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    Cathodic ProtectionCathodic Protectionfor Onfor On--Grade Storage Tanks andGrade Storage Tanks and

    Buried PipingBuried Piping

    John FitzgeraldJohn Fitzgerald

    CorrproCorrpro

    Freshwater Spills SymposiumFreshwater Spills SymposiumApril 6April 6--8, 20048, 2004

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    Preserve AssetsPreserve Assets

    Reduce Maintenance CostsReduce Maintenance Costs Governmental ComplianceGovernmental Compliance

    Preserve The EnvironmentPreserve The Environment

    Why is Corrosion ControlWhy is Corrosion Control

    Important?Important?

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    What I Will Cover.What I Will Cover.

    -- Causes of CorrosionCauses of Corrosion

    -- SPCC/State/OPS RegulationsSPCC/State/OPS Regulations

    -- Cathodic Protection ApplicationsCathodic Protection Applications-- Maintenance RequirementsMaintenance Requirements

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    Spill Prevention Control andSpill Prevention Control and

    Countermeasure (SPCC) RegulationCountermeasure (SPCC) Regulation

    (Implementation Required by 2/18/05 )(Implementation Required by 2/18/05 )

    -- Provide buried piping that is installed orProvide buried piping that is installed or

    replaced after August 16th, 2002replaced after August 16th, 2002

    protective coating andprotective coating and cathodiccathodic protection.protection.

    -- Should a section of line be exposed for anyShould a section of line be exposed for any

    reason it must be inspected for deterioration.reason it must be inspected for deterioration.If corrosion damage is found you must takeIf corrosion damage is found you must take

    additional examination and corrective action.additional examination and corrective action.

    with awith a

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    Federal Level(Breakout Tanks)

    a) Relieves surges in a hazardous

    liquid pipeline system or b) receive

    and store hazardous liquid transported

    by a pipeline for reinjection andcontinued transportation by pipeline

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    Breakout Tank Piping (DOT)

    M

    Main Line

    Valve

    OPS

    Inspection

    MeterM

    ProductTank

    (Breakout)

    M

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    -- Approximately 25% of States nowApproximately 25% of States now

    requirerequire cathodiccathodic protection be installedprotection be installedand maintained on new, refurbished, orand maintained on new, refurbished, or

    repaired tanks in contact with soil or sandrepaired tanks in contact with soil or sand

    foundations.foundations.

    -- A number of other states are in theA number of other states are in the

    process of implementing regulationsprocess of implementing regulationsgoverning ASTs.governing ASTs.

    State Level

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    Terminal Tankage

    Main Line

    M

    Valve

    OPS

    Inspection

    MeterM

    No OPSInspection

    OPS Inspection Stops

    (Enforcement Policy)

    LoadingTerminalProduct

    Tank

    (Terminal)

    Product

    Tank

    (Terminal)

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    Corrosion Can be Defined as Either:

    Practical

    Tendency of a Metal to Revert

    to its Native State

    ScientificElectrochemical Degradation

    of Metal as a Result of a Reaction

    with its Environment

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    IRON REFINING MILLING

    IRON CORROSION IRON OXIDE

    Corrosion - A Natural Process

    OXIDE

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    1) ANODE

    2) CATHODE

    3) ELECTROLYTE

    4) ELECTRICAL

    CONNECTION

    Anode-600mV

    Cathode

    -550mV

    -575mV

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    CorrosionCorrosion ofof MetallicMetallic StructureStructure

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    Anodic Area

    ( - )

    Current Flow

    Cathodic Area

    ( + )

    Structure

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    SANDCURRENT FLOW

    Corrosion Cell on TankBottom

    CLAY

    Steel Tank Floor

    ANODEANODECATHODECATHODE CATHODECATHODE

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    DRYSAND

    MOIST SAND

    WATER

    Corrosion Caused byPoor Water Drainage

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    New Bottom (Anode)

    CURRENT FLOW

    SAND

    SAND

    New Steel Coupled to Old Steel

    Old Bottom (Cathode)

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    Galvanic AnodeCathodic Protection

    Current is obtained

    from a metal of a higherenergy level

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    PRACTICAL GALVANIC SERIES

    Material Potential*

    Pure Magnesium -1.75

    Magnesium Alloy -1.60

    Zinc -1.10Aluminum Alloy -1.00

    Cadmium -0.80

    Mild Steel (New) -0.70

    Mild Steel (Old) -0.50

    Cast Iron -0.50

    Stainless Steel -0.50 to + 0.10

    Copper, Brass, Bronze -0.20

    Titanium -0.20

    Gold +0.20

    Carbon, Graphite, Coke +0.30

    * Potentials With Respect to Saturated Cu-CuSO4 Electrode

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    Structure

    Magnesium

    Anode

    Current Flow

    Galvanic Cathodic Protection on

    Coated Pipeline

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    Cathodic Protection Test Station

    Test

    Station

    Magnesium

    Anode

    Coated Pipe

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    FLANGE INSULATION KIT

    INSULATING UNIONS

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    Typically limited to new piping, that has agood quality coating and electrical isolation.

    If the particular location is lacking any of the

    above, an impresses current system may bewarranted.

    Galvanic Anodes

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    Anode Cathode

    Water / Sediment

    Fuel Product

    Internal Corrosion

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    Internal Corrosion

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    CoatingAnode

    Bolt

    Tank Bottom

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    Conventional CP Systems forConventional CP Systems for

    ASTsASTs

    -- Shallow (Distributed) AnodesShallow (Distributed) Anodes

    -- Deep AnodeDeep Anode GroundbedGroundbed

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    Impressed Current Transformer Rectifier UnitImpressed Current Transformer Rectifier Unit

    I d C t S t

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    Rectifier

    Anode

    Groundbed

    ( - ) ( + )

    Pipeline(Structure)

    Current

    Flow

    Impressed Current System

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    TankTank

    Anode

    Splice

    Typical Depth 20

    Shallow Anodes

    Rectifier

    (-)(+)

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    Shallow Anodes

    Tank

    Rectifier

    (-)(+)

    Anode

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    Anodes

    Junction

    Box

    Rectifier

    -+

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    Directional Boring Under

    Existing AST

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    ABOVEGROUND STORAGE TANK

    CATHODIC PROTECTION

    3

    PVC 20%

    Exposure

    Anode Material

    Anode Tube

    10

    Typical

    Test/Access

    Station

    Grade

    Aboveground

    Storage Tank

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    New/Refurbished ASTBottoms with or without

    Secondary Containment

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    Secondary Containment

    Environmental Protection

    Minimize Liability

    State and Local Regulations

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    New Tank Construction with LinerNew Tank Construction with Liner

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    Anode & Reference Cell PlacementAnode & Reference Cell Placement

    in High Resistance Sandin High Resistance Sand

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    Liner

    Floor

    AnodeConduit

    CP Installation on Double Bottom TankCP Installation on Double Bottom Tank

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    CP Installation onCP Installation on RebottomedRebottomed TankTank

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    Installation of CP System onLifted AST

    Installation of CP System onInstallation of CP System onLifted ASTLifted AST

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    Maintenance of CathodicMaintenance of Cathodic

    Protection SystemsProtection Systems

    -- Conduct Annual TestingConduct Annual Testing

    -- Meet NACE Criteria/StandardsMeet NACE Criteria/Standards

    -- Conduct BiConduct Bi--Monthly RectifierMonthly RectifierChecksChecks

    -- NACE Qualified TechniciansNACE Qualified Technicians

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    NACE Cathodic Protection Criteria

    -850mV or more negative with currentapplied

    -850mV Instant off

    -100mV shift between Instant off and

    Native

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    Annual Cathodic Protection Survey

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    Tank

    Rim Potential Measurements

    Portable Reference Cell

    Soil

    (+)

    ????

    --850mV850mV

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    Rim 25' Center 55' Rim

    On -1411 -698 -404 -601 -1455

    Off -902 -664 -402 -578 -911

    Reference Cell

    Bullseye

    MonitoringTube

    Test / Access

    Station

    boveground

    torage Tank

    de

    3

    Typical

    Potentials (mV)

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    Test

    Station

    Structure

    Stray Current Monitoring Test StationStray Current Monitoring Test Station

    Computerized Potential Logging Survey

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    p gg g y

    Reference Cells

    Pipeline

    TestStation

    Backpack ComputerUnit

    Chainer/Wire

    Dispenser & Counter

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    Monitoring

    Record volts and amps s

    Compare values to target setting

    Conduct annual cp survey by NACE engineer

    Maintain cp records

    every 30-60 day

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    BiBi--Monthly Rectifier CheckMonthly Rectifier Check

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    Visual Check of Volts/AmpsVisual Check of Volts/Amps

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    Record KeepingRecord Keeping

    -- Provides HistoryProvides History

    -- Computer Records/Data CollectionComputer Records/Data Collection

    Remote MonitoringRemote Monitoring

    Hand Held ComputersHand Held Computers

    Close Interval SurveysClose Interval SurveysData PrintoutsData Printouts

    Flagging of Problem AreasFlagging of Problem Areas

    Priorit ize Action ItemsPrioritize Action Items--As Built DrawingsAs Built Drawings

    -- Store Data & Records for LifeStore Data & Records for Life

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    Recommended Practices

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    Recommended Practices

    API-651 - Cathodic Protection of Aboveground Petroleum

    Storage Tanks:

    Galvanic anodes method is not practical for

    protection of large bare structures.

    NACE RP0193-01 - External Cathodic Protection of On-Grade

    Metallic Storage Tanks:

    Galvanic protection systems can be applied to tank

    bottoms where the metallic surface area exposed to

    the electrolyte can be minimized through theapplication of a dielectric coating or the area is small

    due to the tank size or configuration.

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    QuestionsQuestions