Nace CP 1, Course Manual

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NACE GLOSSARY OF CORROSION-RELATED TERMS
©
2002, NACE International. This publication may not be reprinted without the written consent of NACE International.
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provide temporary protection
against atmospheric corrosion.
SOLUTION HEAT
TREATMENT
Heating a metal to a suitable
temperature and holding at that
temperature long enough for one
or more constituents to enter into
solid solution, then cooling
rapidly enough to retain the
constituents in solution.
SOLVENT CLEANING
Removal of oil, grease, dirt, soil,
salts, and contaminants by
cleaning with solvent, vapor,
alkali, emulsion, or steam. [See
SSPC-SP 1.]
SPALLING
The spontaneous chipping,
fragmentation, or separation of a
surface or surface coating.
STANDARD ELECTRODE
POTENTIAL
The reversible potential for an
electrode process when all
products and reactions are at unit
activity on a scale in which the
potential for the standard
hydrogen reference electrode is
zero.
STANDARD JETTING
WATER
Water of sufficient purity and
quality that it does not impose
additional contaminants on the
surface being cleaned and does
not contain sediments or
other
impurities that are destructive to
the proper functioning of water
jetting equipment.
STEEL SHOT
Small particles of steel with
spherical shape that are
commonly used as an abrasive in
abrasive blast cleaning or as a
selected medium for shot
peening.
STEP POTENTIAL
The potential difference between
two points on the earth’s surface
separated by a distance of one
human step, which is defined as
one meter, determined in the
direction of maximum potential
gradient.
STEPWISE CRACKING
[See Hydrogen-Induced
Cracking. ]
STRAY CURRENT
Current through paths other than
the intended circuit.
STRAY-CURRENT
CORROSION
Corrosion resulting from current
through paths other than the
intended circuit, e.g., by any
extraneous current in the earth.
STRESS CORROSION
CRACKING
Cracking of a material produced
by the combined action of
corrosion and tensile stress
(residual or applied).
STRESS RELIEVING
(THERMAL)
Heating a metal to a suitable
temperature, holding at that
temperature long enough to
reduce residual stresses, and
then cooling slowly enough to
minimize the development of new
residual stresses.
STRUCTURE-TO-
ELECTROLYTE
POTENTIAL
The potential difference between
the surface of a buried or
submerged metallic structure and
the electrolyte that is measured
with reference to an electrode in
contact with the electrolyte.
STRUCTURE-TO-SOIL
POTENTIAL
[See Structure-to-Electrolyte
Potential. ]
STRUCTURE-TO-
STRUCTURE POTENTIAL
The potential difference between
metallic structures, or sections of
the same structure, in a common
electrolyte.
SUBSURFACE
CORROSION
[See Internal Oxidation. ]
SULFIDATION
The reaction of a metal or alloy
with a sulfur-containing species
to produce a sulfur compound
that forms on or beneath the
surface of the metal or alloy.
SULFIDE STRESS
CRACKING
Cracking of a metal under the
combined action of tensile stress
and corrosion in the presence of
water and hydrogen sulfide (a
form of hydrogen stress
cracking).
SURFACE POTENTIAL
GRADIENT
Change in the potential on the
surface of the ground with
respect to distance.