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OZONE AND OXYGEN OZONE AND OXYGEN GAS SYSTEM GAS SYSTEM

CLEANING AND VERIFICATIONCLEANING AND VERIFICATION

PRESENTED BY:

DARYL L. ROLL, P.E.

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OZONE SYSTEM CLEANINGOZONE SYSTEM CLEANING

Cleanliness requirements and protocol

Fabrication and installation strategies

Welding effects

Qualified subcontractor for component and system cleaning

Ozone system preparations

Basic cleaning and passivation chemistries

Testing and verification

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THEORY OF PASSIVATIONTHEORY OF PASSIVATION

Passive Layer

Transition Zone

Base Metal

SURFACE

2 Chrome: 1 Iron

1 Chrome: 4 Iron

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CLEANING AND CLEANING AND PASSIVATION BENEFITSPASSIVATION BENEFITS

Chemical cleaning and flushing removes particulate contamination and organic filmsPassivation increases corrosion protection at weld areas and mechanically damaged surfacesEliminates potential oxidation of contaminants within distribution systemClean systems maintain product purityReduction of particulate generation

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SPECIFICATIONS FOR SPECIFICATIONS FOR CLEANLINESSCLEANLINESS

CGA G – 4.1, 1996CGA G – 4.4, 1993CGA P – 34, 2001ASTM G93 – 96ASTM A380 – 99ASTM A967 – 99ASTM F312 – 97ASTM F331 – 98

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OXYGEN GAS CLEANING OXYGEN GAS CLEANING REQUIREMENTSREQUIREMENTS

The CGA requirements include cleanliness testing of the system after cleaning to meet 47.5 mg/sq.ft. of contamination on the surface

ASTM requirements include alkaline degreasing and passivation of welded and mechanically finished stainless steel

Passivation guidelines are reviewed in ASTM A380 and A967

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CGA G-4.1 REQUIREMENTSCGA G-4.1 REQUIREMENTS

Cleaning Methods Steam Vapor degreasing Solvent washing Alkaline cleaning Acid cleaning Mechanical cleaning Purging

Packaging and Labeling

Inspection

Record Keeping

White light

UV light

Wipe test

Solvent extraction

SafetySafety

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WELD AND FABRICATION WELD AND FABRICATION EFFECTSEFFECTS

Corrosion resistance of surface effected by grinding, welding and mechanical polishing Chrome to iron ratio of surface at weld areas or after grinding will be equal to the base metal (0.25) or lessOxidation of active surfaces will generate iron oxide particlesPassivation will restore surface corrosion resistance and a chrome to iron ratio of 2.0 or greater

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WELD SEAM ANALYSIS:WELD SEAM ANALYSIS:BEFORE PASSIVATIONBEFORE PASSIVATION

0

10

20

30

40

50

60

70

80

9 7 5 3 1 1 3 5 7 9

OXYGENIRONCHROMIUM

Heat Affected Zone

%

Millimeters

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WELD SEAM ANALYSIS:WELD SEAM ANALYSIS:AFTER PASSIVATIONAFTER PASSIVATION

0

10

20

30

40

50

60

70

80

9 7 5 3 1 1 3 5 7

OXYGENIRONCHROMIUM

Heat Affected Zone

%

Millimeters

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FITTINGS & CONNECTIONSFITTINGS & CONNECTIONS

Butt Welds – Smoothest transition

Flanges – Maintenance, accessibility

Socket Welds – Create particle entrapment areas

Preclean of Weld Areas

Post Clean of Weld Areas

Threaded Connections – Particle entrapment

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VALVE CONSIDERATIONSVALVE CONSIDERATIONS

Connection TypesFlangeThreadsSocket weldButt weld

Valve TypesBall - Small diameterButterflyGate or Globe

Removable spools for cleaning & replacementComponents must be oxygen pre-cleaned and replaced during cleaning operations, installed under purge

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PREOPERATIONAL CLEANING PREOPERATIONAL CLEANING REQUIREMENTSREQUIREMENTS

The system must be free of metal grindings, construction debris and organics (oil and grease)The system must contain necessary low point drains and high point ventsThe gas distribution system within the ozone contactor chamber shall be pre-cleaned and installed cleanPneumatic gas test with all components installedQuality welds with no excessive heat effected zonesSpool replacements for all components

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CHEMICAL CLEANING PROCEDURESCHEMICAL CLEANING PROCEDURES

Initial DI flush and leak testAlkaline cleaning with detergents remove surface debris and organic filmsDI water rinse between stagesAcid passivation solution for iron removalFinal DI water rinse and particle count testingDry with clean, dry air or nitrogen and test for dew point. Use solvent (IPA) to test for NVR and total solids. Purge system for installation of components and final pneumatic testing.

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POST CLEANING POST CLEANING REQUIREMENTSREQUIREMENTS

Precleaned and certified components

Removal of spools & replacement of components within clean area & gas purge

Final gas testing of system

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SOLVENT CLEANING & DRYINGSOLVENT CLEANING & DRYING

PART 1: CLEANING Solvent specifications require use of non-

flammable organic solvents 1,1,1 Trichloroethane and Freon are very

expensive regulated solvents ($100 - $300/gal)

N-Propyl Bromide, AK-225, & Vertrel MCA

are replacement solvents “Ozone Depleting” or regulated solvents

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SOLVENT CLEANING & DRYINGSOLVENT CLEANING & DRYING

PART 2: DRYING

Alkaline replacement cleaners require final DI water rinse

Complex piping systems = difficult to dry with traps

Flushing with IPA plus nitrogen gas purge will blend residual water and lower vapor pressure

Allow attainment of -30°F dew point or better

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SUMMARYSUMMARY

Ozone and oxygen enriched generation and

distribution piping systems require a clean and organic free distribution system.

Fabrication operations reduce cleanliness and corrosion resistance which is why cleaning and passivation is required.

Compliance with CGA / ASTM regulations

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SUMMARYSUMMARY (Cont’d)(Cont’d)

Proper testing and certification of cleanliness is required.

Collaboration between engineering design, mechanical installation and precision cleaning contractor is needed.

Systematic preparation, clean fabrication and proper cleaning methods result in improved component performance, ease of system maintenance and overall safety of operations.