The connection of polypropylene pipes with metal pipes: methods, tools, equipment, recommendations

Overhaul of an apartment or private house can often be associated with a complete or partial replacement of water pipes. In old buildings, they are most often metal, but now, as a rule, polypropylene products are presented on the market. Therefore, the owner faces the question of how to connect polypropylene pipes with metal pipes?

When may a polypropylene pipe connection be required with a metal pipe?

A similar need may arise both during the repair and modernization of an existing pipeline, and during the construction of a new one. Without the connection of polypropylene pipes with metal can not do in the following cases:

• the work of several contractors at the same facility, their uncoordinated actions and the use of pipes from different materials;
• the presence of metal findings of household and industrial equipment;
• partial replacement of emergency communications;
• the need to connect the pipeline to technological equipment that operates at a temperature critical for polypropylene pipes;
• laying of main pipeline routes, which in the future will be subject to increased mechanical and thermal loads.

The reasons for the need to connect pipes from different materials are different, therefore, the joining method should be selected optimally to the existing conditions.

Features of the use of metal and polypropylene pipes, their differences

The operational characteristics of the pipeline directly depend on the metal used for its manufacture. Most often it is:

• Cast iron, from which communications are made in buildings erected in Soviet times. The material is fragile, the pipe can be broken by a strong blow of the hammer.
• Steel is susceptible to corrosion, and dirt and various impurities can accumulate on the inside of such pipes.
• Stainless steel, which is the most expensive but difficult to process material with a long service life.
• Galvanized steel - such pipes are difficult to install, but this is leveled by excellent performance.

Despite the strong differences, the connection of polypropylene pipes with metal pipes can be easily performed. But when choosing, it should be borne in mind that polypropylene pipes are not resistant to high temperatures (the limit value is +80 ° C) and their differences. Therefore, most often such a pipeline is mounted only in residential premises.

Types of connections

To connect polypropylene pipes with metal pipes, two types of connections are used:

1. Threaded docking. For this type of connection, a special adapter is used - a threaded coupling. It is suitable for working with pipes with a diameter of less than 40 mm. In this case, fittings having a different design are used. This part is an adapter from a metal pipe to a polypropylene pipe, which has thread for fastening a metal pipe on one side and a smooth sleeve for polypropylene on the other. If necessary, the shape of the fitting can be changed by heating it with a building hair dryer to a temperature of +140 ° C. Also on sale are fittings for connecting pipes of different highways, to perform bends and turns.
   

2. Flange connection. This type of joint is selected when using large diameter pipes. A feature of this design is the ability to disassemble it if necessary. The flange is a collapsible part, consisting of a sleeve for a metal pipe, a cap piece for transition to plastic and a set of bolts.

   
3. Threadless coupling. Such a coupling consists of several parts:

- steel or cast iron housing;

- two nuts located on both sides of the housing;

- four metal nuts inside the coupling cavity;

- rubber gaskets that serve as sealants (their number may vary).

Necessary tools and materials

Before direct work, it is necessary to prepare tools and supplies. To connect polypropylene pipes with metal pipes you need:

• polypropylene pipes of the desired diameter;
• angles of 90 ° and 45 °;
• clips for fixing polypropylene pipes to the wall;
• drill;
• grinder with metal discs;
• thread cutter - a tool for cutting threads on metal pipes, the kit includes the functional part, which is a round frame in the form of a short cylinder, a set of dies or screw clamps, holders, clamps, pliers and other similar tools may be present;
• fum tape;
• tow;
• silicone sealant;
• couplings (American 1/2 is most often used), fittings, flanges;
• special scissors for plastic;
• roulette;
• construction pencil;

The technology of connecting polypropylene pipes with metal

You can do all the work yourself. In this case, you must first carefully select all the elements of the future design. It is also recommended to study the advice of specialists:

• Do not tighten bolts and nuts, as this may lead to cracks in the polypropylene;
• it is necessary to ensure that burrs and sharp elements are absent on the parts of the fittings for metal pipes, since they can cause damage to polypropylene structures (if such defects are found, the surface must be cleaned with a file);
• When upgrading the heating system, it is recommended to replace the rubber gaskets with silicone ones.

Mounting threaded fittings

To perform this work, you need to follow the instructions:

1. Remove the existing coupling from the metal part of the communication. If this was not possible, then you can simply cut off a piece of the pipe, after which put a solid oil on the saw cut, and then use a thread cutter to make a new thread.
2. Wipe the thread of the fitting for metal pipes with a rag, place fum tape or tow on top, and then cover with a layer of silicone sealant. Sealant must be laid along the thread.
3. Screw fitting. Using a key in this case is not recommended, as there is a risk that this part will crack due to excessive force. You can tighten the fitting for water pipes after turning on the system.

This method is most effective when installing pipes of different materials on bends and bends.

When using this type of pipe connection, it should be remembered that polypropylene products can expand when exposed to temperature (for example, if the heating system was installed). This means that when placing pipes under a layer of plaster, it is recommended to leave a gap of 1 cm using tubular insulation. This is especially true for places around contours and tees.

Flange use

The technology for mounting flanges is simple. To connect the pipes:

1. Trim the metal tube at the future joint. The cut should be as even as possible, for which you can use a grinder.
2. Place a flange on this part, and then install the rubber gasket. The last part will serve as a seal.
3. Slide the flange onto the rubber gasket.
4. Perform the same steps with the polypropylene pipe.
5. Connect the two flanges using suitable bolts. This should be done evenly and alternately, while it is recommended to ensure that there are no distortions and displacement of parts. Excessive effort is not necessary.

Use of threadless coupling

First you need to prepare gaskets, washers and nuts, which should correspond to the cross-section of the pipeline elements. After that, you can proceed to the installation of the coupling without thread according to the following instructions:

1. Through nuts, through gaskets and washers, insert metal and polypropylene pipes into the coupling on both sides.
2. Tighten the nuts all the way, while making sure that the gaskets are fully clamped.

Such a connection, subject to technology, will be durable and durable.

You can join the elements of the pipeline yourself. To do this, you need to select parts of a suitable size, while it is worth considering the diameter of the pipes (metal and polypropylene pipes at the same time, since there are connecting elements with different connectors on both sides), prepare the tool and follow the instructions. Test run of the system will help determine the quality of the connection.