Fundamentals of metallic corrosion: atmospheric and media corrosion of metals

750 Pages·2006·14.46 MB·English

by  Philip A. Schweitzer

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8243—Prelims—10/11/2006—18:40—CRCPAG—14180—XMLMODELB–pp.1–18
8243—Prelims—10/11/2006—18:40—CRCPAG—14180—XMLMODELB–pp.1–18
8243—Prelims—10/11/2006—18:40—CRCPAG—14180—XMLMODELB–pp.1–18
Preface
Corrosionisbothcostlyanddangerous.Billionsofdollarsarespentannually
for the replacement of corroded structures, machinery, and components,
includingmetalroofing,condensertubes,pipelines,andmanyother items.
In addition to replacement costs are those associated with preventive
maintenance to prevent corrosion, inspections, and the upkeep of
cathodically protected structures and pipelines. Indirect costs of corrosion
resultfromshutdown,lossofefficiency,andproductcontaminationorloss.
Althoughtheactualreplacementcostofanitemmaynotbehigh,theloss
ofproductionresultingfromtheneedtoshutdownanoperationtopermitthe
replacement may amount to hundreds of dollars per hour. When a tank
or pipeline develops a leak, product is lost. If the leak goes undetected for
aperiodoftime,thevalueofthelostproductcouldbeconsiderable.Inaddition,
contaminationcanresultfromtheleakingmaterial,requiringcleanup,andthis
canbequiteexpensive.Whencorrosiontakesplace,corrosionproductsbuild
up, resulting in reduced flow in pipelines and reduced efficiency of heat
transferinheatexchangers.Bothconditionsincreaseoperatingcosts.Corrosion
productsmayalsobedetrimentaltothequalityoftheproductbeinghandled,
makingitnecessarytodiscardvaluablematerials.
Premature failure of bridges or structures because of corrosion can also
resultin human injury oreven loss of life. Failuresof operating equipment
resultingfrom corrosioncan have the same disastrousresults.
When all of these factors are considered, it becomes obvious why the
potentialproblemofcorrosionshouldbeconsideredduringtheearlydesign
stages of any project, and why it is necessary to constantly monitor the
integrity of structures, bridges, machinery, and equipment to prevent
prematurefailures.
To cope with the potential problems of corrosion, it is necessary to
understand
1. Mechanisms ofcorrosion
2. Corrosion resistantproperties ofvariousmaterials
3. Properfabrication and installation techniques
4. Methods to preventorcontrolcorrosion
5. Corrosion testing techniques
6. Corrosion monitoring techniques
Corrosionisnotonlylimitedtometallicmaterialsbutalsotoallmaterials
of construction. Consequently, this handbook covers not only metallic
materialsbut alsoall materialsof construction.
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Chapter1andChapter2coverthemechanismsofcorrosionandtheeffects
of atmospheric corrosion.
Chapter 3 through Chapter 27 cover metallic materials and their alloys.
Corrosion’spotentialisdiscussedforeachmetaloralloy.Chartsareprovided
for the compatibility of each metal or alloy with selected corrodents.
Referencesareprovidedforadditionalcompatibilitydata.
It is the intention of this book that regardless of what is being built,
whether it be a bridge, tower, pipeline, storage tank, or processing vessel,
informationforthedesigner/engineer/maintenancepersonnel/orwhoever
isresponsiblefortheselectionofconstructionmaterial,thisbookwillenable
them to avoid unnecessary loss ofmaterial throughcorrosion.
Philip A.Schweitzer
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Author
Philip A. Schweitzer is a consultant in corrosion prevention, materials of
construction, and chemical engineering based in York, Pennsylvania. A
formercontractmanagerandmaterialspecialistforChem-ProCorporation,
Fairfield, New Jersey, he is the editor of the Corrosion Engineering Handbook
and the Corrosion and Corrosion Protection Handbook, Second Edition; and the
author of Corrosion Resistance Tables, Fifth Edition; Encyclopedia of Corrosion
Technology, Second Edition; Metallic Materials; Corrosion Resistant Linings and
Coatings; AtmosphericDegradationandCorrosionControl;What Every Engineer
Should Know About Corrosion; Corrosion Resistance of Elastomers; Corrosion
Resistant Piping Systems; Mechanical and Corrosion Resistant Properties of
PlasticsandElastomers(alltitlesMarcelDekker,Inc.);andPaintandCoatings,
Applications andCorrosion Resistance(Taylor &Francis).Schweitzer received
the BChE degree (1950) from Polytechnic University (formerly Polytechnic
Institute of Brooklyn),Brooklyn,NewYork.
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Contents
Chapter1 Fundamentalsof MetallicCorrosion......................................... 1
1.1 Forms of Corrosion...................................................................................... 2
1.1.1 Uniform Corrosion......................................................................... 3
1.1.1.1 Passive Film on Iron......................................................... 3
1.1.1.2 Passive Film on Nickel..................................................... 4
1.1.1.3 Passive Film on Austenitic Stainless Steel.................... 4
1.1.1.4 Passive Film on Copper................................................... 4
1.1.1.5 Passive Film on Aluminum............................................ 5
1.1.1.6 Passive Film on Titanium................................................ 5
1.1.1.7 Passive Film on Tantalum............................................... 5
1.1.1.8 Uniform Corrosion Rates................................................. 5
1.1.2 Intergranular Corrosion................................................................. 7
1.1.3 Galvanic Corrosion......................................................................... 8
1.1.4 CreviceCorrosion......................................................................... 10
1.1.5 PittingCorrosion........................................................................... 12
1.1.6 ErosionCorrosion......................................................................... 15
1.1.7 StressCorrosion Cracking (SCC)............................................... 16
1.1.8 Biological Corrosion..................................................................... 18
1.1.8.1 Corrosion of Specific Materials..................................... 21
1.1.9 Selective Leaching......................................................................... 23
1.2 Corrosion Mechanisms............................................................................. 24
1.3 Measuring Polarization............................................................................. 31
1.3.1 Anodic Polarization...................................................................... 34
1.4 Other Factors Affecting Corrosion.......................................................... 35
Reference.............................................................................................................. 37
Chapter2 Atmospheric Corrosion............................................................... 39
2.1 Atmospheric Types.................................................................................... 40
2.2 Factors Affecting Atmospheric Corrosion............................................. 41
2.2.1 Time of Wetness............................................................................ 42
2.2.1.1 Adsorption Layers.......................................................... 43
2.2.1.2 Phase Layers.................................................................... 43
2.2.1.3 Dew................................................................................... 43
2.2.1.4 Rain................................................................................... 43
2.2.1.5 Fog..................................................................................... 44
2.2.1.6 Dust................................................................................... 44
2.2.1.7 Measurementof Time of Wetness................................ 44
2.2.2 Composition of SurfaceElectrolyte........................................... 45
2.2.2.1 Oxygen.............................................................................. 45
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