Eurotubi Pressfitting System - Technical Guide ... - Damstahl

In water heating systems the “closed circuit” must be guaranteed, so that the oxygen is not able to be
introduced from external sources. In these conditions carbon steel pipes are not subject to internal corrosion.
Any small amount of oxygen that penetrates when filling, during the heating of the water, is freed and must
be evacuated from the system through the vent valves. Furthermore special additives must be used, which
stop oxygen from causing corrosion.
However, such systems must always be kept filled, even when not operating, or should be emptied and kept
dry, to avoid both air and water being in contact with the metal, a situation that can lead to corrosion. On this
point, after the system has been emptied, it is worth passing forced dry air through the interior, to ensure
complete drying.
Resistance to bimetallic corrosion
Carbon steel components can also be used in mixed installations with non-ferrous metals, such as copper,
aluminum, etc. Importantly, direct contact between carbon steel and stainless steel must be avoided, as this
situation may give rise to bimetallic corrosion. This risk can be reduced by inserting a non-ferrous joint
between the two metals or it can be completely eliminated by using non-ferrous spacers at least 50 mm in
length.
It is absolutely forbidden to create systems with joints in stainless steel and carbon steel pipes, or vice versa.
Resistance to external corrosion
Carbon steel components present an external galvanised or hot zinc plated coating which, however, does
not guarantee on its own a long lasting and effective protection from corrosion. Protection from corrosive
agents must be obtained through insulation, painting or plastic coating on the pipes. In the absence of
protection, a prolonged exposure to moisture, particularly for chased installations, may cause internal
corrosion. It is therefore necessary to cover the pipes with a closed-cell coating or with anti-corrosion tape,
making sure that no part remains uncovered or detachment areas form between the insulating material and
the pipe, where condensation may generate. Felt sheathing must not be used as it holds moisture and
encourages corrosion.
10.4. Carbon steel installations for sprinkler fire fighting and other applications
Carbon steel does not require additional anticorrosion protection in any of the other applications foreseen for
its use.
Note. Please bear in mind that Eurotubi advises against using carbon steel for cooling system due to the
considerable risks of corrosion induced by condensation on the cold pipes.
11. SYSTEM COMMISSIONING
11.1 Testing
After installation and before covering, insulation or painting, the system must undergo testing to ensure its
suitable carrying capacity and seal integrity. The test method and result must be necessarily documented in
a report (see annexes 1-4 of this guide).