Corrosion prevention
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Transcript of Corrosion prevention
AL-KHODARI AL-KHODARI INDUSTRIAL TRADING & INDUSTRIAL TRADING &
SERVICESSERVICES
Dealing with corrosionDealing with corrosion
Company headlines
Know-how in processes and installations for powders and liquids, Consulting and implementing installations with optimal R.O.I., Reliable process solutions with minimal complexity, Innovative and active supporting in process issues.
Services
Process engineeringEngineering• Mechanical• Electrical
ProductionProcess controlMechanical installationElectrical installationMaintenance & service
Experience & know-how
Milk of lime• Storage & dosing of (quick) lime• Mixing, storage & dosing of milk of lime
Slurry handling• Coal, sand, sulfur, magnesium oxide, etc.
Paint & compoundingStorage, dosing and handling of hard-to-handle materialsGlue preparation• Preparing, cooking & dosing of PVA or starch
based glueLiquid handling• Dosing skids
Storage & handling corrosive materials
References
Akzo NobelAkzo Salt Chemistry Carmeuse ChemetallDegussaInterbrew Nederland Koninklijke Marine – Royal Dutch NavyNestlé Nederland PPG - SigmaKalon Coatings Rockwool Lapinus B.V. Sabic MelafSHELL Ned. ChemieSmurfit Kappa PackagingFokker Nederland – Parts for JSF and Apache 9 helicopterWaterschap Zuiveringschap Limburg – waste water treatmentWaterschap Zuiveringschap Brabant – waste water treatment
Designing & engineering on material behavior
CorrosionErosionViscosityChemistryHazard
Corrosion
General CorrosionPitting CorrosionCrevice CorrosionStress Corrosion CrackingGalvanic CorrosionMicrobiologically Influenced CorrosionSulphide Stress Corrosion CrackingIntergranular Corrosion
Pitting corrosionDefect in passive layer allows metal to dissolve
Passive oxide layer
Concentrated iron chloride solutionCathodi
c
Anodic
Corrosion products
Electrochemical processElectrochemical process
Pitting corrosion
Inhibitors:Inhibitors:Chloride (catalyst)High temperaturesAcidic conditions, low pH, such as CO2, H2S
Damaged oxide layer (chemically inhibited)
Pitting corrosion
Crevice corrosion
Similar to pitting corrosion
Occurring:Occurring:Under gaskets, Sharp re-entrant corners Incomplete weld penetration Overlapping surfaces
Pipe weldings
Welding pre-
treatment
Sufficient weld
penetration
Sufficient weld
penetration
Insufficient weld
penetration
Sufficient weld
penetration
crevice
crevice
crevice
Crevice corrosion
Pitting & crevice resistance
High grades of chromium, molybdenum and nitrogenPitting Resistance Equivalent number (PRE):
PRE = %Cr + 3.3 x %Mo + 16 x %NPRE = %Cr + 3.3 x %Mo + 16 x %N
Pitting & Crevice resistance
316L
316L
Chloride content water
Chloride content water
Temperature 88-100 °F 31-38 °C
75% recoveryFlow rate
[GPM]Chloride [ppm]
Feed Flow 1667 1400
Brine Flow 417 5595
Permeate Flow 1250 0,5
68% recoveryFlow rate
[GPM]Chloride [ppm]
Feed Flow 1838 1400
Brine Flow 588 4375
Permeate Flow 1250 0,5
Chloride content water
316L
316L
FEED
68% 75%
Stress Corrosion Cracking
InhibitorsInhibitors::Stress and corrosive environmentStainless steelElevated temperature
Only applicable to austenitic Only applicable to austenitic steelsteel
(201, 301, 303, 304, 305, 316, 321, 347, 631)
Stress Corrosion Cracking
Galvanic corrosion
Contact of dissimilar metals in electrically conductive liquid Welds, containing ferrites and due to different structureContact metal with corrosion products
Contact corrosion accelerates pitting & crevice corrosion
Contact corrosionContact corrosion
Galvanic corrosion
Microbiologically Influenced Corrosion (MIC)
Microbiologically Influenced Corrosion (MIC)
InhibitorsInhibitors::Stagnant areas of flowMicro-organismsBio-films of (other) micro-organismsSurface roughnessNutrientsOxygen!
Microbiologically Influenced Corrosion (MIC)
Types of organismsTypes of organisms::Algae (Probable in saltwater with O2)
Fungi (Improbable)Bacteria (Aerobic & Anaerobic)
Microbiologically Influenced Corrosion (MIC)
Tubercles formation facilitating
pitting/crevice corrosion
Corrosion underneath biofilm
Bio-film creating isolated
environment
Microbiologically Influenced Corrosion (MIC)
Prevention / resistancePrevention / resistance::Maintaining cleanlinessMonitoring quality of waterSmooth surfacesAvoiding stagnant areas
Stainless steels with Stainless steels with molybdenum > 6% are molybdenum > 6% are
virtually resistant to MICvirtually resistant to MIC
PRE = %Cr + 3.3 x %Mo + 16 x PRE = %Cr + 3.3 x %Mo + 16 x %N%N
Sequence of corrosion
1. Crevice corrosion at gaskets, crevice / galvanic corrosion at welds.
2. Contact corrosion due to corrosion products.
3. Algae settle on corrosion induced roughness
4. Bacteria settling at algae/roughness5. Formation bio-films and degrading agents6. Acceleration of corrosion processes up to
1000 times of ‘normal’ process
Unusual and excessive degree Unusual and excessive degree of corrosion can occur of corrosion can occur
unpredictably, due to specific unpredictably, due to specific local conditions local conditions
Chloride content water
316L
316L
FEED
68% 75%
Pictures RO skid
Penetrated weld
Crevice corrosion
Contact/galvanic corrosion
Pictures RO skid
Pitting corrosion
Facilitated by stagnant water
Pictures RO skid
Contact corrosion
Corrosion by polluted welding material
Pictures RO skid
Contact corrosion by polluted welds
Pictures RO skid
Contact corrosionConsequential MIT on rough surface
Density MIT related to lines
Corrosion processes related to stagnant water
Conclusions
Basic types corrosion: pitting & crevice corrosionPrimary corrosion propagated by contact corrosion and Microbiological Influenced CorrosionStagnant areas over a longer period of time are facilitating & accelerating corrosion enormouslyStainless steel 316L in RO skid willwill corrodeWorst case circumstances were availableSerious riskSerious risk is unpredictability of corrosion reaction velocity; several cases of sudden unusual degree of corrosion are known
AL-KHODARI AL-KHODARI INDUSTRIAL TRADING & INDUSTRIAL TRADING &
SERVICESSERVICES
Specialized in process installations Specialized in process installations for handling dry and liquid materialsfor handling dry and liquid materials
Proposed actions
Survey of similar installations at Aramco:• Compare differences in materials / set-up• Examine water compositions• Compare biological analyses• Evaluate state of corrosion to age
Conclude either whether risk level incurred in common practice is acceptable or common practice is to be re-defined