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Corrosion Glossary - W
- Wall shear stress: the shear stress
at the wall or surface caused by a liquid moving past it.
- Wash primer: a thin, inhibiting
paint, usually chromate pigmented
with a polyvinyl butyrate binder.
- Waste heat: sensible heat in non-combustible
gases discharged to the environment.
- Water: a liquid composed of two parts
of hydrogen and sixteen parts oxygen by weight.
- Water conditioning: virtually any form
of water treatment designed to improve the aesthetic quality of water by the
neutralization, inhibition or removal of undesirable substances.
- Water softener: removes hardness (caco3)
from water through an ion exchange of sodium with calcium and magnesium.
- Water softening: the removal of calcium
and magnesium, the ions which are the principle cause of hardness, from water.
- Water spotting: change in surface appearance
resulting from the action of water standing on the paint film or substrate.
Spotting usually is caused by water sensitivity of the coating, although the
defect can be the result of dissolved material deposited as water evaporates.
- Water table: the level of the top of
the zone of saturation, in which free water exists in the pores and crevices
of rocks and other earth strata.
- Water tube: a tube in a boiler having
the water and steam on the inside and heat applied to the outside.
- Waveguide: a system of material boundaries
capable of guiding electromagnetic waves. A transmission line comprising a hollow
conducting tube within which electromagnetic waves are propagated on a solid
dielectric or dielectric-filled conductor.
- Weak base load faction: the sum of the
chloride, sulfate, and nitrate in a given water.
- Wear: loss of material from a surface
by means of some mechanical action.
- Weep: a term usually applied to a minute
leak in a boiler joint which forms droplets (or tears) of water very slowly.
- Weld cracking: cracking that occurs
in the weld metal.
- Weld decay: not a preferred term meaning
usually of stainless steels or certain
nickel-base alloys, that occurs as the result of sensitization in the heat
affected zone during the welding operation.
- Welding process: the joining of materials
by the application of heat or friction. Usually involves the localized fusion
of both contacting surfaces.
- Wet edge: the ability of a wet coating
to blend smoothly together in the overlap areas during application.
- Wet steam: steam containing moisture.
- Wet-bulb temperature: the lowest temperature
which a water wetted body will attain when exposed to an air current. this is
the temperature of adiabatic saturation, and can be used to measure humidity.
- Wetness: a term used to designate the
percentage of water in steam. also used to describe the presence of a water
film on heating surface interiors.
- Wetting: a condition in which the interfacial
tension between a liquid and a solid is such that the contact angle is 0º to
- Wetting agent: a substance that reduces
the surface tension of a liquid, thereby causing it to spread more readily on
a solid surface.
- White rust: zinc oxide, the powdery
product of corrosion of zinc or zinc-coated surfaces.
- Windbox: a chamber below the grate or
surrounding a burner, through which air under pressure is supplied for combustion
of the fuel.
- Windbox pressure: the static pressure
in the windbox of a burner or stoker.
- Wire spraying: a thermal spray process
whereby the supply for the coating material is fed into the gun in the form
of a continuous wire.
- Work hardening: same as strain hardening
- Working electrode: the test or specimen
electrode in an electrochemical
- Wrap around: the phenomenon by which
electrically charged paint droplets curve around the rear side of the object
- Wrinkling: a defect in which the film
surface skins over and then absorbs liquid within the film.