Condensate Corrosion and then Protection

Condensate recovery is amongst the areas of energy levels conservation hence widely used in sectors today. Condensate still is made up of about twenty percent of filled steam, in fact it is distilled water, almost free from dissolved hues. Therefore , the recovery offers advantages to boilers which include reducing fuel costs, reducing chemical treatment, conserving water, and increasing furnace efficiency. Non-contaminated condensate, which can be the product from non-contact heavy steam application, comes back to steam boiler's program as give food to water. You will find two types in condensate receiving system for boilers supports the pressurized condensate program and the gravity-vented condensate program. The thumb steam from high pressure condensate is hauled by heading back this condensate to the deaerator while the gravity-vented condensate comes back to the boiler feed aquarium.

Oxygen Episode

Often people stated due to its pureness in nature; steam condensate requires not any chemical cure, but is the fact so? Condensate is rust and can be dirtied by rusts, something that hardly any people are knowledgeable. Sometimes, condensate can be slightly acidic. This is exactly why condensate dispatch deteriorates more rapidly than steam piping. Air corrosion takes place in condensate piping seeing that pitting, which is the most damaging form of corrosion.

The reaction of oxygen invasion is:

4Fe + 6H2O + 3O2 4Fe(OH)3
Carbonic acidity thins condensate pipes and causes grooving in the bottom section of the pipes. The results is, when a condensate line has greatly pitting, the condensate is rich in oxygen, although if the pipe divider is thinning, the condensate pipe is afflicted with carbonic acid solution attack. Nonetheless where do oxygen and carbon dioxide on condensate conveyor originate from? Are not all mixed oxygen and carbon dioxide on boiler normal water arrested by artificial means by the deaerator and chemically by salt sulphite as well as DEHA from the boiler? In fact, there are two main reasons due to this phenomenon. First, when water vapor condenses, the flow amount shrinks thereby allowing o2 to infiltrate and break up. Secondly, o2 can also be pulled into condensate system throughout condensate pumps, leaking temperature exchangers, and vents of condensate acquiring tanks.

Acidity Corrosion

Carbon can imbed in the same way because oxygen, on the other hand, the main origin of carbon dioxide for steam certainly is the breakdown of bicarbonate and carbonate alkalinity in boiler water to make carbon dioxide.

Listed below are the typical reactions that be held:

Carbonate reaction: CO3 & H2O CO2 plus 2OH
Bicarbonate reaction: 2HCO3 + high temperature LASER + 2H2O
Carbon dioxide mixes with vapor, condenses for condensate to form weak carbonic acid, and lowers the pH. Condensate is so natural that also small amount of poor carbonic acidity can drop the pH to 5. 5.

The reaction is:

In Malaysia, there was a case in a petrochemical industry in which less than twenty percent of the condensate was came back into the furnace because of carbonic acid infiltration. In furnace, acidic condensate lowers pH, erodes alloy, increases break down iron, and increases the total dissolved hues (TDS) while iron bicarbonate. Iron bicarbonate mixes with boiler water to form straightener oxide and carbon dioxide, and therefore the carbon dioxide mixes with steam yet again. That is why many people cannot take care of a high pH in their central heating boiler despite doubling the dosage of caustic soda. This trouble in condensate recovery can be disadvantageous to steam boilers and have to be prevented.


Protection of after-boiler condensate lines is necessary. condensate range can be reduced by unstable amines because corrosion blockers. Volatile amines commonly used intended for 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 the commonly used normalizing amines is cyclohexylamine. Recording amines, alternatively, form protective films at metal surface types and shield from o2 attack, similar to the way magnetite film does. A good example of filming amines is octyldecylamine. Having oil-like property, filming amines cover the metallic surface with one-molecule solid. Filming amines have no affect on condensate pH. Carbon dioxide and oxygen are definitely more corrosive in combination. Accordingly, if a system faces both much needed oxygen and acid attacks, different both amines is always recommended.

Besides chemical treatment, condensate quality monitoring should be included on the daily or weekly basis. Have a test of condensate to monitor straightener content, hardness, and TDS. Check for color and get. Any change indicates the wrong type of treatment or perhaps contamination. Condensate is not viewed to remove disease, therefore , to counteract iron hydroxide infiltration; magnet filter could be applied to eliminate it from condensate. Total iron bars in central heating boiler feed normal water for medium sized pressure boiler should be minimal than zero. 05 ppm, and any increase could mean flat iron hydroxide infiltration from the condensate line. Pertaining to boiler operating below 2 0 bars, a recommended alkalinity rating is one hundred and forty to six hundred ppm. If the alkalinity level exceeds seven-hundred ppm, bicarbonate and carbonate will tenderize producing co2 and drive in steam, as stated ahead of. However , the best method is to remove the alkaline firmness (carbonate and bicarbonate) conclusively by using the reverse-osmosis system or maybe demineralization.


Finally, condensate is rust and detrimental to condensate piping. The risk happens when plenty of steam technicians, based on decent boiler drinking water field-test success, feel comfortable with their boiler mineral water treatments. A few engineers by no means seriously consider or simply realize the damage that can happen to their very own condensate creases. This is a heavy negligence. The moment leaks following leaks happen to be detected, it can be too late and costly fixes would be inescapable. It is the remedying of condensate go back that makes it needless to replace condensate piping for several years.