TrilliumSeries™ Adiabatic
Cooler - TRF Operation & Maintenance Manual
–
Unit Operation & Storage
Page | 93
Long Term Care of Stainless Steel
When the percentage of chromium in steel exceeds 10.5%, it is called stainless steel. The chromium in the steel reacts with the
oxygen in the air to form a chromium-oxide surface layer, also called the passivation layer that provides the corrosion
resistance in stainless steel. BAC takes precautions to prevent cross-contamination, processing galvanized and stainless-steel
parts separately. Also, stainless steel brushes are used to clean welds on stainless parts and care is taken to avoid scratching
parts during processing. Organic cleaners are used to clean the finished product prior to shipping.
While stainless steel itself does not rust so long as the chromium-oxide surface layer is intact, it is not immune to contamination
from its surroundings. Some common sources of surface contamination are:
•
Dirt and soil
•
Shop oil or grease that may carry other contaminants such as metal chips
•
Machining or welding galvanized steel at the jobsite may cause debris to embed itself into the stainless steel
These contaminants can deposit on the surface and scratch the passivation layer or prevent it from re-forming. They can also
get trapped underneath the passivation layer and reduce corrosion resistance.
Recommended Stainless Steel Cleaning Procedure
NOTICE:
Never use chloride or chlorine-based solvents such as bleach or muriatic
(hydrochloric) acid to clean stainless steel. It is important to rinse the surface with warm
water and wipe with a dry cloth after cleaning.
Stainless steel needs to be cleaned regularly to maintain the corrosion resistance as well as to maintain the overall aesthetics
of the stainless steel. It is simple to clean most contaminants off the surface of stainless steel. Most dirt and soil can be
cleaned with a clean cloth, warm water, and mild detergent. For persistent dirt, a little vinegar can be added in the cleaning
water. It is important to always rinse the surface with warm water and wipe with a dry cloth after any cleaning, whether mild or
aggressive.
•
Fingerprints, mild stains, or grease spots can be cleaned using organic solvents such as acetone, methyl or ethyl alcohol,
or mineral spirits. Stainless steel wipes or glass cleaners commonly available in stores may also be used.
•
Occasionally the surface of stainless steel can get iron chips or shavings embedded in it from having galvanized steel
machined or welded in the vicinity. The iron chips can start to rust, reducing the corrosion resistance of the stainless steel,
and stain the surface giving the impression that the stainless steel is rusting. These types of contaminants require more
aggressive cleaning. Mild abrasives such as Scotch-
Brite™ products may be used where aesthetic considerations are not
important followed by solvent cleaning with organic solvents as described above. It is important to rinse the surface with
warm water and wipe with a dry cloth after cleaning.
•
If the iron chips are not removed with the Scotch-
Brite™
products, electro-chemical cleaning may be required. Contact
your local BAC Representative for more information on commercially available equipment for electrochemical cleaning in
the field.
