How to combine a plastic pipe with a metal one. Connection types

At carrying out capital repairs it is quite often necessary to carry out partial or full replacement of water pipes and sewer systems. Due to the high cost of materials, homeowners decide to connect the old metal elements of the pipeline with new plastic pipes. Despite the fundamental difference between these materials in physicochemical characteristics, today there are several options for implementing this idea.

Special fittings will be required to connect the plastic and metal segments of the pipeline

When there is a need for such a combination

The need to connect plastic pipes with metal may arise as in the repair and modernization of existing pipelines, and in the construction of new ones. Experts call such typical cases, in which without such docking can not do:

• uncoordinated actions of different contractors can lead to the installation of elements of communication systems, made of different materials;
• usually, metal terminals of household and industrial equipment are connected to plastic pipes;
• with partial replacement of emergency communications;
• when it is necessary to connect the pipeline to the process equipment, which has a critical temperature for plastic products;
• during the construction of sections of highways, which are exposed to high mechanical and thermal loads.

As you can see, the cause of these cases are various factors. Therefore, the methods of the most reliable connection of pipes directly depend on the purpose and type of pipeline.

Features of application of metal products and polymer pipe products

Properties of any, including metal pipes, determined by the characteristics of the material, used for their manufacture:

• cast iron was used when laying the pipeline not so long ago in Soviet times. It is still considered a fragile material. The cast iron pipe is easy to break with one more or less strong blow. However, products with a relative novelty - High-strength Cast Iron with Spherical Graphite (abbreviated VCHSHG) - the level of impact resistance can be compared with the value of this parameter of the steel pipe;
• steel. This material is subject to corrosion, and on the inner surface of the elements of the pipeline made of it, accumulations of dirt and impurities are formed;
• Stainless Steel. It is still the most expensive metal, employees for many years, but difficult to handle.
• galvanized steel has proven itself in terms of resistance to corrosion, but professionals note the difficulty of installing pipes made of it.

Steel pipes are used for pipeline installation in the modern world, as on durability they practically have no competitors

Plastic elements of pipelines are also divided into several types:

• polypropylene details. Not demanding in care and easy to install. Often purchased material;
• polyethylene are suitable for plumbing, and for laying the sewer;
• PVC products are used for laying sewers of autonomous type;
• metal-plastic pipe products.

Useful to know! Restrictions on the use of PVC pipes are due to the fact, that they do not withstand the circulation of large streams of water.

Types of joints between metal and plastic pipes

Today, there are two ways to perform this procedure:

1. Threaded connection. Applies, when connecting pipe products, whose diameter does not exceed 40 mm.
2. Flange connection. Optimally with a large cross section of pipes, as tightening the thread in such cases requires considerable physical effort.

Features of threaded connections

To understand, how a plastic pipe is connected to a metal one by a thread, fittings should be studied, used for these purposes. Essentially, such a detail is an adapter. On the other side, to which the metal pipeline will be connected, the fitting has a thread. On the opposite side is a smooth clutch, to which the plastic pipe is soldered. Models are also available, by means of which it is possible to make connections of various highways in greater quantity and fittings for performance of bends and turns.

The threaded coupling is selected depending on the type of plastic pipe - for soldering, with crimp or compression connection

To connect a steel pipe to a polypropylene pipe, you need to follow the following steps:

• remove the coupling with steel communication at the site of its intended connection to the plastic branch of the pipeline. You can also cut a piece of old pipe, apply solid oil or oil and make a new thread with a thread cutter;
• walk on the thread with a rag, fasten a layer of fume tape or rags on top, cover the surface with silicone. Wind on the thread 1-2 turn so, so that the edges of the seal go along their course;
• screw the fitting. Perform this operation with a plastic to metal pipe adapter without using a wrench. Otherwise, the product may crack. If, when you open the tap, leaks will appear, tighten the adapter.

The convenience of the design of this part is, that it simplifies the procedure of connecting metal pipes with polypropylene on turns and bends. Interesting, that if necessary the form of a fitting can be changed. Heat it with a construction blow dryer to a temperature +140?C and provide this part with the required configuration.

Flange connection

As mentioned above, large diameter metal and plastic pipes are connected in a similar way. The final design is collapsible. The technology of such connection of a plastic pipe from a metal without a thread is just as simple, as in the case of a threaded adapter.

• Carefully and evenly cut the pipe at the intended connection;
• put a flange on it and install a rubber gasket. It will act as a sealant;
• Carefully slide the flange onto this sealing element;
• do the same with the other pipe;
• fasten both flanges to each other with bolts.