Connection of polypropylene pipes with metal pipes

The connection of polypropylene and metal pipes plays a big role in replacing the water supply and heating system. In most apartment buildings, metal is mainly used for sewage and water pipes. This material quickly rusts, accordingly the passability of pipes decreases, leaks begin. In plastic, the shelf life is about 50 years. But replacing pipes is not as easy as it seems at first glance. The best option would be to change the entire riser, but this requires the consent of all tenants. As practice shows, this option is rarely possible to implement. Often tenants carry out a plastic insert into the general water supply system only in their apartment.

Connection options

There are two ways to combine metal with plastic: using thread or flanges. Each of the methods has its own characteristics. For example, the threaded version is ideally suited for pipes with diameters up to 40 mm. In other words, for residential apartments. Docking between pipes is carried out using a special adapter - fitting. This device is ideally suited for combination joints. On the one hand, it is made in the form of a smooth coupling for polypropylene, on the other hand, a threaded connection.

Flanges are only suitable for large pipelines over 100 millimeters in diameter.

Threaded

This type of plumbing connection is called "American." On the coupling side, plastic is soldered. By the way, are considered plastic polypropylene, metal-plastic, polyethylene and polyvinyl chloride pipelines. The metal part is respectively threaded. Here's what it looks like in practice:

• Installation begins with unscrewing the coupling at the site of the intended joint. If there is no coupling, then the pipe is simply cut off. Then at the junction it is necessary to cut the thread. To do this, it is recommended to lubricate the point of entry of the thread cutter with oil or solid oil.

• The threaded joint must be sealed to prevent possible leaks. This is done using fum tape or linen, which is wound between the threads. For greater reliability, silicone is applied on top. The amount of wound material should not exceed 1-2 turns. Otherwise, it will be problematic to screw the fitting. Winding flax or fum tape must be clockwise.
• Then they screw fitting. This is best done by hand, without using a gas key. The fittings are made of a rather brittle material, and excessive compression can damage the adapter. The best solution is to slightly extend the fitting if leakage is detected after water has been supplied. But remember that you must use the tool with extreme caution.

• On the smooth coupling side, the polypropylene pipe is welded.
• Water is supplied to the pipes.

Tip. If a threaded connection is used for the heating system, it is recommended to replace the rubber gasket on the coupling side with silicone. Temperature changes will quickly destroy the rubber, and water will flow at the junction of the pipes. Silicone in this regard looks more reliable.

Flange connections

The basis of this method is the docking of a steel pipe and a plastic insert with a detachable device - a flange. A flange in the form of a sleeve is inserted into a metal pipe, a cap flange is attached to it with bolts with a transition to plastic. This is done as follows:

1. The insertion point is determined and a neat pipe cut is done. Irregularities at the cutting site must be treated with a grinder.
2. Inspect the flange in the form of a sleeve, smooth the sharp edges with a file. This precaution will protect the plastic pipe from damage. Only after this the flange is installed in place.
3. Another flange with an adapter for polypropylene pipes is attracted to it by bolts. A rubber gasket is installed at the junction. The fixing bolts are tightened without unnecessary effort.

To make a pipe connection of different materials, anyone can afford. But if you are not sure that you can do the job efficiently, it is better to contact the plumber.