Modification, marking and dimensions of polypropylene pipes

Over time, gradually, but surely, water supply and heating systems from metal are transferred to polymers. It is noteworthy that the sizes of polypropylene pipes are calculated in mm, and not in inches, as was done earlier (you can calculate in any units, but documentation is created in the metric system).

We mentioned PPR for good reason, since we’ll talk about it, that is, about modification, labeling and dimensions that are used to transport liquids of different temperatures. If you are interested, more detailed information is below. And besides, you will see a video in this article that will clearly demonstrate our topic.

PPR

Marking of polypropylene pipes

• The most popular products of this type are marked with PPR, as seen in the photo above, and this is all due to the very high heat resistance - such products are used for hot and cold water supply, as well as heating systems. Whatever it was, in any case, the first letters of the abbreviation will be PP. But you can meet PPH or PP-1, which means that the products are made of homopolymer (the first generation product for cold water). You can also find the symbols of PPB, which indicates the possibility of applying for hot water and heating.
• PN symbols indicate nominal pressure in bar. For example, if PPR is polypropylene, a pipe is 110 mm and other diameters are designated as PN20, then its working pressure is 20 bar, which is 2 MPa or 20.4 kg / cm². Among all the symbolism in this case, there are four categories - PN10, PN16, PN20 and PN25. And the first two are made with a uniform wall, and the last two in the middle or closer to the surface have a reinforcing layer, which is made of fiberglass or aluminum foil.
• In addition to the basic data, the marking also indicates auxiliary, such as the name of the manufacturer, class, outer diameter and wall thickness, the normative document of this product.

Note. It should be said that PN10 and PN19 are produced without a reinforcing layer, which serves not to increase the resistance to internal pressure, but as protection against PPR deformation when heated.

Geometric parameters

Size chart for polypropylene pipes PN10, PN20 and PN25

Pay attention to the table and you will see how the geometric parameters change depending on the nominal pressure with the same external section.

For example, a polypropylene pipe of 20 mm, here:

• PN10 will have an internal diameter of 16.2 mm, a wall - 1.9 mm;
• PN20 - inner diameter 13.2 mm, wall - 3.4 mm;
• PN25 - inner diameter 13.2, wall - 4.0 mm, but here the external cross-section increases a little - in this case it turns out to be 21.2 mm.

Similarly, the geometric proportions of other sections change, for example, polypropylene pipes 32 mm:

• PN10 will have an internal diameter of 26.0 mm, a wall of 3.0 mm;
• PN20 - internal diameter of 21.2 mm, wall - 5.4 mm;
• PN25 internal diameter of 21.2 mm, wall - 6.0 mm.

And again, PN25 will be slightly thicker than the conditional section - it will already be not 32 mm, but 33.2 mm.

Note. Considering the fact that the reinforcing layer of aluminum foil is not in the middle of the wall, but closer to the surface, and the PN25 section slightly exceeds the conditional one, before welding the products with the coupling, the instruction requires cleaning the solder spot from the top PPR layer and the foil. To carry out such a procedure with a knife will be extremely difficult, so in such cases use a special shaver of a certain diameter.

The depth and time of soldering, depending on the size

As you understand, when installing PPR polypropylene - a pipe of 50 mm, 32 mm or with other parameters, must be welded for joining through fittings. But a certain section of the product implies a certain depth of landing its end in the fitting.

Also, the retention time of parts during welding and after it during freezing depends on the section. You can determine the depth of the product fit in the fitting and its holding time using the upper table.

Welding parameters are extremely important for each size, because if PPR is polypropylene - a pipe of 16 mm of nominal internal diameter is pushed into the fitting more than expected, then due to flattening of the walls, the permeability will be reduced, or the passage will be blocked at all. If this happens in a tee or chetverike, then the end will simply block the perpendicular outlet, which also threatens to decrease the patency or congestion.

Application

In addition to our usual use of polypropylene pipes for water supply and heating systems, which are often many homemade craftsmen assemble their own hands, they are also used for outdoor sewage systems and ventilation of premises.

For example, for sewage drains use PPR with a diameter from 40 mm to 110 mm, with a typical length of 5 m. docking is done here using couplings with rubber seals, and the product itself can be either smooth-wall or corrugated.

For ventilation ducts, as in the top photo, they use the same diameters as for external sewage, but only here the section configuration can be not only circular, but also oval, square or rectangular. The main requirement for ventilation ducts is not increased strength and low heat transfer capacity, but low weight.

Conclusion

When choosing polypropylene pipes, you certainly will not pay the last attention to the cost of the material. In this case, you should bear in mind that the price is not only the size and nominal pressure of the walls, but also on the brand. Brand manufacturers always sell their products more expensive, although in quality they may not be inferior (and even overtake) completely unknown beginner manufacturers.