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 integranular corrosion 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 90º.
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 cell.
Wrap around: the phenomenon by which electrically charged paint droplets curve around the rear side of the object being painted.
Wrinkling: a defect in which the film surface skins over and then absorbs liquid within the film.