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The Cause of Boiler Corrosion and How to Handle the Issue


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You can concentrate on serious issues like system failures or component failures when it comes to boiler maintenance. You must also watch out for boiler corrosion, a less evident but highly dangerous issue that can quickly worsen into your boiler’s catastrophic collapse.

Any iron in the boiler system that is in contact with water and oxygen will corrode. Due to the chemical reaction brought on by this mixture, the metal in the boiler tubes and associated pressure parts eventually corrodes and disintegrates, resulting in rust development.

What Causes Boiler Corrosion?

Pitting corrosion is a specific type of corrosion that can be very harmful. The beginning of a pit or patch of corrosion is a local anodic or cathodic point. 

This corrosion might be accelerated by oxygen present in the boiler’s water feed. When pitting is noticed, it’s crucial to make sure that auxiliary equipment like deaerators, feedwater tanks, and chemical pumps are in good working order. 

You should also ensure that no leaks have formed that could let freshwater or process impurities into the system.

If inadequate water circulation hinders the washing of caustic components from the boiler surfaces, crevice corrosion may develop close to fissures. This is more typical in boilers with big water tubes.

On the metal near a joint, another sort of boiler corrosion may manifest itself. This corrosion, known as galvanic corrosion, develops when metals with different electrochemical compositions come into electrical contact with one another in an electrolytic environment. 

This kind of corrosion is more frequently observed in hydronic systems where the boiler heat exchanger and pipework are made of different metals. This kind of degradation can be avoided by using a dielectric joint or another form of safeguard.

In a boiler, corrosion can also occur if the water’s pH is too high or too low. Caustic, corrosive damage occurs when a concentrated caustic substance dissolves and generates a high pH. 

When the boiler water’s pH is too low, acidic corrosion begins to form. Acidic corrosion can also be caused by cleaning supplies that are not handled properly.

How to Prevent and Control Boiler Corrosion

Even though boiler corrosion cannot be completely avoided, it is still vital and manageable to remove the factors that favour it. Your boiler will have the longest possible service life if you take proactive measures to stop corrosion from spreading.

You can keep track of the boiler’s performance and its supporting machinery with a routine boiler inspection program. Keep an eye out for things like variations in the water’s pH and temperature in the feed tank.

Check the system frequently for leaks and look for any indications of corrosion. Daily pH, hardness, and chemical checks should be made on boiler water, feed water, make-up water, and condensate.


You can get a heads-up on issues by looking at how these variables have changed over time. Your maintenance team may be relieved of the responsibility of monitoring by signing a contract with a reputable and professional chemical treatment business.

The majority of problems can be solved with adequate chemical treatment and gas removal using a deaerator or feed water tank. 

Regular boiler maintenance will provide you the chance to maintain your boiler clean and free of scale, rust, and corrosion while also alerting you to potential issues.

Climate Experts can take care of your boiler repair in Pickering! We’re a Canadian-owned and -operated company that installs, services, and maintains all major furnace and air conditioner brands. Call us anytime, as we’re available to serve you with 24/7 emergency service!

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