Skip to main content

The drain mystery

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 happened because the pits formed continued to grow through the thickness of the material, which finally gave way and fell down the drain. The shape of the circle to the top left is distorted and we can observe a small nick in the circle. There is also a variation in the widths of each of the sections between the circles - all because of corrosion.

Then, there is the green color. This is the corrosion product ferric chloride. A quick look shows the green formation around the part between two holes at the top right. General corrosion is visible, and there may be pitting going on underneath the corrosion products.

We will have to wait and see if that small section is the next to break off.

UPDATE: It did break off.

Comments

Popular posts from this blog

What is a Corrosion Loop - PART 1 - CONCEPT

Corrosion loop is used to simplify inspection procedures in refining processes. Corrosion loop is defined as a group of components with common materials, processes, and operating parameters.  Source: Rachman, A. and Ratnayake, R.M.C. (2020), "Corrosion loop development of oil and gas piping system based on machine learning and group technology method", Journal of Quality in Maintenance Engineering, Vol. 26 No. 3, pp. 349-368. https://doi.org/10.1108/JQME-07-2018-0058 It is needed when the scenario has - 1. Complex process 2. Several variables such a materials of construction, process parameters, functions 3. Multiple damage mechanisms WATCH THE VIDEO FOR A DETAILED EXPLANATION - Click here for part 2 ! https://corrospective.com/ 😀Happy learning! 😀

3 steps to begin experiments...aka...I am lost in this lab!

  All the students in the first few days of research are faced with the dilemma of the right time and way to begin experimentation. There are as many ways and thought processes to do so as there are people. I will share my learnings here. The problem is that the literature review tends to become so vast that it is difficult to decide what the exact problem is. 1. The best way is to NOT WAIT for the literature review to get over. Begin with the experiments simultaneously. Gain experience on as many new techniques as possible. 2. Start with that research paper which will most likely form the basis of your work. Attempt to reproduce the experiments in the paper. Try to see what other experiments can corroborate those results. 3. Select the correct research papers to continue the literature review. P.S. All the experiments should have a reason for doing them. You should be able to answer the question 'Why should I do this experiment? What will I learn?'

Corrosion risk planning - 2 - Above ground storage tanks - oil and gas- PART 2

 Above ground storage tanks - PART 2 9.      Splash plate corrosion at welds atmospheric corrosion coating damage, if applicable pitting due to chloride salt deposition in marine environment 10.      Spiral staircase corrosion at welds of individual bars and critical joints to the tank coating damage and delamination cracks near welds uniform corrosion at exposed surface near delamination galvanic corrosion near weld/staircase/tank interface due to dissimilar alloys 11.      Manometer corrosion of screws, nuts, and bolts used for attachment possible moisture penetration in case of cracks due to improper handling 12.      Manhole Internal corrosion due to water either as a moisture or as storage product External coating damage due to moisture penetration, dust, rainfall, UV radiation Coating damage at fixtures and edges galvanic corrosion at nuts and bolts due to dissimilar alloys atmospheric corrosion at area where coating...