What is Corrosion?- Oxidation is the reason for Corrosion. Oxygen content in the water or air in the system reacts with metal to form oxides which eat up the body resulting in formation of Cavities and holes.
A. Corrosion in Boilers
A1. Reasons for Corrosion in Boilers
· Improper and unscheduled maintenance in the system
Timely maintenance is required to prevent the corrosion in Boilers and Hot Water Systems
· Non treated Feed Water in Boiler System
If the feed water is not treated, removed oxygen from the water will accelerate corrosion
· Oxygen or Carbon Dioxide present in Water
· Unbalanced pH- Water Shall be maintained Ph value as recommended
Periodic maintenance and Water treatment is essential to control corrosion in Boilers
B. Corrosion in Storage Units
Normal Heating Systems are provided with Storage units to cover the hot water peak demand. Storage units (Calorifiers) are normally offered with Corrosion resistive Tanks- Internal Lined Steel (Glass/Epoxy or Copper) or Stainless Steel.
B1. Internal Lined Steel (Enamel/Epoxy)
Steel Storage Tanks are with internal lining for corrosion. But care shall be taken to ensure the lining is not damaging.
Reasons:
· Improper maintenance – During maintenance care shall be taken to not to have any sratches on the lining. Cleaning shall be done with soft brush
· Mechanical Damages- Mechanical stress can cause crack in the lining, which will start the corrosion
· No Anodic Protection- Anodic protection is the only good option to maintain the Calorifier no corrosive. Anode will actively supply irons which will make Oxides with Oxygen and CO in Water which will restrict the Steel to corrode or anodize.
B2. Stainless Steel
Stainless Steel Storage Tanks are the best options for the storage units as SS have better corrosion resistance. Stainless Steel are available in many grads like- SS304. SS316. SS316L, SS316Ti etc, and to be chosen based on the water quality and application.
Reasons for Corrosion:
Even though Stainless Steel is corrosion resistive, corrosion can take place in rare situations.
· Lack of Periodic maintenance- Maintenance shall be done to remove the scaling in the Tank body
· Wrong selection on Water quality- SS grade shall be selected based on the water quality, else it may corrode if water quality in poor. If chloride content is more, shall not be using SS304, instead go for SS316L or higher grade based on the quality.
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