Connecting plastic pipes with metal

Principles of connecting pipes

1. Threaded. When connecting small diameter pipelines, it is recommended to use connecting elements, for which the metal pipe is intended for threading, and for polymers - a coupling.
   

   To form a reliable tight connection, the thread on the metal pipeline is wrapped with linseed or hemp fiber rope impregnated with linseed oil.

2. Flanged. It is most often used for large diameter pipelines due to the ease of installation compared with other types of connections.

Piping features of plastic and metal pipes

The connection of plastic pipes to metal pipes is carried out with the help of special fittings, the device of which includes internal or external threads for metal, and a coupling for soldering plastic.

Connection diagram for piping using fittings:

• The old coupling is removed from the metal tube, or some of it is cut off, after which the edges are cleaned and lubricated, and then a new thread is made with a thread-cutting tool.
• The thread is cleaned, then a spool or a special tape is wound up, it is smeared with silicone on top. The ends of the ribbon or fiber should follow the thread of the
• . The fitting is installed without tools to prevent damage. If there is water leakage after winding the part, it is necessary to strengthen it.

Details for the connection of polypropylene are very convenient for the arrangement of turns and bends of pipeline networks in all directions. Because of the properties of the material. From which such fittings are made, the shape of the part can be changed by heating it by less than 140 degrees with a construction hair dryer. When carrying out this operation, it is necessary to take into account the possibility of overheating of the polymer and prevent it.

When installing heating systems or hot water systems, it is worth remembering that the plastic is capable of expansion and contraction under the influence of temperature, so if the pipes are laid in a closed way, it is necessary to provide an opening between the pipe and the wall, using tubular insulation. Pay attention to the places of connection pipes - tees, contours.

Flange connection

Connections of this type are separable and are often used for pipes larger than 40 mm in diameter. The connection of plastic pipes to metal pipes is carried out using metal flanges or welded to the edges of pipelines of flanged bushings.

This connection is used to connect pipelines to valves, pumps and other parts of the system, as it provides easy and quick disassembly of the connector during maintenance or repair work.

For pipes made of polymers, most commonly used are free flanges, which rest on the shoulder. The connection of metal pipes to plastic is carried out by flanges of steel, the size of which is the same as the size of metal pipes.

When selecting parts for the flange connection to plastic pipes, it must be remembered that the flange surface must be smooth and free of clamps to prevent damage to the polymer.

Characteristic features of flange connections:

• For plastic medium and high density pipelines of diameters less than 150 mm and less than 300 mm for low density pipes, it is recommended to use free flanges supported by straight flanges
• To increase the reliability of the connection, use straight beads with cone transitions
• Forlarge diameter pipes( more than 200 mm) use free flanges resting on the conical collar
• A wedge-type connection using shaped flanges is used for laboroprovodov all diameters

Compound plastic pipes with metal by means of flanges made as follows:

1. pipe smoothly trimmed at the connection
2. Loose flange fits over the conduit from
3. metal is then necessary to establish a lining of rubber so as to go beyond the slice boundary is greater than 10 mm.
4. The flange is put on the gasket and screwed to the other flange with bolts.

The bolts must be tightened with the same force, taking into account the flanges and other parts recommended by the specifications themselves.

Connections with flanges and threaded connections are characterized by their ease of implementation. In order to connect pipelines from different materials, you do not need to have professional skills and, if you follow all the recommendations, everyone will be able to do this work themselves.