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 in the process of performing construction works became more acute. High-rise 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 the correct and high-quality performance of knitting reinforcement. It is the reinforcement of ordinary concrete that provides structural strength to reinforced concrete structures.
More recently, the reinforcement was joined by welding or with an overlapping knitting wire. Today in our country for joining reinforcement rods, the main inexpensive and proven method is coupling on couplings. The use of a coupling system consists in replacing fragmentary joints of knitting pins with coupling joints of reinforcement. This technique eliminates any damage from mechanical stress and is actively used in all areas of construction.
Application
A strong metal skeleton of a building made of concrete is necessary for stable resistance of the structure to bending loads. The commonly used methods of tying reinforcement with wire or by welding are laborious, complex, ineffective, and expensive.
The connection of the reinforcement with a clutch 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 securely lock inside and not become loose during operation. Today, manufacturers of metal products offer a huge selection of couplings for fittings of any kind, made of high-quality high-grade carbon steel.
Such a connection of the fittings makes it easy and simple to dock two construction pins located in the same direction. That is, to carry out their butt connection butt. Such an assembly is ineffective through the use of wire binding and was previously carried out by a combination of welding and wire strapping. The use of coupling fittings significantly reduces the level of labor costs, the cost of building materials and increases the speed of construction of a strong and reliable reinforced concrete structure.
The use of mechanical docking makes it possible to quickly fix the connection of reinforcing bars. In about 7-10 minutes, a thread is cut at the ends of the pins, the coupling is centered and screwed on with a torque wrench. The quality control of joints is also simplified.
Kinds
Couplings connecting fittings are classified according to various criteria.
- Couplings with tapered internal thread allow connecting reinforcing bars with a diameter of 12 to 50 mm.
- If necessary, fix the already built-in fittings using crimp (threadless) connections. They fix the rods by the action of special friction linings inside the integral pipe element.
- The helical pins are secured by two locking nuts. This compact connection is used when connecting pins that carry a high load.
Coupling joints are separated depending on the diameter of the pins:
- Bars with the appropriate diameter are connected with a standard mount.
- Rods with different cross-sectional sizes are fixed with transitional joints.
- In some cases, combined reinforcement is used.
Crimp connection sequence
- Crimp elements are installed on the reinforcing bars in the place of joining.
- The coupling is pressure tested with a hydraulic device.
- Build quality is visually checked.
- Comprehensive verification of the entire assembled structure.
If we use special crimping devices for mechanized joining, durable fixation of joints of coupling fittings is guaranteed for a long time.
Docking couplings are made of pipes with a small diameter corresponding to the sizes of reinforcing bars. For twisting with a key, the upper surface has the appearance of a hexagon. An inch thread with a minimum pitch is cut inside. The use of pipes with thick walls allows you to cut the turns of the required depth and ensure the strength of the connection. Experts consider coupling fittings to be the ideal solution for overlapping pins.
Assembly steps for longitudinal reinforcing pins with threaded couplings
- Couplings of appropriate sizes are purchased and equipment is being prepared.
- A thread is cut at the ends of the rods.
- The fittings are installed in the working position.
- The coupling is wound at one end.
- The second end is wound.
- The node is tightened to extreme positions.
- Build quality is checked.
In order to prevent future problems with the condition of the frame, it is necessary to tighten the reinforcing assemblies with high-quality and special keys.
The fittings connected by the coupling method form a very strong connection. For such an assembly, there is no need to hire expensive specialists. Simply connect the prepared ends of the pins and secure with the appropriate metal cylinders.
Benefits
- The ability to connect the rods at any angle.
- Special connecting devices increase the intensity of assembly work.
- Identical connectors guarantee a high-quality docking process.
- The economical use of reinforcing pins.
- Connection blocks are used without restriction.
- A simplified visual method for controlling the quality of joints.
- Regardless of the concrete array, the reinforcing cage maintains integrity.
- No need to hire qualified welders saves financial resources.
- Strength is distributed evenly over the entire length of the pin.
- Features of the equipment used reduce construction time.
- Thread cutting is carried out by universal devices by rolling or stamping.
Installation of coupling fittings greatly simplifies and accelerates the process of erecting monolithic buildings. Practice proves that a bar tens of meters long, assembled by coupling fasteners, is not inferior in reliability and strength to a solid (not divided into segments) rod.
Coupling Pipe Fittings
Today, the building materials market offers a wide selection of pipe fittings made of different materials: time-tested, strong and durable cast iron, less resistant to mechanical damage to steel and brass. Pipe fittings made of aluminum, nickel and titanium alloys are less popular. Lightness, ductility, low price is characterized by polymer fittings. Boilers and valves made of porcelain, ceramics and glass can boast of resistance to any chemicals.
Choosing the locking elements of the coupling fittings for the pipeline, it is recommended to focus on the material of pipe production. With the same material, many indicators coincide:
- The chemical composition of the liquid.
- Galvanic neutrality of all pipeline elements.
- Resistance to mechanical damage.
- Thermal identity.
Hand-operated coupling fittings
It is customary to call a manual drive a flywheel or a handle mounted on a valve spindle bushing, on a valve spindle, on a drive head roller or a built-in electric drive roller.
The manual valve moves the valve shutter. Such systems are installed in convenient service areas.
More often, remote manual actuators are used, which allow controlling valves with any diameter installed in inaccessible places.