Modern heating and water supply systems for apartments have long moved away from the use of cast-iron pipes. They were replaced by light, easy-to-use and corrosion-resistant plastic. It has been widely used due to its long service life and ease of installation. With a special apparatus and compliance with the technology of work, do-it-yourself welding of polypropylene pipes for beginners is not considered such a difficult task. Pipes of various categories are produced from pure polypropylene or with a reinforced inner layer of metal foil, which increases the strength of this material.
PP pipe categories
The outer surface of the product is marked, according to which it is easy to determine under what pressure this material can be operated.
There are the following types of polypropylene pipes:
- PN10 are pipes designed for cold water supply systems, as well as floor heating devices. These thin-walled products canwork at a pressure of 1 MPa.
- PN16 - withstand pressure of 1.6 MPa and temperature up to 64℃. These products are used as pipelines of a heating system with reduced pressure, as well as distribution of cold liquid.
- PN20 - are considered universal pipes that are widely used in both cold and hot water supply. Working pressure - 2 MPa.
- PN25 - aluminum foil reinforced pipes that can be used in any system at a pressure of 2.5 MPa.
Material features
Reinforced polypropylene is made using a special technology that allows the layers of material to be fastened together not by glue, but by perforation. Each manufacturer applies holes differently, which distinguishes pipes in quality. Due to this type of connection of the layers, the products are thin-walled, which significantly increases the fluid consumption.
The environmental friendliness of the material allows it to be used in the drinking system, without consequences for human he alth.
Methods of connecting polypropylene pipes
Depending on the equipment and materials used, do-it-yourself welding of polypropylene pipes can be done in the following ways:
- The diffuse connection method allows you to get the most reliable and durable welding seam. This method is based on the principle of material diffusion, which occurs due to the heating of the edges of the workpieces to the melting point. At the same time, the polypropylene of both parts of the productmixes with each other and after cooling forms a high-quality compound. A feature of the diffuse method is the ability to work only with homogeneous materials.
- Polyfusion connection is similar to diffuse welding. Only in this case, one of the two workpieces is heated by the contact of the welding machine.
- The socket method is used for joining pipes of small diameter. The diameter of the pipe to be connected is slightly larger than the internal section of the coupling, after melting and a little physical effort, the workpiece enters the coupling to the heating depth.
The method of joining welded surfaces is used when welding polypropylene pipes of the same diameter and the same type. The ends of the blanks must be located strictly coaxially. As a result of simultaneous heating and mechanical pressing on the workpiece, the polypropylene of the two pipes merges. Due to the need for a high-precision welding machine for welding polypropylene pipes at home, this method is almost never used
- In the coupling method, special-purpose equipment is used for connection - an electrical fitting. The two ends of the pipe, cut strictly at right angles, are inserted into the coupling. After applying voltage to the device, the parts are heated to the optimum value and the workpieces are welded together.
- The cold method is used when installing home plumbing with low working pressure. This view is more like the technology of gluing two surfaces. The inner edge of the fitting and the edge of the pipe are lubricated with an adhesive solution, after which the workpieces are connected and held until the glue hardens.
When welding polypropylene pipes with a diameter of 4 cm or more, it is very difficult to center and connect them, so special units are used, which are expensive and high-tech equipment operating in automatic mode.
Technological operations during welding
The most common is welding with fittings, in which the workpiece is inserted into a special fixture, which ensures a tight fit of the products. Main steps of welding joint:
- cutting blanks;
- preparation of surfaces for welding;
- setting up the machine for welding polypropylene pipes;
- direct welding process;
- cooling parts after joining.
Cutting pipes
The process of cutting blanks is carried out with a special tool. Although at home, the cutting stage is often performed with a hacksaw, a grinder or an electric jigsaw. With this method of cutting, the surface is obtained with large burrs, therefore, before welding polypropylene pipes, the edges must be carefully cleaned.
For novice installers, it is better to cut pipes with special scissors:
- The precision type model is very convenient to operate. It has a serrated blade and a special ratchet. Scissors allowget a good and even cut. But if you need to work with a large number of blanks, your hand can quickly get tired.
- Even better cut quality can be achieved by using the roller model. The cutting technology is carried out by a guide roller that rotates around the pipe. The negative feature is considered to be low cutting speed.
- Battery-type models combine all the advantages - quality and speed of cutting. They are equipped with a small electric motor and can be used for a large amount of work.
Large-diameter workpieces are cut with special pipe cutters, allowing you to get a high-quality and clean cut.
Preparing the workpiece for welding
Accurate adherence to the technological process when welding polypropylene pipes with their own hands for beginners is considered half the success of this work. Therefore, an important step is to prepare the surface of the parts to be joined.
Following a few recommendations will get a positive result:
- Welding of polypropylene pipes begins with marking and making a cut in the right place, of good quality.
- On the reinforced blanks, the metal top layer of the material is removed, otherwise the presence of the foil will not make it possible to obtain a reliable, long-term connection. The protection layer is cleaned with a special tool. If the reinforcement is made with a layer of fiberglass, then stripping it is not required.
- The inner side of the fitting and the edges of the pipe are degreased with an alcohol solution, as well aschecked for contamination or surface defects. Then the welding process itself is carried out.
Apparatus for connecting pipes by welding
Any machine for welding polypropylene pipes has a working surface that is heated by the action of electric current. The device may be equipped with one or more heating elements that heat various nozzles. It is these devices of different diameters that allow you to work with various pipes with one device. At home, this equipment is called an iron for welding polypropylene pipes.
As a rule, the devices have four sets of welding nozzles in the set, which allow you to connect almost any pipe used in domestic systems. Nozzles for welding polypropylene pipes are coated with Teflon, which eliminates the possibility of plastic sticking to them during heating. Self-manufacturing of these devices is impossible due to the complexity of the deposition process.
Six-shaped devices
Such inexpensive devices are designed to work in domestic conditions. They weld polypropylene pipes with a diameter of up to 40 mm. The appearance of the heating plates in many models is very similar to a household iron. The plates of the heating element have holes in which replaceable nozzles are installed.
Welding for polypropylene pipes positive feedbackcharacter refer to the PRORAB 6405-K model. It is distinguished by sufficient reliability and relatively low cost. Great for doing work at home. This device consists of a heating plate, a thermostat and a handle. The kit of a soldering iron for welding polypropylene pipes may also include additional equipment: a cutter, a device for chamfering, a device for removing reinforcement.
Cylindrical units
Models of this series are professional welding machines. Nozzles in such devices are mounted on an elongated side or straight cylinder.
Apparatuses with an L-shaped heater are used for welding in hard-to-reach places.
Of course, the high cost of such devices makes it difficult to use them at home, but many craftsmen still prefer to weld pipes with these devices. They provide high quality work with large diameter pipes.
Criteria for selecting devices
First of all, when choosing a device, it is necessary to correctly set the range of tasks that need to be solved during work. With a one-time use of the welding process at home, the purchase of an expensive professional apparatus is considered unprofitable. It is enough to have an inexpensive high-quality medium-power device.
Power of welding machines
The speed of the work is completely dependent on the rated power of the welding machine. Anythe device heats up to a predetermined temperature, so the power indicator of the device does not affect the quality of the connection. For home use, a device with a power of up to 1 kW is sufficient.
A more powerful fixture is brought to a state of readiness much faster after switching on, since any appliance needs time to make up for the loss of heat during operation.
Also high power is needed when welding large diameter workpieces.
Temperature and heating time
Obtaining a high-quality and durable connection of polypropylene pipes depends entirely on the correct choice of the heating temperature of the surfaces to be welded. The optimum is considered to be 260 ℃. If its parameters are deviated, surface damage may occur during operation and, as a result, leaks in the system.
At a low heating temperature, the fastening of parts is fragile due to weak melting of the material. Excessively high temperatures cause plastic deformation and sagging, resulting in a reduction in pipe diameter.
The heating temperature level is set by an electronic or bimetal thermostat.
The time of temperature exposure depends on the diameter of the pipes to be welded. It must be within:
- workpiece with a diameter of up to 20 mm is heated for no more than 6 seconds;
- to solder a 25 mm pipe, 7 seconds is enough;
- parts up to 32 mm processed in 8 seconds;
- 40mm products take 12 seconds to heat up.
Despite seemingly simpletechnology of work, you must always heed the advice of experienced operators. Before welding polypropylene pipes for beginners, it is better to practice on unnecessary pieces of workpieces, since the connection turns out to be one-piece, and poor-quality work can ruin the basic materials.
