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*Controlled by the formation of iron carbonate on the metal surface *Can cause pitting if the protective scale is damaged *Forms carbonic acid *Corrosion rate is affected by temp., velocity, pressure, pH *aka "sweet corrosion" |
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*Can produce iron sulfide as a by-product *Damages metal by causing embrittlement to hard alloys & blistering to softer alloys
*Unaffected by velocity *aka "sour corrosion" |
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*Exist when fertilizers contact metal surfaces *inhibited using water *in the form of SCC *Can be reduced by stress relieving storage tanks before exposure to this corrosive substance |
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*includes chemicals (acetic acid, propionic acid, formic acid)
*weak compared to hydrochloric and sulfuric acid |
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*very localized attack *formation of biofilm *controlled in pipelines by regular pigging
*controlled using biocide chemicals *if found it water, may not indicate there is a problem on the surface of the steel |
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*result from stresses related to welding processes
*accelerated by stress concentrations, material properties, fabrication, and weld size and quality
*remedies-use of proper weld procedures, correct cooling procedures, proper technique |
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*requires tensile stress, specific environmental conditions, and a specific set of metallurgical factors
*increased levels of zinc in carbon steel alloys reduce this corrosion
*well bonded coating will prevent this form of corrosion externally
*low, near neutral or high pH electrolytes are susceptible to this corrosion |
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*dependent mainly on the temp. and chemical concentration of the corrodent
*slightly corrosive at low temps and low flow velocities
*under concentrations above 70% it can be handled w/ ordinary carbon steel
*below 70%, chemical lead is commonly utilized |
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*similar to wet chlorine corrosion *encountered in bleaching, sanitizing, deodorizing, and waste treatment applications
*sodium version = liquid bleach *calcium version = bleaching powder *lower temp. will greatly reduce the corrosion rate of this corrodent |
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*encountered when it made form ammonia *colorless, corrosive, toxic liquid *important industrial raw material that even attacks copper and high carbon 304 stainless steel |
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*involves the gas that is considered the most corrosive
*can be removed mechanically or chemically
*found in surface equipment *use of plastic materials or internally plastic coating is common practice when this corrosion is expected
*cement lining is also effective |
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*caused by a greenish yellow gas or liquid
*utilized in water purification, bleaches, and mustard gas
*used in swimming pools *attack iron, steel, aluminum, nickel, stainless steel, copper, and titanium
*attack is minimized if the corrodent is kept dry except in the case of titanium corrosion where the corrodent should be kept wet |
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*one of the few that attacks glass *corrodent can only be stored in plastic or Teflon containers
*corrodent is utilized to purify aluminum and uranium |
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Hydrogen Fluoride Corrosion |
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