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C24GA SERIES GAS CONVECTION STEAMERS
STAINLESS STEEL EQUIPMENT CARE AND LEANING
(Supplied courtesy of NAFEM. For more information, visit their web site at www.nafem.org)
Contrary to popular belief, stainless steels ARE suscep-
tible to rusting.
Corrosion on metals is everywhere. It is recognized quickly on
iron and steel as unsightly yellow/orange rust. Such metals
are called “active” because they actively corrode in a natural
environment when their atoms combine with oxygen to form rust.
Stainless steels are passive metals because they contain other
metals, like chromium, nickel and manganese that stabilize the
atoms. 400 series stainless steels are called ferritic, contain
chromium, and are magnetic; 300 series stainless steels are
called austenitic, contain chromium and nickel; and 200 series
stainless, also austenitic, contains manganese, nitrogen and
carbon. Austenitic types of stainless are not magnetic, and
generally provide greater resistance to corrosion than ferritic
types.
With 12-30 percent chromium, an invisible passive film covers
the steel’s surface acting as a shield against corrosion. As long
as the film is intact and not broken or contaminated, the metal is
passive and stain-less. If the passive film of stainless steel has
been broken, equipment starts to corrode. At its end, it rusts.
Enemies of Stainless Steel
There are three basic things which can break down stainless
steel’s passivity layer and allow corrosion to occur.
1.
Mechanical abrasion
2.
Deposits and water
3.
Chlorides
Mechanical abrasion
means those things that will scratch a
steel surface. Steel pads, wire brushes and scrapers are prime
examples.
Water
comes out of the faucet in varying degrees of hardness.
Depending on what part of the country you live in, you may
have hard or soft water. Hard water may leave spots, and when
heated leave deposits behind that if left to sit, will break down
the passive layer and rust stainless steel. Other deposits from
food preparation and service must be properly removed.
Chlorides
are found nearly everywhere. They are in water, food
and table salt. One of the worst chloride perpetrators can come
from household and industrial cleaners.
So what does all this mean? Don’t Despair!
Here are a few steps that can help prevent stainless steel rust.
1. Use the proper tools.
When cleaning stainless steel products, use non-abrasive
tools. Soft cloths and plastic scouring pads will not harm
steel’s passive layer. Stainless steel pads also can be used
but the scrubbing motion must be in the direction of the
manufacturers’ polishing marks.
2. Clean with the polish lines.
Some stainless steel comes with visible polishing lines or
“grain.” When visible lines are present, always scrub in a
motion parallel to the lines. When the grain cannot be seen,
play it safe and use a soft cloth or plastic scouring pad.
3. Use alkaline, alkaline chlorinated or non-chloride
containing cleaners.
While many traditional cleaners are loaded with chlorides,
the industry is providing an ever-increasing choice of non-
chloride cleaners. If you are not sure of chloride content
in the cleaner used, contact your cleaner supplier. If your
present cleaner contains chlorides, ask your supplier if they
have an alternative. Avoid cleaners containing quaternary
salts; it also can attack stainless steel and cause pitting and
rusting.
4. Treat your water.
Though this is not always practical, softening hard water
can do much to reduce deposits. There are certain filters
that can be installed to remove distasteful and corrosive
elements. To insure proper water treatment, call a treatment
specialist.
5. Keep your food equipment clean.
Use alkaline, alkaline chlorinated or non-chloride cleaners
at recommended strength. Clean frequently to avoid build-
up of hard, stubborn stains. If you boil water in stainless
steel equipment, remember the single most likely cause
of damage is chlorides in the water. Heating cleaners that
contain chlorides have a similar effect.
6. Rinse, rinse, rinse.
If chlorinated cleaners are used, rinse and wipe equipment
and supplies dry immediately. The sooner you wipe off
standing water, especially when it contains cleaning agents,
the better. After wiping equipment down, allow it to air dry;
oxygen helps maintain the stainless steel’s passivity film.
7. Never use hydrochloric acid (muriatic acid) on
stainless steel.
8. Regularly restore/passivate stainless steel.
Job
Cleaning Agent
Comments
Routine cleaning Soap, ammonia,
detergent, Medallion
Apply with soft
cloth or sponge.
Fingerprints
and smears
Arcal 20, Lac-O-
Nu Ecoshine
Provides
barrier film
Stubborn stains
and discoloration
Cameo, Talc, Zud,
First Impression
Rub in direction
of polish lines.
Grease and fatty
acids, blood,
burnt-on foods
Easy-off, DeGrease
It Oven Aid
Excellent removal
on all finishes
Grease and Oil
Any good
commercial
detergent
Apply with soft
cloth or sponge.
Restoration/
Passivation
Benefit, Super
Sheen
Review
1.
Stainless steels rust when passivity (film-shield) breaks
down as a result of scrapes, scratches, deposits and
chlorides.
2.
Stainless steel rust starts with pits and cracks.
3.
Use the proper tools. Do not use steel pads, wire brushes
or scrapers to clean stainless steel.
4.
Use non-chlorinated cleaners at recommended
concentrations. Use only chloride free cleaners.
5.
Soften your water. Use filters and softeners whenever
possible.
6.
Wipe off cleaning agent(s) and standing water as soon as
possible. Prolonged contact causes eventual problems.
To learn more about chloride-stress corrosion and how to
prevent it, contact the equipment manufacturer or cleaning
materials supplier.
Developed by Packer Engineering, Naperville, Ill., an
independent testing laboratory.
