Condensate Corrosion and Protection

Condensate recovery is amongst the areas of energy source conservation therefore widely exercised in business today. Condensate still consists of about 20% of fats steam, along with being distilled mineral water, almost without dissolved solids. Therefore , their recovery provides advantages to boilers that include reducing gas costs, lessening chemical treatment, conserving water, and increasing boiler efficiency. Non-contaminated condensate, which is the product in non-contact heavy steam application, earnings to steam boiler's system as give food to water. There is two types from condensate getting system during boilers supports the pressurised condensate system and the gravity-vented condensate system. The adobe flash steam right from high pressure condensate is recovered by going back this condensate to the deaerator while the gravity-vented condensate returns to the central heating boiler feed reservoir.

Oxygen Invasion

Often people stated due to its pureness in characteristics; steam condensate requires virtually no chemical cure, but usually so? Condensate is corrosive and can be infected by rusts, something that a small number people are mindful. Sometimes, condensate can be a little bit acidic. This is exactly why condensate piping deteriorates faster than heavy steam piping. O2 corrosion happens in condensate piping since pitting, which is the most harmful to your home form of corrosion.

The reaction in oxygen assault is:

4Fe + 6H2O + 3O2 → 4Fe(OH)3
Carbonic acidity thins condensate pipes to result in grooving at the end section of the pipes. The end result is, when a condensate tube has predominantly pitting, the condensate is rich in oxygen, however if the pipe structure is thinning hair, the condensate pipe suffers from carbonic acid solution attack. Nevertheless , where perform oxygen and carbon dioxide for condensate conveyor originate from? Are definitely not all wiped out oxygen and carbon dioxide through boiler standard water arrested by mechanical means by the deaerator and chemically by salt sulphite or perhaps DEHA inside the boiler? Basically, there are two main reasons due to this phenomenon. First, when steam condenses, the flow size shrinks thereby allowing o2 to bypass and melt. Secondly, much needed oxygen can also be driven into condensate system through condensate heels, leaking warmth exchangers, and vents in condensate obtaining tanks.

Acid solution Corrosion

Carbon can bypass in the same way since oxygen, even so, the main source of carbon dioxide in steam is a breakdown from bicarbonate and carbonate alkalinity in furnace water to create carbon dioxide.

Here i will discuss the doubts that be held:

Carbonate effect: CO3 & H2O → CO2 & 2OH
Bicarbonate reaction: 2HCO3 + warmth → CARBON DIOXIDE + 2H2O
Carbon dioxide blends with water vapor, condenses through condensate to form weak carbonic acid, and lowers the pH. Condensate is so natural that also small amount of poor carbonic chemical can drop the ph level to five. 5.

The reaction is:

In Malaysia, there was an incident in a petrochemical industry exactly where less than 20% of the condensate was go back into the boiler because of carbonic acid infiltration. In central heating boiler, acidic condensate lowers ph level, erodes metallic, increases waste iron, and increases the total dissolved shades (TDS) when iron bicarbonate. Iron bicarbonate mixes with boiler water to form iron oxide and carbon dioxide, and consequently the carbon dioxide mixes with steam yet again. That is why some people cannot maintain a high ph level in their central heating boiler despite duplicity the dosage of caustic soda. This problem in condensate recovery is disadvantageous to steam central heating boiler and should be prevented.


Protection in after-boiler condensate lines becomes necessary. Corrosion during condensate range can be minimized by unpredictable amines as corrosion inhibitors. Volatile amines commonly used to get condensate range protection today are normalizing amines and filming amines. Neutralizing amines react with carbonic stomach acid and carbon to increase condensate pH to 9. One of many commonly used normalizing amines is definitely cyclohexylamine. Filming amines, however, form defensive films about metal types of surface and defend from fresh air attack, similar to the way magnetite film does. An illustration of this filming amines is octyldecylamine. Having oil-like property, filming amines coat the sheet metal surface with one-molecule dense. Filming amines have no impact on condensate pH. Carbon dioxide and oxygen are certainly more corrosive in combination. Accordingly, if a system face both breathable oxygen and stomach acid attacks, a blend of both amines is always suggested.

Besides chemical substance treatment, condensate quality monitoring should be included on the daily or regular basis. Take a test of condensate to monitor golf club content, firmness, and TDS. Check for coloration and purchase. Any transformation indicates poor treatment or maybe contamination. Condensate is not cared for to remove damage, therefore , in order to avoid iron hydroxide infiltration; permanent magnet filter can be applied to remove it from condensate. Total straightener in central heating boiler feed water for low to medium pressure central heating boiler should be reduced than zero. 05 ppm, and any increase may possibly mean in terms of iron hydroxide infiltration from the condensate line. Meant for boiler operating below zwanzig bars, a suggested alkalinity standing is one hundred forty to seven-hundred ppm. If the alkalinity level exceeds 800 ppm, bicarbonate and carbonate will breakdown producing co2 and drive in water vapor, as stated prior to. However , condensation reaction is to remove the alkaline solidity (carbonate and bicarbonate) decisivelydefinitively, determinately, once and for all, once for all by using the reverse-osmosis system or perhaps demineralization.

Bottom line

Finally, condensate is rust and harmful to condensate piping. The danger happens when plenty of steam engineers, based on fantastic boiler normal water field-test outcome, feel comfortable with their whole boiler mineral water treatments. Some engineers do not ever seriously consider and even realize the damage that can happen to their condensate creases. This is a significant negligence. Every time leaks soon after leaks will be detected, it truly is too late and costly repairs would be inevitable. It is the treatment of condensate give back that makes it needless to replace condensate piping for quite some time.

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