Glossary of Corrosion Related Terms

POLYGUARD PRODUCTS, INC.

	GLOSSARY OF TERMS "H"
THE SOLUTION TO CORROSION UNDER INSULATION
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RG-2400 STOPS CORROSION	GLOSSARY OF CORROSION RELATED TERMS
RG-2400 will STOP existing corrosion and will prevent corrosion on new piping systems. Minimal surface preparation is required.

The Corrosion Process Science of Minetics/Surface Conversion Buffering Water Vapor Corrosion Under Insulation (CUI) Corrosion Control Corrosion Prevention Corrosion Remediation Priming and Painting Stainless Steel Stress Crack Corrosion (SCC) Corrosion on Steam Systems Corrosion on Tanks & Vessels Corrosion Anti-Seize Corrosion on Valves Corrosion Control in Natural Gas Vaults Corrosion Control on Bridges Corrosion Control on Marine & Oil Derek Pilings "Down Hole" Corrosion Control Insulation Joint Sealers Specialty Military Installations RG-2400 LT RG-2400 AK RG-2400 ET RG-2401 RG-1700 RG-2400 has many uses: Anti-Seize (Bolts) Bridge Rockers Steel Cable Steel Piers & Pilings Pig Doors Flange Bolts Unions	A \| B \| C \| D \| E \| F \| G \| H \| I \| J \| K \| L \| M \| N \| O \| P \| Q \| R \| S \| T \| U \| V \| W \| X \| Y \| Z
	H
	HALF CELL	An electrode immersed in a suitable electrolyte, designed for measurements of electrode potential; A pure metal in contact with a solution of known concentration of its own ion, at a specific temperature develops a potential which is characteristic and reproducible; when coupled with another half cell, an overall potential develops which is the sum of both half cells.
	HALOGEN	Any of the elements of the halogen family, consisting of fluorine. chlorine, bromine, iodine, and astatine.
	HARD CHROMIUM	Chromium plated for engineering rather than decorative applications.
	HARD WATER	Water that contains certain salts, such as those of calcium or magnesium, which form insoluble deposits in boilers and form precipitates with soap.
	HARDENABILITY	The relative ability of a ferrous alloy to form martensite when quenched from a temperature above the upper critical temperature. Hardenability is commonly measured as the distance below a quenched surface at which the metal exhibits a specific hardness (50 HRC, for example) or a specific percentage of martensite in the microstructure.
	HARDFACING	Depositing filler metal on a surface by welding. spraying, or braze welding to increase resistance to abrasion, erosion, wear, galling. impact, or cavitation damage.
	HEAT CHECK	A pattern of parallel surface cracks that are formed by alternate rapid heating and cooling of the extreme surface metal, sometimes found on forging dies and piercing punches. There may be two sets of parallel cracks one set perpendicular to the other.
	HEAT-AFFECTED ZONE	That portion of the base metal that was not melted during brazing, cutting, or welding, but whose microstructure and mechanical properties were altered by the heat.
	HEMATITE	(1) An iron mineral crystallizing in the rhombohedral system; the most important ore of iron. (2) An iron oxide, Fe2O3, corresponding to an iron content of approximately 70%.
	HIGH-TEMPERATURE HYDROGEN ATTACK	A loss of strength and ductility of steel by high-temperature reaction of absorbed hydrogen with carbides in the steel resulting in decarburization and internal fissuring.
	HOLIDAYS	Discontinuities in a coating (such as porosity, cracks, etc.) that allow areas of base metal to be exposed to any corrosive environment that contacts the coated surface.
	HOT CORROSION	An accelerated corrosion of metal surfaces that results from the combined effect of oxidation and reactions with sulfur compounds and other contaminants, such as chlorides, to form a molten salt on a metal surface that fluxes, destroys, or disrupts the normal protective oxide. See also gaseous corrosion.
	HOT CRACKING	Also called solidification cracking, hot cracking of weldments is caused by the segregation at grain boundaries of low-melting constituents in the weld metal. This can result in grain-boundary tearing under thermal contraction stresses. Hot cracking can be minimized by the use of low-impurity welding materials and proper joint design. See also cold cracking. Iamellar tearing and stress-relief cracking.
	HOT DIP COATING	A metallic coating obtained by dipping the base metal into a molten metal.
	HOT SHORTNESS	A tendency for some alloys to separate along grain boundaries when stressed or deformed at temperatures near the melting point. Hot shortness is caused by a low-melting constituent, often present only in minute amounts, that is segregated at grain boundaries.
	HOT WORKING	Deforming metal plastically at such a temperature and strain rate that recrystallization takes place simultaneously with the deformation, thus avoiding any strain hardening. Contrast with cold working.
	HUEY TEST	Corrosion testing in a boiling solution of nitric acid. This test is mainly used to detect the susceptibility to intergranular corrosion of stainless steel.
	HUMIDITY TEST	A corrosion test involving exposure of specimens at controlled levels of humidity and temperature. Contrast with salt-fog test.
	HYDROGEN BLISTERING	The formation of blisters on or below a metal surface from excessive internal hydrogen pressure. Hydrogen may be formed during cleaning, plating, corrosion, and so forth.
	HYDROGEN DAMAGE	A general term for the embrittlement, cracking, blistering. and hydride formation that can occur when hydrogen is present in some metals.
	HYDROGEN DISINTEGRATION	Deep internal cracks caused by hydrogen.
	HYDROGEN EMBRITTLEMENT	A process resulting in a decrease of the toughness or ductility of a metal due to the presence of atomic hydrogen. Hydrogen embrittlement has been recognized classically as being of two types. The first known as internal hydrogen embrittlement, occurs when the hydrogen enters molten metal which becomes supersaturated with hydrogen immediately after solidification. The second type, environmental hydrogen embrittlement, results from hydrogen being absorbed by solid metals. This can occur during elevated-temperature thermal treatments and in service during electroplating, contact with maintenance chemicals, corrosion reactions, cathodic protection, and operating in high-pressure hydrogen. In the absence of residual stress or external loading, environmental hydrogen embrittlement is manifested in various forms, such as blistering, internal cracking, hydride formation, and reduced ductility. With a tensile stress or stress-intensity factor exceeding a specific threshold, the atomic hydrogen interacts with the metal to induce subcritical crack growth leading to fracture. In the absence of a corrosion reaction (polarized cathodically), the usual term used is hydrogen-assisted cracking(HAC) or hydrogen stress cracking (HSC). In the presence of active corrosion, usually as pits or crevices (polarized anodically), the cracking is generally called stress-corrosion cracking(SCC), but should more properly be called hydrogen-assisted stress-corrosion cracking (HSCC). Thus HSC and electrochemically anodic SCC can operate separately or in combination(HSCC). In some metals, such as high-strength steels, the mechanism is believed to be all, or nearly all, HSC. The participating mechanism of HSC is not always recognized and may be evaluated under the generic heading of SCC.
	HYDROGEN OVERVOLTAGE	Overvoltage associated with the liberation of hydrogen gas.
	HYDROGEN STRESS CRACKING (HSC)	See hydrogen embrittlement.
	HYDROGEN-ASSISTED CRACKING (HAC)	See hydrogen embrittlement.
	HYDROGEN-ASSISTED STRESS-CORROSION CRACKING (HSCC)	See hydrogen embrittlement.
	HYDROGEN-INDUCED CRACKING (HIC)	See hydrogen embrittlement.
	HYDROLYSIS	(1) Decomposition or alteration of a chemical substance by water. (2) In aqueous solutions of electrolytes, the reactions of cations with water to produce a weak base or of anions to produce a weak acid.
	HYDROPHILIC	Having an affinity for water. Contrast with hydrophobic.
	HYDROPHOBIC	Lacking an affinity for, repelling, or failing to absorb or adsorb water. Contrast with hydrophilic.

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RG-2400 STOPS CORROSION - PERIOD.
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