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 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. 8243—Prelims—10/11/2006—18:40—CRCPAG—14180—XMLMODELB–pp.1–18 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 8243—Prelims—10/11/2006—18:40—CRCPAG—14180—XMLMODELB–pp.1–18 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. 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 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 8243—Prelims—10/11/2006—18:40—CRCPAG—14180—XMLMODELB–pp.1–18