You can avoid boiler corrosion.
Cathodic protection acts to attract particles and impurities from the water thereby arresting the corrosion in a steel boiler. A law of chemistry known as the galvanic property of metals, requires that when two dissimilar metals are in contact with each other and exposed to a corrosive liquid or conductive solution (ie, the boiler water), a potential is set up between the two metals and an electric flows. When this occurs the galvanic property of metals requires that the metal higher or more electropositive, such as magnesium, will corrode or "sacrifice" in preference to slower oxidizing metals, such as steel. Cathodic protection has been used extensively on bridges, boat motors, pipe-lines, hot water heaters and tunnels. For over 20 years the technology of cathodic protection has been applied successfully to the boiler industry. Cathodic protection is designed to provide complete and automatic protection against scale and corrosion in your steel boiler.
The purpose of boiler water treatment is to remove the help prevent accumulation of hard-adhering scale and to inhibit corrosion on the water-side of the boiler. Excessive scale buildup reduces the efficiency of a boiler and increases the fuel costs. Cathodic protection will gradually loosen and prevent further scale build-up. Corrosion caused by oxygen and carbon dioxide is inhibited by the use of cathodic protection. Water treatment can not properly protect a boiler that has been poorly maintained and is in need of repair.
Chemical water treatments must be properly administered in the correct amount and proper time. Your labor costs and your uncertainty can be eliminated by utilizing cathodic protection. Since cathodic protection is automatic and it works 24 hours a day, the unit accommodates any change in the make-up water as it occurs. Pure steam is assured for your process with no chemical carry-over; therefore, there are no pollution problems as there are with chemical water treatments. Also, there is no human element involved to cause over or under chemicalization. Cathodic protection is completely automatic, only normal blowdown is necessary for good operating conditions.
Water conditions play a most important part 1n the failure of boilers and their tubes. Experience over many years has verified the fact that oxygen dissolved in the feed water probably causes more trouble to users of boilers than does any other one condition.
Here are some general rules to help you avoid boiler corrosion. Keep a maintenance record of the type of work done.
1. Whenever the boiler has been filled with fresh water (which contains oxygen), it should be fired and brought to steaming temperature in order to prevent the formation of air bubbles (air bubbles cause corrosion)
2. Boil out the boiler thoroughly once a year. This can be done during the summer months. Also, boil out the boiler with an alkaline cleaner after installing new tubes to remove oil or other coatings from the tube surfaces. These protective coatings are commonly applied to new tubes to prevent rusting during storage and transit, and will cause corrosion if left on the tubes during operation of the boiler.
3. Prevent water leakage and do not periodically drain water out of the boiler. This adds to the necessity of constant addition of make-up water and introduces oxygen into the boiler. Maintain the proper water level in the boiler at all times.
4. Blow down water level control frequently to prevent sediment from accumulating.
5. Make sure all piping, valves, nipples, plugs, etc. are free from leaks no matter how small
6. Clean tubes whenever soots, scale or any residue accumulate. Never allow soot or scale to remain in boiler when boiler is out of service -- especially if boiler room is damp. (The sulphur content in the oil can become sulfuric acid and will pit and corrode all heating surfaces). Maintain a smoke-free fire
7. Utilize catholic protection for complete and automatic protection against water-side corrosion and scale. The Neutro-Chem Company is recommended
Rockmills has tested both chemical water treatments and cathodic protection and have found cathodic protection to be most effective. Proper and consistent boiler care provided by an experienced boiler operator or service company is also essential to the long and healthy life of your boiler.
James J. O'Brien, President Rockmills Steel Products Corproration
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|Author:||O'Brien, James J.|
|Publication:||Real Estate Weekly|
|Date:||Sep 30, 1992|
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