Caustic embrittlement, Chemistry

Assignment Help:

Caustic Embrittlement: Caustic embrittlement is a type of boiler corrosion caused by using highly alkaline water in the boiler. During softening process by lime-soda processes, free Na2CO3 is usually present in small proportion in the softening of water. In high pressure boilers, Na2CO3 decomposes to give sodium hydroxide and carbon-dioxide.

  Na2CO3 + H2O = 2NaOH + CO2

And this makes boiler water "Caustic". The NaOH containing water flows into the minute hair cracks, always present in the inner side of boiler, by capillary action. Here water evaporated and the dissolved caustic soda concentration increases progressively. This caustic soda attacks the surrounding area, thereby dissolving iron of boiler as sodium ferrate. This causes embrittlement of boiler parts, causing even failure of the boiler. Caustic cracking can be explained by considering the following concentration cell. The iron surrounded by the dilute NaOH becomes the cathodes sides, which the iron in contact with concentrated NaOH becomes anodic part, which is consequently dissolved or corroded.

 

 


Related Discussions:- Caustic embrittlement

Anamalous behaviour of lithium, why lithium is the strongest reducing agent...

why lithium is the strongest reducing agent in alkali metals

Vespr, Give the name of the molecular shape of each of the following. (1 m...

Give the name of the molecular shape of each of the following. (1 mark each) 1) silicon tetraiodide

Acidic & basic radical, what is the chemistry of reaction for NH4+ with SO4...

what is the chemistry of reaction for NH4+ with SO4 2- and CO3 2- ?

Detect the presence of synthetic food colours, Q. Detect the presence of sy...

Q. Detect the presence of synthetic food colours in the given samples? Objectives After conducting this activity, you will be able to: • describe the kind of natural

The positive charge of an atom, The positive charge of an atom is: (1) ...

The positive charge of an atom is: (1) Spread all over the atom    (2) Distributed around the nucleus  (3)Concentrated at the nucleus (4) All of these Ans: Concentr

Soda lime glass and safety glasses, Q.   Write an account of soda lime glas...

Q.   Write an account of soda lime glass and safety glasses. Ans. Soda-Lime Glass or soft glass: It is the ordinary glass in which Na 2 O is added to the melt to oxide on hea

Independent and dependent variables, what is the difference between both in...

what is the difference between both independent and dependent variables?

Substitution reactions - types of organic reactions, Substitution reactions...

Substitution reactions Replacement of a molecule or set/group of the substrate by any another type of atom or group is termed as substitution reactions. Examples :

Postulate of bohr theory that electrons jump from one orbit, The postulate ...

The postulate of Bohr theory that electrons jump from one orbit to the other, rather than flow is according to : (1) The quantisation concept     (2) The wave nature of elect

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd