DIY welding technology for polypropylene pipes: an overview of methods and nuances

Want to repair or replace communications made of polymer pipes? Agree that it’s not bad to save on the call of the master by assembling a new pipeline yourself. But you do not know how you can connect the individual elements of the system among themselves and what is needed for this.

In our article, the technology for welding polypropylene pipes is described in detail - any novice plumber can connect them with their own hands. We will tell you what to consider, how to use a soldering iron to dock plastic elements. Let me show you in which cases other methods are used.

To help the novice master, we selected detailed video clips demonstrating the step-by-step process of welding polypropylene, and photo illustrations.

Pipes and assembly accessories

One of the indisputable advantages of polymer pipes is ease of assembly.

Installation of elements can be done almost everywhere: laid openly on walls or placed hidden under the floor.

If the welding of the water pipes made of polypropylene is carried out correctly, then the assembled system will regularly serve for several decades without repair

Polymer pipes are available in diameters from 20 to 110 mm. For household purposes, products most often used are 20/25/32/40 mm in size. The field of application determines the indicator of the nominal pressure of the material.

In the marking, it is indicated by the letters "PN":

• PN 10 - choose to equip cold water supply.
• PN 16 - used for cold water, but with a higher pressure, as well as in the arrangement of the "warm floor" system.
• PN 20 - products, the only limiter of which is the temperature regime of liquids transported through them. It should not exceed 75 ° C.
• PN 25 - universal products used for arranging both “cold” and “hot” systems, the temperature of which reaches 90 ° С.

On sale you can find polymer products equipped with additional reinforcement.

Reinforced products are used for laying in long sections in conditions where it is necessary to reduce the linear expansion that occurs when temperature fluctuations

The main feature of polymer pipes is the impossibility of bending them.

Therefore, all changes in the trajectory of the laid highway are carried out only from straight sections interconnected by auxiliary fittings:

• crosses - for the possibility of branching the main stream;
• tees - stream multipliers;
• couplings - for connecting pipes in a straight section;
• bends - for changes in the direction of the pipeline.

The fittings can be equipped with an embedded metal thread, which makes it possible to connect the polymer pipeline with metal elements.

To make the seams as strong and tight as possible, it is important to ensure exact matching of the diameters of the joined elements

When choosing auxiliary elements, two parameters should be taken as a basis: the internal section of the products and the thickness of their walls. These parameters should correspond to the technical characteristics of the polypropylene pipes used.

Methods of joining polymer pipes

When joining pipes made of polymeric materials, depending on the installation conditions, one of two methods is used:

1. Soldering - involves heating and joining the molten ends of the elements.
2. No soldering - involves connecting pipes by means of compression fittings or by implementing the so-called “cold” welding.

The second installation method is convenient in the sense that for its implementation there is no need to use special equipment. All work can be done using a simple tool - a crimp key.

A polypropylene pipe with a wall thickness of more than 4 mm and a diameter of more than 50 mm is connected using the butt welding technique:

Connection tools

The main tool used to connect plastic pipes is an iron for welding. This is a kind of soldering iron, powered by a 220V network. The principle of operation of the device is quite simple. The role of the heating element of the iron is performed by a welding heater, placed in a metal casing.

It warms up to a predetermined temperature the stove, which heats the nozzles. The temperature controller is responsible for maintaining the optimum temperature of the nozzles. Soldering and typical mistakes made when joining polypropylene pipes is devoted to next article, which we advise you to familiarize yourself with.

The iron is a compact and lightweight welding device equipped with seats for placing a sleeve for pipes and mandrels for fittings

Included with the iron are heating nozzles of standard sizes. Heating up to a certain temperature, they soften the propylene to a viscosity that will ensure a tight connection of the elements.

Nozzles are selected depending on the diameter of the pipes used:

• The 20th size - for pipes with a diameter of half an inch;
• 25th - for products with a diameter of 0.75 inches;
• 40th - for elements with a cross section of 1.25 inches.

Since the cost of such a welding machine is quite high, and it is not necessary to use it so often already, it makes no sense to purchase equipment. It is better to rent a tool for a day or two.

For high-quality cutting and preparation of the welded sections, it is best to use a special tool designed for this - pipe cutter. With its help, you can get a smooth, smooth and beautiful cut.

The role of the cutting element of the pipe cutter is performed by a stainless steel blade; for ease of use, the tool is equipped with a rubberized handle

For lack of a pipe cutter, work can be done with a grinder or a hacksaw for metal. The only thing - at the place of the cut after such tools, fringe remains. But it will not be difficult to remove it by stripping a strip of sandpaper.

In addition to the basic tools for the work, you will also need:

• square;
• building tape;
• a simple pencil or marker.

When planning to connect pipes using the cold welding method, it is necessary to purchase thermoactive adhesive made on the basis of polyester or epoxy resin or its thermoplastic analogue made on the basis of rubber in advance.

The main stages of soldering technology

The key conditions for a successful installation of plumbing or heating system of polymers are a careful calculation of the required material and well-made welding of elements.

Stage # 1 - calculation of material and components

To facilitate your work, thereby minimizing installation errors, the first thing you need to do is draw a diagram of the future system, indicating the number of turns and branches on it. When calculating the number of pipes, 25-40 mm spent on “penetration” should be added to each length of the segment.

The price of polymer products and the shaped elements necessary for their installation is low, and therefore, in case of defective soldered pairs, which often arise at the beginning of operation, it makes sense to make a small margin

If you have not yet had to weld polypropylene pipes, experienced specialists recommend that you even purchase several pipe sections for preliminary training. Such costs will come at a low price and will avoid gross errors during the installation of the system.

Feature polypropylene pipes is an increase in the coefficient of linear expansion under the influence of high temperatures.

As a result: when heating or increasing pressure inside the system, the pipes lengthen and begin to sag over time. To prevent this phenomenon, when laying sections longer than 4-5 meters, it will also be necessary to use compensators.

Compensators are “П” -shaped connecting elements that look like wrapped loops that ensure the reliability of the system during its operation

Compensators are installed both on horizontal and vertical sections, mounting them between two fixed supports. If necessary, it is possible to purchase compensators of a special modification, which can eliminate linear expansion at the angular bends of the pipeline.

We will find out how to properly weld polypropylene pipes so that there are no leaks at the joints.

Stage # 2 - soldering pipeline elements

Briefly the essence of welding technology polypropylene pipes lies in the fact that under the influence of high temperature the ends of the docked elements are heated and by tight pressing against each other are connected.

To create a strong connection when performing soldering, the pipe itself is heated from the outside, and the auxiliary elements involved in its joining are heated from the inside. In the figure, the order of the actions: 1 - mark up; 2 - warm up the desired number of seconds; 3 - we connect 2 segments with each other; 4 - we maintain the recommended number of seconds before cooling

Before starting work, pieces of pipes cut to the specified length eliminate bumps and burrs. If a layer of internal or external foil is provided in the pipe, it must first be cleaned with a crosscutter equipped with well-sharpened and adjusted knives.

When performing stripping using a crosscutter, the pipe must be deepened into the tool until it stops.

Do-it-yourself plastic pipe welding work is performed in the following sequence:

1. Connect soldering iron for PP pipes to power supply in order to warm up the equipment to the optimum temperature of 260-270 ° C.
2. The pipe segments to be joined are simultaneously put on the nozzles, ensuring the most even entry. This work should be done quickly and confidently.
3. Having withstood the time specified in the instructions until the fittings and pipe ends melt, they remove the elements from the heating nozzles.
4. Dock the molten ends together, gently squeezing each other for 15-20 seconds.
5. Bonded parts are left in a static position so that the seam cools completely and the joint becomes monolithic.

You can determine the duration of heating from the instructions supplied with the equipment or by using the table below.

The duration of heating to achieve complete polymerization of the docked elements depends on the diameter of the products and the thickness of their walls

It is impossible to neglect the requirements for heating time indicated in the table. Insufficient warming is not able to provide a reliable connection. Excessive overheating will cause the polypropylene to “leak” and the parts to deform.

As a result: protrusions are formed on the inner surface of the welds, which will significantly reduce the diameter of the pipeline.

In order to be able to control the depth of entry of the segments into the heating element, thereby reducing the likelihood of a defect, it is desirable to pre-make cuts at their ends. Legend: 1 - heating of two segments of a polypropylene pipeline; 2 - timely removal of pipes from the soldering iron; 3 - connection of two elements with each other; 4 - the depth of the joint is marked on the pipe to make the correct connection

After completion of polymerization and solidification, which takes about 20 seconds, the joint is ready. Using the same technology, all subsequent nodes are soldered to the bitter end, while the heating system or polypropylene water supply will not be fully assembled.

Temperature parameters soldering PP pipes are given in the article, which independent home masters should definitely familiarize themselves with before starting work.

Quick photo guide for welding PP pipes

The following selection of step-by-step photos will help to visualize the sequence of work on assembling a polypropylene pipeline and connecting its parts:

Typical installation errors

The main mistakes that beginners make when working with polymer products:

1. Heating parts. At the time of heating, the parts should be located in the most even position. The slightest displacement can adversely affect the operational parameters of the entire plumbing system.
2. Dock polymerized ends. When pressing the molten ends of the elements, you cannot rotate the parts around its axis. This can lead to the seam being not strong enough.
3. Alignment. When joining the elements, only a slight adjustment of their alignment is allowed, the duration of the procedure of which is no more than 1-2 seconds.

Another important point: when soldering fittings with fittings, it is necessary to take into account the location of the valves, providing them with a free full stroke.

Heated polypropylene cools so quickly that in an hour from the moment of completion of installation, you can safely supply water to the system

If after joining the elements as any kind of seam doubts arise, it is better to cut the joint and redo it.

It is better to eliminate defects at the stage of installation of the structure, since it is much more problematic to replace a leaking joint in a running system.

Assembly of elements without soldering

The use of compression fittings and modern adhesives makes it possible to carry out the installation of polypropylene pipes efficiently, quickly and with minimal material investment.

Option # 1 - installing a compression fitting

To implement this method of connection, you will need to purchase compression fittings and use a crimp wrench.

Compression fittings are equipped with sealing clamping rings, which act as dampers in the event of shock impulse loads (unlike simple union nuts)

Installation of compression fitting includes three main stages:

1. A blue nut is put on the end of the pipe cut off at right angles and deburred.When placing a white crimp ring, it is necessary to give it a position in which the thickened part is directed towards the tail of the pipe.
2. The pipe is inserted into the fitting until it stops, pushing the clamping ring to the maximum.
3. Tighten the blue nut, "baiting" it first by hand, and then booster with a key.

The assembly of compression fittings does not require special knowledge and skills. Products are delivered ready for installation for sale. Their installation can be performed under any temperature conditions.

Option # 2 - gluing elements

The adhesive method is used to assemble a water supply system, along which it is planned to transport only cold water. To apply the method of "cold" welding, you will need to use the "aggressive" adhesive composition type LN-915.

The glue is able to dissolve the surfaces of the joined parts by one third, thereby creating conditions for cold diffusion welding

In order to protect the skin of the hands from accidental ingress of the composition and “corroding” of its active components, gluing procedures are best performed with protective gloves.

The sequence of actions when bonding products:

1. Check the correspondence of the cut angles of the joined sections and mark the places for gluing with a pencil.
2. The ends of the pipes to be joined are cleaned and degreased.
3. An adhesive layer is applied to the ends of the pipes and to the area of ​​the flares of the fittings in an even layer.
4. Cuts of pipes are inserted into the holes of the fitting, focusing on the marks made in pencil. The structure is kept in a fixed position for three minutes, after which excess composition is removed with a napkin.
5. The combined elements are laid out on a flat surface and left for 5-6 hours until completely dry.

Run water to check the quality of bonding is possible only a day after completion of installation.

When implementing this installation technology of PP pipes It is important to observe two basic conditions: temperature and humidity conditions. All work must be performed at an air temperature of +5, +35 ° C. When gluing in hot weather, work should be done as quickly as possible so that the glue does not have time to dry before installation is completed.

Conclusions and useful video on the topic

You can learn about the intricacies of the processes of soldering and gluing pipes from the following videos:

Video # 1. How to solder pipes:

Video # 2. Water supply assembly without soldering:

Work on self-aligning polypropylene pipes, even for a novice master, should not cause special difficulties. It is only necessary to clearly and conscientiously comply with all technological standards. And then the pipeline assembled by yourself will please you with trouble-free operation.

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