Pitting Corrosion Boiler Tubing

Our customer the Serbian Heating Plant Sabac wrote the following report:

SUBJECT: Installation of Merus ring on boiler number 1

In our compay we have 3 large boilers on which we encounter the phenomenon of '' pitting corrosion''.

In cooperation with the company HPL DOO, ŠABAC, we installed in September 2020 on the supply line of boiler number 1 a MERUS Ring, type HCI, size 2''.

According to the representative of the above-mentioned company, the ring is very effective in preventing the occurrence of limescale, corrosion, as well as in preventing oxygen corrosion or "pitting corrosion'', which is our biggest problem when operating boilers.

Being skeptical about the functionality of the ring, the representatives of the company "HPL doo" suggested us to install the ring on a trial basis. Until the end of the heating season, during the overhaul in 2021. During the emptying and cleaning of the boiler, the condition of the boiler surfaces will be determined and compared with the condition before the heating season and the other two boilers. Based on the results obtained on the efficiency of the ring. We will decide on the purchase of the same. Since we had pictures of the condition of the boilers at the end of the previous heating season 2019/20, we decided to compare them with the pictures at the end of this heating season 2020/21.

Pitting is stopped

pitting corrosion boilerNow that we have opened the boilers, an inspection in the boiler itself. Having made a comparison of the pictures of the same surfaces, we can say that the ring is as effective as claimed by the representatives of the company ''HPL DOO''. On the surfaces of the tubes there are no more ''yellow coatings'', under which oxygen corrosion occurs and craters are formed in them. On the contrary, the pipes are covered with a black film of magnetite, which acts as an anti-corrosion agent.

When inspecting the areas in boilers number 2 and number 3, we find that this situation has not changed compared to previous years. The surfaces have ''yellow coatings'', which means that oxygen corrosion ''pitting'' is severely destroying the pipes.

Based on the above, we believe that it is necessary to purchase a Merus ring for all three boilers. In order to protect the flue tubes in the boilers, thus saving important material resources for their replacement. We have done this process several times and know how complicated it is in terms of preparing documentation and permits, as well as how much it costs.

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