Pipes and fittings for gas overview of options
The above requirements force the use of the following types of pipes and fittings in household gas pipelines:
Steel fittings and pipes
Steel pipes and fittings are renowned for their durability. At the same time, for domestic gas pipelines, it is possible to use not only seamless rolled products, but also welded pipes, the strength of which is slightly less than that of the hot-rolled or cold-rolled version.
Steel pipes and fittings
The inner diameter of gas pipes is usually no more than ½ inch. After all, the gaseous medium has practically no viscosity. That is why most corner mates and tie-ins connect pipeline elements at a right angle.
Fittings for gas pipes made of steel are designed for threaded (detachable) or welded (one-piece) installation. The last option (one-piece installation) involves the formation of an annular seam applied to the cutting of the joint between the fitting and the pipe using gas soldering or electric arc technology.
And yet - such installation can be used only on long sections of the pipeline itself, beating joints, tie-ins or corner mates. But the fittings to the gas meter, as well as the connecting elements of consumption points, can only be detachable.
Detachable installation is carried out as follows: on the body of the pipe, a clamp is cut with a die, onto which a lock nut and a fitting (with an internal thread) are screwed. Moreover, the junction is pre-sealed with a polymer tape (FUM) and pressed (for reliability) with a lock nut. Threaded fittings for gas equipment are also mounted according to the same principle, by screwing the connecting elements onto the threaded outlet of the stove or boiler.
After the assembly of the gas pipeline is completed, the system is primed and painted yellow. Although in everyday life the yellow marking, which is mandatory in production, can be replaced with any other color scheme.
Rubber and polymer hoses with metal fittings
Rubber or polymer hoses are used to supply gas pipelines to consumption points. That is, a steel pipe reaches a certain mark, onto which a valve is screwed, and a flexible pipeline - a hose - is placed between this point and the fitting of the gas-consuming device.
In this case, the gas hose is supplied complete with already fixed compression fittings, for internal or external threads. Therefore, the installation of the gas pipeline section (where the hose will be used) is carried out immediately.
To do this, apply FUM to the fitting with an external thread and screw it into the valve. After that, you can screw the fitting with an internal thread onto the fitting of the gas appliance (wrapped with the same FUM).
Rubber and polymer hoses with metal fittings
If you made a mistake and chose the wrong fittings for gas hoses, then adapters will help you - a sleeve (two external threads) and a fitting (internal and external threads). But the use of adapters reduces the strength of the structure, so before installation, think again about which fittings should be on the hose.
Polymer pipes and fittings
Polymer pipes are easy to cut, withstand enormous pressure, have no seams and are mounted on welded fittings using a conventional soldering iron.
At the same time, the pipe is afraid of mechanical damage, but is not subject to corrosion. Therefore, polymer gas pipelines are used in the installation of underground utilities and the connection of a domestic pipeline with a medium-pressure main gas pipeline.
Metal pipes and metal fittings
Metal-plastic pipes, in most cases, are used in the construction of water pipes or mains of domestic heating systems.
However, this type of pipe can also be used when assembling a domestic gas pipeline.After all, metal-plastic pipes withstand a pressure of 4.5 MPa and are easily mounted on threaded or compression fittings.
Moreover, it is best to use compression fittings in gas pipelines, which maintain tightness during the entire period of operation. But threaded fittings unwind over time, turning from a reliable connecting element into a source of threat to the safety of homeowners.
The main advantage of metal-plastic pipes is the high corrosion resistance of such products and the equally high flexibility of the pipeline body. As a result, corner fittings are not needed during installation - metal-plastic gas pipes can be bent at any angle, even by hand.
Features of gas pipe connections of various types
Connection options and the use of a particular type of fitting depends on the material from which the pipes are made.
For gas lines can be used:
- steel pipes, brass or cast iron fittings;
- rubber flexible hose, metal crimp bushings and fittings;
- polyethylene pipes marked with a yellow stripe, brass fittings, fittings for welding and electrofusion elements;
- metal-plastic pipes and press fittings.
metal pipes
Components for the construction of external gas pipelines are made of steel. For their installation, metal fittings made of cast iron or brass for welding or threaded are used. Moreover, the first connection option is preferable, since it is the most reliable.
FUM tape is used for tightness.
Flexible hoses
It is acceptable to connect to devices using rubber pipes, but the fittings for connecting them use metal crimps, which are usually equipped with flexible hoses, these are ordinary fittings of a suitable diameter. When connecting, pull the hose onto the fitting with force and secure with an aluminum clamp. Solidol can be used to create tightness.
plastic pipes
The use of polymer pipes in gas pipelines is less common, although the anti-corrosion properties of these products and ease of installation, as well as resistance to pressure drops, would seem to be very important qualities for a gas pipeline. However, plastic is afraid of mechanical damage, therefore, such pipes are used mainly for laying underground utilities when connecting household systems to a gas main that has an average load.
metal-plastic
Metal-plastic pipes also meet the requirements, they do not rust, withstand pressure up to 4 MPa, they can be easily bent, simply mounted on threads or compression fittings, so you can save on corner fittings. Therefore, these pipes are also quite suitable for the installation of a household gas line. For installation use a special tool and press fittings.
Choice of gas fittings
Various fittings for gas equipment and docking of individual elements of the system are not suitable for every pipe. Connection to the gas pipeline and its branching to the points where various devices operating on blue fuel are installed are carried out by those products that are most suitable for each other.
For steel pipes
If a steel pipe is used during the installation of the gas pipeline system, the fittings for it are taken from the same material. The element size is ½ inch, which is enough for unobstructed gas flow.
The fitting and the steel pipe are connected in two ways - threaded detachable and welded one-piece. The second method is used for joining and fastening together the structural parts of the gas pipeline by welding them with an annular seam between adjacent elements or using electric arc technology.
If it is necessary to create a temporary connection at the connection point of a gas stove or boiler, the threaded method is used. To begin with, on the pipe, with the help of a die, a squeegee with turns is cut.To ensure tightness, a sealant (fum-tape, tow) is placed over the entire area. Screw on the locknut, and then the fitting. In the same way, they make attachment points for gas equipment by connecting the fitting to the threads on it.
It is required to paint the pipe to prevent its destruction under the influence of harmful factors. Inside the room, you can choose any color, and it is customary to paint the outer areas in yellow.
For polyethylene pipes
When creating a gas supply from polypropylene pipes, plastic fittings are used, they are connected by welding. Such a system is durable and tight. To carry out all the work, you will need special equipment. During installation, adjacent elements are heated and glued together, becoming one.
To create a detachable connection, combined fittings are used, which on the one hand are a polypropylene base, on the other - a metal thread. First, one side is welded, and then the gas equipment is connected by screwing the coupling onto the coils.
Due to the need to connect pipes of different diameters, docking elements are produced in different sizes.
For metal-plastic pipes
When working with metal-plastic pipes, brass fittings are used, which have high strength and a long service life. As in the case of metal and polypropylene systems, fastening is carried out using a one-piece and detachable method using various products.
The most reliable and easy to use are press fittings equipped with a special capsule around the fitting.
Connection of a geyser with a gas pipeline: educational program
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Types and characteristics
There are many different devices designed for the installation of gas pipelines. According to the type of connection fittings are:
- Threaded (cylindrical). They are screwed onto the gas pipe and provide for preliminary sealing of the joints with flax, fum-tape, etc.
- Welded cast elements fix the seam over the joint.
- Electrofusion machines are equipped with a spiral, which, when current is supplied, heats up and welds the parts from the inside.
- Flange fittings are used when connecting steel elements of large diameters. A distinctive feature is the ability to disassemble the connection at any time.
- Crimp adapters are the most reliable connections. They provide tightness even when exposed to vibration.
- Press fittings are equipped with a fitting and a sleeve, which, after installing the end of the pipe, is clamped until it is completely fixed.
- PVC fasteners come in a variety of configurations.
Depending on the location and purpose of the location, the fittings are divided into:
- Couplings designed to connect elements with the same diameter.
- Bends and corners - provide a change in the direction of the pipe at a given angle.
- Tees - are installed in order to create one additional branch.
- Crosses - designed to equip a branch in two directions.
- Adapters - help to connect pipes with different diameters.
- Plugs - are installed if it is necessary to create a tight connection at the end point of the system.
- Fittings - used to fix a flexible hose.
When choosing gas pipeline elements, it is necessary to take into account the requirements of regulatory documents governing the installation and operation of these structures.
Installation
Establishing connections by different methods has its own rules and nuances. If you decide to do the work yourself, you must carefully study each process.
The simplest is the installation of a structure made of polypropylene pipes. To implement it, you will need a special soldering iron.After connecting two adjacent plastic parts, it is put on the joint and heats the material to a predetermined temperature, at which it sticks together, but does not have time to melt.
To make a threaded connection, it is necessary that the pipes have an external thread. Fittings are used with internal threaded turns. After sealing the attachment point, one part is screwed onto the other until it stops.
The method of connecting metal-plastic systems with the use of crimp fittings is fundamentally different. To do this, the pipe is cut into segments of the desired size, the edges are cleaned and a crimp collar and nut are put on them. After the pipe is stretched to the maximum on the fitting, it is partially fixed by installing the clamp, and then the nut is tightened until crackling appears.
