Little by little, multilayer pipes are making their way onto construction sites. But do they all look alike? Here is our guide to choosing a multilayer Carbon Steel Pipe Fittings, which details the important criteria.

1. The thickness of the steel core of the multilayer tube

A multilayer tube is made up of a Carbon Steel Pipe inserted between two synthetic material tubes. Depending on the thickness of the steel, the tube more or less retains its shape after bending. In renovations, the tubes circulate on the surface and must match the shape of the walls and ceilings. With a 0.4 mm steel core, we are sure that they keep it and that they resist shock well.

2. The nature of the plastic material of the multilayer pipe

In addition to ASTM A106 steel, multilayer pipes are made of PER (or Anglo-Saxon PEX) or PERT. Because it is crosslinked, PEX is more resistant to high temperatures. The “c” indicates the method of crosslinking by irradiation, which, according to Wikipedia, would be more respectful of the environment.

3. Pressure losses at the multilayer pipe fittings

In a copper tube circuit, diameter continuity is ensured at the fittings, because the ASTM A333 tube is inserted inside. But this is not the case with a multilayer network, because it is the fitting which, crimped, is inserted into the tube. The section is therefore necessarily reduced, causing pressure drops in the circuit that do not exist with copper.

This is why, with multilayer, it is recommended not to choose a diameter smaller than the recommendations of the DTU. To limit as much as possible the number of API 5L Grade B fittings - which the flexibility of the tubes allows. The more elbows are reduced - by bending tube - and fittings, the more pressure drops in the circuit are lowered.

4. The multilayer fitting/tube system

A multilayer X42 Pipe is a part of a system which, associated with fittings, even the crimping tool, has been the subject of a Technical Assessment. In other words, using the connector of one manufacturer and tube of another is a certainty, in the event of a problem, of not being able to benefit from any support from manufacturers and insurance companies.

Manufacturers offer, in addition to the 2-year legal warranty, an additional warranty if the professional has used a crimping tool certified by them. In some, several clamps can be certified, in others, only one. The brands of compatible crimping pliers are listed in the Technical Assessment.

5. The type of fitting

According to the manufacturers, the X52 Pipe fittings, mostly made of brass with stainless steel crimping rings, are endowed with functions intended to reinforce safety on construction sites. The crimping indicator is one, which generally consists of a collapsing ring, which the installer can see. Another feature is provided by a seal, which automatically creates a leak during the water pressure test if the fitting has not been crimped.

Certain connections also make it possible to visualize that the X65 Pipe is well fitted, that it is well in abutment.