Corrosion is a serious issue. However, corrosion engineers are rarely asked about it during the designing of components. It is only when the components fail that people remember there are people who have studied corrosion for their whole life and would provide a solution. The design problems are really quite simple, and the loss of money could have been avoided had the company bothered to involve a corrosion engineer in the first place. Let me illustrate this with an example of a factory near the sea. Suppose a mild steel pipe is fitted inside the factory to transport 1 wt. % hydrochloric acid. The engineer has a choice between selecting pipes of 5 mm and 10 mm thickness. To save money, they go for the pipe with the 5 mm thickness because it has been 'successfully used by the other customers'. Over the course of a year, it is seen that the pipe has started leaking at certain places. Further investigation reveals that those sections have thinned to half of their thickn

I recently moved to a new house. As expected, there was a lot of cleaning up to do. One of the tasks was the cleaning of the washbasin. Usually, the drain is a circular part with  5 to 6 holes for the water to flow out. What I saw was this - I have not had a chance to analyse the material of the drain. However, a quick search tells me that this is most probably stainless steel. The water that this drain is exposed to is the bore water. Thus, the drain has encountered a lot of chlorides. There is general as well as localized corrosion. The damage started off as a simple process of pitting. Pitting due to chlorides is one of the most common headaches for poor stainless steel. They break the passive oxide film, and reach the underlying fresh iron. This iron then reacts with the usual suspects (ions, oxygen, water) and forms what we see as the rust. As can be seen in the picture, the thin sections of the drain between the holes have disappeared in three places. This may have happe

Corrosion is the journey of an element from its most active form to its most stable form.  The birth At the place of its birth, inside the earth, an element such as iron comes into contact with atmospheric oxygen, chlorides, sulphate, and moisture. and is quite happy to remain in peace with them in the form of Fe 2 O 3 , Fe 3 O 4 , FeCl 3 and such. The growth It is then extracted and made to go through a number of processes which separate it from the ions and bring it to its elemental form. It is then put into use to make steel, where it coexists with carbon, manganese, chromium, and other alloying elements. The interaction However, iron has three electrons that it desperately need to give away. That is exactly what it does the moment the steel is brought out from the factory and put outside in the shed. Iron is more than happy to reunite with its old buddies - oxygen and moisture. It gladly gives away its electrons to them and returns to its peaceful state of Fe 2 O 3  and Fe