcement assembled using couplings in a frame

We will now look at unique methods of connecting reinforcement, in particular, a coupling connection.

Features and purpose

What exactly is a reinforcement connection and why is it needed? It is necessary to create a reinforcement frame, which is a kind of skeleton of any reinforced concrete structure.

Concrete itself is a very durable material. But its strength is partially offset by its fragility. It can crack, break and collapse, especially if it is subjected to bending rather than compressive loads. A destroyed concrete structure cannot be restored.

The presence of metal rods inside the concrete stabilizes it, improves its resistance to bending loads and turns it into a full-fledged load-bearing structure that is in demand.

This process is called concrete reinforcement. Reinforcement involves assembling a reinforcement cage from individual rods, then placing it in formwork and pouring concrete.

It is precisely to form the frames that the rods need to be assembled. The most popular and easiest assembly method is wire binding. The wire is purchased tempered, up to 1.5 mm thick.

Builders use crochet hooks or guns to tighten reinforcement joints with wire. This solution is not very reliable, but it is suitable for standard tasks.

The fittings are prepared for installation in the coupling

The problem of connecting with wire is the inconvenience when assembling individual rods that continue the frame structure in one direction. That is, those that need to be connected end to end.

Obviously, wire is not suitable for such tasks. It is impossible to effectively tie the reinforcement end-to-end; you can move the rods towards each other and then tie them in several places. However, such a solution confronts us with a lot of problems.

It is necessary to spend extra materials, take into account the weak strength of the frame assembly, and increase the overall level of labor costs, and therefore reduce the speed of construction.

The second option is even more complicated and more expensive.
It consists of combining wire knitting with welding. Obviously, hiring a qualified welder means increasing the cost of the product even more. The coupling alternative saves us from such problems. to menu

Operating principle and design

To understand how the assembly of fittings with couplings works, it is enough to recall their analogues in pipelines. A reinforcing coupling is a hollow metal cylinder with a specific fixation scheme for the two ends of the reinforcement in it.

The cylinder has a length from 7 to 20 cm, its diameter is equal to the diameter of a suitable rod.

The inside of the cylinder can be threaded or special ferrules installed. Their task is to fix the rod inside and prevent it from becoming loose during operation.

Source: https://armaturniy.ru/arm/vyazka/muftovaya.html