Manual ROG - ROLL’N’GRILL
®
Annexes
Translation
Last change: 2020-02-27
Technical details are subject to change.
Version: 4.0
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13
Annexes
13.1
Notes on caring for stainless steel
Possible causes of corrosion on stainless steel equipment
“Stainless steel”
is the designation for specially corrosion-resistant and hygienic types of steel. These
types of steel have a chromium content of at least 10.5 % and in many cases contain additional ingredi-
ents, such as nickel and molybdenum.
The surface of this material is smooth and non-porous and meets the hygienic and microbiological spec-
ifications. Typical applications are: hospital equipment, canteen kitchens, facades and covers.
The non-corroding properties of stainless steel are due to a passive layer formed on the surface when
exposed to oxygen. The oxygen in the air is enough to repair the passive layer automatically if it has
been damaged or impaired due to mechanical impact.
Corrosive substances with a reducing effect (oxygen-consuming), such as substances containing hydro-
chloric or sulphuric acid, chlorides and spice concentrates, such as mustard, essences of vinegar, spice
blocks, table salt solutions, etc., can chemically disturb or damage the passive layer, depending on the
concentration and temperature, and therefore cause rust.
Moreover, stainless steel can be damaged by extraneous rust (from other components, tools, or flash
rust or abrasive dust or water containing iron). Surface phenomena, such as rust-like deposits, can occur
all over a surface or in spots or clusters.
Experience has shown that rust-like surface deposits can be caused by improper cleaning practice, for
example, use of cleaning agents containing hydrochloric acid (HCl). It only takes a small amount of res-
idue, which becomes more concentrated after cleaning due to condensation or evaporation, to cause
noticeable red deposits.
Where rubber seals are used, so-called crevice corrosion frequently also occurs. This means that, here
too, pockets of residual dampness are not dried or ventilated thoroughly, which can result in corrosion
due to the relatively low chloride content of the condensate or residues of cleaning agent.
