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Corrosion Glossary - O
- Occluded cell: an electrochemical cell
created at a localized site on a metal surface which has been partially obstructed
from the bulk environment.
- Oil burner: a burner for firing oil.
- Oil paint: a
paint that contains drying oil,
oil varnish or oil-modified resin as the film-forming ingredient. The term isincorrectly
used to refer to any paint soluble by organic
- Oleoresin: a natural plant product that
contains oil and resins, e.g.
potential: the potential
of an electrode measured with respect to a
reference electrode or another
electrode when no current flows to or from it.
- Operating pressure: the pressure at
the top of a pressure vessel at which it normally operates. It cannot exceed
the maximum allowable working pressure (Stamped Pressure).
- Orange peel: a surface bumpiness or
waviness that resembles the skin of an orange. Orange peel is often caused by
poor leveling and is a common defect in both spray and roll applied
- Organic matter: substances of or derived
from plant or animal matter. Organic matter is characterized by its carbon-hydrogen
- ORP: for an electrode that gives a measure
of the Oxidation Reduction Potential more commonly known as REDOX
- Osmosis: a process of diffusion of a
solvent such as water through a semi-permeable membrane which will transmit
the solvent but impede most dissolved substances. The normal flow of solvent
is from the dilute solution to the concentrated solution in an attempt to bring
the solutions on both sides of the membrane to equilibrium.
- Overpressure: minimum operating pressure
of a hot water boiler sufficient to prevent the water from steaming.
- Overspray: sprayed
paint that misses the area being
painted and falls upon the surrounding surface. Can cause gloss loss with gloss
paints or mottling with flats paints.
- Overvoltage: the change in potential
of an electrode from its equilibrium or steady state value when current is applied.
loss of electrons by a constituent of a chemical reaction. (Also refers to the
corrosion of a metal that is exposed
to an oxidizing gas at elevated temperatures.
- Oxidized surface (on steel): surface
having a thin, tightly adhering, oxidized skin (from straw to blue in color),
extending in from the edge of a coil or sheet.
- Oxidizing agent: a compound that causes
oxidation, thereby itself being reduced.
- Oxidizing atmosphere: an atmosphere
which tends to promote the oxidation of materials.
- Oxygen: gas used to support combustion
of fuel gases in combustion thermal spray processes. Achieves much higher flame
temperatures than using air. (see
- Oxygen attack: corrosion or pitting
in a boiler caused by oxygen.
a galvanic cell resulting from difference in oxygen concentration between two
locations; see differential aeration cell.
- Ozone: a powerfully oxidizing allotropic
form of the element oxygen. The ozone molecule contains three atoms (O3).