I was asked how many months ago there was a problem with a fire network that the pipes appeared in some parts with holes and erosion, although the network is not as old as it is clear from the attached pictures, so what is the reason behind this 👀?
The answer is simply summed up in several points:
01- Corrosion takes place in two ways, either through oxidation, and this is called general corrosion. It means that layers of rust form along the path of the metal as a result of its oxidation due to oxygen and water, and the second type is the result of the presence of types of bacteria 🦠 that cause corrosion, and this will be in certain parts of the network in what is called “microbiological influence” Corrosion (MIC)”
02- The second type of corrosion as a result of MIC bacteria is very dangerous because it can cause several problems, including: holes and cracks in parts of the network such as pipes and valves – the blockage of pipes as a result of the accumulation of layers of corroded iron parts and bacterial colonies, which affects the flow rate and pressure – Reducing the efficiency of the fire network to reach 60% in some cases – the corrosion rate will be much faster than the first type resulting from oxidation.
03- Types of corrosive bacteria: 3 types, including aerobic, anaerobic and facultative bacteria, where the first type needs oxygen to coexist and reproduce, while the second coexist without oxygen and the third coexist in the presence or absence of oxygen.
04- Bacteria 🦠 is not only present in water, but it can also be present in the different parts of the network that is being installed.
05- There are different types of bacteria, each of which is classified as different families and strains, and the bacteria work with several types of corrosive causes, including the decomposition of iron, including the reduction of sulfur materials to sulfides, and some of them produce acids.
06- The Mechanism that bacteria follow 🦠 to cause corrosion in the pipes is as follows:
A- Bacteria 🦠 enter the fire network 🔥 then attach to the wall of the pipe from the inside, then begin to form colonies and multiply.
B – It begins to secrete a polymer covering the inner wall of the pipe.
C- Anaerobic bacteria form under the polymer layer and are adjacent to the pipe wall and represent the anode.
D- Aerobic bacteria form on top of the polymer layer and are adjacent to water in humid systems or air in dry systems and represent the cathode.
f- Electrons are transferred from the anode to the cathode, causing the metal atoms to carry with it, causing corrosion to occur in the pipe wall.
E- The anaerobic bacteria adjacent to the pipe wall secrete acids that greatly help in eroding the pipe wall.
07- The MIC has a great effect in reducing the life of the fire network ⏰ and its problems may appear quickly if the amount of bacteria is large and the network has not been treated after its installation with appropriate antibacterials (problems may start to appear in the first year of the installation of the network).
08- A water analysis must be done to ensure the presence of bacteria 🦠 that causes MIC, and add the appropriate chemicals with the first filling of the network.
09- When an appropriate amount of chemicals is not pumped to kill bacteria, it may make bacteria more able to resist this type of material.
10- In the existing networks, when holes appear, as is clear in the pictures, the network must be evaluated 🩺 If the affected places are simple, they are replaced with washing the net and treating it with chemicals 💉 suitable for killing bacteria 🦠 But if the injury is severe and the network has leaks in many places, it will have to be completely changed And therefore a huge cost 💰 due to the failure to take the necessary measures from the beginning.
11- Choosing at the beginning of the design pipes 💧 with a large schedule or a high thickness does not reduce the risks of the MIC, but it will somewhat increase the life of the network ⏰ because the layer of metal exposed to corrosion is large.
12- Substances used to kill bacteria, the most famous of which are
- quaternary ammonium compounds
- organosulfur compounds
- bromines
- carbamates
- Isothiazalone
- phosphates
- chlorines
- Sodium silicate
I ask God Almighty to benefit us with what he teaches us.
good luck for everbody
(M. Ali Hassan 🔥🔥 #firematrix)
Source: Fire Protection Handbook – Sec15