Electropolishing & Mechanical Polishing

DEFINITIONSAnode – the positive electrode into which metallic anions flowoff of the work-piece or componentCathode - the negative electrode from which cations flowonto the copper conductorElectrolyte – the ionic solution (usually phosphoric acid blend)that carries the metal ions from the anode towards thecathodeElectropolish – An electrolytic polishing process that removesmetallic ions from the anodic work-piece in a reducingenvironment through an acidic solution2ASTRO PAK Electropolishing & Mechanical Polishing

POLISHED SURFACES ATTRIBUTESMechanical Polishing ScratchesSurface imperfectionsMPElectropolishing CleanabilityFeaturelessEPMicroscopic AppearanceRa readings 15 Ramax3ASTRO PAK Electropolishing & Mechanical Polishing

EP PROCESS TECHNOLOGY Electrical power formsanodic filmFilm thickness regulatesspeed of material removalPeaks are removed fasterthan valley areas – anodiclevelingSurface becomes smoothand featurelessRemoves surface damage4ASTRO PAK Electropolishing & Mechanical Polishing

TOPICS COVEREDSurface Conditioning Services PassivationRouge (Iron Oxide) RemovalCO2 Ice Pellet Impingement CleaningAbrasive BlastingMechanical PolishingThermal Arc Spray Metal Deposition5ASTRO PAK Electropolishing & Mechanical Polishing

PASSIVATIONMechanism of Chloride PittingFe2O3Cr2O3 10Cl- 2H2O 2CrCl3 4HClO2Fe 3ClO- Fe2O3 3Cl-6ASTRO PAK Electropolishing & Mechanical Polishing

MECHANICAL POLISHINGMechanical Polishing (ASME BPE approved for 2014 edition): a process by whichabrasive media is applied to a surface with intent to smoothen until a desiredand/or specified surface roughness (Ra) is achieved.Process Sanding operationAluminum oxide abrasive used to restoreoriginal surface RaRequired Utilities: 110V electric and orcompressed air (100 psi)BEFOREWhere Applicable Where restoration of original metalsurface Ra is requiredAfter Dry Ice Blasting, Bead Blasting or,Thermal Arc SprayingAFTERBenefits Process used to meet specific Ra oraesthetic requirements7ASTRO PAK Electropolishing & Mechanical Polishing

BENEFITS OF EP SURFACES Optimum surface finish Higher corrosion resistance Removal of Bielby damage layer Minimizes surface area Improves cleanability Featureless microscopic surface Lowered rouge formation Improved sterility8ASTRO PAK Electropolishing & Mechanical Polishing

COMPARISON OF MP vs. EP500x2000xELECTROPOLISHEDMECHANICAL POLISHED9ASTRO PAK Electropolishing & Mechanical Polishing

MECHANICAL POLISHINGMP technique performed in-situ in vessel10ASTRO PAK Electropolishing & Mechanical Polishing

MECHANICAL POLISHINGInspection Inspection after derouging willshow areas that need MP toresolve pitting or scratches Rouge removal prior to ElectroCleaning allows closerinspection of surface. White streaks or heavy hazedareas require MP prior toElectro-Cleaning or EP Visible pitting will require MP11ASTRO PAK Electropolishing & Mechanical Polishing

MECHANICAL POLISHINGDebris on Surface Polishing debris consists of stainless steelparticles, abrasives and adhesives Wipe test of surface illustrates its presence Removal of debris from surface – wiping withalkaline cleaner EP removal of surface damage – includes MPdebris, cold worked surface cracking, andmicroscopic scratchesASTRO12PAK Electropolishing & Mechanical Polishing

BUFFING – DETRIMENTAL EFFECTS Entraps stainless particles, polishing debrisand organic compounds Decreases corrosion resistance Not recommended for high purityapplications Smears damage into the surface Looks shiny, but surface damage is hidden13ASTRO PAK Electropolishing & Mechanical Polishing

IN-SITU EP OPERATIONS14ASTRO PAK Electropolishing & Mechanical Polishing

IN-SITU EP OPERATIONSElectropolishing of vessel interior15ASTRO PAK Electropolishing & Mechanical Polishing

REASONS TO EP IN-SITU Reduce downtime and subsequent re-validation because noremoval / replacement is needed Customer can monitor work progress and provide immediateapproval for return to service Repair corrosion damage Remove small scratches and shallow pitting Smooth microscopic surface Improve cleanability Reduce corrosion potential Restore original factory surface condition16ASTRO PAK Electropolishing & Mechanical Polishing

ELECTROLYTIC CLEANINGProcess access is required Tank Entry Safety Program May be completed from outside vesselWhat does it remove? Light levels of rouge or discoloration Smooths surface imperfectionsWhat does it not remove? Electrically insulating residue Heavy rouge deposits (slow) Pits17ASTRO PAK Electropolishing & Mechanical Polishing

BENEFITS OF ELECTROLYTIC CLEANING Removal of light rouge Removal of corrosion effects that generatedthe rouge Microscopic pitting/roughness is smoothed Smoother surface reduces corrosion rate Decreases frequency of derouging18ASTRO PAK Electropolishing & Mechanical Polishing

BEFORE AND AFTER EP REPAIRBEFOREBEFOREAFTERAFTER19ASTRO PAK Electropolishing & Mechanical Polishing

BIOFILM AND ROUGESurface Contamination onProduct-Contact Surface Organic contamination, and insevere cases “biofilm”, occurs whenbacteria form protective clusters onthe metal surface.Biofilm inside waterstorage vessel Surface roughness and porositycaused by corrosion promotes biocolonization. Chemical cleaning and passivationcan correct contaminated surfaces.20ASTRO PAK Electropolishing & Mechanical Polishing

PASSIVATION AFTER ELECTROPOLISHING Chromium to Iron ratiotesting with AES Passivation’s dramaticimprovement Corrosion resistanceincreased21ASTRO PAK Electropolishing & Mechanical Polishing

ASME BPE REQUIREMENTSBPE SF-2 Acceptance Criteria BlisteringBuffingCloudinessHazeEnd Grain EffectFixture marksOrange PeelStringer indicationsWeld whiteningNone AcceptedNone Accepted (following EP)None AcceptedNone AcceptedAcceptable, if Ra max is metAcceptable, if ElectropolishedAcceptable, if Ra max is metAcceptable, if Ra max is metAcceptable, if Ra max is met22ASTRO PAK Electropolishing & Mechanical Polishing

ASTM B-912Passivation Using ElectropolishingASTM B-912 Acceptance CriteriaMetal removalBetween 10 and 50 micronsFixture marksAcceptable, with approvalVisible defects such as pits,roughness, striations, or discolorationNone AcceptedCurrent densityMeasured and followed per procedurePost dip or PassivationNitric acid 10-30% v/v orPassivation testing perASTM A-967 or A-380Citric based UltraPass PassivationMeet requirementsInspection, Testing & Documentation Reference B-912, test method, quantity and locationOperator name and test dateTesting ResultsASTRO23PAK Electropolishing & Mechanical Polishing

BPEElectropolish Procedure QualificationProcedure MethodWritten Quality ControlProgram Pre-polish inspection processPre-cleaning processSpecific gravity range for electrolyte bathConductivity of rinse waterEssential Variables Amperage/timeTemperature rangeEP processFinal rinse and clean processFinal inspectionDocumentation SEM photos of process qualification sampleXPS data of 1.0 or greaterQualification samples for inspectionProcess control recordsEP procedure usedFinal RaCertificate of Compliance Vender companyCustomer nameDescription of componentEP procedure usedFinal surface finish reportASTRO24PAK Electropolishing & Mechanical Polishing

SUMMARY - CONCLUSIONS MP or Buffing can be a source of particles andcorrosion Ra measurement does not reveal microscopicallyfeatureless surface EP Results in:oRemoval of damaged layeroRemoval of embedded polishing debris and abrasivesoFeatureless surface conditionoResistance to corrosion, rouge formation, and bioburdenattachmentoMeets ASME BPE requirements and ASTM B-91225ASTRO PAK Electropolishing & Mechanical Polishing

QUESTIONSASTRO PAK270 E. BAKER ST., STE 100Costa Mesa, CA 92626888. 278. 7672info@astropak.comastropak.com26ASTRO PAK Electropolishing & Mechanical Polishing

o Meets ASME BPE requirements and ASTM B-912 25. ASTRO PAK Electropolishing & Mechanical Polishing QUESTIONS ASTRO PAK 270 E. BAKER ST., STE 100 Costa Mesa, CA 92626 888.278.7672 info@astropak.com astropak.com 26. Title: ASTRO PAK ACADEMY Author: Marina Holmes Created Date: 1/7/2019 11:13:23 AM .