A half-fitting is a type of installation connector composed of a loose nut, a sleeve and often also a gasket. It is used in water supply, gas and heating installations in buildings. In cold and hot water and central heating systems, a brass half-fitting is standardly used. It allows you to install a water or heat meter. Half-fittings made of stainless steel, polypropylene and PVC are also available. Learn about the types of half-fittings used in water installations, the mechanism of operation of the connector and its most important applications.
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Types of semi-screw fittings in hydraulics
Plumbing installations (water and sewage, gas, central heating) are subject to regular maintenance. Therefore, they should not only be easily accessible, but also dismountable/detachable in selected areas, enabling trouble-free disassembly of elements that may require replacement or repair. Thanks to this, it was not necessary to dismantle a large section of the pipeline. It is often necessary to disconnect installation elements in places where valves, sight glasses, flow meters, filters or pumps are connected. These types of parts are usually equipped with disconnecting connections made using screw connections and semi-screw connections.
The half-screw is a type of disconnecting connector. It consists of a nut with pipe thread and a sleeve. Can be connected to any pipeline element. The solidity of the connector and its correct size are very important for the tightness of the obtained connection. The half-fitting can be made of metal (brass, steel, cast iron) or plastic (polypropylene, PVC material).
Screw fittings are also used to create screw connections in irrigation installations. The union is a complete connector that consists of three threaded parts. It has threads on both sides. It can be available in a reducing version (reducing union) or with a change of direction (angular union).
How does a half-screw work?
There are many types of screw connections on the market, differing in their purpose and operating principle. Firstly, unions ensure effective and tight connections in the pipe infrastructure - in places requiring periodic inspection, maintenance or replacement of components. Bolted connections are detachable. They allow for easy disconnection of pipes and their rotation relative to each other, because the contact surfaces of the elements are pressed together using a nut (front clamping). The sleeve in the half-connection ensures adaptation to all fittings of the same diameter. The nut allows you to create a threaded connection with another receiver.
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Use of semi-screw fittings
Thanks to screw connections and semi-screw connections, elements of hydraulic installations can be easily dismantled in order to perform service work. Ensuring detachability is the most important distinguishing feature of this type of hydraulic connector! The use of unions and semi-screw unions significantly simplifies and speeds up the process of assembly and disassembly of pipe infrastructure elements. It also allows you to reduce the number of connections, which significantly affects the efficiency of work and the life of the entire installation. A typical example of the use of screw connections is the installation of a radiator (a special radiator half-fitting is used for this purpose), a pump and valves in a central heating system.
Flares and semi-flares are also used when replacing damaged parts of the piping system, when it was not possible to unscrew the pipe, so it was cut or it was accidentally damaged, e.g. drilled during construction work. The use of these installation fittings allows you to incorporate a new part into an existing installation and thus avoid the dismantling of a large section of pipeline.
Flares and semi-flares are also used to fasten hydraulic devices that are subject to periodic inspections and maintenance (e.g. pumps), may require replacement (e.g. valves) or are dismantled for legal verification (e.g. meters). To facilitate service work, these devices often have factory-built screw connections.
A special type of connector - a half-reduction nipple, allows you to reduce the thread size of the connected element. In the case of central heating installations, when the thread on the pipes is smaller than the connection thread of the heating device, the union will enable its installation in the system, ensuring a reduction in diameter.
Semi-screw fittings at the Onninen wholesaler
In the Onninen hydraulic wholesaler you will find straight and angular half-fittings made of brass, stainless steel, cast iron and modern plastics. All connectors have been carefully selected to ensure ease of installation, wide compatibility and uncompromising resistance and tightness of connections. We offer semi-screw fittings with various thread sizes, including:
You don't know which half-screw to choose? Contact us! We will help you match connectors to a specific installation.