March 18, 2016 admin

Cause of Corrosion

Corrosion caused by oxygen – Preven Corrosion

Corrosion has always been an inhibiting factor in advanced building materials and structures. It has caused us great trouble in modern industries ranging from automotive to construction. Oxygen Attack or corrosion caused by oxygen is a serious concern for your heating appliances. Let us take a look at what it is and how to delay or even prevent corrosion caused by oxygen:

What it is?

An oxygen attack is an electrochemical process which enables the temperature to rise so much with additional energy that chemical reactions are accelerated on metal surfaces.This results in quite quick and severe corrosion. Dissolved oxygen in water is the key catalyst and potentially dangerous for your heating appliances.

Oxygen attacks inside the boilers

The metal surface of your boiler system is always vulnerable to oxygen attack. It is the most common source of corrosion inside your boiler system. As the temperature rises, so does the chances of oxygen attack in the boiler system. The three factors that lead to oxygen attack in the boiler system are: Presence of moisture,presence of dissolved oxygen and unguarded metal surface.

Dissolved oxygen forms certain localised corrosion areas known as pits. These oxygen pits cause the metals to fatigue and fail. When the boiler’s internal surface is heated, the dissolved oxygen in feed water can become very aggressive and forms these pits on metal surface. Oxygen attack can lead to failure of critical parts of the boiler system such as steam drums, mud dams, boiler headers and so on. Not only does oxygen corrode the boiler system, it also dissolves the iron surface which impairs the metal site. Henceforth, dissolved iron reaches inside the boiler and causes dysfunctions such as overheating and tube failure. Corrosion caused by oxygen can be in a localised region or it can impair the whole functioning of the boiler system.

Ways to prevent corrosion caused by oxygen

Oxygen attack has been a severe threat to your boiling and heating systems. Here are some ways to prevent it:

Controlling oxygen

The amount of oxygen in the boiler feed water is reduced by heating it to reduce its solubility. Furthermore, a Deaerator is used that removes most of the oxygen from the system. Still, small traces of oxygen remain that may cause corrosion. Oxygen scavengers may be added to feed water to further reduce the amount of oxygen. This method has been quite efficient and is used widely.

Coating the metal

Organic and inorganic coatings have been used to protect equipment, dealing with oil and gas to prevent corrosion. Asphalt enamel, sacrificial coating, nickel coating, etc. can be used to protect the metal surface from moisture thereby, protecting it from oxygen attack.

Interrupting the corrosion process chemically

Neutralising inhibitors such as amine, ammonia and so on can be used to hinder the oxygen attack. These inhibitors will absorb themselves to the metal surface and act as barriers for the harmful corrosive elements. The chemical layer has been proven to be quite thick and effective in keeping corrosion at bay.

For further ways to prevent corrosion click here